@article{9903377, title = {Design of Antennas through Artificial Intelligence: State-of-the-Art and Challenges}, author = {Sotirios K Goudos and Panagiotis D Diamantoulakis and Mohammad A Matin and Panagiotis Sarigiannidis and Shaohua Wan and George K Karagiannidis}, doi = {10.1109/MCOM.006.2200124}, issn = {1558-1896}, year = {2022}, date = {2022-09-26}, journal = {IEEE Communications Magazine}, pages = {1-7}, abstract = {Antenna is a critical part of the RF front end of a communication system. In this study, we present some of the major applications of artificial intelligence (AI) to antenna design. We review the previous research and applications of several AI techniques such as evolutionary algorithms,machine learning, and knowledge representation ontologies. Applications may vary from antenna design to antenna features evaluation in a research field, which is rapidly growing. Finally, we summarize the challenges of new AI techniques in antenna design based on the current state-of-the-art and predict its future research directions.}, keywords = {Antenna arrays, Antennas, Behavioral sciences, Codes, Genetic algorithms, Linear antenna arrays, Optimization}, pubstate = {published}, tppubtype = {article} } @article{articled, title = {Time-slotted LoRa MAC with variable payload support}, author = {Anna Triantafyllou and Dimitrios Zorbas and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/361718810_Time-slotted_LoRa_MAC_with_variable_payload_support}, doi = {10.1016/j.comcom.2022.06.043}, year = {2022}, date = {2022-09-01}, journal = {Computer Communications}, volume = {193}, abstract = {LoRaWAN is an upcoming Low Power Wide Area Network (LPWAN) technology for Internet of Things implementations in various application domains. Despite its various advantages, LoRaWAN employs an Aloha-based MAC, which in terms of performance can not guarantee high packet delivery ratio and low latency. To overcome this issue, we propose a time-slotted scheme, called TS-VP-LoRa, which supports multiple transmission times and packet sizes at the same time. In TS-VP-LoRa, scheduling is coordinated by the LoRa gateway, broadcasting beacon frames periodically for the synchronization of LoRa end-devices. A channel hopping mechanism is also proposed in order to minimize the occurrence of collisions and to evenly split the transmission load among all channels. TS-VP-LoRa is evaluated and compared to three other MAC-layer schemes in single gateway simulation scenarios with up to 500 nodes. The proposed scheme has proven to achieve low latency with high packet delivery ratios, significantly minimize collisions and maintain a relatively low energy consumption despite the scaling of the LoRa network.}, keywords = {LoRaWAN, time-slotted scheme, TS-VP-LoRa}, pubstate = {published}, tppubtype = {article} } @conference{10.1145/3538969.3544479b, title = {Fault-Tolerant SDN Solution for Cybersecurity Applications}, author = {Athanasios Liatifis and Christos Dalamagkas and Panagiotis Radoglou-Grammatikis and Thomas Lagkas and Evangelos Markakis and Valeri Mladenov and Panagiotis Sarigiannidis}, url = {https://doi.org/10.1145/3538969.3544479 }, doi = {10.1145/3538969.3544479}, isbn = {9781450396707}, year = {2022}, date = {2022-08-23}, booktitle = {Proceedings of the 17th International Conference on Availability, Reliability and Security}, publisher = {Association for Computing Machinery}, address = {Vienna, Austria}, series = {ARES '22}, abstract = {The rapid growth of computer networks in various sectors has led to new services previously hard or impossible to implement. Internet of Things has also assisted in this evolution offering easy access to data but at the same time imposing constraints on both security and quality of service. In this paper, an SDN fault tolerant and resilient SDN controller design approach is presented. The proposed solution is suitable for a wide range of environments. Benefits stemming from actual scenarios are presented and discussed among other solutions.}, keywords = {Cybersecurity, Smart Grid, Software Defined Networking}, pubstate = {published}, tppubtype = {conference} } @article{articleb, title = {Advancing SDN: from OpenFlow to P4, a Survey}, author = {Athanasios Liatifis and Panagiotis Sarigiannidis and Vasileios Argyriou and Thomas Lagkas}, url = {https://www.researchgate.net/publication/362963601_Advancing_SDN_from_OpenFlow_to_P4_a_Survey}, doi = {10.1145/3556973}, issn = {0360-0300}, year = {2022}, date = {2022-08-01}, journal = {ACM Computing Surveys}, abstract = {Software Defined Networking (SDN) marked the beginning of a new era in the field of networking by decoupling the control and forwarding processes through the OpenFlow protocol. The Next Generation SDN is defined by Open Interfaces and full programmability of the data plane. P4 is a domain specific language that fulfills these requirements and has known wide adoption over the last years from Academia and Industry. This work is an extensive survey of the P4 language covering domains of application, a detailed overview of the language and future directions.}, keywords = {Next Generation SDN, P4, Programmable Networks, SDN}, pubstate = {published}, tppubtype = {article} } @article{articlec, title = {The road to 6G: a comprehensive survey of deep learning applications in cell-free massive MIMO communications systems}, author = {Lazaros Alexios Iliadis and Zaharias Zaharis and Sotirios Sotiroudis and Panagiotis Sarigiannidis and George Karagiannidis and Sotirios Goudos}, url = {https://www.researchgate.net/publication/362590698_The_road_to_6G_a_comprehensive_survey_of_deep_learning_applications_in_cell-free_massive_MIMO_communications_systems}, doi = {10.1186/s13638-022-02153-z}, year = {2022}, date = {2022-08-01}, journal = {EURASIP Journal on Wireless Communications and Networking}, volume = {2022}, abstract = {The fifth generation (5G) of telecommunications networks is currently commercially deployed. One of their core enabling technologies is cellular Massive Multiple-Input-Multiple-Output (M-MIMO) systems. However, future wireless networks are expected to serve a very large number of devices and the current MIMO networks are not scalable, highlighting the need for novel solutions. At this moment, Cell-free Massive MIMO (CF M-MIMO) technology seems to be the most promising idea in this direction. Despite their appealing characteristics, CF M-MIMO systems face their own challenges, such as power allocation and channel estimation. Deep Learning (DL) has been successfully employed to a wide range of problems in many different research areas, including wireless communications. In this paper, a review of the state-of-the-art DL methods applied to CF M-MIMO communications systems is provided. In addition, the basic characteristics of Cell-free networks are introduced, along with the presentation of the most commonly used DL models. Finally, future research directions are highlighted.}, keywords = {6G, Cell-free massive MIMO, Deep Learning, User-centric cell-free massive MIMO}, pubstate = {published}, tppubtype = {article} } @conference{9850291, title = {Risk Analysis of DNP3 Attacks}, author = {Vasiliki Kelli and Panagiotis Radoglou-Grammatikis and Thomas Lagkas and Evangelos K Markakis and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/362741509_Risk_Analysis_of_DNP3_Attacks}, doi = {10.1109/CSR54599.2022.9850291}, isbn = {978-1-6654-9952-1}, year = {2022}, date = {2022-07-27}, booktitle = {2022 IEEE International Conference on Cyber Security and Resilience (CSR)}, pages = {351-356}, abstract = {The integration of intelligent devices in the industry allows the automation and control of industrial processes, in an efficient and effective manner. Such systems have contributed to the rapid evolution of production infrastructures, increasing the reliability, reducing production costs, and automating the entire manufacturing operations. However, the utilization of intelligent devices has led to an increased attack surface in critical infrastructures, threatening to compromise regular operations. Attacks against such environments can have disastrous consequences in case their goal is achieved, due to the critical nature of such infrastructures. Thus, the timely identification of vulnerable spots through high-quality risk assessment, is considered highly important for avoiding or mitigating potential risks. In this paper, we focus on Distributed Network Protocol 3 (DNP3), a protocol with high utility in smart grids. Specifically, we investigate, identify and describe the vulnerabilities-by-design of DNP3 through 8 DNP3-centered cyberattacks. In addition, we present a novel method for conducting risk assessment, stemming from the combination of two techniques, namely, Attack Defence Trees (ADTs) and Common Vulnerability Scoring System v3.1 (CVSS). Through our proposed technique, the risk of a cyberattack occurring is calculated, thus contributing in securing the critical infrastructure.}, keywords = {cyberattacks, Cybersecurity, DNP3, SCADA}, pubstate = {published}, tppubtype = {conference} } @conference{9850329, title = {Protecting IEC 60870-5-104 ICS/SCADA Systems with Honeypots}, author = {Elisavet Grigoriou and Athanasios Liatifis and Panagiotis Radoglou Grammatikis and Thomas Lagkas and Ioannis Moscholios and Evangelos Markakis and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/362744045_Protecting_IEC_60870-5-104_ICSSCADA_Systems_with_Honeypots}, doi = {10.1109/CSR54599.2022.9850329}, isbn = {978-1-6654-9952-1}, year = {2022}, date = {2022-07-27}, booktitle = {2022 IEEE International Conference on Cyber Security and Resilience (CSR)}, pages = {345-350}, abstract = {Both signature-based and anomaly-based Intrusion Detection and Prevention System (IDPS) have already demonstrated their efficiency towards recognising and mitigating various intrusions. However, the first category cannot detect zero-day attacks, while the second one lacks the presence of appropriate datasets. Therefore, the presence of additional cybersecurity mechanisms is necessary, especially in the area of the Industrial Internet of Things (IIoT), including critical infrastructures, such as the smart electrical grid. Thus, honeypots are used to hide and protect critical assets. IEC 60870-5-104 (IEC104) is a widely used telemetry protocol in Industrial Control Systems (ICS)/Supervisory Control and Data Acquisition (SCADA). However, IEC104 lacks critical security features, such as encryption, integrity protection and authentication. This work presents the IEC104 honeypot, which is capable of hiding the actual IEC104 assets and detecting potential intrusions and anomalies. The experimental results demonstrate the effectiveness of our work.}, keywords = {Cybersecurity, Honeypots, ICS, SCADA}, pubstate = {published}, tppubtype = {conference} } @conference{inproceedingsd, title = {UAV Energy Awareness based on Network Communication Optimization and Power Efficient Trajectories}, author = {Georgios Fevgas and Thomas Lagkas and Vasileios Argyriou and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/364233835_UAV_Energy_Awareness_based_on_Network_Communication_Optimization_and_Power_Efficient_Trajectories}, doi = {10.1109/CSNDSP54353.2022.9907977}, isbn = {978-1-6654-1044-1}, year = {2022}, date = {2022-07-20}, pages = {756-761}, abstract = {The purpose of energy-efficient Coverage Path Planning (CPP) methods is to minimize energy consumption using multiple Unmanned Aerial Vehicles (UAVs) of the coverage area. In multiple UAVs systems, the network configuration plays a crucial role in the network’s survivability and mission execution. However, the network’s survivability and stability depend on the network’s resources optimization. This paper presents a review of single or multiple UAV energy-efficient CPP methods. Furthermore, we discuss the network configurations of multiple UAVs systems. Likewise, we aim to present networks’ energy optimization approaches and directions for future research.}, keywords = {Coverage Path Planning (CPP), Energy-Efficient CPP methods, Multiple UAVs Networks, Networks Energy Optimization, Unmanned Aerial Vehicles (UAVs)}, pubstate = {published}, tppubtype = {conference} } @conference{9907951, title = {Swarm Mobility Models and Impact of Link State Awareness in Ad Hoc Routing}, author = {George Amponis and Thomas Lagkas and Vasileios Argyriou and Ioannis Moscholios and Maria Zevgara and Savvas Ouzounidis and Panagiotis Sarigiannidis}, doi = {10.1109/CSNDSP54353.2022.9907951}, isbn = {978-1-6654-1044-1}, year = {2022}, date = {2022-07-20}, booktitle = {2022 13th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, pages = {762-767}, abstract = {With the development of new communication models and the establishment of next-generation cellular communications, new applications have been enabled and new communication requirements have emerged. Flying ad hoc networks are pivotal in supporting this technological leap, and as such, resorting to application- and mobility-aware routing is a promising enabler of this emerging set of use cases. This paper discusses matters of swarm mobility modelling, types of applicable routing protocols, whilst aiming to correlate channel link state awareness with quality of service in different mobility scenarios. The results of this paper will help formulate new methodologies and best practices for ad hoc routing protocols, considering computational and communication quality demands.}, keywords = {Ad Hoc Communications, Drone swarms, FANETs, Mobility Models}, pubstate = {published}, tppubtype = {conference} } @article{9820768, title = {Joint Wireless Resource and Computation Offloading Optimization for Energy Efficient Internet of Vehicles}, author = {Dimitrios Pliatsios and Panagiotis Sarigiannidis and Thomas D Lagkas and Vasileios Argyriou and Alexandros-Apostolos A Boulogeorgos and Peristera Baziana}, url = {https://www.researchgate.net/publication/361864374_Joint_Wireless_Resource_and_Computation_Offloading_Optimization_for_Energy_Efficient_Internet_of_Vehicles}, doi = {10.1109/TGCN.2022.3189413}, issn = {2473-2400}, year = {2022}, date = {2022-07-08}, journal = {IEEE Transactions on Green Communications and Networking}, volume = {6}, number = {3}, pages = {1468-1480}, abstract = {The Internet of Vehicles (IoV) is an emerging paradigm, which is expected to be an integral component of beyond-fifth-generation and sixth-generation mobile networks. However, the processing requirements and strict delay constraints of IoV applications pose a challenge to vehicle processing units. To this end, multi-access edge computing (MEC) can leverage the availability of computing resources at the edge of the network to meet the intensive computation demands. Nevertheless, the optimal allocation of computing resources is challenging due to the various parameters, such as the number of vehicles, the available resources, and the particular requirements of each task. In this work, we consider a network consisting of multiple vehicles connected to MEC-enabled roadside units (RSUs) and propose an approach that minimizes the total energy consumption of the system by jointly optimizing the task offloading decision, the allocation of power and bandwidth, and the assignment of tasks to MEC-enabled RSUs. Due to the original problem complexity, we decouple it into subproblems and we leverage the block coordinate descent method to iteratively optimize them. Finally, the numerical results demonstrate that the proposed solution can effectively minimize total energy consumption for various numbers of vehicles and MEC nodes while maintaining a low outage probability.}, keywords = {6G, B5G, block coordinate descent, Computation offloading}, pubstate = {published}, tppubtype = {article} } @conference{inproceedingsc, title = {Call Admission Control under a Probabilistic Bandwidth Reservation Policy and Handover Queueing in Mobile Hotspots}, author = {Marinos Vlasakis and Irene Keramidi and Ioannis Moscholios and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/364234461_Call_Admission_Control_under_a_Probabilistic_Bandwidth_Reservation_Policy_and_Handover_Queueing_in_Mobile_Hotspots}, doi = {10.1109/CSNDSP54353.2022.9907974}, isbn = {978-1-6654-1044-1}, year = {2022}, date = {2022-07-01}, pages = {263-268}, abstract = {In this paper we study a mobility-aware call admission control algorithm in a mobile hotspot. More specifically, we consider a vehicle which has an access point of a fixed capacity and may alternate between stop and moving phases. In the stop phase, the vehicle services new and handover calls. To prioritize handover calls a probabilistic bandwidth reservation (BR) policy is considered where a fraction of the capacity is reserved for handover calls. Based on this policy, new calls may enter the reservation space with a predefined probability. In addition, handover calls have the option to wait in a queue of finite size if there are no available resources at the time of their arrival. In the moving phase, the vehicle services only new calls under the classical complete sharing policy. In both phases, calls arrive according to a Poisson process, require a single bandwidth unit for their acceptance in the system and have an exponentially distributed service time. To analytically determine the various performance measures such as call blocking probabilities an efficient iterative algorithm is proposed.}, keywords = {admission, handover, hotspot, loss, mobility, queueing, Reservation}, pubstate = {published}, tppubtype = {conference} } @conference{9844034, title = {Dynamic Risk Assessment and Certification in the Power Grid: A Collaborative Approach}, author = {Athanasios Liatifis and Pedro Ruzafa Alcazar and Panagiotis Radoglou Grammatikis and Dimitris Papamartzivanos and Sofianna Menesidou and Thomas Krousarlis and Molinuevo Martin Alberto and Iñaki Angulo and Antonios Sarigiannidis and Thomas Lagkas and Vasileios Argyriou and Antonio Skarmeta and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/362464616_Dynamic_Risk_Assessment_and_Certification_in_the_Power_Grid_A_Collaborative_Approach}, doi = {10.1109/NetSoft54395.2022.9844034}, isbn = {978-1-6654-0694-9}, year = {2022}, date = {2022-06-27}, booktitle = {2022 IEEE 8th International Conference on Network Softwarization (NetSoft)}, pages = {462-467}, abstract = {The digitisation of the typical electrical grid introduces valuable services, such as pervasive control, remote monitoring and self-healing. However, despite the benefits, cybersecurity and privacy issues can result in devastating effects or even fatal accidents, given the interdependence between the energy sector and other critical infrastructures. Large-scale cyber attacks, such as Indostroyer and DragonFly have already demonstrated the weaknesses of the current electrical grid with disastrous consequences. Based on the aforementioned remarks, both academia and industry have already designed various cybersecurity standards, such as IEC 62351. However, dynamic risk assessment and certification remain crucial aspects, given the sensitive nature of the electrical grid. On the one hand, dynamic risk assessment intends to re-compute the risk value of the affected assets and their relationships in a dynamic manner based on the relevant security events and alarms. On the other hand, based on the certification process, new approach for the dynamic management of the security need to be defined in order to provide adaptive reaction to new threats. This paper presents a combined approach, showing how both aspects can be applied in a collaborative manner in the smart electrical grid.}, keywords = {certification, Cybersecurity, energy, Honeypot, Power Grid, Risk Assessment, Software Defined Networking}, pubstate = {published}, tppubtype = {conference} } @conference{9837524, title = {Rectifier circuit design for 5G energy harvesting applications}, author = {Ioannis D Bougas and Maria S Papadopoulou and Achilles D Boursianis and Panagiotis Sarigiannidis and Spyridon Nikolaidis and Sotirios. K Goudos}, url = {https://www.researchgate.net/publication/362327796_Rectifier_circuit_design_for_5G_energy_harvesting_applications}, doi = {10.1109/MOCAST54814.2022.9837524}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-4}, abstract = {The need for electronic devices usage has risen significantly over the years. This has in turn generated greater demands for electricity and in addition for green energy sources. These include Radio-Frequency (RF) energy harvesting. In this concept we design a rectifier circuit for RF to DC conversion suitable for operation at sub-6 GHz 5G bands. Such a circuit can be used to supply low-power electronic devices. The proposed rectifier works at the frequency band FR1 of 5G cellular network and more specifically at 3.5 GHz. The most important problem in the RF energy harvesters is low system efficiency, something that limits the popularity of the power harvest. The proposed design is found to be highly efficient in its current form. Numerical results show that the system in a single-tone signal provides maximum power conversion efficiency equal to 42.5% when the load of the circuit is 1.1 KΩ and the input power reaches 9 dBm. The presented rectifier circuit performs better or equally with similar designs in the literature.}, keywords = {5G, impedance matching network, power conversion efficiency, radio frequency energy harvesting, rectifier, voltage doubler, voltage multiplier, wireless power transfer}, pubstate = {published}, tppubtype = {conference} } @conference{9837760, title = {Smart Refrigeration Equipment based on IoT Technology for Reducing Power Consumption}, author = {Kyriakos Koritsoglou and Maria S Papadopoulou and Achilles D Boursianis and Panagiotis Sarigiannidis and Spyridon Nikolaidis and Sotirios K Goudos}, url = {https://www.researchgate.net/publication/362329831_Smart_Refrigeration_Equipment_based_on_IoT_Technology_for_Reducing_Power_Consumption}, doi = {10.1109/MOCAST54814.2022.9837760}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-4}, abstract = {In developed countries, companies active in the food retail sector consume about 20% of the total power required for cooling and are therefore ranked among them with the largest energy footprint after the industries. For this reason, refrigeration equipment manufacturers are increasingly focusing on methods that will reduce the power consumption required for its efficient operation. The solutions that are currently implemented mainly focus on interventions in the development phase of freezer units (better insulation, variable frequency compressors, etc.), which, however, do not adequately address the problem. This paper presents the development of an IoT-based technology device which, using machine learning techniques, aims to reduce the power consumption of refrigeration equipment and consecutively, the energy footprint of food retailers.}, keywords = {artificial intelligence (AI) algorithms, embedded system, Internet of Thing (IoT), smart refrigerator, wireless sensor network (WSN)}, pubstate = {published}, tppubtype = {conference} } @conference{inproceedingse, title = {Real Time Sign Language Translation Systems: A review study}, author = {Maria Papatsimouli and Konstantinos Kollias and Lazaros Lazaridis and George S Maraslidis and Heracles Michailidis and Panagiotis Sarigiannidis and George Fragulis}, url = {https://www.researchgate.net/publication/362331604_Real_Time_Sign_Language_Translation_Systems_A_review_study}, doi = {10.1109/MOCAST54814.2022.9837666}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, pages = {1-4}, abstract = {There are people who cannot communicate in the same way with others. Deaf and hard-of-hearing people use sign languages for their communication with other people. Sign languages are also used for the communication between deaf and non-deaf people, including different types of hand gestures and facial expressions for communication and emotional expression. Sign language recognition and gesture-based controls are applications that are used by gesture recognition technologies, and it is a fact that this technology has reduced the communication gap, while these systems are used for converting gestures to text or speech. The focus of our research is to analyze real-time sign language translators that are used for language translation. Sign Language Translation Systems that were developed from 2017 to 2021 are analysed in this paper.}, keywords = {Application Program Interfaces, Handicapped aids, IoT, Sign Language, Sign Language Recognition}, pubstate = {published}, tppubtype = {conference} } @conference{9837645, title = {Comparative Performance of Algorithmic Techniques for Optimizing Dual-Band Rectifier}, author = {Maria S Papadopoulou and Achilles D Boursianis and Argyrios Chatzopoulos and Panagiotis Sarigiannidis and Spyridon Nikolaidis and Sotirios K Goudos}, url = {https://www.researchgate.net/publication/362330125_Comparative_Performance_of_Algorithmic_Techniques_for_Optimizing_Dual-Band_Rectifier}, doi = {10.1109/MOCAST54814.2022.9837645}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-4}, abstract = {Radio Frequency (RF) energy harvesting (EH) is a technique to replenish the source of wireless sensor networks (WSNs). Also, many interdisciplinary fields in the Internet-of-Things (IoT) era use RF-EH, like precision agriculture, biomedical, and robotics. Over the years, various designs have been presented in the literature operating in multi- or wide-band frequencies. Usually, a designed system is optimized using specific goals and optimization parameters to obtain maximization in power conversion efficiency (PCE). In this work, a dual-band RF rectifier system that resonates in the Wi-Fi frequency bands of 2.45 GHz and 5.8 GHz is presented. The proposed system is optimized using four optimization techniques, namely the Gradient algorithm, the Minimax algorithm, the Simulated Annealing, and the Genetic algorithm. A set of comparative results is presented to assess the performance of each technique and to obtain the feasible solution of the proposed design. Numerical results demonstrate that a 42.8% efficiency is achieved, having a 16 dBm input power and a 1.7 kΩ output resistance load.}, keywords = {genetic algorithm, impedance matching, Optimization technique, rectenna, rectifier, RF energy harvesting, wireless sensor network}, pubstate = {published}, tppubtype = {conference} } @conference{9837541, title = {Music Deep Learning: A Survey on Deep Learning Methods for Music Processing}, author = {Lazaros Alexios Iliadis and Sotirios P Sotiroudis and Kostas Kokkinidis and Panagiotis Sarigiannidis and Spiridon Nikolaidis and Sotirios K Goudos}, url = {https://www.researchgate.net/publication/333014972_Deep_Learning_Techniques_for_Music_Generation_-_A_Survey}, doi = {10.1109/MOCAST54814.2022.9837541}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-4}, abstract = {Deep Learning has emerged as a powerful set of computational methods achieving great results in a variety of different tasks. Music signal processing, a field with rich commercial applications, seems to benefit too from this data-driven approach. In this paper a review of the state of the art Deep Learning methods applied on music signal processing is provided. A special focus is given in music information retrieval and music generation. In addition, possible future research directions are discussed.}, keywords = {Deep Learning, Music Generation, Music Information Retrieval, Music Signal Processing}, pubstate = {published}, tppubtype = {conference} } @conference{9837653, title = {Autism detection in High-Functioning Adults with the application of Eye-Tracking technology and Machine Learning}, author = {Konstantinos-Filippos Kollias and Christine K Syriopoulou-Delli and Panagiotis Sarigiannidis and George F Fragulis}, url = {https://www.researchgate.net/publication/362340239_Autism_detection_in_High-Functioning_Adults_with_the_application_of_Eye-Tracking_technology_and_Machine_Learning}, doi = {10.1109/MOCAST54814.2022.9837653}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-4}, abstract = {High-Functioning Autism Detection in Adults is significantly difficult compared with early Autism Spectrum Disorder (ASD) diagnosis with severe symptoms. ASD diagnosis is usually achieved by behavioural instruments relying on subjective rather on objective criteria, whereas advances in research indicate cutting -edge methods for early assessment, such as eye-tracking technology, machine learning, Internet of Things (IoT), and other assessment tools. This study suggests the detection of ASD in high-functioning adults with the contribution of Transfer Learning. Decision Trees, Logistic Regression and Transfer Learning were applied on a dataset consisting of high-functioning ASD adults and controls, who looked for information within web pages. A high classification accuracy was achieved regarding a Browse (80.50%) and a Search (81%) task showing that our method could be considered a promising tool regarding automatic ASD detection. Limitations and suggestions for future research are also included.}, keywords = {eye-tracking, High-Functioning Autism detection, IoT, machine learning, Transfer learning, web}, pubstate = {published}, tppubtype = {conference} } @conference{9837727, title = {A Cloud Computing web-based application for Smart Farming based on microservices architecture}, author = {Vasileios Moysiadis and Konstantinos Tsakos and Panagiotis Sarigiannidis and Euripides G M Petrakis and Achilles D Boursianis and Sotirios K Goudos}, doi = {10.1109/MOCAST54814.2022.9837727}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-08}, booktitle = {2022 11th International Conference on Modern Circuits and Systems Technologies (MOCAST)}, pages = {1-5}, abstract = {The agriculture sector is envisioning a revolution of traditional farming supported by Information and Communications Technologies (ICT) and Cloud Computing is one of them. This tendency is called Smart Farming and promises to boost productivity while reducing production costs and chemical inputs. Cloud Computing aims to provide the necessary resources and the central orchestration of all devices involved in a Smart Farming scenario. To achieve high scalability, usability and performance in Cloud-based applications, we have to move from a monolithic development approach to microservices architecture using cutting edge technologies like containerisation. This paper presents a Smart Farming application based on Cloud Computing that promises to provide useful information to agronomists and farmers to support their decisions based on measurements from ground sensors and images captured from UAVs or ground cameras. Our implementation is based on microservices architecture using Docker Containers as the virtualisation technology. Each microservice runs on a different container and communicates through a RESTful API interface. The proposed architecture is highly scalable in future upgrades and promises high performance and security.}, keywords = {Cloud Computing, Containerisation, Microservices, smart farming}, pubstate = {published}, tppubtype = {conference} } @conference{9858306, title = {Towards 6G: Deep Learning in Cell-Free Massive MIMO}, author = {Lazaros Alexios Iliadis and Zaharias D Zaharis and Sotirios P Sotiroudis and Panagiotis Sarigiannidis and George K Karagiannidis and Sotirios K Goudos}, url = {https://www.researchgate.net/publication/362924666_Towards_6G_Deep_Learning_in_Cell-Free_Massive_MIMO}, doi = {10.1109/BlackSeaCom54372.2022.9858306}, isbn = {978-1-6654-9749-7}, year = {2022}, date = {2022-06-06}, booktitle = {2022 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom)}, pages = {269-273}, abstract = {Massive Multiple-Input-Multiple-Output (MIMO) technology is considered a crucial part of the fifth generation (5G) telecommunications systems. However, moving towards sixth generation (6G) wireless networks, novel solutions have to be incorporated into the current telecommunications' systems. Cell-free Massive MIMO and especially the user-centric approach, seems to be the most promising idea to this direction at this moment. Nevertheless, there are many open issues to be resolved. Deep Learning has been successfully applied to a wide range of problems in many different fields, including wireless communications. In this paper, a review of the state-of-the-art Deep Learning methods applied to Cell-free Massive MIMO communications systems is provided. In addition future research directions are discussed.}, keywords = {6G, Cell-free massive MIMO, Deep Learning, User-centric cell-free massive MIMO}, pubstate = {published}, tppubtype = {conference} } @conference{inproceedingsb, title = {Integration of Information and Communication Technologies in Agriculture for Farm Management and Knowledge Exchange}, author = {Christos Chaschatzis and Anastasios Lytos and Stamatia Bibi and Thomas Lagkas and Christina Petaloti and Sotirios Goudos and Ioannis Moscholios and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/362336475_Integration_of_Information_and_Communication_Technologies_in_Agriculture_for_Farm_Management_and_Knowledge_Exchange}, doi = {10.1109/MOCAST54814.2022.9837534}, isbn = {978-1-6654-6717-9}, year = {2022}, date = {2022-06-01}, pages = {1-4}, abstract = {The demographic growth of the last centuries has been followed by a demand for higher productivity of agriculture activities and an increase in the quality of farming products. Modern consumers seek quality by selecting foods containing high concentrations of healthy nutrients (e.g., antioxidants, vitamins, minerals) while also valuing eco-friendly practices and sustainable consumption. In line with the modern social needs, integrating Information Communication Technologies (ICT) solutions could assist in different levels of the agriculture lifecycle, such as crop monitoring, animal production, food safety, and farm management. Two aspects that are often neglected from many ICT solutions are the compilation of different data sources into the proposed software architecture and the facilitation of knowledge exchange between domain experts. In order to fill the gap of knowledge accumulation in this paper we take into consideration the PestNu architecture, as defined in section V that illustrates the different steps that are required for a complete data analysis life cycle into the development and deployment of the OpenHub platform. The OpenHub aims to cover the knowledge hub between experts with different backgrounds and promote the best practices from different users with hands-on experience.}, keywords = {Education material, Farm-to-Fork, Green Deal, Information systems, Knowledge exchange}, pubstate = {published}, tppubtype = {conference} } @article{articledb, title = {Strategic Honeypot Deployment in Ultra-Dense Beyond 5G Networks: A Reinforcement Learning Approach}, author = {Panagiotis Radoglou Grammatikis and Panagiotis Sarigiannidis and Panagiotis Diamantoulakis and Thomas Lagkas and Theocharis Saoulidis and Eleftherios Fountoukidis and George Karagiannidis}, url = {https://www.researchgate.net/publication/361139812_Strategic_Honeypot_Deployment_in_Ultra-Dense_Beyond_5G_Networks_A_Reinforcement_Learning_Approach}, doi = {10.1109/TETC.2022.3184112}, issn = {2168-6750}, year = {2022}, date = {2022-06-01}, urldate = {2022-01-01}, journal = {IEEE Transactions on Emerging Topics in Computing}, abstract = {The progression of Software Defined Networking (SDN) and the virtualisation technologies lead to the beyond 5G era, providing multiple benefits in the smart economies. However, despite the advantages, security issues still remain. In particular, SDN/NFV and cloud/edge computing are related to various security issues. Moreover, due to the wireless nature of the entities, they are prone to a wide range of cyberthreats. Therefore, the presence of appropriate intrusion detection mechanisms is critical. Although both Machine Learning (ML) and Deep Learning (DL) have optimised the typical rule-based detection systems, the use of ML and DL requires labelled pre-existing datasets. However, this kind of data varies based on the nature of the respective environment. Another smart solution for detecting intrusions is to use honeypots. A honeypot acts as a decoy with the goal to mislead the cyberatatcker and protect the real assets. In this paper, we focus on Wireless Honeypots (WHs) in ultradense networks. In particular, we introduce a strategic honeypot deployment method, using two Reinforcement Learning (RL) techniques: (a) e−Greedy and (b) Q−Learning. Both methods aim to identify the optimal number of honeypots that can be deployed for protecting the actual entities. The experimental results demonstrate the efficacy of both methods.}, keywords = {Honeypot, Intrusion detection, ReinforcementLearning, Wireless communication}, pubstate = {published}, tppubtype = {article} } @conference{9881726, title = {Attacking and Defending DNP3 ICS/SCADA Systems}, author = {Vasiliki Kelli and Panagiotis Radoglou-Grammatikis and Achilleas Sesis and Thomas Lagkas and Eleftherios Fountoukidis and Emmanouil Kafetzakis and Ioannis Giannoulakis and Panagiotis Sarigiannidis}, doi = {10.1109/DCOSS54816.2022.00041}, isbn = {978-1-6654-9512-7}, year = {2022}, date = {2022-05-30}, booktitle = {2022 18th International Conference on Distributed Computing in Sensor Systems (DCOSS)}, pages = {183-190}, abstract = {The highly beneficial contribution of intelligent systems in the industrial domain is undeniable. Automation, supervision, remote control, and fault reduction are some of the various advantages new technologies offer. A protocol demonstrating high utility in industrial settings, and specifically, in smart grids, is Distributed Network Protocol 3 (DNP3), a multi-tier, application layer protocol. Notably, multiple industrial protocols are not as securely designed as expected, considering the highly critical operations occurring in their application domain. In this paper, we explore the internal vulnerabilities-by-design of DNP3, and proceed with the implementation of the attacks discovered, demonstrated through 8 DNP3 attack scenarios. Finally, we design and demonstrate a Deep Neural Network (DNN)-based, multi-model Intrusion Detection Systems (IDS), trained with our experimental network flow cyberattack dataset, and compare our solution with multiple machine learning algorithms used for classification. Our solution demonstrates a high efficiency in the classification of DNP3 cyberattacks, showing an accuracy of 99.0%.}, keywords = {cyberattack, DNP3, ICS, Intrusion detection, SCADA}, pubstate = {published}, tppubtype = {conference} } @article{unknown, title = {Threatening the 5G Core via PFCP DoS Attacks: The Case of Blocking UAV Communications}, author = {Georgios Amponis and Panagiotis Radoglou Grammatikis and Thomas Lagkas and W Mallouli and Ana Cavalli and Dimitris Klonidis and Evangelos Markakis and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/361231451_Threatening_the_5G_Core_via_PFCP_DoS_Attacks_The_Case_of_Blocking_UAV_Communications}, doi = {10.21203/rs.3.rs-1708948/v1}, year = {2022}, date = {2022-05-01}, abstract = {The modern communications landscape requires reliable, high-speed, high- throughput and secure links and sessions between user equipment instances and the data network. The 5G core implements the newly defined 3GPP network ar- chitecture enabling faster connectivity, low latency, higher bit rates and network reliability. The full potential of this set of networks will support a set of critical Internet of Things (IoT) and industrial use cases. Nevertheless, several compo- nents and interfaces of the Next-Generation Radio Access Network (NG-RAN) have proven to be vulnerable to attacks that can potentially obstruct the net- work’s capability to provide reliable end-to-end communication services. Various inherent security flaws and protocol-specific weaknesses have also been identified within the 5G core itself. However, little to no research has gone into testing and exposing said core-related weaknesses, contrary to those concerning the NG-RAN. In this paper, we investigate, describe, develop, implement and finally test a set of attacks on the Packet Forwarding Control Protocol (PFCP) inside the 5G core. We find that, by transmitting unauthorised session control packets, we were able to disrupt established 5G tunnels without disrupting subscribers’ connectivity to the NG-RAN, thus hindering the detection of said attacks. We evaluate the identi- fied PFCP attacks in a drone-based scenario involving 5G tunnelling between two swarms.}, keywords = {5G Security, 5G Testbed, DoS Attacks, PFCP, UAV Communications}, pubstate = {published}, tppubtype = {article} } @article{electronics11060965, title = {Data Protection and Cybersecurity Certification Activities and Schemes in the Energy Sector}, author = { M. Stauch P. Radoglou-Grammatikis P. Sarigiannidis G. Lazaridis A. Drosou I. Nwankwo and D. Tzovaras}, url = {https://www.researchgate.net/publication/359370929_Data_Protection_and_Cybersecurity_Certification_Activities_and_Schemes_in_the_Energy_Sector}, doi = {10.3390/electronics11060965}, issn = {2079-9292}, year = {2022}, date = {2022-02-12}, journal = {Electronics}, volume = {11}, number = {6}, abstract = {Cybersecurity concerns have been at the forefront of regulatory reform in the European Union (EU) recently. One of the outcomes of these reforms is the introduction of certification schemes for information and communication technology (ICT) products, services and processes, as well as for data processing operations concerning personal data. These schemes aim to provide an avenue for consumers to assess the compliance posture of organisations concerning the privacy and security of ICT products, services and processes. They also present manufacturers, providers and data controllers with the opportunity to demonstrate compliance with regulatory requirements through a verifiable third-party assessment. As these certification schemes are being developed, various sectors, including the electrical power and energy sector, will need to access the impact on their operations and plan towards successful implementation. Relying on a doctrinal method, this paper identifies relevant EU legal instruments on data protection and cybersecurity certification and their interpretation in order to examine their potential impact when applying certification schemes within the Electrical Power and Energy System (EPES) domain. The result suggests that the EPES domain employs different technologies and services from diverse areas, which can result in the application of several certification schemes within its environment, including horizontal, technological and sector-specific schemes. This has the potential for creating a complex constellation of implementation models and would require careful design to avoid proliferation and disincentivising of stakeholders.}, keywords = {certification, Cybersecurity, data protection, energy}, pubstate = {published}, tppubtype = {article} } @conference{9682162, title = {Covert Distributed Training of Deep Federated Industrial Honeypots}, author = { Ilias Siniosoglou and Vasileios Argyriou and Thomas Lagkas and Apostolos Tsiakalos and Antonios Sarigiannidis and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/358085083_Covert_Distributed_Training_of_Deep_Federated_Industrial_Honeypots}, doi = {10.1109/GCWkshps52748.2021.9682162}, isbn = {978-1-6654-2391-5}, year = {2022}, date = {2022-01-24}, booktitle = {2021 IEEE Globecom Workshops (GC Wkshps)}, pages = {1-6}, abstract = {Since the introduction of automation technologies in the Industrial field and its subsequent scaling to horizontal and vertical extents, the need for interconnected industrial systems, supporting smart interoperability is ever higher. Due to this scaling, new and critical vulnerabilities have been created, notably in legacy systems, leaving Industrial infrastructures prone to cyber attacks, that can some times have catastrophic results. To tackle the need for extended security measures, this paper presents a Federated Industrial Honeypot that takes advantage of decentralized private Deep Training to produce models that accumulate and simulate real industrial devices. To enhance their camouflage, SCENT, a new custom and covert protocol is proposed, to fully immerse the Federated Honeypot to its industrial role, that handles the communication between the server and honeypot during the training, to hide any clues of operation of the honeypot other that its supposed objective to the eye of the attacker.}, keywords = {Autoencoder, Data Generation, Deep Learning, Honeypots, Industrial Control System, SCADA}, pubstate = {published}, tppubtype = {conference} } @conference{9798011, title = {A Hybrid RF-FSO Offloading Scheme for Autonomous Industrial Internet of Things}, author = { Dimitrios Pliatsios and Thomas Lagkas and Vasileios Argyriou and Antonios Sarigiannidis and Dimitrios Margounakis and Theocharis Saoulidis and Panagiotis Sarigiannidis}, doi = {10.1109/INFOCOMWKSHPS54753.2022.9798011}, isbn = {978-1-6654-0926-1}, year = {2022}, date = {2022-01-01}, booktitle = {IEEE INFOCOM 2022 - IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS)}, pages = {1-6}, abstract = {The ever increasing demand for bandwidth triggered by data-intensive applications is imposing a considerable burden on the radio-frequency (RF) spectrum. A promising solution to address the spectrum congestion problem is the adoption of free-space optical (FSO) communications. In this work, we consider a hybrid RF-FSO system that enables the task offloading process from Industrial Internet-of-Things devices to a multi-access edge computing (MEC)-enabled base station (BS). We propose a solution that minimizes the total energy consumption of the system by deciding whether the RF or FSO link will be used for the task offloading and optimally allocating the device transmission power while taking into account the task requirements in terms of delay. The proposed solution is based on a decomposition-driven algorithm that employs integer linear programming (ILP) and Lagrange dual decomposition. Finally, we carry out system-level Monte Carlo simulations to evaluate the performance of the solution. The simulation results show that the proposed solution can minimize the total energy consumption within a few iterations, while also considering the respective latency requirements.}, keywords = {Computation offloading, energy efficiency, Free-space Optical Communications, Industrial Internet of Things, Multi-access Edge Computing}, pubstate = {published}, tppubtype = {conference} } @article{article, title = {Detection and Characterization of Stressed Sweet Cherry Tissues Using Machine Learning}, author = { C. Chaschatzis and C. Karaiskou and E. Mouratidis and E. Karagiannis and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/357257849_Detection_and_Characterization_of_Stressed_Sweet_Cherry_Tissues_Using_Machine_Learning}, doi = {10.3390/drones6010003}, year = {2021}, date = {2021-12-22}, journal = {Drones}, volume = {6}, pages = {3}, abstract = {Recent technological developments in the primary sector and machine learning algorithms allow the combined application of many promising solutions in precision agriculture. For example, the YOLOv5 (You Only Look Once) and ResNet Deep Learning architecture provide high-precision real-time identifications of objects. The advent of datasets from different perspectives provides multiple benefits, such as spheric view of objects, increased information, and inference results from multiple objects detection per image. However, it also raises crucial obstacles such as total identifications (ground truths) and processing concerns that can lead to devastating consequences, including false-positive detections with other erroneous conclusions or even the inability to extract results. This paper introduces experimental results from the machine learning algorithm (Yolov5) on a novel dataset based on perennial fruit crops, such as sweet cherries, aiming to enhance precision agriculture resiliency. Detection is oriented on two points of interest: (a) Infected leaves and (b) Infected branches. It is noteworthy that infected leaves or branches indicate stress, which may be due to either a stress/disease (e.g., Armillaria for sweet cherries trees, etc.) or other factors (e.g., water shortage, etc). Correspondingly, the foliage of a tree shows symptoms, while this indicates the stages of the disease.}, keywords = {diseases detection, machine learning, precision agriculture, ResNet, smart farming, stress detection, sweet cherries trees, Yolov5}, pubstate = {published}, tppubtype = {article} } @article{Pliatsios2021b, title = {Drone-Base-Station for Next-Generation Internet-of-Things: A Comparison of Swarm Intelligence Approaches}, author = {Dimitrios Pliatsios and Sotirios K. Goudos and Thomas Lagkas and Vasileios Argyriou and Alexandros Apostolos A. Boulogeorgos and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/356863442_Drone-Base-Station_for_Next-Generation_Internet-of-Things_A_Comparison_of_Swarm_Intelligence_Approaches}, doi = {10.1109/OJAP.2021.3133459}, issn = {2637-6431}, year = {2021}, date = {2021-12-07}, journal = {IEEE Open Journal of Antennas and Propagation}, abstract = {The emergence of next-generation internet-of-things (NG-IoT) applications introduces several challenges for the sixth-generation (6G) mobile networks, such as massive connectivity, increased network capacity, and extremely low-latency. To countermeasure the aforementioned challenges, ultra-dense networking has been widely identified as a possible solution. However, the dense deployment of base stations (BSs) is not always possible or cost-efficient. Drone-base-stations (DBSs) can facilitate network expansion and efficiently address the requirements of NG-IoT. In addition, due to their flexibility, they can provide on-demand connectivity in emergency scenarios or address temporary increases in network traffic. Nevertheless, the optimal placement of a DBS is not a straightforward task due to the limited energy reserves and the increased signal quality degradation in air-to-ground links. To this end, swarm intelligence approaches can be attractive solutions for determining the optimal position of the DBS in the three-dimensional (3D) space. In this work, we explore well-known swarm intelligence approaches, namely the Cuckoo Search (CS), Elephant Herd Optimization (EHO), Grey Wolf Optimization (GWO), Monarch Butterfly Optimization (MBO), Salp Swarm Algorithm (SSA), and Particle Swarm Optimization (PSO) and investigate their performance and efficiency in solving the aforementioned problem. In particular, we investigate the performance of three scenarios in the presence of different swarm intelligence approaches. Additionally, we carry out non-parametric statistical tests, namely the Friedman and Wilcoxon tests, in order to compare the different approaches.}, keywords = {Drone base station, evolutionary algorithms, mobile communications, Optimization methods, Swarm intelligence}, pubstate = {published}, tppubtype = {article} } @article{digital1040013, title = {SDN-Based Resilient Smart Grid: The SDN-microSENSE Architecture}, author = { Panagiotis Radoglou Grammatikis and Panagiotis Sarigiannidis and Christos Dalamagkas and Yannis Spyridis and Thomas Lagkas and Georgios Efstathopoulos and Achilleas Sesis and Ignacio Labrador Pavon and Ruben Trapero Burgos and Rodrigo Diaz and Antonios Sarigiannidis and Dimitris Papamartzivanos and Sofia Anna Menesidou and Giannis Ledakis and Achilleas Pasias and Thanasis Kotsiopoulos and Anastasios Drosou and Orestis Mavropoulos and Alba Colet Subirachs and Pol Paradell Sola and José Luis Domínguez-García and Marisa Escalante and Molinuevo Martin Alberto and Benito Caracuel and Francisco Ramos and Vasileios Gkioulos and Sokratis Katsikas and Hans Christian Bolstad and Dan-Eric Archer and Nikola Paunovic and Ramon Gallart and Theodoros Rokkas and Alicia Arce}, url = {https://www.researchgate.net/publication/354992483_SDN-Based_Resilient_Smart_Grid_The_SDN-microSENSE_Architecture}, doi = {10.3390/digital1040013}, issn = {2673-6470}, year = {2021}, date = {2021-09-24}, journal = {Digital}, volume = {1}, number = {4}, pages = {173--187}, abstract = {The technological leap of smart technologies and the Internet of Things has advanced the conventional model of the electrical power and energy systems into a new digital era, widely known as the Smart Grid. The advent of Smart Grids provides multiple benefits, such as self-monitoring, self-healing and pervasive control. However, it also raises crucial cybersecurity and privacy concerns that can lead to devastating consequences, including cascading effects with other critical infrastructures or even fatal accidents. This paper introduces a novel architecture, which will increase the Smart Grid resiliency, taking full advantage of the Software-Defined Networking (SDN) technology. The proposed architecture called SDN-microSENSE architecture consists of three main tiers: (a) Risk assessment, (b) intrusion detection and correlation and (c) self-healing. The first tier is responsible for evaluating dynamically the risk level of each Smart Grid asset. The second tier undertakes to detect and correlate security events and, finally, the last tier mitigates the potential threats, ensuring in parallel the normal operation of the Smart Grid. It is noteworthy that all tiers of the SDN-microSENSE architecture interact with the SDN controller either for detecting or mitigating intrusions.}, keywords = {Anomaly Detection, Blockchain, Cybersecurity, energy management; honeypots, intrusiondetection, islanding, Privacy, Smart Grid, Software Defined Networking}, pubstate = {published}, tppubtype = {article} } @conference{D2021, title = {Semi-Grant-Free Non-Orthogonal Multiple Access for Tactile Internet of Things}, author = {D. Pliatsios and A.A. Boulogeorgos and T. Lagkas and V. Argyriou and I. Moscholios and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/352551145_Semi-Grant-Free_Non-Orthogonal_Multiple_Access_for_Tactile_Internet_of_Things}, doi = {10.1109/PIMRC50174.2021.9569640}, year = {2021}, date = {2021-09-12}, booktitle = {2021 IEEE 32nd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) (IEEE PIMRC 2021)}, abstract = {Ultra-low latency connections for a massive number of devices are one of the main requirements of the nextgeneration tactile Internet-of-Things (TIoT). Grant-free nonorthogonal multiple access (GF-NOMA) is a novel paradigm that leverages the advantages of grant-free access and non-orthogonal transmissions, to deliver ultra-low latency connectivity. In this work, we present a joint channel assignment and power allocation solution for semi-GF-NOMA systems, which provides access to both grant-based (GB) and grant-free (GF) devices, maximizes the network throughput, and is capable of ensuring each device's throughput requirements. In this direction, we provide the mathematical formulation of the aforementioned problem. After explaining that it is not convex, we propose a solution strategy based on the Lagrange multipliers and subgradient method. To evaluate the performance of our solution, we carry out system-level Monte Carlo simulations. The simulation results indicate that the proposed solution can optimize the total system throughput and achieve a high association rate, while taking into account the minimum throughput requirements of both GB and GF devices.}, keywords = {Grant-Free, Internet of things, Non-orthogonal multiple access}, pubstate = {published}, tppubtype = {conference} } @article{Chousainov2021, title = {Multiservice Loss Models for Cloud Radio Access Networks}, author = {I.A. Chousainov and I. Moscholios and P. Sarigiannidis and M. Logothetis}, url = {https://www.researchgate.net/publication/353991171_Multiservice_Loss_Models_for_Cloud_Radio_Access_Networks}, doi = {10.1109/ACCESS.2021.3105946}, year = {2021}, date = {2021-08-18}, journal = {IEEE Access}, abstract = {In this paper, a cloud radio access network (C-RAN) is considered where the remote radio heads (RRHs) are separated from the baseband units which form a common pool of computational resource units. Depending on their capacity, the RRHs may form one or more clusters. Each RRH accommodates multiservice traffic, i.e., calls from different service-classes with different radio and computational resource requirements. Arriving calls follow a Poisson process and simultaneously require radio and computational resource units in order to be accepted in the serving RRH. If their resource requirements cannot be met then calls are blocked and lost. Otherwise, calls remain in the serving RRH for a generally distributed service time. Assuming the single-cluster C-RAN, we model it as a multiservice loss system, prove that a product form solution exists for the steady-state probabilities and determine call blocking probabilities via an efficient convolution algorithm whose accuracy is validated via simulation. Furthermore, we generalize the previous multiservice loss model by considering the more complex multi-cluster case where RRHs of the same capacity are grouped in different clusters.}, keywords = {call blocking, Cloud-radio access, convolution, poisson process}, pubstate = {published}, tppubtype = {article} } @conference{Siniosoglou2021c, title = {Unsupervised Ethical Equity Evaluation of Adversarial Federated Networks}, author = {I. Siniosoglou and V. Argyriou and S. Bibi and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/353936098_Unsupervised_Ethical_Equity_Evaluation_of_Adversarial_Federated_Networks}, doi = {10.1145/3465481.3470478}, year = {2021}, date = {2021-08-17}, booktitle = {The 16th International Conference on Availability, Reliability and Security}, pages = {1-6}, abstract = {While the technology of Deep Learning (DL) is a powerful tool when properly trained for image analysis and classification applications, some factors for its optimization rely solely on the training data and their environment. In an effort to tackle the problem of knowledge bias created during the training process of a Deep Neural Network (DNN) and specifically Adversarial Networks for image augmentation, this work presents an entirely unsupervised methodology for discovering the unfairness level of Deep Learning (DL) models and in extend, its wrongly accumulated or biased classes. Fdi, the proposed evaluation metric for quantizing the level of unfairness of a model is introduced, along with the method of weighting the model’s knowledge and producing its weakest aspects in a data-agnostic way.}, keywords = {adverserial federated networks, machine learning, security}, pubstate = {published}, tppubtype = {conference} } @article{Diamantoulakis2021, title = {Optimal Design and Orchestration of Mobile Edge Computing with Energy Awareness}, author = {P. Diamantoulakis and P. Bouzinis and P. Sarigiannidis and Z. Ding and G. Karagiannidis}, url = {https://www.researchgate.net/publication/352908814_Optimal_Design_and_Orchestration_of_Mobile_Edge_Computing_with_Energy_Awareness}, doi = {10.1109/TSUSC.2021.3103476}, year = {2021}, date = {2021-08-13}, journal = {IEEE Transactions on Sustainable Computing }, volume = {1}, number = {1}, abstract = {In this work, we propose the use of an advanced multiple access technique and its joint design with adaptive task offloading, in order to reduce delay and energy consumption. More specifically, the use of generalized hybrid orthogonal/non-orthogonal multiple access (OMA/NOMA) for MEC is introduced, which is theoretically superior to other alternatives from the existing literature. In more detail, the proposed scheme is based on the joint utilization of dynamic user scheduling among OMA/NOMA phases and variable decoding order during the successive interference cancellation in NOMA phase. Also, the systems orchestration is optimized for both full and partial task offloading. Specifically, in full offloading scenario, the user scheduling, time allocation, and power control are jointly optimized. Regarding partial offloading, the computational resources, i.e., the clock speed of the local processors and the number of offloaded bits, are jointly optimized with the communication resources, taking into account the constraint of the energy that is consumed for both local processing and task offloading, which is particularly challenging due to the non-convex nature of the corresponding optimization problem. All optimization problems are efficiently solved by either using closed-form solutions that provide useful insights or low-complexity algorithms.}, keywords = {energy consumption, mobile edge computing, multiple access, task offloading}, pubstate = {published}, tppubtype = {article} } @article{Moysiadis2021b, title = {Extending ADR mechanism for LoRa enabled mobile end-devices}, author = {V. Moysiadis and T. Lagkas and V. Argyriou and A. Sarigiannidis and I. Moscholios and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/353860976_Extending_ADR_mechanism_for_LoRa_enabled_mobile_end-devices}, doi = {10.1016/j.simpat.2021.102388}, year = {2021}, date = {2021-08-08}, journal = {Simulation Modelling Practice and Theory}, volume = {102388}, abstract = {A considerable percentage of Internet of Things end-devices are characterised by mobility, a feature that adds extra complexity to protocols used in Wireless Sensor Networks. LoRa is one of the newly introduced wireless sensor protocols, capable of delivering messages in long distances and consuming low energy, features that make it proper for low cost devices. Although LoRa was introduced as a technology for stationary devices, it can also be used for mobile devices of low speed. In this paper, we introduce an enhancement to Adaptive Data Rate (ADR) mechanism to enable mobile LoRa, by improving the connection reliability of mobile end-devices, while keeping energy consumption at low levels. Firstly, we propose the Linear Regression - ADR (LR-ADR) mechanism for the Network Server side to smooth the Signal to Noise Ratio (SNR) estimates per gateway and predict the SNR of the next transmission. Secondly, we propose the Linear Regression + ADR (LR+ADR) mechanism, an adaptive method for the end-device side to regain the connectivity faster with the Network Server. We conducted simulation modelling to evaluate the performance of our implementation while we compared our results with four alternative solutions ADR, ADR+, EMA-ADR, G-ADR. The results prove that our first approach (LR-ADR) performs better than the best competitor, and our second approach (LR+ADR) brings an additional improvement in terms of Packet Delivery Ratio (PDR), while they retain the Energy Consumption per Packet Delivered (ECPD) at low levels. In particular, in a scenario that mimics real world conditions, LR+ADR presents an increase of up to 520% for PDR compared to the original ADR and an improvement of up to 38% compared to the best competitor (G-ADR). Moreover, it reduces ECPD up to 74% compared to the original ADR, while keeping it at the same level with the best competitor (G-ADR).}, keywords = {adaptive data rate, energy consumption, LoRa, LoRaWAN, mobile devices}, pubstate = {published}, tppubtype = {article} } @conference{Sachinidis2021, title = {Dual-hop Blockchain Radio Access Networks for Advanced Coverage Expansion}, author = {T. Sachinidis and A. A. Boulogeorgos and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/351437505_Dual-hop_Blockchain_Radio_Access_Networks_for_Advanced_Coverage_Expansion}, doi = {10.1109/MOCAST52088.2021.9493339}, year = {2021}, date = {2021-07-27}, booktitle = {10th International Conference on Modern Circuits and Systems Technologies (MOCAST 2021)}, abstract = {Dynamic dual-hop relaying network topologies that enable access to end-users through intermediate individual and commercial, static as well as moving, infrastructures are expected to become fundamental pillars of the sixth-generation wireless systems. Their main requirement is to ensure end-users information privacy. Motivated by this, the current contribution focuses on introducing a dual-hop blockchain radio access network (DH-BRAN) topology for dynamic coverage expansion. To analyze the performance of this topology, we present the theoretical framework that captures its characteristics. Building upon it, the DH-BRAN performance, in terms of latency and waiting probability, is quantified. Our results reveal that DR-BRAN can be employed in several realistic use-cases and that there exists a trade-off between latency and security.}, keywords = {Blockchain, Coverage, Radio Access Network}, pubstate = {published}, tppubtype = {conference} } @conference{Pliatsios2021, title = {A Dynamic Recommendation-based Trust Scheme for the Smart Grid}, author = {D. Pliatsios and P. Sarigiannidis and G. Fragulis and A. Tsiakalos and D. Margounakis}, url = {https://www.researchgate.net/publication/353484865_A_Dynamic_Recommendation-based_Trust_Scheme_for_the_Smart_Grid}, doi = {10.1109/NetSoft51509.2021.9492542 +Date: 26 July 2021}, year = {2021}, date = {2021-07-26}, booktitle = {3rd International Workshop on Cyber-Security Threats, Trust and Privacy management in Software-defined and Virtualized Infrastructures (SecSoft 2021)}, abstract = {The integration of the internet of things (IoT) concept into the traditional electricity grid introduces several critical vulnerabilities. Intrusion detection systems (IDSs) can be effective countermeasures against cyberattacks, however, they require considerable computational and storage resources. As IoT-enabled metering devices have limited resources, IDSs cannot efficiently ensure security. To this end, trust evaluation schemes have emerged as promising solutions toward protecting resource-constrained metering devices. In this work, we proposed a trust evaluation scheme for the smart grid, that is based on direct trust evaluation and recommendation. The proposed hierarchical scheme is able to evaluate the trustiness of each metering device without requiring any significant modifications to the already deployed infrastructure. Additionally, the proposed scheme features is dynamic, meaning that it is robust against nonadversarial events that negatively impact the device’s trustiness. To validate the performance of the proposed scheme, we carry out network-level simulations and investigate how the various network parameters impact the trust evaluation performance.}, keywords = {cyberattacks, security, Smart Grid, smart meters, trust management}, pubstate = {published}, tppubtype = {conference} } @conference{Lazaridis2021, title = {Hitboxes: A Survey About Collision Detection in Video Games}, author = {L. Lazaridis and M. Papatsimouli and K. Kollias and P. Sarigiannidis and G. Fragulis}, url = {https://www.researchgate.net/publication/352958813_Hitboxes_A_Survey_About_Collision_Detection_in_Video_Games}, doi = {doi.org/10.1007/978-3-030-77277-2_24}, year = {2021}, date = {2021-07-24}, booktitle = {Lecture Notes in Computer Science}, volume = {12789}, publisher = {Springer, Cham. }, abstract = { Over the past decades, video games have become a mainstream form of entertainment and are increasingly used for other purposes such as education or health. This paper surveys recent research and practice in Collision detection in computer gaming that is the detection when two or more objects collide with each other and it plays a crucial role in almost every game as the majority of them are about one thing hitting another. Ground for your feet; a sword and a warrior’s body; a golf ball and a golf club. Hence we have a lot of hitboxes, an invisible geometry around objects that inform them when a collision takes place. There are several methods which solve this kind of problems but what is proven so far from the research is that computers are unexpectedly bad at dealing with collisions. As a result, it is sensible different games take dissimilar approaches on how the way hitboxes work. In this paper we will be focused on Bounding Volumes Hierarchy (BVH) class analyzing three basic methods: OBB, AABB and k-DOP along with some improvements that have been done throughout the years and how these are applied in modern video games.}, keywords = {collision detection, hitboxes, k-DOP}, pubstate = {published}, tppubtype = {conference} } @article{Lagkas2021, title = {Optimized Joint Allocation of Radio, Optical, and MEC Resources for the 5G and Beyond Fronthaul}, author = {T. Lagkas and D. Klonidis and P. Sarigiannidis and I. Tomkos}, url = {https://www.researchgate.net/publication/353062079_Optimized_Joint_Allocation_of_Radio_Optical_and_MEC_Resources_for_the_5G_and_Beyond_Fronthaul}, doi = {10.1109/TNSM.2021.3094789}, year = {2021}, date = {2021-07-06}, journal = {IEEE Transactions on Network and Service Management}, abstract = {In 5G and beyond telecommunication infrastructures a crucial challenge in achieving the strict Key Performance Indicators (KPIs) regarding capacity, latency, and guaranteed quality of service, is the efficient handling of the fronthaul bottleneck. This part of the next generation networks is expected to comprise the New Radio (NR) access and the Next Generation Passive Optical Network (NGPON) domains. Latest developments load the fronthaul with computing tasks as well (e.g., for AI-based processes) in the context of Mobile Edge Computing (MEC). Towards efficient management of all resource types, this paper proposes a joint allocation scheme with three optimization phases for radio, optical, and MEC resources. This scheme, which has been developed in the context of the blueSPACE 5G Infrastructure Public Private Partnership (5G PPP) project, exploits cutting-edge technologies, such as radio beamforming, spatial-spectral granularity in optical networks, and Network Function Virtualization (NFV), to provide dynamic, adaptive, and energy efficient allocation of resources. The devised model is mathematically described and the overall solution is evaluated in a realistic simulation scenario, demonstrating its effectiveness.}, keywords = {5G and beyond, energy efficiency, joint resource allocation, Learning automata, MEC, New Radio, NFV}, pubstate = {published}, tppubtype = {article} } @conference{inproceedings, title = {Synthetic Traffic Signs Dataset for Traffic Sign Detection & Recognition In Distributed Smart Systems}, author = { I. Siniosoglou and P. Sarigiannidis and S. Yannis and A. Khadka and G. Efstathopoulos and T. Lagkas}, url = {https://www.researchgate.net/publication/356351910_Synthetic_Traffic_Signs_Dataset_for_Traffic_Sign_Detection_Recognition_In_Distributed_Smart_Systems}, doi = {10.1109/DCOSS52077.2021.00056}, year = {2021}, date = {2021-07-01}, pages = {302-308}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Siniosoglou2021, title = {Federated Intrusion Detection In NG-IoT Healthcare Systems: An Adversarial Approach}, author = { I. Siniosoglou and P. Sarigiannidis and V. Argyriou and T. Lagkas and S. Goudos and M. Poveda}, url = {https://www.researchgate.net/publication/349158602_Federated_Intrusion_Detection_In_NG-IoT_Healthcare_Systems_An_Adversarial_Approach}, doi = {10.1109/ICC42927.2021.9500578}, year = {2021}, date = {2021-06-14}, booktitle = {2021 IEEE International Conference on Communications (ICC)}, journal = {IEEE International Conference on Communications}, abstract = {In recent years and with the advancement of IoT networks, malicious intrusions aiming at disrupting the services and getting access to confidential information in medical environments is ever progressing. To that end, this paper proposes a Federated Layered Architecture to be used in Medical CyberPhysical Systems (MCPS) Networks that entails the creation of multiple aggregation layers to induce further security to the model training process. Moreover, two Deep Adversarial Neural Networks (GANs) are presented for use with data found in the MCPS environment. The evaluation of the presented work showed that the models trained in the Federated system have an increase in their ability to detect possible intrusions in the MCPS network than the commonly trained models. © 2021 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou_icc2021, title = {A Self-Learning Approach for Detecting Intrusions in Healthcare Systems}, author = { P. Radoglou and P. Sarigiannidis and G. Efstathopoulos and T. Lagkas and G. Fragulis and A. Sarigiannidis}, url = {https://www.researchgate.net/publication/349158703_A_Self-Learning_Approach_for_Detecting_Intrusions_in_Healthcare_Systems}, doi = {10.1109/ICC42927.2021.9500354}, year = {2021}, date = {2021-06-14}, booktitle = {2021 IEEE International Conference on Communications (ICC)}, journal = {IEEE International Conference on Communications}, abstract = {The rapid evolution of the Internet of Medical Things (IoMT) introduces the healthcare ecosystem into a new reality consisting of smart medical devices and applications that provide multiple benefits, such as remote medical assistance, timely administration of medication, real-time monitoring, preventive care and health education. However, despite the valuable advantages, this new reality increases the cybersecurity and privacy concerns since vulnerable IoMT devices can access and handle autonomously patients’ data. Furthermore, the continuous evolution of cyberattacks, malware and zero-day vulnerabilities require the development of the appropriate countermeasures. In the light of the aforementioned remarks, in this paper, we present an Intrusion Detection and Prevention System (IDPS), which can protect the healthcare communications that rely on the Hypertext Transfer Protocol (HTTP) and the Modbus/Transmission Control Protocol (TCP). HTTP is commonly adopted by conventional ICT healthcare-related services, such as web-based Electronic Health Record (EHR) applications, while Modbus/TCP is an industrial protocol adopted by IoMT. Although the Machine Learning (ML) and Deep Learning (DL) methods have already demonstrated their efficacy in detecting intrusions, the rarely available intrusion detection datasets (especially in the healthcare sector) complicate their global application. The main contribution of this work lies in the fact that an active learning approach is modelled and adopted in order to re-train dynamically the supervised classifiers behind the proposed IDPS. The evaluation analysis demonstrates the efficiency of this work against HTTP and Modbus/TCP cyberattacks, showing also how the entire accuracy is increased in the various re-training phases. © 2021 IEEE.}, keywords = {Active Learning, Cybersecurity, Healthcare, Intrusion De-tection}, pubstate = {published}, tppubtype = {conference} } @conference{Kelli2021, title = {A Cyber Resilience Framework for NG-IoT Healthcare Using Machine Learning and Blockchain}, author = { V. Kelli and P. Sarigiannidis and T. Lagkas and V. Vitsas}, url = {https://www.researchgate.net/publication/349158783_A_Cyber_Resilience_Framework_for_NG-IoT_Healthcare_Using_Machine_Learning_and_Blockchain}, doi = {10.1109/ICC42927.2021.9500496}, year = {2021}, date = {2021-06-14}, booktitle = {2021 IEEE International Conference on Communications (ICC)}, journal = {IEEE International Conference on Communications}, abstract = {Internet of Things (IoT) technology such as intelligent devices, sensors, actuators and wearables have been integrated in the healthcare industry, thus contributing in the creation of smart hospitals and remote assistance environments. Ensuring the eHealth network adopts the appropriate security measures in order to effectively protect sensitive patient data against malicious attempts is a tough challenge. Devices composing eHealth infrastructure are considered to be easily exploitable. To that end, a solution monitoring the intelligent healthcare environment is of essence. In addition, by digitalising all health records, appropriate measures need to be implemented in order for patient records to be accessible by authorized personnel only. Furthermore, creating interoperable systems, capable of being integrated by multiple organizations such as hospitals and insurance companies, while maintaining a General Data Protection Regulation-friendly posture, providing access to health data is a great importance for optimal patient assistance. To address both concerns, we present a framework featuring a multi-layer tool for providing a highly effective security solution specifically designed to address the eHealth requirements, and a blockchain access control component, based on smart contracts to provide access control for authorized users to patient records and health data in a distributed way.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sotiroudis2021b, title = {Enhancing Machine Learning Models for Path Loss Prediction Using Image Texture Techniques}, author = {S. Sotiroudis and K. Siakavara and G. Koudouridis and P. Sarigiannidis and S. Goudos}, url = {https://www.researchgate.net/publication/352111245_Enhancing_Machine_Learning_Models_for_Path_Loss_Prediction_Using_Image_Texture_Techniques}, doi = {10.1109/LAWP.2021.3086180}, year = {2021}, date = {2021-06-03}, journal = {IEEE Antennas and Wireless Propagation Letters}, volume = {(Early Access)}, abstract = {The performance of machine learning-based path loss models relies heavily on the data they use at their inputs. Feature engineering is therefore essential for the models success. In the work at hand, we extract a new set of input features, based on image texture. The image that we use represents the footprint of the urban built-up area, where the gray scale values of the building blocks are analogue to their heights. We extract texture information by applying the Segmentation-based Fractal Texture Analysis algorithm on the orthogonal area that is bounded between the transmitter and the receiver. To the best of our knowledge this is the first time that such a technique is applied to a path loss modeling problem in electromagnetics. The algorithm thus delivers a new set of features, based on the images texture, which eventually reveal the built-up profile of the area. These new features are injected to an already existing feature set. Comparative analysis shows that the addition of texture-based features leads to enhanced predictions, for a diverse set of transmitter heights, machine learning algorithms, and performance metrics.}, keywords = {image texture, machine learning, mobile communications, pathloss prediction}, pubstate = {published}, tppubtype = {article} } @article{Siniosoglou2021b, title = {A Unified Deep Learning Anomaly Detection and Classification Approach for Smart Grid Environments}, author = {Ilias Siniosoglou and Panagiotis Radoglou-Grammatikis and Georgios Efstathopoulos and Panagiotis Fouliras and Panagiotis Sarigiannidis}, url = {https://www.researchgate.net/publication/351344684_A_Unified_Deep_Learning_Anomaly_Detection_and_Classification_Approach_for_Smart_Grid_Environments}, doi = {10.1109/TNSM.2021.3078381}, year = {2021}, date = {2021-05-07}, journal = {{IEEE} Transactions on Network and Service Management}, volume = {1}, number = {1}, pages = {1}, abstract = {The interconnected and heterogeneous nature of the next-generation Electrical Grid (EG), widely known as Smart Grid (SG), bring severe cybersecurity and privacy risks that can also raise domino effects against other Critical Infrastructures (CIs). In this paper, we present an Intrusion Detection System (IDS) specially designed for the SG environments that use Modbus/Transmission Control Protocol (TCP) and Distributed Network Protocol 3 (DNP3) protocols. The proposed IDS called MENSA (anoMaly dEtection aNd claSsificAtion) adopts a novel Autoencoder-Generative Adversarial Network (GAN) architecture for (a) detecting operational anomalies and (b) classifying Modbus/TCP and DNP3 cyberattacks. In particular, MENSA combines the aforementioned Deep Neural Networks (DNNs) in a common architecture, taking into account the adversarial loss and the reconstruction difference. The proposed IDS is validated in four real SG evaluation environments, namely (a) SG lab, (b) substation, (c) hydropower plant and (d) power plant, solving successfully an outlier detection (i.e., anomaly detection) problem as well as a challenging multiclass classification problem consisting of 14 classes (13 Modbus/TCP cyberattacks and normal instances). Furthermore, MENSA can discriminate five cyberattacks against DNP3. The evaluation results demonstrate the efficiency of MENSA compared to other Machine Learning (ML) and Deep Learning (DL) methods in terms of Accuracy, False Positive Rate (FPR), True Positive Rate (TPR) and the F1 score.}, keywords = {Anomaly Detection, Auto-encoder, Cybersecurity, Deep Learning, Generative Adversarial Network, machine learning, Modbus, Smart Grid}, pubstate = {published}, tppubtype = {article} } @article{Kotsiopoulos2021, title = {Machine Learning and Deep Learning in smart manufacturing: The Smart Grid paradigm}, author = { T. Kotsiopoulos and P. Sarigiannidis and D. Ioannidis and D. Tzovaras}, url = {https://www.researchgate.net/publication/346545781_Machine_Learning_and_Deep_Learning_in_Smart_Manufacturing_The_Smart_Grid_Paradigm}, doi = {10.1016/j.cosrev.2020.100341}, year = {2021}, date = {2021-05-01}, journal = {Computer Science Review}, volume = {40}, pages = {100341}, publisher = {Elsevier BV}, abstract = {Industry 4.0 is the new industrial revolution. By connecting every machine and activity through network sensors to the Internet, a huge amount of data is generated. Machine Learning (ML) and Deep Learning (DL) are two subsets of Artificial Intelligence (AI), which are used to evaluate the generated data and produce valuable information about the manufacturing enterprise, while introducing in parallel the Industrial AI (IAI). In this paper, the principles of the Industry 4.0 are highlighted, by giving emphasis to the features, requirements, and challenges behind Industry 4.0. In addition, a new architecture for AIA is presented. Furthermore, the most important ML and DL algorithms used in Industry 4.0 are presented and compiled in detail. Each algorithm is discussed and evaluated in terms of its features, its applications, and its efficiency. Then, we focus on one of the most important Industry 4.0 fields, namely the smart grid, where ML and DL models are presented and analyzed in terms of efficiency and effectiveness in smart grid applications. Lastly, trends and challenges in the field of data analysis in the context of the new Industrial era are highlighted and discussed such as scalability, cybersecurity, and big data.}, keywords = {Deep Learning, Industrial AI, Industry 4.0, machine learning, Smart Grid}, pubstate = {published}, tppubtype = {article} } @inbook{iot_reference_architectures, title = {IoT Reference Architectures}, author = {V. Kelli and E.G. Sfakianakis and B. Ghita, P. Sarigiannidis}, editor = {Stavros Shiaeles and Nicholas Kolokotronis}, url = {https://www.routledge.com/Internet-of-Things-Threats-Landscape-and-Countermeasures/Shiaeles-Kolokotronis/p/book/9780367433321}, isbn = {9780367433321}, year = {2021}, date = {2021-04-29}, booktitle = {Internet of Things, Threats, Landscape, and Countermeasures }, publisher = {CRC Press}, chapter = {2}, keywords = {Internet of things, Wireless communication}, pubstate = {published}, tppubtype = {inbook} } @inbook{cybersecbook2021, title = {Network Threats }, author = {P. Radoglou-Grammatikis and P. Sarigiannidis}, editor = {Nicholas Kolokotronis and Stavros Shiaeles}, isbn = {9780367433314}, year = {2021}, date = {2021-04-20}, booktitle = {Cyber-Security Threats, Actors, and Dynamic Mitigation}, publisher = {CRC Press}, chapter = {5}, keywords = {Cybersecurity, network threats}, pubstate = {published}, tppubtype = {inbook} } @article{RadoglouGrammatikis2021, title = {SPEAR SIEM: A Security Information and Event Management system for the Smart Grid}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and E. Iturbe and E. Rios and S. Martinez and A. Sarigiannidis and G. Eftathopoulos and I. Spyridis and A. Sesis and N. Vakakis and D. Tzovaras and E. Kafetzakis and I. Giannoulakis and M. Tzifas and A. Giannakoulias and M. Angelopoulos and F. Ramos}, url = {https://www.researchgate.net/publication/350287201_SPEAR_SIEM_A_Security_Information_and_Event_Management_system_for_the_Smart_Grid}, doi = {10.1016/j.comnet.2021.108008}, year = {2021}, date = {2021-04-01}, journal = {Computer Networks}, pages = {108008}, publisher = {Elsevier BV}, abstract = {The technological leap of smart technologies has brought the conventional electrical grid in a new digital era called Smart Grid (SG), providing multiple benefits, such as two-way communication, pervasive control and self-healing. However, this new reality generates significant cybersecurity risks due to the heterogeneous and insecure nature of SG. In particular, SG relies on legacy communication protocols that have not been implemented having cybersecurity in mind. Moreover, the advent of the Internet of Things (IoT) creates severe cybersecurity challenges. The Security Information and Event Management (SIEM) systems constitute an emerging technology in the cybersecurity area, having the capability to detect, normalise and correlate a vast amount of security events. They can orchestrate the entire security of a smart ecosystem, such as SG. Nevertheless, the current SIEM systems do not take into account the unique SG peculiarities and characteristics like the legacy communication protocols. In this paper, we present the Secure and PrivatE smArt gRid (SPEAR) SIEM, which focuses on SG. The main contribution of our work is the design and implementation of a SIEM system capable of detecting, normalising and correlating cyberattacks and anomalies against a plethora of SG application-layer protocols. It is noteworthy that the detection performance of the SPEAR SIEM is demonstrated with real data originating from four real SG use case (a) hydropower plant, (b) substation, (c) power plant and (d) smart home.}, keywords = {Anomaly Detection, Cybersecurity, Deep Learning, Intrusion detection, machine learning, SCADA, Security Information and Event Management, Smart Grid}, pubstate = {published}, tppubtype = {article} } @article{Triantafyllou2021, title = {Leveraging fairness in LoRaWAN: A novel scheduling scheme for collision avoidance}, author = { A. Triantafyllou, P. Sarigiannidis, T. Lagkas, I. D. Moscholios and A. Sarigiannidis}, url = {https://www.researchgate.net/publication/346627962_Leveraging_Fairness_in_LoRaWAN_A_Novel_Scheduling_Scheme_for_Collision_Avoidance}, doi = {10.1016/j.comnet.2020.107735}, year = {2021}, date = {2021-02-01}, journal = {Computer Networks}, volume = {186}, pages = {107735}, publisher = {Elsevier BV}, abstract = {The employment of Low-Power Wide Area Networks (LPWANs) has proven quite beneficial to the advancement of the Internet of Things (IoT) paradigm. The utilization of low power but long range communication links of the LoRaWAN technology promises low energy consumption, while ensuring sufficient throughput. However, due to LoRa's original scheduling process there is a high chance of packet collisions, compromising the technology's reliability. In this paper, we propose a new Medium Access Control (MAC) protocol, entitled the FCA-LoRa leveraging fairness and improving collision avoidance in LoRa wide-area networks. The novel scheduling process that is introduced is based on the broadcasting of beacon frames by the network's gateway in order to synchronize communication with end devices. Our results demonstrate the benefits of FCA-LoRa over an enhanced version of the legacy LoRaWAN employing the ALOHA protocol and an advanced adaptive rate mechanism, in terms of throughput and collision avoidance. Indicatively, in a single gateway scenario with 600 nodes, FCA-LoRa can increase throughput by nearly 50%while in a multiple gateway scenario, throughput reaches an increase of 49% for 500 nodes. © 2020 Elsevier B.V.}, keywords = {Collision avoidance, Fairness, Internet of things, LoRa, LoRaWAN, Low-Power Wide Area Networks, Medium Access Control, Scalability}, pubstate = {published}, tppubtype = {article} } @article{Moysiadis2021, title = {Smart Farming in Europe}, author = { V. Moysiadis and P. Sarigiannidis and V. Vitsas and A. Khelifi}, url = {https://www.researchgate.net/publication/346716261_Smart_Farming_in_Europe}, doi = {10.1016/j.cosrev.2020.100345}, year = {2021}, date = {2021-02-01}, journal = {Computer Science Review}, volume = {39}, pages = {100345}, publisher = {Elsevier BV}, abstract = {Smart Farming is the new term in the agriculture sector, aiming to transform the traditional techniques to innovative solutions based on Information Communication Technologies (ICT). Concretely, technologies like Unmanned Aerial Vehicles (UAVs), Unmanned Ground Vehicles (UGVs), Image Processing, Machine Learning, Big Data, Cloud Computing, and Wireless Sensor Networks (WSNs), are expected to bring significant changes in this area. Expected benefits are the increase in production, the decrease in cost by reducing the inputs needed such as fuel, fertilizer and pesticides, the reduction in labor efforts, and finally improvement in the quality of the final products. Such innovative methods are crucial in recent days, due to the exponential increase of the global population, the importance of producing healthier products grown with as much fewer pesticides, where public opinion of European citizens is sensitized. Moreover, due to the globalization of the world economy, European countries face the low cost of production of other low-income countries. In this vein, Europe tries to evolve its agriculture domain using technology, aiming at the sustainability of its agricultural sector. Although many surveys exist, most of them tackle in a specific scientific area of Smart Farming. An overview of Smart Farming covering all the involved technologies and providing an extensive reference of good practices around Europe is essential. Our expectation from our work is to become a good reference for researchers and help them with their future work. This paper aims to provide a comprehensive reference for European research efforts in Smart Farming and is two-fold. First, we present the research efforts from researchers in Smart Farming, who apply innovative technology trends in various crops around Europe. Second, we provide and analyze the most significant projects in Europe in the area of Smart Farming. © 2021 Institute of Electrical and Electronics Engineers Inc.. All rights reserved.}, keywords = {Big Data, Cloud Computing, Image Processing, machine learning, smart farming, Unmanned Aerial Vehicles (UAVs), Unmanned Ground Vehicles (UGVs), Wireless Sensor Networks (WSNs)}, pubstate = {published}, tppubtype = {article} } @article{Spyridis2021, title = {Modelling and simulation of a new cooperative algorithm for UAV swarm coordination in mobile RF target tracking}, author = { Y. Spyridis, T. Lagkas, P. Sarigiannidis and J. Zhang}, url = {https://www.researchgate.net/publication/346563683_Modelling_and_simulation_of_a_new_cooperative_algorithm_for_UAV_swarm_coordination_in_mobile_RF_target_tracking}, doi = {10.1016/j.simpat.2020.102232}, year = {2021}, date = {2021-02-01}, journal = {Simulation Modelling Practice and Theory}, volume = {107}, pages = {102232}, publisher = {Elsevier BV}, abstract = {Recent advancements in sensor technology have allowed unmanned aerial vehicles (UAVs) to function as sensing devices in cooperative aerial communication networks, offering novel solutions in applications of environment inspection, disaster detection and search and rescue operations. Towards this trend, the efficient deployment and coordination of UAV networks is of vital importance. Generating controlled experimental conditions to implement and evaluate different approaches in this context can be impractical and costly and thus the solution of modelling is often preferred. This paper introduces a tracking model in which multirotor UAVs, equipped with received signal strength indicator (RSSI) sensors, are organized in a swarm and cooperate to approximate and trail a moving target. The proposed algorithm is able to offer autonomous tracking in large scale environments, by utilising just the strength of the communication signal emitted by a radio frequency transmitter carried by the target. A model of the proposed algorithm is created, and its performance is thoroughly evaluated in a specialized simulator developed in the Processing IDE. Results demonstrate the increased tracking efficiency of the proposed solution compared to a trilateration method. © 2020 Elsevier Ltd}, keywords = {Mobile target tracking, Modelling, RSSI, Simulation, UAV swarm, unmanned aerial vehicles, wireless sensor networks}, pubstate = {published}, tppubtype = {article} } @article{Sun2021, title = {End-to-End Deep Graph Convolutional Neural Network Approach for Intentional Islanding in Power Systems Considering Load-Generation Balance}, author = { Z. Sun, Y. Spyridis, T. Lagkas, A. Sesis, G. Efstathopoulos and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/349726654_End-to-End_Deep_Graph_Convolutional_Neural_Network_Approach_for_Intentional_Islanding_in_Power_Systems_Considering_Load-Generation_Balance}, doi = {10.3390/s21051650}, year = {2021}, date = {2021-02-01}, journal = {Sensors}, volume = {21}, number = {5}, pages = {1650}, publisher = {MDPI AG}, abstract = {Intentional islanding is a corrective procedure that aims to protect the stability of the power system during an emergency, by dividing the grid into several partitions and isolating the elements that would cause cascading failures. This paper proposes a deep learning method to solve the problem of intentional islanding in an end-to-end manner. Two types of loss functions are examined for the graph partitioning task, and a loss function is added on the deep learning model, aiming to minimise the load-generation imbalance in the formed islands. In addition, the proposed solution incorporates a technique for merging the independent buses to their nearest neighbour in case there are isolated buses after the clusterisation, improving the final result in cases of large and complex systems. Several experiments demonstrate that the introduced deep learning method provides effective clustering results for intentional islanding, managing to keep the power imbalance low and creating stable islands. Finally, the proposed method is dynamic, relying on real-time system conditions to calculate the result.}, keywords = {Deep Learning, Graph convolutional networks, graph partition, Intentional islanding, Load-generation balance, Power system, Spectral clustering}, pubstate = {published}, tppubtype = {article} } @article{Kakamoukas2021, title = {Towards Climate Smart Farming - A Reference Architecture for Integrated Farming Systems}, author = { G. Kakamoukas and P. Sarigiannidis and A. Maropoulos and T. Lagkas and K. Zaralis and C. Karaiskou}, url = {https://www.researchgate.net/publication/349141429_Towards_Climate_Smart_Farming-A_Reference_Architecture_for_Integrated_Farming_Systems}, doi = {10.3390/telecom2010005}, year = {2021}, date = {2021-02-01}, journal = {Telecom}, volume = {2}, number = {1}, pages = {52--74}, publisher = {MDPI AG}, abstract = {Climate change is emerging as a major threat to farming, food security and the livelihoods of millions of people across the world. Agriculture is strongly affected by climate change due to increasing temperatures, water shortage, heavy rainfall and variations in the frequency and intensity of excessive climatic events such as floods and droughts. Farmers need to adapt to climate change by developing advanced and sophisticated farming systems instead of simply farming at lower intensity and occupying more land. Integrated agricultural systems constitute a promising solution, as they can lower reliance on external inputs, enhance nutrient cycling and increase natural resource use efficiency. In this context, the concept of Climate-Smart Agriculture (CSA) emerged as a promising solution to secure the resources for the growing world population under climate change conditions. This work proposes a CSA architecture for fostering and supporting integrated agricultural systems, such as Mixed Farming Systems (MFS), by facilitating the design, the deployment and the management of crop–livestock-= forestry combinations towards sustainable, efficient and climate resilient agricultural systems. Propelled by cutting-edge technology solutions in data collection and processing, along with fully autonomous monitoring systems, eg, smart sensors and unmanned aerial vehicles (UAVs), the proposed architecture called MiFarm-CSA, aims to foster core interactions among animals, forests and crops, while mitigating the high complexity of these interactions, through a novel conceptual framework}, keywords = {climate smart agriculture, Internet of things, mixed farming systems, participatory learning, socio-economic modelling, unmanned aerial vehicles}, pubstate = {published}, tppubtype = {article} } @article{Sotiroudis202130441, title = {Fusing Diverse Input Modalities for Path Loss Prediction: A Deep Learning Approach}, author = { Sotirios P. Sotiroudis and Panagiotis Sarigiannidis and Sotirios K. Goudos and Katherine Siakavara}, url = {https://www.researchgate.net/publication/349369501_Fusing_Diverse_Input_Modalities_for_Path_Loss_Prediction_A_Deep_Learning_Approach}, doi = {10.1109/ACCESS.2021.3059589}, year = {2021}, date = {2021-01-01}, journal = {IEEE Access}, volume = {9}, pages = {30441--30451}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, abstract = {Tabular data and images have been used from machine learning models as two diverse types of inputs, in order to perform path loss predictions in urban areas. Different types of models are applied on these distinct modes of input information. The work at hand tries to incorporate both modes of input data within a single prediction model. It therefore manipulates and transforms the vectors of tabular data into images. Each feature of the tabular data vector is spread into several pixels, corresponding to the calculated importance of the particular feature. The resulting synthetic images are then fused with images representing selected regions of the area's map. Compound pseudoimages, having channels of both map-based and tabular data-based images, are then being used as inputs for a Convolutional Neural Network (CNN), which predicts the path loss value at a specific point of the area of interest. The results are clearly better than those obtained from models based on a single mode of input data, as well as from the results produced by other bimodal-input approaches. This approach could be applied for path loss prediction in urban environments for several state-of-art wireless networks like 5G and Internet of Things (IoT). © 2013 IEEE.}, keywords = {Convolutional Neural Networks, Data to Image Transformation, Deep Learning, Path loss, Pseudoimages, Radio Propagation}, pubstate = {published}, tppubtype = {article} } @article{Boursianis2021, title = {Multiband Patch Antenna Design Using Nature-Inspired Optimization Method}, author = { A. D. Boursianis and M. S. Papadopoulou and J. Pierezan and V. C. Mariani and L. S. Coelho and P. Sarigiannidis and S. Koulouridis and S. K. Goudos}, url = {https://www.researchgate.net/publication/348145703_Multiband_Patch_Antenna_Design_Using_Nature-Inspired_Optimization_Method}, doi = {10.1109/ojap.2020.3048495}, year = {2021}, date = {2021-01-01}, journal = {IEEE Open Journal of Antennas and Propagation}, volume = {2}, pages = {151--162}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, abstract = {Radio frequency energy harvesting has attracted considerable interest as a technique of enabling self-powered wireless networks. This technique faces several challenges, such as the receiving and the rectifying modules of a rectenna system. Multiband antennas provide several comparative advantages against the goal of maximizing the amount of energy harvesting. In this work, we present a multiband microstrip patch antenna with three slits operating in the LoRaWAN (Long Range Wide Area Network) and the cellular (GSM-1800 and UMTS) communication frequency bands. A feasible solution of the antenna is obtained by the application of a recently introduced nature-inspired optimization technique, namely the Coyote Optimization Algorithm. The proposed antenna operates satisfactorily in the LoRaWAN (Long Range Wide Area Network) and the cellular (GSM-1800 and UMTS) communication frequency bands. Measured results of the proposed antenna exhibit an acceptable performance (multiband frequency operation, maximum gain of 3.94 dBi, broadside operation) and demonstrate features of operation, which make it a strong candidate for various RF energy harvesting applications. © 2021 IEEE.}, keywords = {microstrip line, multiband antenna, optimization method, patch antenna, radio frequency energy harvesting}, pubstate = {published}, tppubtype = {article} } @article{Kelli2021b, title = {Ids for industrial applications: A federated learning approach with active personalization}, author = { V. Kelli and V. Argyriou and T. Lagkas and G. Fragulis and E. Grigoriou and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/355191910_IDS_for_Industrial_Applications_A_Federated_Learning_Approach_with_Active_Personalization}, doi = {10.3390/s21206743}, year = {2021}, date = {2021-01-01}, journal = {Sensors}, volume = {21}, number = {20}, abstract = {Internet of Things (IoT) is a concept adopted in nearly every aspect of human life, leading to an explosive utilization of intelligent devices. Notably, such solutions are especially integrated in the industrial sector, to allow the remote monitoring and control of critical infrastructure. Such global integration of IoT solutions has led to an expanded attack surface against IoT-enabled infrastructures. Artificial intelligence and machine learning have demonstrated their ability to resolve issues that would have been impossible or difficult to address otherwise; thus, such solutions are closely associated with securing IoT. Classical collaborative and distributed machine learning approaches are known to compromise sensitive information. In our paper, we demonstrate the creation of a network flow-based Intrusion Detection System (IDS) aiming to protecting critical infrastructures, stemming from the pairing of two machine learning techniques, namely, federated learning and active learning. The former is utilized for privately training models in federation, while the latter is a semi-supervised approach applied for global model adaptation to each of the participant’s traffic. Experimental results indicate that global models perform significantly better for each participant, when locally personalized with just a few active learning queries. Specifically, we demonstrate how the accuracy increase can reach 7.07% in only 10 queries. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.}, note = {cited By 0}, keywords = {Active learning, Critical infrastructure, Federated learning, IDS, IoT, machine learning, Personalization}, pubstate = {published}, tppubtype = {article} } @article{Boursianis2021b, title = {Novel design framework for dual-band frequency selective surfaces using multi-variant differential evolution}, author = { A.D. Boursianis and M.S. Papadopoulou and S. Nikolaidis and P. Sarigiannidis and K. Psannis and A. Georgiadis and M.M. Tentzeris and S.K. Goudos}, url = {https://www.researchgate.net/publication/354873810_Novel_Design_Framework_for_Dual-Band_Frequency_Selective_Surfaces_Using_Multi-Variant_Differential_Evolution}, doi = {10.3390/math9192381}, year = {2021}, date = {2021-01-01}, journal = {Mathematics}, volume = {9}, number = {19}, abstract = {Frequency Selective Surfaces (FSSs) have become increasingly popular during the last years due to their combined characteristics, which meet, in general, the requirements of the next-generation wireless communication networks. In this work, a cross-platform design framework for FSS structures is presented and evaluated by utilizing a recently introduced evolutionary optimization algorithm, namely, the Multi-Variant Differential Evolution (MVDE). To the best of the authors knowledge, this is the first time that the MVDE algorithm is applied to a design problem in Electromagnetics. The proposed design framework is described in detail and the utilized evolutionary algorithm is assessed in terms of its performance by applying several benchmark functions. In this context, the MVDE is comparatively evaluated against other popular evolutionary algorithms. Moreover, it is applied to the design and optimization of two different representative examples of FSS structures based on three use cases of unit cell geometry. Optimization results indicate the efficacy of the proposed framework by quantifying the performance of the designed FSS structures in terms of several system metrics. The optimized FSS structures exhibit dual-band operation and quite acceptable results in the ISM frequency bands of 2.45 GHz and 5.8 GHz. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Design framework, Evolutionary algorithm, Frequency selective surface, Meta-heuristics, Multi-variant differential evolution, Optimization process, radio frequency energy harvesting}, pubstate = {published}, tppubtype = {article} } @article{Chousainov2021b, title = {Multiservice loss models in single or multi-cluster c-ran supporting quasi-random traffic}, author = { I.-A. Chousainov and I. Moscholios and P. Sarigiannidis and M. Logothetis}, url = {https://www.researchgate.net/publication/354616239_Multiservice_Loss_Models_in_Single_or_Multi-Cluster_C-RAN_Supporting_Quasi-Random_Traffic}, doi = {10.3390/app11188559}, year = {2021}, date = {2021-01-01}, journal = {Applied Sciences (Switzerland)}, volume = {11}, number = {18}, abstract = {In this paper, a cloud radio access network (C-RAN) is considered where the baseband units form a pool of computational resource units and are separated from the remote radio heads (RRHs). Based on their radio capacity, the RRHs may form one or many clusters: a single cluster when all RRHs have the same capacity and multi-clusters where RRHs of the same radio capacity are grouped in the same cluster. Each RRH services the so-called multiservice traffic, i.e., calls from many service classes with various radio and computational resource requirements. Calls arrive in the RRHs according to a quasi-random process. This means that new calls are generated by a finite number of mobile users. Arriving calls require simultaneously computational and radio resource units in order to be accepted in the system, i.e., in the serving RRH. If their requirements are met, then these calls are served in the (serving) RRH for a service time which is generally distributed. Otherwise, call blocking occurs. We start with the single-cluster C-RAN and model it as a multiservice loss system, prove that the model has a product form solution, and determine time congestion probabilities via a convolution algorithm whose accuracy is validated with the aid of simulation. Furthermore, the previous model is generalized to include the more complex case of more than one clusters. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.}, note = {cited By 0}, keywords = {Cloud-radio access, Cluster, convolution, Product form, Quasi-random, Time congestion}, pubstate = {published}, tppubtype = {article} } @article{Boursianis2021c, title = {Emerging swarm intelligence algorithms and their applications in antenna design: The gwo, woa, and ssa optimizers}, author = { A.D. Boursianis and M.S. Papadopoulou and M. Salucci and A. Polo and P. Sarigiannidis and K. Psannis and S. Mirjalili and S. Koulouridis and S.K. Goudos}, url = {https://www.researchgate.net/publication/354446201_Emerging_Swarm_Intelligence_Algorithms_and_Their_Applications_in_Antenna_Design_The_GWO_WOA_and_SSA_Optimizers}, doi = {10.3390/app11188330}, year = {2021}, date = {2021-01-01}, journal = {Applied Sciences (Switzerland)}, volume = {11}, number = {18}, abstract = {Swarm Intelligence (SI) Algorithms imitate the collective behavior of various swarms or groups in nature. In this work, three representative examples of SI algorithms have been selected and thoroughly described, namely the Grey Wolf Optimizer (GWO), the Whale Optimization Algorithm (WOA), and the Salp Swarm Algorithm (SSA). Firstly, the selected SI algorithms are reviewed in the literature, specifically for optimization problems in antenna design. Secondly, a comparative study is performed against widely known test functions. Thirdly, such SI algorithms are applied to the synthesis of linear antenna arrays for optimizing the peak sidelobe level (pSLL). Numerical tests show that the WOA outperforms the GWO and the SSA algorithms, as well as the well-known Particle Swarm Optimizer (PSO), in terms of average ranking. Finally, the WOA is exploited for solving a more computational complex problem concerned with the synthesis of an dual-band aperture-coupled E-shaped antenna operating in the 5G frequency bands. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Antenna design, Aperture-coupled antenna, Grey wolf optimizer, Meta-heuristics, Nature-inspired algorithms, Optimization technique, Salp swarm algorithm, Swarm intelligence, Whale optimization algorithm}, pubstate = {published}, tppubtype = {article} } @conference{Radoglou-Grammatikis2021485, title = {TRUSTY: A solution for threat hunting using data analysis in critical infrastructures}, author = { P. Radoglou-Grammatikis and A. Liatifis and E. Grigoriou and T. Saoulidis and A. Sarigiannidis and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/354396254_TRUSTY_A_Solution_for_Threat_Hunting_Using_Data_Analysis_in_Critical_Infrastructures}, doi = {10.1109/CSR51186.2021.9527936}, year = {2021}, date = {2021-01-01}, journal = {Proceedings of the 2021 IEEE International Conference on Cyber Security and Resilience, CSR 2021}, pages = {485-490}, abstract = {The rise of the Industrial Internet of Things (IIoT) plays a crucial role in the era of hyper-connected digital economies. Despite the valuable benefits, such as increased resiliency, self-monitoring and pervasive control, IIoT raises severe cybersecurity and privacy risks, allowing cyberattackers to exploit a plethora of vulnerabilities and weaknesses that can lead to disastrous consequences. Although the Intrusion Detection and Prevention Systems (IDPS) constitute valuable solutions, they suffer from several gaps, such as zero-day attacks, unknown anomalies and false positives. Therefore, the presence of supporting mechanisms is necessary. To this end, honeypots can protect the real assets and trap the cyberattackers. In this paper, we provide a web-based platform called TRUSTY , which is capable of aggregating, storing and analysing the detection results of multiple industrial honeypots related to Modbus/Transmission Control Protocol (TCP), IEC 60870-5-104, BACnet, Message Queuing Telemetry Transport (MQTT) and EtherNet/IP. Based on this analysis, we provide a dataset related to honeypot security events. Moreover, this paper provides a Reinforcement Learning (RL) method, which decides about the number of honeypots that can be deployed in an industrial environment in a strategic way. In particular, this decision is converted into a Multi-Armed Bandit (MAB), which is solved with the Thompson Sampling (TS) method. The evaluation analysis demonstrates the efficiency of the proposed method. © 2021 IEEE.}, keywords = {Cybersecurity, Dataset, Honeypot, Industrial Internet of Things, Multi-Armed Bandit, Reinforcement Learning, Thompson Sampling}, pubstate = {published}, tppubtype = {conference} } @conference{Pasias2021497, title = {Enabling cyber-attack mitigation techniques in a software defined network}, author = { A. Pasias and T. Kotsiopoulos and G. Lazaridis and A. Drosou and D. Tzovaras and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/354417325_Enabling_Cyber-attack_Mitigation_Techniques_in_a_Software_Defined_Network}, doi = {10.1109/CSR51186.2021.9527932}, isbn = {978-1-6654-0285-9}, year = {2021}, date = {2021-01-01}, journal = {Proceedings of the 2021 IEEE International Conference on Cyber Security and Resilience, CSR 2021}, pages = {497-502}, abstract = {Software Defined Networking (SDN) is an innovative technology, which can be applied in a plethora of applications and areas. Recently, SDN has been identified as one of the most promising solutions for industrial applications as well. The key features of SDN include the decoupling of the control plane from the data plane and the programmability of the network through application development. Researchers are looking at these features in order to enhance the Quality of Service (QoS) provisioning of modern network applications. To this end, the following work presents the development of an SDN application, capable of mitigating attacks and maximizing the network's QoS, by implementing mixed integer linear programming but also using genetic algorithms. Furthermore, a low-cost, physical SDN testbed was developed in order to evaluate the aforementioned application in a more realistic environment other than only using simulation tools. © 2021 IEEE.}, keywords = {Application programs, Genetic algorithms, Integer programming, Quality of Service, Security of data, Software Defined Networking}, pubstate = {published}, tppubtype = {conference} } @conference{Griva2021, title = {Performance Evaluation of LoRa Networks in an Open Field Cultivation Scenario}, author = { A. Griva and A.D. Boursianis and S. Wan and P. Sarigiannidis and G. Karagiannidis and S.K. Goudos}, url = {https://www.researchgate.net/publication/353498225_Performance_Evaluation_of_LoRa_Networks_in_an_Open_Field_Cultivation_Scenario}, doi = {10.1109/MOCAST52088.2021.9493416}, year = {2021}, date = {2021-01-01}, journal = {2021 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021}, abstract = {The employment of Internet of Things (IoT) technology in agriculture could be beneficial in managing the cultivation production in a highly-customizable way. LoRa (Long Range) is one of the most important technologies in cultivation fields mainly thanks to its ability to provide long-range transmission and low power consumption. In this paper, we evaluate the performance of LoRa networks in an open field cultivation scenario via simulations using FLoRa, an open-source framework in OMNeT++. The number of nodes, the number of gateways, the antenna gain, and the size of the deployment area have a considerable impact on both the data extraction rate and the energy consumption of a LoRa network. Our results show that the optimization of the parameters that affect the performance of a LoRa network could transform traditional agriculture into a new perspective of smart cultivation. Finally, we evaluate the impact of the density and the geometric characteristics of three types of crop (tomatoes, grapes, apples) on the number of intersections that were caused by the insertion of physical objects-obstacles in a LoRa network. © 2021 IEEE.}, keywords = {Data Extraction Rate, Internet of Things (IoT), Long Range (LoRa), Network Energy Consumption, Smart Agriculture}, pubstate = {published}, tppubtype = {conference} } @conference{Rekkas2021, title = {Unsupervised Machine Learning in 6G Networks -State-of-the-art and Future Trends}, author = { V.P. Rekkas and S. Sotiroudis and P. Sarigiannidis and G.K. Karagiannidis and S.K. Goudos}, doi = {10.1109/MOCAST52088.2021.9493388}, year = {2021}, date = {2021-01-01}, journal = {2021 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021}, abstract = {Wireless communication systems play a very crucial role for business, commercial, health and safety applications. With the commercial deployment of fifth generation (5G), academic and industrial research focuses on the sixth generation (6G) of wireless communication systems. Artificial Intelligence (AI) and especially Machine Learning (ML), will be a key component of 6G systems. Here, we present an up-to-date review of future 6G wireless systems and the role of unsupervised ML techniques in them. © 2021 IEEE.}, note = {cited By 0}, keywords = {6G, Artificial Intelligence, Sixth Generation, Unsupervised Machine Learning, Wireless Communications}, pubstate = {published}, tppubtype = {conference} } @conference{Kollias2021, title = {The contribution of Machine Learning and Eye-tracking technology in Autism Spectrum Disorder research: A Review Study}, author = { K.-F. Kollias and C.K. Syriopoulou-Delli and P. Sarigiannidis and G.F. Fragulis}, url = {https://www.researchgate.net/publication/352737405_The_contribution_of_Machine_Learning_and_Eye-tracking_technology_in_Autism_Spectrum_Disorder_research_A_Review_Study}, doi = {10.1109/MOCAST52088.2021.9493357}, year = {2021}, date = {2021-01-01}, journal = {2021 10th International Conference on Modern Circuits and Systems Technologies, MOCAST 2021}, abstract = {According to Diagnostic and Statistical Manual of Mental Disorders, Autism spectrum disorder (ASD) is a developmental disorder characterised by reduced social interaction and communication, and by restricted, repetitive, and stereotyped behaviour. An important characteristic of autism, referred in several diagnostic tests, is a deficit in eye gaze. The objective of this study is to review the literature concerning machine learning and eye-tracking in ASD studies conducted since 2015. Our search on PubMed identified 18 studies which used various eye-tracking instruments, applied machine learning in different ways, distributed several tasks and had a wide range of sample sizes, age groups and functional skills of participants. There were also studies that utilised other instruments, such as Electroencephalography (EEG) and movement measures. Taken together, the results of these studies show that the combination of machine learning, and eye-tracking technology can contribute to autism identification characteristics by detecting the visual atypicalities of ASD people. In conclusion, machine learning and eye-tracking ASD studies could be considered a promising tool in autism research and future studies could involve other technological approaches, such as Internet of Things (IoT), as well. © 2021 IEEE.}, keywords = {ASD, ASD; Autism; Eye-tracking technology; Machine learning, Autism, Eye-tracking technology, machine learning}, pubstate = {published}, tppubtype = {conference} } @article{Spyridis2021b, title = {Towards 6g iot: Tracing mobile sensor nodes with deep learning clustering in uav networks}, author = { Y. Spyridis and T. Lagkas and P. Sarigiannidis and V. Argyriou and A. Sarigiannidis and G. Eleftherakis and J. Zhang}, url = {https://www.researchgate.net/publication/352197709_Towards_6G_IoT_Tracing_Mobile_Sensor_Nodes_with_Deep_Learning_Clustering_in_UAV_Networks}, doi = {10.3390/s21113936}, year = {2021}, date = {2021-01-01}, journal = {Sensors}, volume = {21}, number = {11}, abstract = {Unmanned aerial vehicles (UAVs) in the role of flying anchor nodes have been proposed to assist the localisation of terrestrial Internet of Things (IoT) sensors and provide relay services in the context of the upcoming 6G networks. This paper considered the objective of tracing a mobile IoT device of unknown location, using a group of UAVs that were equipped with received signal strength indicator (RSSI) sensors. The UAVs employed measurements of the target’s radio frequency (RF) signal power to approach the target as quickly as possible. A deep learning model performed clustering in the UAV network at regular intervals, based on a graph convolutional network (GCN) architecture, which utilised information about the RSSI and the UAV positions. The number of clusters was determined dynamically at each instant using a heuristic method, and the partitions were determined by optimising an RSSI loss function. The proposed algorithm retained the clusters that approached the RF source more effectively, removing the rest of the UAVs, which returned to the base. Simulation experiments demonstrated the improvement of this method compared to a previous deterministic approach, in terms of the time required to reach the target and the total distance covered by the UAVs. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {6G, Deep Learning, Graph convolutional network, IoT, RSSI, Sensor tracking, unmanned aerial vehicles}, pubstate = {published}, tppubtype = {article} } @conference{Bougas202018, title = {State-of-the-Art Technologies in RF Energy Harvesting Circuits – A Review}, author = { I. D. Bougas and M. S. Papadopoulou and K. Psannis and P. Sarigiannidis and S. K. Goudos}, url = {https://www.researchgate.net/publication/346719011_State-of-the-Art_Technologies_in_RF_Energy_Harvesting_Circuits_-_A_Review}, doi = {10.1109/wsce51339.2020.9275507}, year = {2020}, date = {2020-10-01}, booktitle = {2020 3rd World Symposium on Communication Engineering (WSCE)}, journal = {2020 3rd World Symposium on Communication Engineering, WSCE 2020}, pages = {18-22}, publisher = {IEEE}, abstract = {Nowadays electricity is undoubtedly one of the most important goods. Over the years, the dependence of people on electrical devices has sharply increased. The need for continuous use of these devices has created greater demand for electricity as well as more efficient transmission techniques. Environmental energy scavenging, as well as wireless transmission, is an increasing research field during the last years. The use of Radio Frequency (RF) Energy Harvesting (EH) technique contributes to the development of autonomous energy devices and sensors, to reduce the need of supplying them with power by using batteries or the mains. In this paper, the state-of-the-art technologies of radio frequency energy harvesting are discussed and analyzed. © 2020 IEEE.}, keywords = {impedance matching network, radio frequency energy harvesting, rectifier, voltage multiplier, wireless power transfer}, pubstate = {published}, tppubtype = {conference} } @conference{Pliatsios202012, title = {Big Data against Security Threats: The SPEAR Intrusion Detection System}, author = { D. Pliatsios and P. Sarigiannidis and K. Psannis and S. K. Goudos and V. Vitsas and I. Moscholios}, doi = {10.1109/wsce51339.2020.9275580}, year = {2020}, date = {2020-10-01}, booktitle = {2020 3rd World Symposium on Communication Engineering (WSCE)}, journal = {2020 3rd World Symposium on Communication Engineering, WSCE 2020}, pages = {12-17}, publisher = {IEEE}, abstract = {The environmental concerns, the limited availability of conventional energy sources, the integration of alternative energy sources and the increasing number of power-demanding appliances change the way electricity is generated and distributed. Smart Grid (SG) is an appealing concept, which was developed in response to the emerging issues of electricity generation and distribution. By leveraging the latest advancements of Information and Communication Technologies (ICT), it offers significant benefits to energy providers, retailers and consumers. Nevertheless, SG is vulnerable to cyber attacks, that could cause critical economic and ecological consequences. Traditional Intrusion Detection Systems (IDSs) are becoming less efficient in detecting and mitigating cyberattacks, due to their limited capabilities of analyzing the exponentially increasing volume of network traffic. In this paper, we present the Secure and PrivatE smArt gRid (SPEAR) platform, which features a Big Data enabled IDS that timely detects and identifies cyber attacks against SG components. In order to validate the efficiency of the SPEAR platform regarding the protection of critical infrastructure, we installed the platform in a small wind power plant. © 2020 IEEE.}, keywords = {Big Data, Cyber Attack, intrusion detection system, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Mladenov2020, title = {Defense against cyber-attacks on the Hydro Power Plant connected in parallel with Energy System}, author = { V. Mladenov and V. Chobanov and P. Sarigiannidis and P. I. Radoglou-Grammatikis and A. Hristov and P. Zlatev}, url = {https://www.researchgate.net/publication/348642791_Defense_against_cyber-attacks_on_the_Hydro_Power_Plant_connected_in_parallel_with_Energy_System}, doi = {10.1109/bulef51036.2020.9326016}, year = {2020}, date = {2020-09-01}, booktitle = {2020 12th Electrical Engineering Faculty Conference (BulEF)}, journal = {2020 12th Electrical Engineering Faculty Conference, BulEF 2020}, publisher = {IEEE}, abstract = {In today's modern energy sector, driven more and more towards decentralization, which includes many smaller energy producers rather than huge government projects, security against cyber-attacks is becoming more crucial for the energy grid. Since many small energy plants do not have the resources to finance very expensive existing cyber-security systems, they often have no security system in place at all. Although with small energy producers, the risks of being under attack are not as devastating as in a huge power plants, they still pose a serious threat to the energy system and to the supply of electricity to whole regions. Moreover, in the era of technology, such cyber-attacks could be carried out simultaneously at many locations, thus risking the lack of electricity to larger areas. Since there was a clearly identified need for such an instrument, the SPEAR consortium, started to develop tailor made solution for different types of actors in the energy sector, to prevent such occurrences and help secure the energy system. One of the use cases, investigated in the project, is a real operating hydro power plant in the mountain area of Bulgaria called Leshnitsa, which will be one of the four sites to first test the functionality of the finished product. The plant had no previous cyber-security system in place and had already experienced one attack, where one of the computers in the plant was hacked and a ransom was demanded from the attackers to unlock it. Exactly events like this one are proof, that the energy sector has a need to protect the growing number of small independent actors in the energy system.. © 2020 IEEE.}, keywords = {Cyber security, Energy System, Grid infrastructure, Hydro Power Plant, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Kakamoukas2020, title = {High Level Drone Application Enabler: An Open Source Architecture}, author = { G. Kakamoukas and P. Sarigiannidis and I. Moscholios}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/346857166_High_Level_Drone_Application_Enabler_An_Open_Source_Architecture}, doi = {10.1109/csndsp49049.2020.9249442}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {The interest of open source software in order to empower the capabilities of Unmanned Aerial Vehicles (UAVs) is growing rapidly into various business applications. In this paper, a complete, multi-layered, and open source flight architecture is proposed. This architecture includes an integrated flight stack, which comprises two side stacks: the UAV side stack and the Ground Control Station (GCS) side stack. Furthermore, a communication layer is used for managing the communication between the two side stacks. The proposed architecture is evaluated on a simulated UAV, and it envisions to be a software stack that will facilitate the development of more complex UAV concepts such as Flying Ad-hoc Networks (FANETs). © 2020 IEEE.}, keywords = {flying ad-hoc networks, MAVLink protocol, UAV system architecture, unmanned aerial vehicles}, pubstate = {published}, tppubtype = {conference} } @conference{Moscholios2020, title = {Teletraffic Loss/Queueing Models in LEO Mobile Satellite Systems: a Short Survey}, author = { I. Moscholios and P. Sarigiannidis and M. Logothetis}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/346846594_Teletraffic_LossQueueing_Models_in_LEO_Mobile_Satellite_Systems_a_Short_Survey}, doi = {10.1109/csndsp49049.2020.9249490}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {In this paper we present teletraffic loss/queueing models that can be applied in low earth orbit mobile satellite systems (LEO-MSS) with "satellite-fixed"cells for the determination of call blocking probabilities of new and handover calls. We study two different model categories: a) those that focus on single-rate traffic where calls belong to a single service-class and require one channel for service and b) those that focus on multirate traffic where the LEO-MSS accommodates many service-classes whose calls may require more than one channels for service. © 2020 IEEE.}, keywords = {call blocking, loss, low earth orbit, mobile satellite system, queueing}, pubstate = {published}, tppubtype = {conference} } @conference{Kakamoukas2020b, title = {Towards Protecting Agriculture from Exogenous and Endogenous Factors: An Holistic Architecture}, author = { G. Kakamoukas and P. Sarigiannidis and I. Moscholios}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/346808047_Towards_Protecting_Agriculture_from_Exogenous_and_Endogenous_Factors_An_Holistic_Architecture}, doi = {10.1109/csndsp49049.2020.9249561}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {An holistic architecture that fosters the application of Smart Farming (SF) in the context of agriculture is proposed in this paper. The proposed architecture exploits the benefits of Internet of Things (IoT), by utilizing a) Wireless Sensor Networks (WSN) for real time monitoring and b) Unmanned Aerial Vehicles (UAVs) / flying Ad-hoc Networks (FANETs) for macroscopic monitoring of the field and inspecting the crops using multispectral cameras. The aggregated data coming from the monitoring process feed the cloud infrastructure, where Machine Learning (ML) and Computer Vision (CV) techniques are applied in order to protect plants from exogenous (e.g., pests) and endogenous (e.g., diseases) factors. © 2020 IEEE.}, keywords = {flying ad-hoc networks, plant protection, smart farming, unmanned aerial vehicles, wireless sensor networks}, pubstate = {published}, tppubtype = {conference} } @conference{Spyridis2020, title = {Rule-based Autonomous Tracking of RF Transmitter Using a UAV Swarm}, author = { Y. Spyridis and T. Lagkas and P. Sarigiannidis and J. Zhang}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/346808103_Rule-based_Autonomous_Tracking_of_RF_Transmitter_Using_a_UAV_Swarm}, doi = {10.1109/csndsp49049.2020.9249591}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {In this paper, a local decision rule-based algorithm is introduced that allows a group of unmanned aerial vehicles (UAVs) to cooperatively trail a mobile radio frequency transmitter. The algorithm utilizes the received signal strength indicator (RSSI) values at each UAV to take a decision that leads the group closer to the target and allows them to preserve minimum distance. The novelty of the proposed solution lies in the fact that it provides an effective tracking technique in noisy environments without relying in distance calculations, which are inevitably inaccurate due to measurement errors. A comprehensive simulation compared the introduced algorithm with a trilateration-based method and demonstrated the increased time efficiency of the proposed technique. © 2020 IEEE.}, keywords = {Mobile target tracking, RSSI, UAV swarm, Unmanned Aerial Vehicles (UAVs), wireless sensor networks}, pubstate = {published}, tppubtype = {conference} } @conference{Moscholios2020b, title = {A Multirate System of Quasi-Random Arrivals and a Threshold Call Admission Policy}, author = { I. Moscholios and I.A. Chousainov and P. Panagoulias and P. Sarigiannidis and M. Logothetis}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/346841887_A_Multirate_System_of_Quasi-Random_Arrivals_and_a_Threshold_Call_Admission_Policy}, doi = {10.1109/CSNDSP49049.2020.9249590}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {We consider a link that services multirate quasirandom traffic. Calls are distinguished to handover and new calls. New calls compete for the available bandwidth under a threshold call admission policy. In that policy, new calls of a service-class are blocked if the in-service handover and new calls of the same service-class including the new call, exceeds a predefined threshold. Handover calls compete for the available bandwidth under the complete sharing policy. The steady state probabilities in the proposed model have a product form solution which leads to a convolution algorithm for the accurate calculation of congestion probabilities and link utilization. © 2020 IEEE.}, keywords = {blocking, Congestion, convolution, Product form, Quasi-random}, pubstate = {published}, tppubtype = {conference} } @conference{Livanos2020, title = {Extraction of Reflectance Maps for Smart Farming Applications Using Unmanned Aerial Vehicles}, author = { G. Livanos and D. Ramnalis and V. Polychronos and P. Balomenou and P. Sarigiannidis and G. Kakamoukas and T. Karamitsou and P. Angelidis and M. Zervakis}, editor = { Networks 2020 12th International Symposium on Communication Systems and Digital Signal Processing ({CSNDSP})}, url = {https://www.researchgate.net/publication/343306275_Extraction_of_Reflectance_Maps_for_Smart_Farming_Applications_Using_Unmanned_Aerial_Vehicles}, doi = {10.1109/csndsp49049.2020.9249628}, year = {2020}, date = {2020-07-01}, booktitle = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing (CSNDSP)}, journal = {2020 12th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2020}, publisher = {IEEE}, abstract = {In this application paper, a robust framework for smart remote sensing of cultivations using Unmanned Aerial Vehicles is presented, yielding to a useful tool with advanced capabilities in terms of time-efficiency, accuracy, user-friendly operability, adjustability and expandability. The proposed system incorporates multispectral imaging, automated navigation and real-time monitoring functionalities into a fixed-wing Unmanned Aerial Vehicle platform. Offline analysis of captured data is performed, at this stage of system development, via powerful commercial software so as to extract the reflection map of the crop area under study based on the Normalized Difference Vegetation Index. The proposed approach has been tested on selected cultivations in two regions (Greece), aiming at recording field variability and early detecting factors related to crop stress. Preliminary results indicate that the proposed framework can prove a cost-effective, precise, flexible and operative solution for agriculture industry, enabling the application of smart farming procedures for productive farm management. Adopting a collaborative group of aerial vehicles via Flying Ad hoc Networks, the proposed sensing approach could be further enhanced for large-scale applications, fusing data from multiple nodes into an advanced Decision Support System and providing information on bigger areas at the same time with respect to a single sensing source. © 2020 IEEE.}, keywords = {flying ad-hoc networks, multispectral imaging, reflectance map, remote sensing, smart farming, spectral signature, unmanned aerial vehicles, vegetation index}, pubstate = {published}, tppubtype = {conference} } @conference{Siniosoglou2020, title = {NeuralPot: An Industrial Honeypot Implementation Based On Deep Neural Networks}, author = { I. Siniosoglou and G. Efstathopoulos and D. Pliatsios and I.D. Moscholios and A. Sarigiannidis and G. Sakellari and G. Loukas and P. Sarigiannidis}, editor = { 2020 {IEEE} Symposium on Computers and Communications ({ISCC})}, url = {https://www.researchgate.net/publication/347267819_NeuralPot_An_Industrial_Honeypot_Implementation_Based_On_Deep_Neural_Networks}, doi = {10.1109/ISCC50000.2020.9219712}, year = {2020}, date = {2020-07-01}, booktitle = {2020 IEEE Symposium on Computers and Communications (ISCC)}, journal = {Proceedings - IEEE Symposium on Computers and Communications}, publisher = {IEEE}, abstract = {Honeypots are powerful security tools, developed to shield commercial and industrial networks from malicious activity. Honeypots act as passive and interactive decoys in a network attracting malicious activity and securing the rest of the network entities. Since an increase in intrusions has been observed lately, more advanced security systems are necessary. In this paper a new method of adapting a honeypot system in a modern industrial network, employing the Modbus protocol, is introduced. In the presented NeuralPot honeypot, two distinct deep neural network implementations are utilized to adapt to network Modbus entities and clone them, actively confusing the intruders. The proposed deep neural networks and their generated data are then compared. © 2020 IEEE.}, keywords = {Autoencoder Network, Data Generation, GAN Network, Honeypots, Industrial Control System, SCADA}, pubstate = {published}, tppubtype = {conference} } @conference{Lagkas2020, title = {Joint Spatial and Spectral Resource Optimization over Both Wireless and Optical Fronthaul Domains of 5G Architectures}, author = { T. D. Lagkas and D. Klonidis and P. Sarigiannidis and I. Tomkos}, url = {https://www.researchgate.net/publication/345375644_Joint_Spatial_and_Spectral_Resource_Optimization_over_Both_Wireless_and_Optical_Fronthaul_Domains_of_5G_Architectures}, doi = {10.1109/icton51198.2020.9203039}, year = {2020}, date = {2020-07-01}, booktitle = {2020 22nd International Conference on Transparent Optical Networks (ICTON)}, publisher = {IEEE}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Chousainov2020, title = {An Analytical Framework of a C-RAN Supporting Bursty Traffic}, author = { I.-A. Chousainov and I. Moscholios and P. Sarigiannidis and A. Kaloxylos and M. Logothetis}, url = {https://www.researchgate.net/publication/343243729_An_Analytical_Framework_of_a_C-RAN_Supporting_Bursty_Traffic}, doi = {10.1109/ICC40277.2020.9149219}, year = {2020}, date = {2020-06-01}, booktitle = {ICC 2020 - 2020 IEEE International Conference on Communications (ICC)}, journal = {IEEE International Conference on Communications}, publisher = {IEEE}, address = {ICC 2020 - 2020 IEEE International Conference on Communications (ICC)}, abstract = {In this paper we consider a cloud radio access network (C-RAN) architecture where the baseband signal processing servers, named baseband units (BBUs) are separated from the remote radio heads (RRHs). The RRHs form a single cluster while the BBUs form a centralized pool of data center resources. Each RRH of the C-RAN accommodates bursty traffic which is expected to play a dominant role in 5G networks. We approximate bursty traffic via the compound Poisson process according to which batches of calls, with a generally distributed batch size, occur at time points that follow a negative exponential distribution. Each call of a new batch is treated separately from the other calls of the same batch. A new call requires a computational resource unit from the centralized pool of BBUs and a radio resource unit from the serving RRH. If both units are available, then the call is accepted in the RRH for an exponentially distributed service time. Otherwise, call blocking occurs. We model this C-RAN as a loss system and show that the steady state probabilities have a product form solution (PFS). Based on the PFS, we propose an efficient convolution algorithm for the accurate calculation of the main performance measures which are time and call congestion probabilities. The accuracy of this algorithm is verified via simulation. © 2020 IEEE.}, keywords = {batch, Bursty, Cloud, Congestion, Product form, Radio access}, pubstate = {published}, tppubtype = {conference} } @conference{Grammatikis2020450, title = {Secure and private smart grid: The SPEAR architecture}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and E. Iturbe and E. Rios and A. Sarigiannidis and O. Nikolis and D. Ioannidis and V. Machamint and M. Tzifas and A. Giannakoulias and M. Angelopoulos and A. Papadopoulos and F. Ramos}, url = {https://www.researchgate.net/publication/343621502_Secure_and_Private_Smart_Grid_The_SPEAR_Architecture?_sg=ajSET8e8bb-KvKba1e9QHd7a7IFuKtI-72RhxDMcm-yozF1Q-5Jx4b8jAVrAhVncE1vtLBx2eVdgcx4}, doi = {10.1109/NetSoft48620.2020.9165420}, year = {2020}, date = {2020-06-01}, booktitle = {2020 6th IEEE Conference on Network Softwarization (NetSoft)}, journal = {Proceedings of the 2020 IEEE Conference on Network Softwarization: Bridging the Gap Between AI and Network Softwarization, NetSoft 2020}, pages = {450-456}, publisher = {IEEE}, abstract = {Information and Communication Technology (ICT) is an integral part of Critical Infrastructures (CIs), bringing both significant pros and cons. Focusing our attention on the energy sector, ICT converts the conventional electrical grid into a new paradigm called Smart Grid (SG), providing crucial benefits such as pervasive control, better utilisation of the existing resources, self-healing, etc. However, in parallel, ICT increases the attack surface of this domain, generating new potential cyberthreats. In this paper, we present the Secure and PrivatE smArt gRid (SPEAR) architecture which constitutes an overall solution aiming at protecting SG, by enhancing situational awareness, detecting timely cyberattacks, collecting appropriate forensic evidence and providing an anonymous cybersecurity information-sharing mechanism. Operational characteristics and technical specifications details are analysed for each component, while also the communication interfaces among them are described in detail. © 2020 IEEE.}, keywords = {Anomaly Detection, Anonymity, Cybersecurity, Forensics, Honeypots, Intrusion detection, Privacy, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @article{Kakamoukas2020c, title = {FANETs in Agriculture - A routing protocol survey}, author = { G. A. Kakamoukas and P. G. Sarigiannidis and A. A. Economides}, url = {https://www.researchgate.net/publication/339904801_FANETs_in_Agriculture_-_A_routing_protocol_survey}, doi = {10.1016/j.iot.2020.100183}, year = {2020}, date = {2020-03-01}, journal = {Internet of Things}, pages = {100183}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } @conference{Triantafyllou2020, title = {A Novel LoRaWAN Scheduling Scheme for Improving Reliability and Collision Avoidance}, author = { A. Triantafyllou and P. Sarigiannidis and T. Lagkas and A. Sarigiannidis}, url = {https://www.researchgate.net/publication/345185837_A_Novel_LoRaWAN_Scheduling_Scheme_for_Improving_Reliability_and_Collision_Avoidance}, doi = {10.1109/MOCAST49295.2020.9200253}, year = {2020}, date = {2020-01-01}, journal = {2020 9th International Conference on Modern Circuits and Systems Technologies, MOCAST 2020}, abstract = {The employment of Low-Power Wide Area Networks (LPWANs) has proven quite beneficial to the advancement of the Internet of Things (IoT) paradigm. The utilization of low power but long range communication links of the LoRaWAN technology promises low energy consumption, while ensuring sufficient throughput. However, due to LoRa's original scheduling process there is a high chance of packet collisions, compromising the technology's reliability. In this paper, we propose a new Medium Access Control (MAC) protocol, entitled the RCA-LoRa towards improving reliability and collision avoidance in LoRa wide-area networks. The novel scheduling process that is introduced is based on the broadcasting of beacon frames by the network's gateway in order to synchronize communication with end devices. Our results demonstrate the benefits of RCA-LoRa over an enhanced version of the legacy LoRaWAN employing the ALOHA protocol and an advanced adaptive rate mechanism, in terms of throughput and collision avoidance. Indicatively, in a single cell scenario with 600 nodes, RCA-LoRa can increase throughput by nearly 50 © 2020 IEEE.}, keywords = {Collision avoidance, Internet of things, Low-Power Wide Area Networks, Medium Access Control}, pubstate = {published}, tppubtype = {conference} } @conference{Pliatsios2020b, title = {Trust Management in Smart Grid: A Markov Trust Model}, author = { D. Pliatsios and P. Sarigiannidis and G. Efstathopoulos and A. Sarigiannidis and A. Tsiakalos}, url = {https://www.researchgate.net/publication/345186037_Trust_Management_in_Smart_Grid_A_Markov_Trust_Model}, doi = {10.1109/MOCAST49295.2020.9200256}, year = {2020}, date = {2020-01-01}, journal = {2020 9th International Conference on Modern Circuits and Systems Technologies, MOCAST 2020}, abstract = {By leveraging the advancements in Information and Communication Technologies (ICT), Smart Grid (SG) aims to modernize the traditional electric power grid towards efficient distribution and reliable management of energy in the electrical domain. The SG Advanced Metering Infrastructure (AMI) contains numerous smart meters, which are deployed throughout the distribution grid. However, these smart meters are susceptible to cyberthreats that aim to disrupt the normal operation of the SG. Cyberattacks can have various consequences in the smart grid, such as incorrect customer billing or equipment destruction. Therefore, these devices should operate on a trusted basis in order to ensure the availability, confidentiality, and integrity of the metering data. In this paper, we propose a Markov chain trust model that determines the Trust Value (TV) for each AMI device based on its behavior. Finally, numerical computations were carried out in order to investigate the reaction of the proposed model to the behavior changes of a device. © 2020 IEEE.}, keywords = {Advanced Metering Infrastructure, Cybersecurity, Markov Model, Smart Grid, Trust Model}, pubstate = {published}, tppubtype = {conference} } @conference{Grammatikis2020, title = {An Anomaly Detection Mechanism for IEC 60870-5-104}, author = { P.R. Grammatikis and P. Sarigiannidis and A. Sarigiannidis and D. Margounakis and A. Tsiakalos and G. Efstathopoulos}, url = {https://www.researchgate.net/publication/344386495_An_Anomaly_Detection_Mechanism_for_IEC_60870-5-104}, doi = {10.1109/MOCAST49295.2020.9200285}, year = {2020}, date = {2020-01-01}, journal = {2020 9th International Conference on Modern Circuits and Systems Technologies, MOCAST 2020}, abstract = {The transformation of the conventional electricity grid into a new paradigm called smart grid demands the appropriate cybersecurity solutions. In this paper, we focus on the security of the IEC 60870-5-104 (IEC-104) protocol which is commonly used by Supervisory Control and Data Acquisition (SCADA) systems in the energy domain. In particular, after investigating its security issues, we provide a multivariate Intrusion Detection System (IDS) which adopts both access control and outlier detection mechanisms in order to detect timely possible anomalies against IEC-104. The efficiency of the proposed IDS is reflected by the Accuracy and F1 metrics that reach 98% and 87%, respectively. © 2020 IEEE.}, keywords = {Anomaly Detection, Cybersecurity, IEC-60870-5-104, Supervisory Control and Data Acquisition}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou-Grammatikis2020, title = {Implementation and detection of modbus cyberattacks}, author = { P. Radoglou-Grammatikis and I. Siniosoglou and T. Liatifis and A. Kourouniadis and K. Rompolos and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/344386530_Implementation_and_Detection_of_Modbus_Cyberattacks}, doi = {10.1109/MOCAST49295.2020.9200287}, year = {2020}, date = {2020-01-01}, journal = {2020 9th International Conference on Modern Circuits and Systems Technologies, MOCAST 2020}, abstract = {Supervisory Control and Data Acquisition (SCADA) systems play a significant role in Critical Infrastructures (CIs) since they monitor and control the automation processes of the industrial equipment. However, SCADA relies on vulnerable communication protocols without any cybersecurity mechanism, thereby making it possible to endanger the overall operation of the CI. In this paper, we focus on the Modbus/TCP protocol, which is commonly utilised in many CIs and especially in the electrical grid. In particular, our contribution is twofold. First, we study and enhance the cyberattacks provided by the Smod pen-testing tool. Second, we introduce an anomaly-based Intrusion Detection System (IDS) capable of detecting Denial of Service (DoS) cyberattacks related to Modbus/TCP. The efficacy of the proposed IDS is demonstrated by utilising real data stemming from a hydropower plant. The accuracy and the F1 score of the proposed IDS reach 81% and 77% respectively. © 2020 IEEE.}, keywords = {intrusion detection system, Modbus, Smart Grid, Smod, Supervisory Control and Data Acquisition}, pubstate = {published}, tppubtype = {conference} } @conference{Protopsaltis2020, title = {Data Visualization in Internet of Things: Tools, Methodologies, and Challenges}, author = { A. Protopsaltis and P. Sarigiannidis and D. Margounakis and A. Lytos}, url = {https://www.researchgate.net/publication/343935293_Data_Visualization_in_Internet_of_Things_Tools_Methodologies_and_Challenges}, doi = {10.1145/3407023.3409228}, isbn = {9781450388337}, year = {2020}, date = {2020-01-01}, booktitle = {Proceedings of the 15th International Conference on Availability, Reliability and Security}, publisher = {Association for Computing Machinery}, address = {Virtual Event, Ireland}, series = {ARES '20}, abstract = {As the Internet of Things (IoT) grows rapidly, huge amounts of wireless sensor networks emerged monitoring a wide range of infrastructure, in various domains such as healthcare, energy, transportation, smart city, building automation, agriculture, and industry producing continuously streamlines of data. Big Data technologies play a significant role within IoT processes, as visual analytics tools, generating valuable knowledge in real-time in order to support critical decision making. This paper provides a comprehensive survey of visualization methods, tools, and techniques for the IoT. We position data visualization inside the visual analytics process by reviewing the visual analytics pipeline. We provide a study of various chart types available for data visualization and analyze rules for employing each one of them, taking into account the special conditions of the particular use case. We further examine some of the most promising visualization tools. Since each IoT domain is isolated in terms of Big Data approaches, we investigate visualization issues in each domain. Additionally, we review visualization methods oriented to anomaly detection. Finally, we provide an overview of the major challenges in IoT visualizations.}, keywords = {Anomaly Detection, Big Data, Data visualization, Internet of Things (IoT)}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou-Grammatikis2020b, title = {DIDEROT: An intrusion detection and prevention system for DNP3-based SCADA systems}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and G. Efstathopoulos and P.-A. Karypidis and A. Sarigiannidis}, url = {https://www.researchgate.net/publication/343853580_DIDEROT_an_intrusion_detection_and_prevention_system_for_DNP3-based_SCADA_systems}, doi = {10.1145/3407023.3409314}, year = {2020}, date = {2020-01-01}, journal = {ACM International Conference Proceeding Series}, abstract = {In this paper, an Intrusion Detection and Prevention System (IDPS) for the Distributed Network Protocol 3 (DNP3) Supervisory Control and Data Acquisition (SCADA) systems is presented. The proposed IDPS is called DIDEROT (Dnp3 Intrusion DetEction pReventiOn sysTem) and relies on both supervised Machine Learning (ML) and unsupervised/outlier ML detection models capable of discriminating whether a DNP3 network flow is related to a particular DNP3 cyberattack or anomaly. First, the supervised ML detection model is applied, trying to identify whether a DNP3 network flow is related to a specific DNP3 cyberattack. If the corresponding network flow is detected as normal, then the unsupervised/outlier ML anomaly detection model is activated, seeking to recognise the presence of a possible anomaly. Based on the DIDEROT detection results, the Software Defined Networking (SDN) technology is adopted in order to mitigate timely the corresponding DNP3 cyberattacks and anomalies. The performance of DIDEROT is demonstrated using real data originating from a substation environment. © 2020 ACM.}, keywords = {Anomaly Detection, Autonencoder, Intrusion detection, machine learning, SCADA, SDN, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Triantafyllou2020252, title = {Modelling deployment costs of Precision Agriculture Monitoring Systems}, author = { A. Triantafyllou and P. Sarigiannidis and S. Bibi and F. Vakouftsi and P. Vassilis}, url = {https://www.researchgate.net/publication/344050120_Modelling_deployment_costs_of_Precision_Agriculture_Monitoring_Systems}, doi = {10.1109/DCOSS49796.2020.00048}, year = {2020}, date = {2020-01-01}, journal = {Proceedings - 16th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2020}, pages = {252-259}, abstract = {Unmanned Aerial Vehicles (UAVs) and smart sensors are the tools towards the fifth agricultural revolution. Remote sensing is thriving in agriculture, broadening the horizons of cultivators and farming practitioners. However, adopting such a technological endeavour in a raw production process is a challenging task for farmers. Operation and maintenance of such systems require specific ICT knowledge. There is also a wide variety of software and hardware equipment to choose from that can greatly impact business costs and system performance according to the kind of cultivation. Due to the lack of guidance regarding the employment of precision agriculture monitoring systems, this paper proposes a detailed decision model regarding the requirements and considerations of deploying remote sensing capabilities on a cultivation. Agricultural businesses are in need of guidance when it comes to the adoption of technological advancements especially in the case when a carefully planned operation can produce a significant amount of profits. © 2020 IEEE.}, keywords = {cost model, Precision agriculture costs, smart farming, SWOT analysis, Unmanned Aerial Vehicle (UAVs), Wireless Sensor Networks (WSNs)}, pubstate = {published}, tppubtype = {conference} } @conference{Drosatos2020219, title = {Privacy-preserving solutions in the Industrial Internet of Things}, author = { G. Drosatos and K. Rantos and D. Karampatzakis and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/344057084_Privacy-preserving_solutions_in_the_Industrial_Internet_of_Things}, doi = {10.1109/DCOSS49796.2020.00044}, year = {2020}, date = {2020-01-01}, journal = {Proceedings - 16th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2020}, pages = {219-226}, abstract = {Industrial Internet of Things (IIoT) is a relatively new area of research that utilises multidisciplinary and holistic approaches to develop smart solutions for complex problems in industrial environments. Designing applications for the IIoT is a non trivial issue and requires to address, among many others, technology concerns, the protection of personal data, and the privacy of individuals. In this review paper, we identify privacy-preserving solutions that have been proposed in the literature to safeguard the privacy of individuals being part, or interacting with, the IIoT environment. As such, it considers two main categories of the analysed protocols, i.e., the privacy-preserving data management and processing solutions, and the privacy-preserving authentication methods. © 2020 IEEE.}, keywords = {Industrial Internet of Things (IIoT), Literature review, Privacy, Privacy-preserving authentication methods, Privacy-preserving solutions}, pubstate = {published}, tppubtype = {conference} } @article{Panagoulias2020674, title = {Congestion probabilities in OFDM wireless networks with compound Poisson arrivals}, author = { P.I. Panagoulias and I.D. Moscholios and P.G. Sarigiannidis and M.D. Logothetis}, url = {https://www.researchgate.net/publication/345353840_Congestion_probabilities_in_OFDM_wireless_networks_with_compound_Poisson_arrivals}, doi = {10.1049/iet-com.2019.0845}, year = {2020}, date = {2020-01-01}, journal = {IET Communications}, volume = {14}, number = {4}, pages = {674-681}, abstract = {The authors study the downlink of an orthogonal frequency division multiplexing (OFDM) based cell that services calls from different service-classes with various resource requirements. They assume that calls arrive in the cell as batches according to a compound Poisson process. They consider that the batch size is generally distributed while each call of a batch is treated separately from the other calls of the same batch, according to the complete sharing policy. To determine the most important performance metrics, i.e. congestion probabilities and resource utilisation in this OFDM-based cell, they model it as a multirate loss model, show that the steady-state probabilities can be determined via a product form solution (PFS) and propose recursive formulas which reduce the complexity of the calculations. In addition, they study the bandwidth reservation (BR) policy which can be used for the reservation of subcarriers in order to favour service-classes whose calls have high subcarrier requirements. The existence of the BR policy destroys the PFS of the steady-state probabilities. However, they show that there exist recursive formulas for the determination of the various performance measures. Simulation verifies the accuracy of the proposed formulas. © The Institution of Engineering and Technology 2019}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Jaddoa2020, title = {Dynamic decision support for resource offloading in heterogeneous Internet of Things environments}, author = { A. Jaddoa and G. Sakellari and E. Panaousis and G. Loukas and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/337218323_Dynamic_decision_support_for_resource_offloading_in_heterogeneous_Internet_of_Things_environments}, doi = {10.1016/j.simpat.2019.102019}, year = {2020}, date = {2020-01-01}, journal = {Simulation Modelling Practice and Theory}, volume = {101}, abstract = {Computation offloading is one of the primary technological enablers of the Internet of Things (IoT), as it helps address individual devices’ resource restrictions. In the past, offloading would always utilise remote cloud infrastructures, but the increasing size of IoT data traffic and the real-time response requirements of modern and future IoT applications have led to the adoption of the edge computing paradigm, where the data is processed at the edge of the network. The decision as to whether cloud or edge resources will be utilised is typically taken at the design stage based on the type of the IoT device. Yet, the conditions that determine the optimality of this decision, such as the arrival rate, nature and sizes of the tasks, and crucially the real-time condition of the networks involved, keep changing. At the same time, the energy consumption of IoT devices is usually a key requirement, which is affected primarily by the time it takes to complete tasks, whether for the actual computation or for offloading them through the network. Here, we model the expected time and energy costs for the different options of offloading a task to the edge or the cloud, as well as of carrying out on the device itself. We use this model to allow the device to take the offloading decision dynamically as a new task arrives and based on the available information on the network connections and the states of the edge and the cloud. Having extended EdgeCloudSim to provide support for such dynamic decision making, we are able to compare this approach against IoT-first, edge-first, cloud-only, random and application-oriented probabilistic strategies. Our simulations on four different types of IoT applications show that allowing customisation and dynamic offloading decision support can improve drastically the response time of time-critical and small-size applications, and the energy consumption not only of the individual IoT devices but also of the system as a whole. This paves the way for future IoT devices that optimise their application response times, as well as their own energy autonomy and overall energy efficiency, in a decentralised and autonomous manner. © 2019 Elsevier B.V.}, keywords = {Cloud Computing, Computation offloading, Decision support, Edge computing, EdgeCloudSim simulator, Internet of things, IoT offloading}, pubstate = {published}, tppubtype = {article} } @article{Lagkas20204, title = {5G/NGPON Evolution and Convergence: Developing on Spatial Multiplexing of Optical Fiber Links for 5G Infrastructures}, author = { T. Lagkas and D. Klonidis and P. Sarigiannidis and I. Tomkos}, url = {https://www.researchgate.net/publication/339325496_5GNGPON_Evolution_and_Convergence_Developing_on_Spatial_Multiplexing_of_Optical_Fiber_Links_for_5G_Infrastructures}, doi = {10.1080/01468030.2020.1725184}, year = {2020}, date = {2020-01-01}, journal = {Fiber and Integrated Optics}, volume = {39}, number = {1}, pages = {4-23}, abstract = {The offering of demanding telecommunication services as promised by the 5G specifications raise the necessity for high capacity, flexible, adaptive, and power conserving fronthaul. Toward this goal, the role of the passive optical network which is responsible for interconnecting the central office (CO) with the cell-sites is crucial. Among the latest related technologies that need to be integrated in the context of the next generation passive optical networks (NGPONs), the most promising for increasing the provided bandwidth, is the optical spatial multiplexing. In this paper, we present the key 5G technologies, focusing on spatial division multiplexing, which constitutes the main innovation of the blueSPACE 5G Infrastructure Public Private Partnership (5G PPP) project. Exploiting the recent developments on multicore fibers (MCFs), optical beamforming networks (OBFNs), analog radio over fiber (ARoF), and spatial-spectral resources granularity in the context of Spectrally Spatially Flexible Optical Networks (SS-FONs), we describe a complete approach for the 5G fronthaul, emphasizing on the efficient allocation of optical resources while aiming at minimizing energy consumption. The modeled optimization problem is thoroughly presented, and the introduced scheme is evaluated through a real-world based simulation scenario, exhibiting quite promising results. © 2020, © 2020 Taylor & Francis.}, keywords = {5G fronthaul, NGPON, ODN granularity, optical SDM, power saving optimization, spatial and spectral dimensions}, pubstate = {published}, tppubtype = {article} } @article{Radoglou-Grammatikis2020c, title = {A compilation of UAV applications for precision agriculture}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and T. Lagkas and I. Moscholios}, url = {https://www.researchgate.net/publication/339233121_A_Compilation_of_UAV_Applications_for_Precision_Agriculture}, doi = {10.1016/j.comnet.2020.107148}, year = {2020}, date = {2020-01-01}, journal = {Computer Networks}, volume = {172}, abstract = {Climate change has introduced significant challenges that can affect multiple sectors, including the agricultural one. In particular, according to the Food and Agriculture Organization of the United Nations (FAO) and the International Telecommunication Union (ITU), the world population has to find new solutions to increase the food production by 70% by 2050. The answer to this crucial challenge is the suitable adoption and utilisation of the Information and Communications Technology (ICT) services, offering capabilities that can increase the productivity of the agrochemical products, such as pesticides and fertilisers and at the same time, they should minimise the functional cost. More detailed, the advent of the Internet of Things (IoT) and specifically, the rapid evolution of the Unmanned Aerial Vehicles (UAVs) and Wireless Sensor Networks (WSNs) can lead to valuable and at the same time economic Precision Agriculture (PA) applications, such as aerial crop monitoring and smart spraying tasks. In this paper, we provide a survey regarding the potential use of UAVs in PA, focusing on 20 relevant applications. More specifically, first, we provide a detailed overview of PA, by describing its various aspects and technologies, such as soil mapping and production mapping as well as the role of the Global Positioning Systems (GPS) and Geographical Information Systems (GIS). Then, we discriminate and analyse the various types of UAVs based on their technical characteristics and payload. Finally, we investigate in detail 20 UAV applications that are devoted to either aerial crop monitoring processes or spraying tasks. For each application, we examine the methodology adopted, the proposed UAV architecture, the UAV type, as well as the UAV technical characteristics and payload. © 2020 The Authors}, keywords = {Precision agriculture (PA), Remote sensing (RS), Unmanned aerial vehicle (UAV)}, pubstate = {published}, tppubtype = {article} } @article{Lytos2020, title = {Towards smart farming: Systems, frameworks and exploitation of multiple sources}, author = { A. Lytos and T. Lagkas and P. Sarigiannidis and M. Zervakis and G. Livanos}, url = {https://www.researchgate.net/publication/339221382_Towards_Smart_Farming_Systems_Frameworks_and_Exploitation_of_Multiple_Sources}, doi = {10.1016/j.comnet.2020.107147}, year = {2020}, date = {2020-01-01}, journal = {Computer Networks}, volume = {172}, abstract = {Agriculture is by its nature a complicated scientific field, related to a wide range of expertise, skills, methods and processes which can be effectively supported by computerized systems. There have been many efforts towards the establishment of an automated agriculture framework, capable to control both the incoming data and the corresponding processes. The recent advances in the Information and Communication Technologies (ICT) domain have the capability to collect, process and analyze data from different sources while materializing the concept of agriculture intelligence. The thriving environment for the implementation of different agriculture systems is justified by a series of technologies that offer the prospect of improving agricultural productivity through the intensive use of data. The concept of big data in agriculture is not exclusively related to big volume, but also on the variety and velocity of the collected data. Big data is a key concept for the future development of agriculture as it offers unprecedented capabilities and it enables various tools and services capable to change its current status. This survey paper covers the state-of-the-art agriculture systems and big data architectures both in research and commercial status in an effort to bridge the knowledge gap between agriculture systems and exploitation of big data. The first part of the paper is devoted to the exploration of the existing agriculture systems, providing the necessary background information for their evolution until they have reached the current status, able to support different platforms and handle multiple sources of information. The second part of the survey is focused on the exploitation of multiple sources of information, providing information for both the nature of the data and the combination of different sources of data in order to explore the full potential of ICT systems in agriculture. © 2020 The Authors}, keywords = {Agriculture, Big Data, Internet of things, machine learning, smart farming}, pubstate = {published}, tppubtype = {article} } @article{Bibi202058094, title = {Crowdsourcing in Software Development: Empirical Support for Configuring Contests}, author = { S. Bibi and I. Zozas and A. Ampatzoglou and P.G. Sarigiannidis and G. Kalampokis and I. Stamelos}, url = {https://www.researchgate.net/publication/339850480_Crowdsourcing_in_Software_Development_Empirical_Support_for_Configuring_Contests}, doi = {10.1109/ACCESS.2020.2982619}, year = {2020}, date = {2020-01-01}, journal = {IEEE Access}, volume = {8}, pages = {58094-58117}, abstract = {Despite the extensive adoption of crowdsourcing for the timely, cost-effective, and high-quality completion of software development tasks, a large number of crowdsourced challenges are not able to acquire a winning solution, on time, and within the desired cost and quality thresholds. A possible reason for this is that we currently lack a systematic approach that would aid software managers during the process of designing software development tasks that will be crowdsourced. This paper attempts to extend the current knowledge on designing crowdsourced software development tasks, by empirically answering the following management questions: (a) what type of projects should be crowdsourced, (b) why should one crowdsource - in terms of acquired benefits, (c) where should one crowdsource - in terms of application domain, (d) when to crowdsource - referring to the time period of the year, (e) who will win or participate in the contest, and (f) how to crowdsource (define contest duration, prize, type of contest etc.) to acquire the maximum benefits - depending on the goal of crowdsourcing. To answer the aforementioned questions, we have performed a case study on 2,209 software development tasks crowdsourced through TopCoder platform. The results suggest that there are significant differences in the level to which crowdsourcing goals are reached, across different software development activities. Based on this observation we suggest that software managers should prioritize the goals of crowdsourcing, decide carefully upon the activity to be crowdsourced and then define the settings of the task. © 2013 IEEE.}, keywords = {cost, crowd factors, Crowdsourcing, duration, software development, success factors}, pubstate = {published}, tppubtype = {article} } @article{Pliatsios20201942, title = {A Survey on SCADA Systems: Secure Protocols, Incidents, Threats and Tactics}, author = { D. Pliatsios and P. Sarigiannidis and T. Lagkas and A.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/340453361_A_Survey_on_SCADA_Systems_Secure_Protocols_Incidents_Threats_and_Tactics}, doi = {10.1109/COMST.2020.2987688}, year = {2020}, date = {2020-01-01}, journal = {IEEE Communications Surveys and Tutorials}, volume = {22}, number = {3}, pages = {1942-1976}, abstract = {Supervisory Control and Data Acquisition (SCADA) systems are the underlying monitoring and control components of critical infrastructures, such as power, telecommunication, transportation, pipelines, chemicals and manufacturing plants. Legacy SCADA systems operated on isolated networks, that made them less exposed to Internet threats. However, the increasing connection of SCADA systems to the Internet, as well as corporate networks, introduces severe security issues. Security considerations for SCADA systems are gaining higher attention, as the number of security incidents against these critical infrastructures is increasing. In this survey, we provide an overview of the general SCADA architecture, along with a detailed description of the SCADA communication protocols. Additionally, we discuss certain high-impact security incidents, objectives, and threats. Furthermore, we carry out an extensive review of the security proposals and tactics that aim to secure SCADA systems. We also discuss the state of SCADA system security. Finally, we present the current research trends and future advancements of SCADA security. © 1998-2012 IEEE.}, keywords = {Cybersecurity, protocols, SCADA, security, Smart Grid, trends}, pubstate = {published}, tppubtype = {article} } @article{Keramidi202061, title = {Performance evaluation of two-link multirate loss models with restricted accessibility}, author = { I.P. Keramidi and I.D. Moscholios and P.G. Sarigiannidis and M.D. Logothetis}, url = {https://www.researchgate.net/publication/342568028_Performance_Evaluation_of_Two-Link_Multirate_Loss_Models_with_Restricted_Accessibility}, doi = {10.26636/jtit.2020.142320}, year = {2020}, date = {2020-01-01}, journal = {Journal of Telecommunications and Information Technology}, number = {2}, pages = {61-69}, abstract = {We consider a two-link communication system with restricted accessibility that services Poisson arriving calls of many service-classes and propose a multirate teletraffic loss model for its analysis. In a restricted accessibility system, call blocking occurs even if available resources do exist at the time of a call's arrival. In the two-link system under consideration, each link has two thresholds (offloading and support) which express the in-service calls in a link. The offloading threshold represents the point from which a link offloads calls. The support threshold (which is lower than the offloading threshold) defines the point up to which a link supports offloaded calls. The two-link system with restricted accessibility is modeled as a loss system whose steady state probabilities do not have a product form solution. However, approximate formulas for the determination of call blocking probabilities are proposed. In addition, we also provide a corresponding analysis related to the case of quasi-random traffic (i.e. traffic generated by a finite number of users). The accuracy of all formulas is verified through simulation and is found to be quite satisfactory. © 2020 National Institute of Telecommunications. All rights reserved.}, keywords = {Accessibility, blocking, Non-product form, Poisson, Quasi-random, Threshold}, pubstate = {published}, tppubtype = {article} } @article{Moscholios202051, title = {Performance evaluation of the threshold call admission policy in multi-rate loss systems}, author = { I.D. Moscholios and I.-A. Chousainov and P.I. Panagoulias and P.G. Sarigiannidis and M.D. Logothetis}, url = {https://www.researchgate.net/publication/342568954_Performance_Evaluation_of_the_Threshold_Call_Admission_Policy_in_Multi-rate_Loss_Systems}, doi = {10.26636/jtit.2020.142120}, year = {2020}, date = {2020-01-01}, journal = {Journal of Telecommunications and Information Technology}, number = {2}, pages = {51-60}, abstract = {In this paper we consider a link, characterized by specific capacity, that services multi-rate random or quasirandom traffic. Random traffic is generated by an infinite number of traffic sources, while quasi-random traffic is generated by a finite population of traffic sources. The link is modeled as a multi-rate loss system. Handover and new calls are distinguished. New calls compete for the available bandwidth under a threshold call admission policy. In that policy, a new call of a particular service-class is not allowed to enter the system if the in-service handover and new calls of the same service-class plus the new call, exceed a predefined threshold (which can be different for each service-class). On the other hand, handover calls compete for the available bandwidth based on the complete sharing policy. We show that the steady state probabilities in the proposed models have a product form solution (PFS). The PFS leads to a convolution algorithm for accurate calculation of congestion probabilities and link utilization. © 2020 National Institute of Telecommunications. All rights reserved.}, keywords = {blocking, Congestion, convolution, Product form, Quasi-random, Rando}, pubstate = {published}, tppubtype = {article} } @article{Chousainov2020b, title = {An analytical framework of a C-RAN supporting random, quasi-random and bursty traffic}, author = { I.-A. Chousainov and I. Moscholios and P. Sarigiannidis and A. Kaloxylos and M. Logothetis}, url = {https://www.researchgate.net/publication/342682428_An_Analytical_Framework_of_a_C-RAN_Supporting_Random_Quasi-Random_and_Bursty_Traffic}, doi = {10.1016/j.comnet.2020.107410}, year = {2020}, date = {2020-01-01}, journal = {Computer Networks}, volume = {180}, abstract = {We consider a cloud radio access network (C-RAN) where the baseband signal processing servers, named baseband units (BBUs) are separated from the remote radio heads (RRHs). The RRHs form a single cluster while the BBUs form a pool of resources. Each RRH may accommodate random (Poisson) or quasi-random or bursty traffic. The latter is approximated via the compound Poisson process according to which batches of calls, with a generally distributed batch size, follow a Poisson process. A call requires a computational resource and a radio resource unit from the BBUs and the serving RRH, respectively. If any of the two units is unavailable, call blocking occurs. Otherwise, the new call is accepted in the RRH. We model this C-RAN as a loss system and study two different cases: i) all RRHs accommodate bursty traffic and ii) some RRHs accommodate random traffic, some quasi-random traffic and the rest RRHs accommodate bursty traffic. In both cases, we show that a product form solution exists for the steady state probabilities and propose efficient convolution algorithms for the accurate calculation of time and call congestion probabilities. The accuracy of these algorithms is verified via simulation. © 2020 Elsevier B.V.}, keywords = {Bursty, Cloud, Congestion, Radio access, Random}, pubstate = {published}, tppubtype = {article} } @article{Tegos20206289, title = {Slotted ALOHA with NOMA for the Next Generation IoT}, author = { S.A. Tegos and P.D. Diamantoulakis and A.S. Lioumpas and P.G. Sarigiannidis and G.K. Karagiannidis}, url = {https://www.researchgate.net/publication/342755668_Slotted_ALOHA_with_NOMA_for_the_Next_Generation_IoT}, doi = {10.1109/TCOMM.2020.3007744}, year = {2020}, date = {2020-01-01}, journal = {IEEE Transactions on Communications}, volume = {68}, number = {10}, pages = {6289-6301}, abstract = {Random access (RA) has recently been revisited and considered as a key technology for the medium access control layer of the Internet of Things applications. Compared to other RA protocols, slotted ALOHA (SA) has the advantages of low complexity and elimination of partially overlapping transmissions, reducing the number of collisions, however it may suffer from congestion as the traffic load and the number of devices increase. To this end, two RA protocols based on SA and uplink non-orthogonal multiple access are proposed and applied to wireless sensor networks and wireless powered sensor networks. More specifically, to reduce the number of collisions and increase the throughput of SA, while maintaining low complexity, two detection techniques are used to mitigate the interference, when two sources transmit information in the same time slot, namely successive interference cancellation (SIC) with optimal decoding order policy and joint decoding (JD). To evaluate the performance of the proposed protocols, the outage probability of SIC and JD is derived, which is used to express the average throughput attained by each protocol in closed-form. Finally, both the analytical results and the simulations verify that the proposed protocols substantially increase the throughput and the number of connected devices compared to SA. © 1972-2012 IEEE.}, keywords = {energy harvesting, outage probability, Random access, slotted ALOHA, uplink NOMA, wireless power transfer, wireless powered sensor network}, pubstate = {published}, tppubtype = {article} } @article{Diamantoulakis20201, title = {Game theoretic honeypot deployment in smart grid}, author = { P. Diamantoulakis and C. Dalamagkas and P. Radoglou-Grammatikis and P. Sarigiannidis and G. Karagiannidis}, url = {https://www.researchgate.net/publication/343188880_Game_Theoretic_Honeypot_Deployment_in_Smart_Grid}, doi = {10.3390/s20154199}, year = {2020}, date = {2020-01-01}, journal = {Sensors (Switzerland)}, volume = {20}, number = {15}, pages = {1-24}, abstract = {The smart grid provides advanced functionalities, including real-time monitoring, dynamic energy management, advanced pricing mechanisms, and self-healing, by enabling the two-way flow of power and data, as well as the use of Internet of Things (IoT) technologies and devices. However, converting the traditional power grids to smart grids poses severe security challenges and makes their components and services prone to cyber attacks. To this end, advanced techniques are required to mitigate the impact of the potential attacks. In this paper, we investigate the use of honeypots, which are considered to mimic the common services of the smart grid and are able to detect unauthorized accesses, collect evidence, and help hide the real devices. More specifically, the interaction of an attacker and a defender is considered, who both optimize the number of attacks and the defending system configuration, i.e., the number of real devices and honeypots, respectively, with the aim to maximize their individual payoffs. To solve this problem, game theoretic tools are used, considering an one-shot game and a repeated game with uncertainty about the payoff of the attacker, where the Nash Equilibrium (NE) and the Bayesian NE are derived, respectively. Finally, simulation results are provided, which illustrate the effectiveness of the proposed framework. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Cybersecurity, Game theory, Honeypots, Smart Grid}, pubstate = {published}, tppubtype = {article} } @article{RadoglouGrammatikis2020, title = {ARIES: A Novel Multivariate Intrusion Detection System for Smart Grid}, author = { P. Radoglou Grammatikis and P. Sarigiannidis and G. Efstathopoulos and E. Panaousis}, url = {https://www.researchgate.net/publication/344176314_ARIES_A_Novel_Multivariate_Intrusion_Detection_System_for_Smart_Grid}, doi = {10.3390/s20185305}, year = {2020}, date = {2020-01-01}, journal = {Sensors (Basel, Switzerland)}, volume = {20}, number = {18}, abstract = {The advent of the Smart Grid (SG) raises severe cybersecurity risks that can lead to devastating consequences. In this paper, we present a novel anomaly-based Intrusion Detection System (IDS), called ARIES (smArt gRid Intrusion dEtection System), which is capable of protecting efficiently SG communications. ARIES combines three detection layers that are devoted to recognising possible cyberattacks and anomalies against (a) network flows, (b) Modbus/Transmission Control Protocol (TCP) packets and (c) operational data. Each detection layer relies on a Machine Learning (ML) model trained using data originating from a power plant. In particular, the first layer (network flow-based detection) performs a supervised multiclass classification, recognising Denial of Service (DoS), brute force attacks, port scanning attacks and bots. The second layer (packet-based detection) detects possible anomalies related to the Modbus packets, while the third layer (operational data based detection) monitors and identifies anomalies upon operational data (i.e., time series electricity measurements). By emphasising on the third layer, the ARIES Generative Adversarial Network (ARIES GAN) with novel error minimisation functions was developed, considering mainly the reconstruction difference. Moreover, a novel reformed conditional input was suggested, consisting of random noise and the signal features at any given time instance. Based on the evaluation analysis, the proposed GAN network overcomes the efficacy of conventional ML methods in terms of Accuracy and the F1 score.}, keywords = {Cybersecurity, intrusion detection system, machine learning, Modbus, SCADA, Smart Grid}, pubstate = {published}, tppubtype = {article} } @article{Li20207429, title = {Resource Allocation in Buffer-Aided Cooperative Non-Orthogonal Multiple Access Systems}, author = { J. Li and X. Lei and P.D. Diamantoulakis and F. Zhou and P. Sarigiannidis and G.K. Karagiannidis}, url = {https://www.researchgate.net/publication/344859337_Resource_Allocation_in_Buffer-Aided_Cooperative_Non-Orthogonal_Multiple_Access_Systems}, doi = {10.1109/TCOMM.2020.3023458}, year = {2020}, date = {2020-01-01}, journal = {IEEE Transactions on Communications}, volume = {68}, number = {12}, pages = {7429-7445}, abstract = {Cooperative non-orthogonal multiple access (C-NOMA) and buffering are promising techniques to improve spectrum efficiency in the next generation of wireless networks. In this article, a buffer-aided cooperative NOMA network with direct links is studied. The throughput maximization problem is firstly formulated under the assumption of fixed power allocation and optimally solved by designing a mode selection policy. In order to further improve system throughput, the problem is extended into the case that power allocation and mode selection are jointly optimized. An optimal solution is obtained, while a sub-optimal one is also provided in order to decrease the implementation complexity. Furthermore, considering the case where the buffer has finite size and the users are delay-sensitive, a throughput-delay aware strategy is also presented. Moreover, it is shown that the proposed schemes outperform the baseline one in terms of throughput. Finally, simulations demonstrate that the sub-optimal solution achieves similar performance to the optimal one, while significantly reduces the implementation complexity. © 1972-2012 IEEE.}, keywords = {buffer-aided relaying, Cooperative non-orthogonal multi-access, direct links, power allocation}, pubstate = {published}, tppubtype = {article} } @article{Kotsiopoulos2020, title = {Deep multi-sensorial data analysis for production monitoring in hard metal industry}, author = { T. Kotsiopoulos and L. Leontaris and N. Dimitriou and D. Ioannidis and F. Oliveira and J. Sacramento and S. Amanatiadis and G. Karagiannis and K. Votis and D. Tzovaras and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/344881380_Deep_multi-sensorial_data_analysis_for_production_monitoring_in_hard_metal_industry}, doi = {10.1007/s00170-020-06173-1}, year = {2020}, date = {2020-01-01}, journal = {International Journal of Advanced Manufacturing Technology}, abstract = {The industry practice of machining hard metal parts using CNC lathe turning machines is through grinding and milling procedures. The typical practice for quality control is through manual inspection, as automated solutions are difficult to integrate in production and do not reach the same level of accuracy. In this scope, the proposed system aims to automate the manufacturing process for the machine condition monitoring and 3D inspection of defective hard metal parts, by utilizing deep neural networks (DNNs) and investigating the defects on real production samples. Concretely, data are collected with (a) shop floor sensors, (b) high-resolution laser microprofilometer and (c) ultrasound scanner. The proposed system analyzes the collected data through AI models for quality control. Moreover, a fusion scheme is proposed to further improve accuracy. The system is validated on the classification of defective and non-defective samples, using metrics including accuracy, F-score, precision and recall for the performance evaluation. © 2020, Springer-Verlag London Ltd., part of Springer Nature.}, keywords = {Deep Learning, Deep multi-sensorial data analysis, Hard metal industry, Production monitoring, Smart manufacturing}, pubstate = {published}, tppubtype = {article} } @article{Chousainov20201, title = {Congestion probabilities in a multi-cluster c-ran servicing a mixture of traffic sources}, author = { I.-A. Chousainov and I.D. Moscholios and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/347616523_Congestion_Probabilities_in_a_Multi-Cluster_C-RAN_Servicing_a_Mixture_of_Traffic_Sources}, doi = {10.3390/electronics9122120}, year = {2020}, date = {2020-01-01}, journal = {Electronics (Switzerland)}, volume = {9}, number = {12}, pages = {1-18}, abstract = {A multi-cluster cloud radio access network (C-RAN) is considered in this paper where the remote radio heads (RRHs) form different clusters. A cluster includes RRHs that have the same radio resource unit capacity. In addition, all RRHs are separated from the common pool of computational resource units named baseband units. Each RRH accommodates calls whose arrival process can be random, quasi-random, or even bursty. The latter is modeled according to the compound Poisson process where calls arrive in the C-RAN in the form of batches whose size (in calls) is generally distributed. An arriving call requires a radio and a computational resource unit so as to be accepted in the C-RAN. If at least one of these units is not available, the call is blocked. To analyze the proposed multi-cluster C-RAN we model it as a loss system, show that the steady-state probabilities have a product form solution and propose an algorithm for the computation of congestion probabilities. The accuracy of the proposed algorithm is verified via simulation. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Bursty, Cloud-radio access, Cluster, Congestion, Poisson, Probability, Product form, Quasi-random}, pubstate = {published}, tppubtype = {article} } @article{Pliatsios2020d, title = {3D Placement of Drone-Mounted Remote Radio Head for Minimum Transmission Power Under Connectivity Constraints}, author = { D. Pliatsios and P. Sarigiannidis and S. K. Goudos and K. Psannis}, url = {https://www.researchgate.net/publication/344807205_3D_Placement_of_Drone-Mounted_Remote_Radio_Head_for_Minimum_Transmission_Power_Under_Connectivity_Constraints}, doi = {10.1109/access.2020.3034881}, year = {2020}, date = {2020-01-01}, journal = {IEEE Access}, volume = {8}, pages = {200338--200350}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Triantafyllou2020c, title = {The Challenges of Privacy and Access Control as Key Perspectives for the Future Electric Smart Grid}, author = { A. Triantafyllou and J. Jimenez and A. Torres and T. Lagkas and K. Rantos and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/345242886_The_Challenges_of_Privacy_and_Access_Control_as_Key_Perspectives_for_the_Future_Electric_Smart_Grid}, doi = {10.1109/ojcoms.2020.3037517}, year = {2020}, date = {2020-01-01}, journal = {IEEE Open Journal of the Communications Society}, volume = {1}, pages = {1934--1960}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Boursianis2020, title = {Smart Irrigation System for Precision Agriculture - The AREThOU5A IoT Platform}, author = { A. D. Boursianis and M. S. Papadopoulou and A. Gotsis and S. Wan and P. Sarigiannidis and S. Nikolaidis and S. K. Goudos}, url = {Smart Irrigation System for Precision Agriculture - The AREThOU5A IoT Platform}, doi = {10.1109/jsen.2020.3033526}, year = {2020}, date = {2020-01-01}, journal = {IEEE Sensors Journal}, pages = {1--1}, publisher = {Institute of Electrical and Electronics Engineers (IEEE)}, abstract = {Agriculture 4.0, as the future of farming technology, includes several key enabling technologies towards sustainable agriculture. The use of state-of-the-art technologies, such as the Internet of Things, transform traditional cultivation practices, like irrigation, to modern solutions of precision agriculture. In this paper, we present in detail the subsystems and the architecture of an intelligent irrigation system for precision agriculture, the AREThOU5A IoT platform. We describe the operation of the IoT node that is utilized in the platform. Moreover, we apply the radiofrequency energy harvesting technique to the presented IoT platform, as an alternative technique to deliver power to the IoT node of the platform. To this end, we fabricate and validate a rectenna module for radiofrequency energy harvesting. Experimental results of the fabricated rectenna exhibit a satisfactory performance as a harvester of ambient sources in an outdoor environment. IEEE}, keywords = {Intelligent sensors, IoT technology, Irrigation, precision agriculture, Radio frequency, radio frequency energy harvesting, smart irrigation, Wireless communication, wireless sensor networks}, pubstate = {published}, tppubtype = {article} } @article{Amponis20211, title = {Inter-UAV routing scheme testbeds}, author = { G. Amponis and T. Lagkas and P. Sarigiannidis and V. Vitsas and P. Fouliras}, url = {https://www.researchgate.net/publication/347949781_Inter-UAV_Routing_Scheme_Testbeds}, doi = {10.3390/drones5010002}, year = {2020}, date = {2020-01-01}, journal = {Drones}, volume = {5}, number = {1}, pages = {1-17}, publisher = {MDPI AG}, abstract = {With the development of more advanced and efficient control algorithms and communication architectures, UAVs and networks thereof (swarms) now find applications in nearly all possible environments and scenarios. There exist numerous schemes which accommodate routing for such networks, many of which are specifically designed for distinct use-cases. Validation and evaluation of routing schemes is implemented for the most part using simulation software. This approach is however incapable of considering real-life noise, radio propagation models, channel bit error rate and signal-to-noise ratio. Most importantly, existing frameworks or simulation software cannot sense physical-layer related information regarding power consumption which an increasing number of routing protocols utilize as a metric. The work presented in this paper contributes to the analysis of already existing routing scheme evaluation frameworks and testbeds and proposes an efficient, universal and standardized hardware testbed. Additionally, three interface modes aimed at evaluation under different scenarios are provided. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Ad hoc networking, Drone swarms, Efficient routing, FANETs}, pubstate = {published}, tppubtype = {article} } @inbook{Goudos_2018, title = {Communication Protocols for the IoT-Based Smart Grid}, author = { S. K. Goudos and P. Sarigiannidis and P. I. Dallas and S. Kyriazakos}, url = {https://www.researchgate.net/publication/329169173_Communication_Protocols_for_the_IoT-Based_Smart_Grid_Design_Challenges_and_Paradigms}, doi = {10.1007/978-3-030-03640-9_4}, year = {2019}, date = {2019-11-01}, booktitle = {IoT for Smart Grids}, pages = {55--83}, publisher = {Springer International Publishing}, abstract = {The Internet of Things (IoT) is the communications paradigm that can provide the potential of ultimate communication. The IoT paradigm describes communication not only human to human (H2H) but also machine to machine (M2M) without the need of human interference. The Smart Grid (SG) is the new paradigm that enables highly efficient energy production, transport, and consumption along the whole chain, from the source to the user. SG is the combination of the classical power grid with emerging communication and information technologies. IoT based smart grid will be one of the largest instantiation of the IoT in the next future. In this chapter, we examine, review and present the current IoT enabler technologies for smart grid applications, starting from the physical layer to the application and data layer. © Springer Nature Switzerland AG 2019.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } @inbook{Keramidi2020239, title = {Call-Level Analysis of a Two-Link Multirate Loss Model with Restricted Accessibility}, author = { I. P. Keramidi and I. D. Moscholios and P. G. Sarigiannidis and M. D. Logothetis}, url = {https://www.researchgate.net/publication/335752015_Call-Level_Analysis_of_a_Two-Link_Multirate_Loss_Model_with_Restricted_Accessibility}, doi = {10.1007/978-3-030-31254-1_29}, year = {2019}, date = {2019-09-01}, booktitle = {Image Processing and Communications}, journal = {Advances in Intelligent Systems and Computing}, volume = {1062}, pages = {239--251}, publisher = {Springer International Publishing}, abstract = {We consider a two-link system with restricted accessibility that accommodates Poisson arriving calls from different service-classes and propose a multirate teletraffic loss model for its analysis. In a restricted accessibility system, a new call may be blocked even if available bandwidth units do exist at the time of its arrival. In the two-link system, each particular link has two thresholds which refer to the number of in-service calls in the link. The lowest threshold, named support threshold, defines up to which point the link can support calls offloaded from the other link. The highest threshold, named offloading threshold, defines the point where the link starts offloading calls to the other link. The two-link system with restricted accessibility is modelled as a loss model whose steady state probabilities do not have a product form solution. However, we propose approximate formulas for the calculation of call blocking probabilities. The accuracy of the formulas is verified through simulation and found to be quite satisfactory. © 2020, Springer Nature Switzerland AG.}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } @conference{Tsouros2019, title = {Data Acquisition and Analysis Methods in UAV- based Applications for Precision Agriculture}, author = { D. C. Tsouros and A. Triantafyllou and S. Bibi and P. G. Sarigannidis}, url = {https://www.researchgate.net/publication/335364671_Data_Acquisition_and_Analysis_Methods_in_UAV-_based_Applications_for_Precision_Agriculture}, doi = {10.1109/dcoss.2019.00080}, year = {2019}, date = {2019-05-01}, booktitle = {2019 15th International Conference on Distributed Computing in Sensor Systems (DCOSS)}, publisher = {IEEE}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Grammatikis2019e, title = {Securing the Internet of Things: Challenges, threats and solutions}, author = { P. I. Radoglou Grammatikis and P. G. Sarigiannidis and I. D. Moscholios}, url = {https://www.researchgate.net/publication/329183740_Securing_the_Internet_of_Things_Challenges_Threats_and_Solutions}, doi = {10.1016/j.iot.2018.11.003}, year = {2019}, date = {2019-03-01}, journal = {Internet of Things}, volume = {5}, pages = {41--70}, publisher = {Elsevier BV}, keywords = {}, pubstate = {published}, tppubtype = {article} } @conference{Pliatsios2019, title = {Cost-efficient Remote Radio Head Deployment in 5G Networks Under Minimum Capacity Requirements}, author = { D. Pliatsios and P. Sarigiannidis and I.D. Moscholios and A. Tsiakalos}, url = {https://www.researchgate.net/publication/338597444_Cost-efficient_Remote_Radio_Head_Deployment_in_5G_Networks_Under_Minimum_Capacity_Requirements}, doi = {10.1109/PACET48583.2019.8956245}, year = {2019}, date = {2019-01-01}, journal = {5th Panhellenic Conference on Electronics and Telecommunications, PACET 2019}, abstract = {Dense small cell deployment is an effective way to address the increasing requirements of the emerging Fifth Generation mobile networks. The Cloud Radio Access Network (C-RAN) is an emerging concept that can achieve very dense small cell deployment. In ultra-dense C-RAN architectures with numerous Remote Radio Heads (RRHs), the minimization of the deployment cost is a critical issue in the radio network planning phase. In this paper, we propose a low complexity algorithm that minimizes the required number of small cells, while ensuring user satisfaction in terms of network capacity. The algorithm is based on the successive elimination of RRHs, and it simultaneously solves the minimization and the optimal deployment problems. The evaluation results indicate that the proposed algorithm can efficiently solve the aforementioned problems. © 2019 IEEE.}, keywords = {5G, Cloud Radio Access Network (C-RAN), cost optimization, small cell deployment, traffic demand}, pubstate = {published}, tppubtype = {conference} } @conference{Panagoulias2019, title = {Performance Metrics in OFDM Wireless Networks with Restricted Accessibility}, author = { P. Panagoulias and I. Moscholios and P. Sarigiannidis and N. Sagias and M. Logothetis}, url = {https://www.researchgate.net/publication/338601635_Performance_Metrics_in_OFDM_Wireless_Networks_with_Restricted_Accessibility}, doi = {10.1109/PACET48583.2019.8956292}, year = {2019}, date = {2019-01-01}, journal = {5th Panhellenic Conference on Electronics and Telecommunications, PACET 2019}, abstract = {In this paper we study the downlink of an Orthogonal Frequency Division Multiplexing (OFDM) based cell that accommodates calls from different service-classes with different resource requirements. We assume that calls arrive in the system according to a Poisson process while the call admission is based on restricted accessibility. In a restricted accessibility system, a new call may be blocked even if available resources do exist at the time of its arrival. To determine, via recursive formulas, the most important performance metrics, i.e., Call Blocking Probabilities (CBP) and resource utilization in this system, we model the system as a multirate loss model. The accuracy of the proposed formulas is verified via simulation and found to be quite satisfactory. © 2019 IEEE.}, keywords = {call blocking, OFDM, Poisson, Recursive, Restricted}, pubstate = {published}, tppubtype = {conference} } @conference{Pliatsios2019b, title = {A novel and interactive industrial control system honeypot for critical smart grid infrastructure}, author = { D. Pliatsios and P. Sarigiannidis and T. Liatifis and K. Rompolos and I. Siniosoglou}, url = {https://www.researchgate.net/publication/335887093_A_Novel_and_Interactive_Industrial_Control_System_Honeypot_for_Critical_Smart_Grid_Infrastructure}, doi = {10.1109/CAMAD.2019.8858431}, year = {2019}, date = {2019-01-01}, journal = {IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks, CAMAD}, volume = {2019-September}, abstract = {The Industrial Control Systems (ICS) are the underlying monitoring and control components of critical infrastructures, which consist of a number of distributed field devices, such as Programmable Logic Controllers (PLCs), Remote Terminal Units (RTUs) and Human Machine Interfaces (HMIs). As modern ICS are connected to the Internet, in the context of their digitalization as a part of the Internet of Things (IoT) domain, a number of security threats are introduced, whose exploitation can lead to severe consequences. Honeypots and honeynets are promising countermeasures that attract attackers and mislead them from hacking the real infrastructure, while gaining valuable information about the attack patterns as well as the source of the attack. In this work, we implement an interactive, proof-of concept ICS honeypot, which is based on Conpot, that is able to emulate a physical ICS device, by replicating realistic traffic from the real device. As the honeypot runs inside a Virtual Machine, it is possible to emulate the entire organization's ICS infrastructure, a fact that is very important for the security of the modern critical infrastructure. In order to assess the proposed honeypot, a real-life demonstration scenario was designed, which involves a hydro power plant. The honeypot architecture is provided, while the structural components are presented in detail. © 2019 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Efstathopoulos2019, title = {Operational data based intrusion detection system for smart grid}, author = { G. Efstathopoulos and P.R. Grammatikis and P. Sarigiannidis and V. Argyriou and A. Sarigiannidis and K. Stamatakis and M.K. Angelopoulos and S.K. Athanasopoulos}, url = {https://www.researchgate.net/publication/335866997_Operational_Data_Based_Intrusion_Detection_System_for_Smart_Grid}, doi = {10.1109/CAMAD.2019.8858503}, year = {2019}, date = {2019-01-01}, journal = {IEEE International Workshop on Computer Aided Modeling and Design of Communication Links and Networks, CAMAD}, volume = {2019-September}, abstract = {With the rapid progression of Information and Communication Technology (ICT) and especially of Internet of Things (IoT), the conventional electrical grid is transformed into a new intelligent paradigm, known as Smart Grid (SG). SG provides significant benefits both for utility companies and energy consumers such as the two-way communication (both electricity and information), distributed generation, remote monitoring, self-healing and pervasive control. However, at the same time, this dependence introduces new security challenges, since SG inherits the vulnerabilities of multiple heterogeneous, co-existing legacy and smart technologies, such as IoT and Industrial Control Systems (ICS). An effective countermeasure against the various cyberthreats in SG is the Intrusion Detection System (IDS), informing the operator timely about the possible cyberattacks and anomalies. In this paper, we provide an anomaly-based IDS especially designed for SG utilising operational data from a real power plant. In particular, many machine learning and deep learning models were deployed, introducing novel parameters and feature representations in a comparative study. The evaluation analysis demonstrated the efficacy of the proposed IDS and the improvement due to the suggested complex data representation. © 2019 IEEE.}, keywords = {Anomaly Detection, Cybersecurity, intrusion detection system, machine learning, Operational Data, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Zozas2019212, title = {Estimating the Maintenance Effort of JavaScript Applications}, author = { I. Zozas and S. Bibi and A. Ampatzoglou and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/332909694_Estimating_the_Maintenance_Effort_of_JavaScript_Applications}, doi = {10.1109/SEAA.2019.00042}, year = {2019}, date = {2019-01-01}, journal = {Proceedings - 45th Euromicro Conference on Software Engineering and Advanced Applications, SEAA 2019}, pages = {212-219}, abstract = {Successful software project survival and progress over time is highly dependent on effectively managing the maintenance process. Estimating accurately maintenance process factors like the maintenance effort and the level of changes required for a new release is considered a crucial task for allocating resources. In this work we examine the maintenance process factors of JavaScript applications, which at the moment are understudied despite the need of language specific maintenance models. Furthermore we propose two maintenance indices for estimating the changes and the effort required for maintaining JavaScript applications by considering a variety of maintenance drivers. We evaluated the proposed indices through a case study on 5,788 releases coming from 60 popular JavaScript applications. The results show that project activity factors (i.e., number of open bugs and number of corrective maintenance activities) are important maintenance drivers. The proposed indices are evaluated in terms of predictive and discriminative power and both achieve high accuracy. © 2019 IEEE.}, keywords = {JavaScript, maintenance index, open source software, software development, software maintenance effort}, pubstate = {published}, tppubtype = {conference} } @conference{Keramidi2019, title = {Call blocking probabilities in a two-link loss model with restricted accessibility}, author = { I.P. Keramidi and I.D. Moscholios and P.G. Sarigiannidis and M.D. Logothetis}, url = {https://www.researchgate.net/publication/336097286_Call_Blocking_Probabilities_in_a_Two-Link_Loss_Model_with_Restricted_Accessibility}, doi = {10.1109/ConTEL.2019.8848554}, year = {2019}, date = {2019-01-01}, journal = {ConTEL 2019 - 15th International Conference on Telecommunications, Proceedings}, abstract = {In this paper we study the impact of restricted accessibility in a system of two parallel links that accommodates Poisson arriving calls from a single service-class. In a restricted accessibility system, a new call may be blocked even if available bandwidth units do exist at the time of its arrival. In the two-link system, each particular link has a low and a high threshold. Both thresholds express the number of in-service calls in the link. The low threshold shows the point up to which the link can support offloaded calls from the other link. The high threshold shows the point where one link starts offloading calls to the other link. The two-link system with restricted accessibility is modelled as a loss model whose steady state probabilities do not have a product form solution. In order to determine the main teletraffic performance metric in this model which is call blocking probabilities, we propose an approximate method. The accuracy of this method is verified via simulation and found to be quite satisfactory. © 2019 IEEE.}, keywords = {call blocking, Loss model, Offloading, Product form, Restricted accessibility, Teletraffic}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou-Grammatikis201941, title = {Attacking IEC-60870-5-104 SCADA Systems}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and I. Giannoulakis and E. Kafetzakis and E. Panaousis}, url = {https://www.researchgate.net/publication/333671061_Attacking_IEC-60870-5-104_SCADA_Systems}, doi = {10.1109/SERVICES.2019.00022}, year = {2019}, date = {2019-01-01}, journal = {Proceedings - 2019 IEEE World Congress on Services, SERVICES 2019}, pages = {41-46}, abstract = {The rapid evolution of the Information and Communications Technology (ICT) services transforms the conventional electrical grid into a new paradigm called Smart Grid (SG). Even though SG brings significant improvements, such as increased reliability and better energy management, it also introduces multiple security challenges. One of the main reasons for this is that SG combines a wide range of heterogeneous technologies, including Internet of Things (IoT) devices as well as Supervisory Control and Data Acquisition (SCADA) systems. The latter are responsible for monitoring and controlling the automatic procedures of energy transmission and distribution. Nevertheless, the presence of these systems introduces multiple vulnerabilities because their protocols do not implement essential security mechanisms such as authentication and access control. In this paper, we focus our attention on the security issues of the IEC 60870-5-104 (IEC-104) protocol, which is widely utilized in the European energy sector. In particular, we provide a SCADA threat model based on a Coloured Petri Net (CPN) and emulate four different types of cyber attacks against IEC-104. Last, we used AlienVault's risk assessment model to evaluate the risk level that each of these cyber attacks introduces to our system to confirm our intuition about their severity. © 2019 IEEE.}, keywords = {Coloured Petri Net, IEC 60870 5 104, OSSIM, SCADA security, Smart Grid, Threat modelling}, pubstate = {published}, tppubtype = {conference} } @conference{Al-Saadi20192025, title = {A novel approach for performance-based clustering and anagement of network traffic flows}, author = { M. Al-Saadi and B.V. Ghita and S. Shiaeles and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/334634109_A_novel_approach_for_performance-based_clustering_and_anagement_of_network_traffic_flows}, doi = {10.1109/IWCMC.2019.8766728}, year = {2019}, date = {2019-01-01}, journal = {2019 15th International Wireless Communications and Mobile Computing Conference, IWCMC 2019}, pages = {2025-2030}, abstract = {Management of network performance comprises numerous functions such as measuring, modelling, planning and optimising networks to ensure that they transmit traffic with the speed, capacity and reliability expected by the applications, each with different requirements for bandwidth and delay. Overall, the objective of this paper is to propose a novel mechanism to optimise the network resource allocation through supporting the routing of individual flows, by clustering them based on performance and integrating the respective clusters with an SDN scheme. In this paper we have employed a particular set of traffic features then applied data reduction and unsupervised machine learning techniques, to derive an Internet traffic performance-based clustering model. Finally, the resulting data clusters are integrated within a unified SDN architectural solution, which improves network management by finding nearly optimal flow routing, to be evaluated against a number of traffic data sources. © 2019 IEEE.}, keywords = {Clustering, Network performance, SDN, Unsupervised algorithm}, pubstate = {published}, tppubtype = {conference} } @conference{Dalamagkas201993, title = {A Survey on honeypots, honeynets and their applications on smart grid}, author = { C. Dalamagkas and P. Sarigiannidis and D. Ioannidis and E. Iturbe and O. Nikolis and F. Ramos and E. Rios and A. Sarigiannidis and D. Tzovaras}, url = {https://www.researchgate.net/publication/332910149_A_Survey_On_Honeypots_Honeynets_And_Their_Applications_On_Smart_Grid}, doi = {10.1109/NETSOFT.2019.8806693}, year = {2019}, date = {2019-01-01}, journal = {Proceedings of the 2019 IEEE Conference on Network Softwarization: Unleashing the Power of Network Softwarization, NetSoft 2019}, pages = {93-100}, abstract = {Power grid is a major part of modern Critical Infrastructure (CIN). The rapid evolution of Information and Communication Technologies (ICT) enables traditional power grids to encompass advanced technologies that allow them to monitor their state, increase their reliability, save costs and provide ICT services to end customers, thus converting them into smart grids. However, smart grid is exposed to several security threats, as hackers might try to exploit vulnerabilities of the industrial infrastructure and cause disruption to national electricity system with severe consequences to citizens and commerce. This paper investigates and compares honey-x technologies that could be applied to smart grid in order to distract intruders, obtain attack strategies, protect the real infrastructure and form forensic evidence to be used in court. © 2019 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Pliatsios2019416, title = {Power allocation in downlink non-orthogonal multiple access IoT-enabled Systems: A particle swarm optimization approach}, author = { D. Pliatsios and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/335366103_Power_Allocation_in_Downlink_Non-orthogonal_Multiple_Access_IoT-enabled_Systems_A_Particle_Swarm_Optimization_Approach}, doi = {10.1109/DCOSS.2019.00085}, year = {2019}, date = {2019-01-01}, journal = {Proceedings - 15th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2019}, pages = {416-422}, abstract = {The exponential proliferation of the Internet of Things (IoT) concept renders it an integral part of the emerging 5th Generation (5G) of mobile networks. In order to address the requirement of massive IoT-type connections, the spectrum has to be better utilized. Non-Orthogonal Multiple Access (NOMA) is a promising technique that can effectively improve the spectrum efficiency. In this paper, we consider the power allocation problem of a downlink Single Input Single Output (SISO) NOMA system. We aim to maximize the total system throughput, while maintaining a good level of fairness among the users. The system available bandwidth is divided into a number of subbands, and each subband is assigned to two users. The combination of the assigned users is based on the performance of each one, in terms of throughput. Two methods are reported for allocating power to each subband. In the first method, the maximum transmission power is equally divided to all bands, whereas, in the second, we use the Particle Swarm Optimization (PSO) algorithm to allocate the power to each band aiming to maximize the total system throughput. The power allocated to each band is further divided into the two multiplexed users. A series of extensive simulations and comparisons were employed to evaluate our proposed power allocation methods. The results indicate that our methods provide a significant improvement over the compared ones, both in terms of achieved system throughput and fairness among the users. © 2019 IEEE.}, keywords = {Internet of Things (IoT), Non Orthogonal Multiple Access (NOMA), Particle Swarm Optimization (PSO)}, pubstate = {published}, tppubtype = {conference} } @conference{Triantafyllou2019385, title = {An architecture model for smart farming}, author = { A. Triantafyllou and D.C. Tsouros and P. Sarigiannidis and S. Bibi}, url = {https://www.researchgate.net/publication/335362251_An_Architecture_model_for_Smart_Farming}, doi = {10.1109/DCOSS.2019.00081}, year = {2019}, date = {2019-01-01}, journal = {Proceedings - 15th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2019}, pages = {385-392}, abstract = {Smart Farming is a development that emphasizes on the use of modern technologies in the cyber-physical field management cycle. Technologies such as the Internet of Things (IoT) and Cloud Computing have accelerated the digital transformation of the conventional agricultural practices promising increased production rate and product quality. The adoption of smart farming though is hampered because of the lack of models providing guidance to practitioners regarding the necessary components that constitute IoT based monitoring systems. To guide the process of designing and implementing Smart farming monitoring systems, in this paper we propose a generic reference architecture model, taking also into consideration a very important non-functional requirement, the energy consumption restriction. Moreover, we present and discuss the technologies that incorporate the four layers of the architecture model that are the Sensor Layer, the Network Layer, the Service Layer and the Application Layer. A discussion is also conducted upon the challenges that smart farming monitoring systems face. © 2019 IEEE.}, keywords = {Cloud Computing, Communication technologies, Internet of things, precision agriculture, smart farming, wireless sensor networks}, pubstate = {published}, tppubtype = {conference} } @conference{Li2019, title = {Buffer-Aided Relaying for Downlink NOMA Systems with Direct Links}, author = { J. Li and X. Lei and P.D. Diamantoulakis and P. Sarigiannidis and G.K. Karagiannidis}, url = {https://www.researchgate.net/publication/334487941_Buffer-Aided_Relaying_for_Downlink_NOMA_Systems_with_Direct_Links}, doi = {10.1109/ICC.2019.8761637}, year = {2019}, date = {2019-01-01}, journal = {IEEE International Conference on Communications}, volume = {2019-May}, abstract = {Non-orthogonal multiple access (NOMA) has recently attracted the academic and industrial interest, due to offering higher spectral efficiency and connectivity compared to conventional orthogonal multiple access schemes. In this paper, buffer-aided relaying for a downlink NOMA system with direct links is proposed, while in order to take advantage the extra degrees of freedom, appropriate transmission modes are presented. Targeting at the throughput maximization, the corresponding optimization problem is formulated and solved and theoretical expressions are derived for the optimal mode selection policy and maximum throughput. Finally, simulation results illustrate the efficiency of the proposed scheme and its superiority compared with a previously presented baseline scheme. © 2019 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Rimboux2019304, title = {Smart IoT cameras for crowd analysis based on augmentation for automatic pedestrian detection, simulation and annotation}, author = { A. Rimboux and R. Dupre and E. Daci and T. Lagkas and P. Sarigiannidis and P. Remagnino and V. Argyriou}, url = {https://www.researchgate.net/publication/333679279_Smart_IoT_Cameras_for_Crowd_Analysis_based_on_augmentation_for_automatic_pedestrian_detection_simulation_and_annotation}, doi = {10.1109/DCOSS.2019.00070}, year = {2019}, date = {2019-01-01}, journal = {Proceedings - 15th Annual International Conference on Distributed Computing in Sensor Systems, DCOSS 2019}, pages = {304-311}, abstract = {Smart video sensors for applications related to surveillance and security are IOT-based as they use Internet for various purposes. Such applications include crowd behaviour monitoring and advanced decision support systems operating and transmitting information over internet. The analysis of crowd and pedestrian behaviour is an important task for smart IoT cameras and in particular video processing. In order to provide related behavioural models, simulation and tracking approaches have been considered in the literature. In both cases ground truth is essential to train deep models and provide a meaningful quantitative evaluation. We propose a framework for crowd simulation and automatic data generation and annotation that supports multiple cameras and multiple targets. The proposed approach is based on synthetically generated human agents, augmented frames and compositing techniques combined with path finding and planning methods. A number of popular crowd and pedestrian data sets were used to validate the model, and scenarios related to annotation and simulation were considered. © 2019 IEEE.}, keywords = {Crowd analysis, Crowd behavior, Data augmentation}, pubstate = {published}, tppubtype = {conference} } @article{Dalamagkas2019103, title = {Dynamic scheduling in TWDM-PONs using game theory}, author = { C. Dalamagkas and P. Sarigiannidis and S. Kapetanakis and I. Moscholios}, url = {https://www.researchgate.net/publication/321881881_Dynamic_scheduling_in_TWDM-PONs_using_game_theory}, doi = {10.1016/j.osn.2017.12.004}, year = {2019}, date = {2019-01-01}, journal = {Optical Switching and Networking}, volume = {33}, pages = {103-113}, abstract = {Efficient utilization of Passive Optical Networks (PONs) within a broad region of high user numbers, heavy bandwidth demand and large-scale central servicing stations seems a challenging task in explosive high-bandwidth environments. New Generation PONs (NG-PONs) enable multiple channels in both directions and they seem promising towards meeting advanced user applications and services. However, sophisticated bandwidth distribution should be in place to ensure appropriate allocation and efficient management of heavy user demands subject to the available channels. Most of the literature on dynamic bandwidth distribution in NG-PONs usually pertains to heuristic techniques that may be susceptible to expert bias, require substantial knowledge and experience to be applied and their evaluation may focus primarily on minor issues vs. few fundamental major ones. To surpass these limitations game theory can be applied to address efficiently the above heuristic disadvantages and solve the heavy user load-heavy demand over large bandwidth problem in a stochastic way. This work presents the next step forwards using multi-channel multi-stochastic reasoning by utilizing the full channel range to satisfy fairly user requests and high network traffic within a NG-PON2 network. We present the full algorithm as applied to standardized NG-PON2 as well as a series of evaluation experiments to prove its applicability in terms of fairness, goodput and delay. According to the simulation results, the proposed scheme succeeds to provide a fair bandwidth distribution, when triggered, while it is able to a) reduce the experienced delay from 1 to 6 msec and b) double the offered goodput compared to the pure allocation scheme. © 2018 Elsevier B.V.}, keywords = {Game theory, Next-generation passive optical network 2, Scheduling, Time and wavelength division multiplexing}, pubstate = {published}, tppubtype = {article} } @article{Loukas2019124, title = {A taxonomy and survey of cyber-physical intrusion detection approaches for vehicles}, author = { G. Loukas and E. Karapistoli and E. Panaousis and P. Sarigiannidis and A. Bezemskij and T. Vuong}, url = {https://www.researchgate.net/publication/328025147_A_taxonomy_and_survey_of_cyber-physical_intrusion_detection_approaches_for_vehicles}, doi = {10.1016/j.adhoc.2018.10.002}, year = {2019}, date = {2019-01-01}, journal = {Ad Hoc Networks}, volume = {84}, pages = {124-147}, abstract = {With the growing threat of cyber and cyber-physical attacks against automobiles, drones, ships, driverless pods and other vehicles, there is also a growing need for intrusion detection approaches that can facilitate defence against such threats. Vehicles tend to have limited processing resources and are energy-constrained. So, any security provision needs to abide by these limitations. At the same time, attacks against vehicles are very rare, often making knowledge-based intrusion detection systems less practical than behaviour-based ones, which is the reverse of what is seen in conventional computing systems. Furthermore, vehicle design and implementation can differ wildly between different types or different manufacturers, which can lead to intrusion detection designs that are vehicle-specific. Equally importantly, vehicles are practically defined by their ability to move, autonomously or not. Movement, as well as other physical manifestations of their operation may allow cyber security breaches to lead to physical damage, but can also be an opportunity for detection. For example, physical sensing can contribute to more accurate or more rapid intrusion detection through observation and analysis of physical manifestations of a security breach. This paper presents a classification and survey of intrusion detection systems designed and evaluated specifically on vehicles and networks of vehicles. Its aim is to help identify existing techniques that can be adopted in the industry, along with their advantages and disadvantages, as well as to identify gaps in the literature, which are attractive and highly meaningful areas of future research. © 2018 Elsevier B.V.}, keywords = {Aircraft, Automobiles, Cyber security, Cyber-physical systems, Driverless pods, Intrusion detection, Robotic land vehicles, unmanned aerial vehicles, VANET, Vehicles, Vehicular networks}, pubstate = {published}, tppubtype = {article} } @article{Radoglou-Grammatikis201946595, title = {Securing the Smart Grid: A Comprehensive Compilation of Intrusion Detection and Prevention Systems}, author = { P.I. Radoglou-Grammatikis and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/332188706_Securing_the_Smart_Grid_A_Comprehensive_Compilation_of_Intrusion_Detection_and_Prevention_Systems}, doi = {10.1109/ACCESS.2019.2909807}, year = {2019}, date = {2019-01-01}, journal = {IEEE Access}, volume = {7}, pages = {46595-46620}, abstract = {The smart grid (SG) paradigm is the next technological leap of the conventional electrical grid, contributing to the protection of the physical environment and providing multiple advantages such as increased reliability, better service quality, and the efficient utilization of the existing infrastructure and the renewable energy resources. However, despite the fact that it brings beneficial environmental, economic, and social changes, the existence of such a system possesses important security and privacy challenges, since it includes a combination of heterogeneous, co-existing smart, and legacy technologies. Based on the rapid evolution of the cyber-physical systems (CPS), both academia and industry have developed appropriate measures for enhancing the security surface of the SG paradigm using, for example, integrating efficient, lightweight encryption and authorization mechanisms. Nevertheless, these mechanisms may not prevent various security threats, such as denial of service (DoS) attacks that target on the availability of the underlying systems. An efficient countermeasure against several cyberattacks is the intrusion detection and prevention system (IDPS). In this paper, we examine the contribution of the IDPSs in the SG paradigm, providing an analysis of 37 cases. More detailed, these systems can be considered as a secondary defense mechanism, which enhances the cryptographic processes, by timely detecting or/and preventing potential security violations. For instance, if a cyberattack bypasses the essential encryption and authorization mechanisms, then the IDPS systems can act as a secondary protection service, informing the system operator for the presence of the specific attack or enabling appropriate preventive countermeasures. The cases we study focused on the advanced metering infrastructure (AMI), supervisory control and data acquisition (SCADA) systems, substations, and synchrophasors. Based on our comparative analysis, the limitations and the shortcomings of the current IDPS systems are identified, whereas appropriate recommendations are provided for future research efforts. © 2013 IEEE.}, keywords = {Advanced Metering Infrastructure, cyberattacks, intrusion detection system, Intrusion prevention system, SCADA, security, Smart Grid, substation, Synchrophasor}, pubstate = {published}, tppubtype = {article} } @article{Goudos2019105687, title = {A Novel Design Approach for 5G Massive MIMO and NB-IoT Green Networks Using a Hybrid Jaya-Differential Evolution Algorithm}, author = { S.K. Goudos and M. Deruyck and D. Plets and L. Martens and K.E. Psannis and P. Sarigiannidis and W. Joseph}, url = {https://www.researchgate.net/publication/334778653_A_Novel_Design_Approach_for_5G_Massive_MIMO_and_NB-IoT_Green_Networks_Using_a_Hybrid_Jaya-Differential_Evolution_Algorithm}, doi = {10.1109/ACCESS.2019.2932042}, year = {2019}, date = {2019-01-01}, journal = {IEEE Access}, volume = {7}, pages = {105687-105700}, abstract = {Our main objective is to reduce power consumption by responding to the instantaneous bit rate demand by the user for 4th Generation (4G) and 5th Generation (5G) Massive MIMO network configurations. Moreover, we present and address the problem of designing green LTE networks with the Internet of Things (IoT) nodes. We consider the new NarrowBand-IoT (NB-IoT) wireless technology that will emerge in current and future access networks. In this context, we apply emerging evolutionary algorithms in the context of green network design. We investigate three different cases to show the performance of the new proposed algorithm, namely the 4G, 5G Massive MIMO, and the NB-IoT technologies. More specifically, we investigate the Teaching-Learning-Optimization (TLBO), the Jaya algorithm, the self-adaptive differential evolution jDE algorithm, and other hybrid algorithms. We introduce a new hybrid algorithm named Jaya-jDE that uses concepts from both Jaya and jDE algorithms in an effective way. The results show that 5G Massive MIMO networks require about 50% less power consumption than the 4G ones, and the NB-IoT in-band deployment requires about 10% less power than guard-band deployment. Moreover, Jaya-jDE emerges as the best algorithm based on the results. © 2013 IEEE.}, keywords = {4G, 5G, evolutionary algorithms, green networks, hybrid networks, Massive MIMO, NB-IoT, network design, network planning, power consumption}, pubstate = {published}, tppubtype = {article} } @article{Lytos2019, title = {The evolution of argumentation mining: From models to social media and emerging tools}, author = { A. Lytos and T. Lagkas and P. Sarigiannidis and K. Bontcheva}, url = {https://www.researchgate.net/publication/334195420_The_evolution_of_argumentation_mining_From_models_to_social_media_and_emerging_tools}, doi = {10.1016/j.ipm.2019.102055}, year = {2019}, date = {2019-01-01}, journal = {Information Processing and Management}, volume = {56}, number = {6}, abstract = {Argumentation mining is a rising subject in the computational linguistics domain focusing on extracting structured arguments from natural text, often from unstructured or noisy text. The initial approaches on modeling arguments was aiming to identify a flawless argument on specific fields (Law, Scientific Papers) serving specific needs (completeness, effectiveness). With the emerge of Web 2.0 and the explosion in the use of social media both the diffusion of the data and the argument structure have changed. In this survey article, we bridge the gap between theoretical approaches of argumentation mining and pragmatic schemes that satisfy the needs of social media generated data, recognizing the need for adapting more flexible and expandable schemes, capable to adjust to the argumentation conditions that exist in social media. We review, compare, and classify existing approaches, techniques and tools, identifying the positive outcome of combining tasks and features, and eventually propose a conceptual architecture framework. The proposed theoretical framework is an argumentation mining scheme able to identify the distinct sub-tasks and capture the needs of social media text, revealing the need for adopting more flexible and extensible frameworks. © 2019 Elsevier Ltd}, keywords = {Argumentation mining, Argumentation models, Argumentation tools, Computational linguistics, machine learning, Social media}, pubstate = {published}, tppubtype = {article} } @article{Panagoulias2019b, title = {An analytical framework in OFDM wireless networks servicing random or quasi-random traffic}, author = { P.I. Panagoulias and I.D. Moscholios and P.G. Sarigiannidis and M. Glabowski and M.D. Logothetis}, url = {https://www.researchgate.net/publication/337850639_An_Analytical_Framework_in_OFDM_Wireless_Networks_Servicing_Random_or_Quasi-Random_Traffic}, doi = {10.3390/app9245376}, year = {2019}, date = {2019-01-01}, journal = {Applied Sciences (Switzerland)}, volume = {9}, number = {24}, abstract = {We consider the downlink of an orthogonal frequency division multiplexing (OFDM)-based cell that services calls from many service-classes. The call arrival process is random (Poisson) or quasi-random, i.e., calls are generated by an infinite or a finite number of sources, respectively. In order to determine congestion probabilities and resource utilization, we model the cell as a multirate loss model. Regarding the call admission, we consider the restricted accessibility, the bandwidth reservation (BR), and the complete sharing (CS) policies. In a system of restricted accessibility, a new call may be blocked even if resources do exist. In a BR system, subcarriers can be reserved in favor of calls of high subcarrier requirements. Finally, in a CS system, a new call is blocked due to resource unavailability. In all three policies, we show that there exist recursive formulas for the determination of the various performance measures. Based on simulation, the accuracy of the proposed formulas is found to be quite satisfactory. © 2019 by the authors.}, keywords = {Complete sharing, Congestion, OFDM, Quasi-random, Random, Recursive, Reservation, Restricted}, pubstate = {published}, tppubtype = {article} } @article{Triantafyllou201834b, title = {Towards An Anonymous Incident Communication Channel for Electric Smart Grids}, author = { A. Triantafyllou and P. Sarigiannidis and A. Sarigiannidis and E. Rios and E. Iturbe}, url = {https://www.researchgate.net/publication/334498387_TOWARDS_AN_ANONYMOUS_INCIDENT_COMMUNICATION_CHANNEL_FOR_ELECTRIC_SMART_GRIDS}, doi = {10.1145/3291533.3291559}, year = {2019}, date = {2019-01-01}, journal = {Azerbaijan Journal of High Performance Computing}, volume = {2}, number = {1}, pages = {7-28}, abstract = {The Electric Smart Grid (ESG) is an intelligent critical infrastructure aiming to create an automated and distributed advanced energy delivery network, while preserving information privacy. This study proposes the implementation of an Anonymous Incident Communication Channel (AICC) amongst smart grids across Europe to improve situational awareness and enhance security of the new electric intelligent infrastructures. All participating organizations will have the ability to broadcast sensitive information, stored anonymously in a repository, without exposing the reputation of the organisation. This work focuses on the requirements of establishment, the possible obstacles and proposed data protection techniques to be applied in the AICC. Furthermore, a discussion is conducted regarding the documentation of cyber-incidents. Last but not least, the benefits and the potential risks of this AICC concept are also provided. © 2018 Association for Computing Machinery.}, keywords = {Anonymity, Anonymous repository of incidents, Group signature, Smart Grid}, pubstate = {published}, tppubtype = {article} } @article{Tsouros2019b, title = {A review on UAV-based applications for precision agriculture}, author = { D.C. Tsouros and S. Bibi and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/337187714_A_Review_on_UAV-Based_Applications_for_Precision_Agriculture}, doi = {10.3390/info10110349}, year = {2019}, date = {2019-01-01}, journal = {Information (Switzerland)}, volume = {10}, number = {11}, abstract = {Emerging technologies such as Internet of Things (IoT) can provide significant potential in Smart Farming and Precision Agriculture applications, enabling the acquisition of real-time environmental data. IoT devices such as Unmanned Aerial Vehicles (UAVs) can be exploited in a variety of applications related to crops management, by capturing high spatial and temporal resolution images. These technologies are expected to revolutionize agriculture, enabling decision-making in days instead of weeks, promising significant reduction in cost and increase in the yield. Such decisions enable the effective application of farm inputs, supporting the four pillars of precision agriculture, i.e., apply the right practice, at the right place, at the right time and with the right quantity. However, the actual proliferation and exploitation of UAVs in Smart Farming has not been as robust as expected mainly due to the challenges confronted when selecting and deploying the relevant technologies, including the data acquisition and image processing methods. The main problem is that still there is no standardized workflow for the use of UAVs in such applications, as it is a relatively new area. In this article, we review the most recent applications of UAVs for Precision Agriculture. We discuss the most common applications, the types of UAVs exploited and then we focus on the data acquisition methods and technologies, appointing the benefits and drawbacks of each one. We also point out the most popular processing methods of aerial imagery and discuss the outcomes of each method and the potential applications of each one in the farming operations. © 2019 by the authors.}, keywords = {Image Processing, IoT, precision agriculture, remote sensing, Review, smart farming, UAS, UAV, Unmanned Aerial System, Unmanned Aerial Vehicle}, pubstate = {published}, tppubtype = {article} } @article{Triantafyllou2019b, title = {Precision agriculture: A remote sensing monitoring system architecture}, author = { A. Triantafyllou and P. Sarigiannidis and S. Bibi}, url = {https://www.researchgate.net/publication/337192880_Precision_Agriculture_A_Remote_Sensing_Monitoring_System_Architecture}, doi = {10.3390/info10110348}, year = {2019}, date = {2019-01-01}, journal = {Information (Switzerland)}, volume = {10}, number = {11}, abstract = {Smart Farming is a development that emphasizes on the use of modern technologies in the cyber-physical field management cycle. Technologies such as the Internet of Things (IoT) and Cloud Computing have accelerated the digital transformation of the conventional agricultural practices promising increased production rate and product quality. The adoption of smart farming though is hampered because of the lack of models providing guidance to practitioners regarding the necessary components that constitute IoT-based monitoring systems. To guide the process of designing and implementing Smart farming monitoring systems, in this paper we propose a generic reference architecture model, taking also into consideration a very important non-functional requirement, the energy consumption restriction. Moreover, we present and discuss the technologies that incorporate the seven layers of the architecture model that are the Sensor Layer, the Link Layer, the Encapsulation Layer, the Middleware Layer, the Configuration Layer, the Management Layer and the Application Layer. Furthermore, the proposed Reference Architecture model is exemplified in a real-world application for surveying Saffron agriculture in Kozani, Greece. © 2019 by the authors.}, keywords = {Cloud Computing, Communication technologies, Internet of things, precision agriculture, smart farming, wireless sensor networks}, pubstate = {published}, tppubtype = {article} } @article{Pliatsios2019d, title = {Resource allocation combining heuristic matching and particle swarm optimization approaches: The case of Downlink Non-Orthogonal Multiple Access}, author = { D. Pliatsios and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/336928272_Resource_Allocation_Combining_Heuristic_Matching_and_Particle_Swarm_Optimization_Approaches_The_Case_of_Downlink_Non-Orthogonal_Multiple_Access}, doi = {10.3390/info10110336}, year = {2019}, date = {2019-01-01}, journal = {Information (Switzerland)}, volume = {10}, number = {11}, abstract = {The ever-increasing requirement of massive connectivity, due to the rapid deployment of internet of things (IoT) devices, in the emerging 5th generation (5G) mobile networks commands for even higher utilization of the available spectrum. Non-orthogonal multiple access (NOMA) is a promising solution that can effectively accommodate a higher number of users, resulting in increased spectrum utilization. In this work, we aim to maximize the total throughput of a NOMA system, while maintaining a good level of fairness among the users. We propose a three-step method where the first step matches the users to the channels using a heuristic matching algorithm, while the second step utilizes the particle swarm optimization algorithm to allocate the power to each channel. In the third step, the power allocated to each channel is further distributed to the multiplexed users based on their respective channel gains. Based on extensive performance simulations, the proposed method offers notable improvement, e.g., 15% in terms of system throughput and 55% in terms of user fairness. © 2019 by the authors.}, keywords = {5G, Heuristic optimization, Non-orthogonal multiple access, Resource allocation}, pubstate = {published}, tppubtype = {article} } @conference{Radoglou-Grammatikis2019b, title = {An Anomaly-Based Intrusion Detection System for the Smart Grid Based on CART Decision Tree}, author = { P. I. Radoglou-Grammatikis and P. G. Sarigiannidis}, url = {An Anomaly-Based Intrusion Detection System for the Smart Grid Based on CART Decision Tree}, doi = {10.1109/GIIS.2018.8635743}, year = {2018}, date = {2018-10-01}, booktitle = {2018 Global Information Infrastructure and Networking Symposium (GIIS)}, journal = {2018 Global Information Infrastructure and Networking Symposium, GIIS 2018}, publisher = {IEEE}, abstract = {The Smart Grid (SG) paradigm constitutes the new technological evolution of the traditional electrical grid, providing remote monitoring and controlling capabilities among all its operations through computing services. These new capabilities offer a lot of benefits, such as better energy management, increased reliability and security, as well as more economical pricing. However, despite these advantages, it introduces significant security challenges, as the computing systems and the corresponding communications are characterized by several cybersecurity threats. An efficient solution against cyberattacks is the Intrusion Detection Systems (IDS). These systems usually operate as a second line of defence and have the ability to detect or even prevent cyberattacks in near real-Time. In this paper, we present a new IDS for the Advanced Metering Infrastructure (AMI) utilizing machine learning capabilities based on a decision tree. Decision trees have been used for multiple classification problems like the distinguishment between the normal and malicious activities. The experimental evaluation demonstrates the efficiency of the proposed IDS, as the Accuracy and the True Positive Rate of our IDS reach 0.996 and 0.993 respectively. © 2018 IEEE.}, keywords = {Advanced Metering Infrastructure, intrusion detection system, security, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou-Grammatikis2019c, title = {An Overview of the Firewall Systems in the Smart Grid Paradigm}, author = { P. Radoglou-Grammatikis and P. Sarigiannidis and T. Liatifis and T. Apostolakos and S. Oikonomou}, url = {https://www.researchgate.net/publication/328998034_An_Overview_of_the_Firewall_Systems_in_the_Smart_Grid_Paradigm?_sg=CEd52g3u0I4mXf4THuYQzeTDbKNpbsG1qpl5tTT-9PASC4E8XbQbzl9YIlg_icl-irrtxOICHyYWGaQ}, doi = {10.1109/giis.2018.8635747}, year = {2018}, date = {2018-10-01}, booktitle = {2018 Global Information Infrastructure and Networking Symposium (GIIS)}, journal = {2018 Global Information Infrastructure and Networking Symposium, GIIS 2018}, publisher = {IEEE}, abstract = {The multiple interconnections and the heterogeneity of the devices and technologies into the Smart Grid (SG) generate possible cyber-physical security vulnerabilities that can be exploited by various cyberattackers. The cyberattacks in SG, usually target the availability and the information integrity of the systems. Replay attacks, Denial of Service (DoS), Distributed DoS (DDoS) and botnets are typical examples. Furthermore, the hacking tools have been largely automated, so even a novice can execute destructive cyberattacks. These situations make it necessary to develop efficient firewall systems that can prevent possible cyberattacks. In this paper, we present an overview of the various firewall systems in the SG paradigm and also we provide new research directions in this field. © 2018 IEEE.}, keywords = {Advanced Metering Infrastructure, cyberattacks, firewall, SCADA, security, Smart Grid, substation}, pubstate = {published}, tppubtype = {conference} } @conference{, title = {A multilayer comparative study of XG-PON and 10G-EPON standards}, author = { A. Lytos and T. Lagkas and P. Sarigiannidis and K. Bontcheva}, editor = { Proceedings of the 9th South East European Doctoral Student Conference DSC201}, url = {https://www.researchgate.net/publication/299124852_A_Multilayer_Comparative_Study_of_XG-PON_and_10G-EPON_Standards}, year = {2018}, date = {2018-09-01}, booktitle = {Proceedings of the 12th South East European Doctoral Student Conference DSC2018}, address = {Thessaloniki, Greece}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @inbook{Sarigiannidis201837, title = {A Novel Lexicon-Based Approach in Determining Sentiment in Financial Data Using Learning Automata}, author = { A. Sarigiannidis and P.A. Karypidis and P. Sarigiannidis and I.C. Pragidis}, url = {https://www.researchgate.net/publication/323714520_A_Novel_Lexicon-Based_Approach_in_Determining_Sentiment_in_Financial_Data_Using_Learning_Automata}, doi = {10.1007/978-3-319-77547-0_4}, year = {2018}, date = {2018-01-01}, booktitle = {Internet Science}, journal = {Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)}, volume = {10750 LNCS}, pages = {37--48}, publisher = {Springer International Publishing}, abstract = {Sentiment analysis refers to the use of natural language processing (NLP) and textual analysis approaches to identify and extract subjective information from textual sources. Extracting sensible financial knowledge from relevant textual material is significant in order to help leverage the predictive power of the financial and econometric forecasting models. However, the determination of the sentiment analysis from textual data such as headlines, news and user comments is not an easy task. One of the most arduous challenges when dealing with sentiment analysis is the accuracy. In this work, a new lexicon-based approach is presented which is based on supervised learning. The introduced model is able to create a new lexicon based on annotated textual data and then it applies that lexicon to determine the sentiment in new, not-annotated data. The proposed method seems able to work effectively with financial data while supporting accurate decisions. © 2018, Springer International Publishing AG, part of Springer Nature.}, keywords = {Financial data, Learning automata, Natural language processing, Sentiment analysis}, pubstate = {published}, tppubtype = {inbook} } @inbook{Tsouros2018373, title = {Efficient methods for constraint acquisition}, author = { D. C. Tsouros and K. Stergiou and P. G. Sarigiannidis}, url = {https://www.researchgate.net/publication/325967779_Efficient_Methods_for_Constraint_Acquisition}, doi = {10.1007/978-3-319-98334-9_25}, year = {2018}, date = {2018-01-01}, booktitle = {Lecture Notes in Computer Science}, journal = {Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)}, volume = {11008 LNCS}, pages = {373--388}, publisher = {Springer International Publishing}, abstract = {Constraint acquisition systems such as QuAcq and MultiAcq can assist non-expert users to model their problems as constraint networks by classifying (partial) examples as positive or negative. For each negative example, the former focuses on one constraint of the target network, while the latter can learn a maximum number of constraints. Two bottlenecks of the acquisition process where both these algorithms encounter problems are the large number of queries required to reach convergence, and the high cpu times needed to generate queries, especially near convergence. We propose methods that deal with both these issues. The first one is an algorithm that blends the main idea of MultiAcq into QuAcq resulting in a method that learns as many constraints as MultiAcq does after a negative example, but with a lower complexity. The second is a technique that helps reduce the number of queries significantly. The third is based on the use of partial queries to cut down the time required for convergence. Experiments demonstrate that our resulting algorithm, which integrates all the new techniques, does not only generate considerably fewer queries than QuAcq and MultiAcq, but it is also by far faster than both of them, both in average query generation time and in total run time. © Springer Nature Switzerland AG 2018.}, keywords = {Constraint acquisition, Learning, Modeling}, pubstate = {published}, tppubtype = {inbook} } @conference{Triantafyllou201834, title = {Towards an anonymous incident communication channel for electric smart grids}, author = { A. Triantafyllou and P. Sarigiannidis and A. Sarigiannidis and E. Rios and E. Iturbe}, doi = {10.1145/3291533.3291559}, year = {2018}, date = {2018-01-01}, journal = {ACM International Conference Proceeding Series}, pages = {34-39}, abstract = {The Electric Smart Grid (ESG) is an intelligent critical infrastructure aiming to create an automated and distributed advanced energy delivery network, while preserving information privacy. This study proposes the implementation of an Anonymous Incident Communication Channel (AICC) amongst smart grids across Europe to improve situational awareness and enhance security of the new electric intelligent infrastructures. All participating organizations will have the ability to broadcast sensitive information, stored anonymously in a repository, without exposing the reputation of the organisation. This work focuses on the requirements of establishment, the possible obstacles and proposed data protection techniques to be applied in the AICC. Furthermore, a discussion is conducted regarding the documentation of cyber-incidents. Last but not least, the benefits and the potential risks of this AICC concept are also provided. © 2018 Association for Computing Machinery.}, keywords = {Anonymity, Anonymous repository of incidents, Group signature, Smart Grid}, pubstate = {published}, tppubtype = {conference} } @conference{Dalamagkas2018, title = {PAS: A Fair Game-Driven DBA Scheme for XG-PON Systems}, author = { C. Dalamagkas and P. Sarigiannidis and I. Moscholios and T.D. Lagkas and M. Obaidat}, url = {https://www.researchgate.net/publication/324979204_PAS_A_Fair_Game-Driven_DBA_Scheme_for_XG-PON_Systems}, doi = {10.1109/CSNDSP.2018.8471787}, year = {2018}, date = {2018-01-01}, journal = {2018 11th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2018}, abstract = {New generation passive optical networks (NG-PONs) are emerged as promising technologies for delivering bandwidth-demanding services in modern access networks. The 10-gigabit-capable passive optical network (XG-PON) standard has been proposed as a high-throughput architecture that realizes the Fiber-To-The-x (FTTx) paradigm, where x stands for curb (FTTC), building (FTTB) or home (FTTH). XG-PON is a powerful technology, capable of supporting 10 Gbit/s in the downstream and 2.5 Gbit/s in the upstream direction. However, in order to fully utilize the huge bandwidth in such technology, an efficient and fair bandwidth allocation scheme is required for adequately coordinating the transmission opportunities of the involved network entities based on their real bandwidth demands. A multitude of techniques and schemes have been presented over the last few years aiming at providing dynamic bandwidth distribution in PONs and NG-PONs systems. However, the vast majority of those techniques are based on heuristics. This paper develops a novel bandwidth distribution algorithm which is based on the tragedy of the commons theory, aiming at ensuring a fair bandwidth distribution among the Optical Network Units (ONUs) in a deployed XG-PON system. The algorithm is able to apply a balanced bandwidth distribution schedule amongst the connected ONUs, formed as players, aiming at ensuring a fair transmission opportunity arrangement in the upstream direction. © 2018 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Tegou2018, title = {Spectrum Allocation in Next Generation Radio Networks using Emerging Nature-inspired Algorithms}, author = { T.I. Tegou and K. Siakavara and S. Nikolaidis and S.K. Goudos and D.D. Vergados and P. Sarigiannidis and M. Obaidat}, url = {https://www.researchgate.net/publication/327938608_Spectrum_Allocation_in_Next_Generation_Radio_Networks_using_Emerging_Nature-inspired_Algorithms}, doi = {10.1109/CSNDSP.2018.8471797}, year = {2018}, date = {2018-01-01}, journal = {2018 11th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2018}, abstract = {The key task of a cognitive radio network (CRN) is the effective allocation of spectrum resources according to user needs and requirements. In order to maximize the utilization of the available spectrum, a dynamic allocation of available channels to secondary users is needed. This problem is known as the spectrum allocation problem and it is a combinatorial optimization problem. A possible optimization algorithm that can be applied is chaotic biogeography-based optimization (CBBO). In this paper, a thorough assessment of CBBO is performed in the sense of comparing CBBO with other popular algorithms. According to the simulation results, the CBBO algorithm outperforms competing algorithms in terms of average convergence rate and accuracy. © 2018 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Moscholios201818, title = {An analytical framework in LEO mobile satellite systems servicing batched Poisson traffic}, author = { I.D. Moscholios and V.G. Vassilakis and P.G. Sarigiannidis and N.C. Sagias and M.D. Logothetis}, url = {https://www.researchgate.net/publication/322734708_An_analytical_framework_in_LEO_mobile_satellite_systems_servicing_batched_Poisson_traffic}, doi = {10.1049/iet-com.2017.0220}, year = {2018}, date = {2018-01-01}, journal = {IET Communications}, volume = {12}, number = {1}, pages = {18-25}, abstract = {The authors consider a low earth orbit (LEO) mobile satellite system (MSS) that accepts new and handover calls of multirate service-classes. New calls arrive in the system as batches, following the batched Poisson process. A batch has a generally distributed number of calls. Each call is treated separately from the others and its acceptance is decided according to the availability of the requested number of channels. Handover calls follow also a batched Poisson process. All calls compete for the available channels under the complete sharing policy. By considering the LEO-MSS as a multirate loss system with 'satellite-fixed' cells, it can be analysed via a multi-dimensional Markov chain, which yields to a product form solution (PFS) for the steady-state distribution. Based on the PFS, they propose a recursive and yet efficient formula for the determination of the channel occupancy distribution, and consequently, for the calculation of various performance measures including call blocking and handover failure probabilities. The latter are much higher compared to the corresponding probabilities in the case of the classical (and less bursty) Poisson process. Simulation results verify the accuracy of the proposed formulas. Furthermore, they discuss the applicability of the proposed model in software-defined LEO-MSS. © 2017. The Institution of Engineering and Technology.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Moscholios2018b, title = {Performance modelling of a multirate loss system with batched Poisson arrivals under a probabilistic threshold policy}, author = { I.D. Moscholios and V.G. Vassilakis and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/323609359_Performance_Modelling_of_a_Multirate_Loss_System_with_Batched_Poisson_Arrivals_under_a_Probabilistic_Threshold_Policy}, doi = {10.1049/iet-net.2017.0216}, year = {2018}, date = {2018-01-01}, journal = {IET Networks}, volume = {7}, number = {4}, abstract = {The authors consider a link accommodating batched Poisson arriving calls of different service classes. A batch of generally distributed number of calls arrive to the link at exponentially distributed time-points. Each call is treated separately from the rest, and its acceptance is decided, according to the available link bandwidth (partial batch blocking discipline). For congestion control, if the number of in-service calls of a service class exceeds a threshold (dedicated to the service class), a new call of the same service class is accepted with a probability, dependent on the system state (probabilistic threshold policy). The link is analysed as a multirate loss system, via a reversible Markov chain. The latter leads to a product form solution (PFS) for the steady-state distribution. Based on the PFS, the authors propose models for the accurate determination of time and call congestion probabilities and link utilisation. Comparison against other existing models under the complete sharing or the bandwidth reservation policy reveals the necessity and consistency of the proposed models. © The Institution of Engineering and Technology 2018.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Tegou2018b, title = {Spectrum Allocation in Next Generation Radio Networks using Emerging Nature-inspired Algorithms}, author = { T.I. Tegou and K. Siakavara and S. Nikolaidis and S.K. Goudos and D.D. Vergados and P. Sarigiannidis and M. Obaidat}, url = {https://www.researchgate.net/publication/325195152_Spectrum_Allocation_in_Next_Generation_Radio_Networks_using_Emerging_Nature-inspired_Algorithms}, doi = {10.1109/CSNDSP.2018.8471797}, year = {2018}, date = {2018-01-01}, journal = {IET Networks}, volume = {7}, number = {5}, pages = {328-335}, abstract = {The key task of a cognitive radio network (CRN) is the effective allocation of spectrum resources according to user needs and requirements. In order to maximize the utilization of the available spectrum, a dynamic allocation of available channels to secondary users is needed. This problem is known as the spectrum allocation problem and it is a combinatorial optimization problem. A possible optimization algorithm that can be applied is chaotic biogeography-based optimization (CBBO). In this paper, a thorough assessment of CBBO is performed in the sense of comparing CBBO with other popular algorithms. According to the simulation results, the CBBO algorithm outperforms competing algorithms in terms of average convergence rate and accuracy. © 2018 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Lagkas2018, title = {Multi-stage resource allocation in hybrid 25GEPON and LTE-Advanced Pro FiWi networks for 5G systems}, author = { T. Lagkas and P. Sarigiannidis and P. Bellavista and C. Giannelli}, url = {https://www.researchgate.net/publication/324017608_Multi-stage_resource_allocation_in_hybrid_25GEPON_and_LTE-Advanced_Pro_FiWi_networks_for_5G_systems}, doi = {10.1049/iet-net.2017.0236}, year = {2018}, date = {2018-01-01}, journal = {IET Networks}, volume = {7}, number = {4}, abstract = {The 5G vision is not restricted solely to the wireless domain and its challenging requirements cannot be fulfilled without the efficient integration of cutting-edge technologies in all portions of the telecommunications infrastructure. The promoted architectures for next generation telecommunications systems involve high capacity network domains, which operate flexibly and seamlessly to offer full quality of experience to all types of subscribers. The proliferation of highly demanding multimedia services and the features of modern communication devices necessitate the development of end-to-end schemes which can efficiently distribute large amount of network resources anywhere and whenever needed. This study introduces a new resource allocation scheme for cutting-edge fibre-wireless networks is introduced that can be applied in the fronthaul portion of 5G-enabled architectures. The adopted technologies are the forthcoming 25G-Ethernet Passive Optical Network (EPON) for the optical domain and the 5G-ready long-term evolution -Advanced Pro for the wireless domain. The proposed scheme performs allocation decisions based on the outcome of an adjustable multi-stage optimisation problem. The optimisation factors are directly related to the major considerations in bandwidth distribution, namely priority-based traffic differentiation, power awareness, and fairness provision. The conducted evaluations prove that this approach is able to ensure high efficiency in network operations. © The Institution of Engineering and Technology 2018.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Bellavista201821324, title = {Quality management of surveillance multimedia streams via federated SDN controllers in Fiwi-iot integrated deployment environments}, author = { P. Bellavista and C. Giannelli and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/324249418_Quality_Management_of_Surveillance_Multimedia_Streams_via_Federated_SDN_Controllers_in_FiWi-IoT_Integrated_Deployment_Environments}, doi = {10.1109/ACCESS.2018.2822401}, year = {2018}, date = {2018-01-01}, journal = {IEEE Access}, volume = {6}, pages = {21324-21341}, abstract = {Traditionally, hybrid optical-wireless networks (Fiber-Wireless - FiWi domain) and last-mile Internet of Things edge networks (Edge IoT domain) have been considered independently, with no synergic management solutions. On the one hand, FiWi has primarily focused on high-bandwidth and low-latency access to cellular-equipped nodes. On the other hand, Edge IoT has mainly aimed at effective dispatching of sensor/actuator data among (possibly opportunistic) nodes, by using direct peer-to-peer and base station (BS)-assisted Internet communications. The paper originally proposes a model and an architecture that loosely federate FiWi and Edge IoT domains based on the interaction of FiWi and Edge IoT software defined networking controllers: The primary idea is that our federated controllers can seldom exchange monitoring data and control hints the one with the other, thus mutually enhancing their capability of end-to-end quality-aware packet management. To show the applicability and the effectiveness of the approach, our original proposal is applied to the notable example of multimedia stream provisioning from surveillance cameras deployed in the Edge IoT domain to both an infrastructure-side server and spontaneously interconnected mobile smartphones, our solution is able to tune the BS behavior of the FiWi domain and to reroute/prioritize traffic in the Edge IoT domain, with the final goal to reduce latency. In addition, the reported application case shows the capability of our solution of joint and coordinated exploitation of resources in FiWi and Edge IoT domains, with performance results that highlight its benefits in terms of efficiency and responsiveness. © 2013 IEEE.}, keywords = {federated SDN controllers, Fiber wireless (FiWi), Internet of Things (IoT), quality management, software defined networking (SDN)}, pubstate = {published}, tppubtype = {article} } @article{Pliatsios2018, title = {Realizing 5G vision through Cloud RAN: technologies, challenges, and trends}, author = { D. Pliatsios and P. Sarigiannidis and S. Goudos and G.K. Karagiannidis}, url = {https://www.researchgate.net/publication/325181057_Realizing_5G_vision_through_Cloud_RAN_technologies_challenges_and_trends}, doi = {10.1186/s13638-018-1142-1}, year = {2018}, date = {2018-01-01}, journal = {Eurasip Journal on Wireless Communications and Networking}, volume = {2018}, number = {1}, abstract = {Achieving the fifth-generation (5G) vision will introduce new technology innovations and substantial changes in delivering cutting-edge applications and services in current mobile and cellular networks. The Cloud Radio Access Network (C-RAN) concept emerged as one of the most compelling architectures to meet the requirements of the 5G vision. In essence, C-RAN provides an advanced mobile network architecture which can leverage challenging features such as network resource slicing, statistical multiplexing, energy efficiency, and high capacity. The realization of C-RAN is achieved by innovative technologies such as the software-defined networking (SDN) and the network function virtualization (NFV). While SDN technology brings the separation of the control and data planes in the playground, supporting thus advanced traffic engineering techniques such as load balancing, the NFV concept offers high flexibility by allowing network resource sharing in a dynamic way. Although SDN and NFV have many advantages, a number of challenges have to be addressed before the commercial deployment of 5G implementation. In addition, C-RAN introduces a new layer in the mobile network, denoted as the fronthaul, which is adopted from the recent research efforts in the fiber-wireless (Fi-Wi) paradigm. As the fronthaul defines a link between a baseband unit (BBU) and a remote radio unit (RRU), various technologies can be used for this purpose such as optical fibers and millimeter-wave (mm-wave) radios. In this way, several challenges are highlighted which depend on the technology used. In the light of the aforementioned remarks, this paper compiles a list of challenges and open issues of the emerging technologies that realize the C-RAN concept. Moreover, comparative insights between the current and future state of the C-RAN concept are discussed. Trends and advances of those technologies are also examined towards shedding light on the proliferation of 5G through the C-RAN concept. © 2018, The Author(s).}, keywords = {5G, Cloud Radio Access Network, Common Public Radio Interface, Network function virtualization, Software-defined networking}, pubstate = {published}, tppubtype = {article} } @article{Bellavista2018b, title = {Multi-domain SDN controller federation in hybrid FiWi-MANET networks}, author = { P. Bellavista and C. Giannelli and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/324960944_Multi-domain_SDN_controller_federation_in_hybrid_FiWi-MANET_networks?_sg=LjB2gbdlzKCJ8dO99ORrJvAEVI0121CE4UzsEIpplV8k21Ai__lnot4ssMp03flkG4TP4QfCoGyBY9o}, doi = {10.1186/s13638-018-1119-0}, year = {2018}, date = {2018-01-01}, journal = {Eurasip Journal on Wireless Communications and Networking}, volume = {2018}, number = {1}, abstract = {Traditionally, mobile ad hoc networks (MANET) and hybrid optical-wireless networks, also known as fiber-wireless (FiWi), have been considered disjointly and independently, with no synergic management solutions. The former has primarily focused on dispatching packets among mobile nodes in infrastructure-less and very dynamic environments, the latter on offering high-bandwidth and low-latency access to cellular-equipped mobile nodes. The recent advancements and penetration of software-defined networking (SDN) techniques have stimulated the adoption of SDN-based flexible monitoring and control also for the MANET and FiWi domains. In this perspective, the paper originally proposes a model and an architecture that loosely federate MANET and FiWi domains based on the interaction of MANET and FiWi controllers: the primary idea is that our MANET and FiWi federated controllers can seldom exchange monitoring data and control hints the one with the other, thus mutually enhancing their capability of packet management over hybrid FiWi-MANET networks. Our model is applied to several relevant use cases to practically point out the benefits of the proposal in terms of both load balancing and fairness improvements. © 2018, The Author(s).}, keywords = {Fiber-wireless, MANET, Multi-domain federation, Software-defined networking}, pubstate = {published}, tppubtype = {article} } @article{Triantafyllou2018b, title = {Network protocols, schemes, and mechanisms for internet of things (IoT): Features, open challenges, and trends}, author = { A. Triantafyllou and P. Sarigiannidis and T.D. Lagkas}, url = {https://www.researchgate.net/publication/327638441_Network_Protocols_Schemes_and_Mechanisms_for_Internet_of_Things_IoT_Features_Open_Challenges_and_Trends}, doi = {10.1155/2018/5349894}, year = {2018}, date = {2018-01-01}, journal = {Wireless Communications and Mobile Computing}, volume = {2018}, abstract = {Internet of Things (IoT) constitutes the next step in the field of technology, bringing enormous changes in industry, medicine, environmental care, and urban development. Various challenges are to be met in forming this vision, such as technology interoperability issues, security and data confidentiality requirements, and, last but not least, the development of energy efficient management systems. In this paper, we explore existing networking communication technologies for the IoT, with emphasis on encapsulation and routing protocols. The relation between the IoT network protocols and the emerging IoT applications is also examined. A thorough layer-based protocol taxonomy is provided, while how the network protocols fit and operate for addressing the recent IoT requirements and applications is also illustrated. What is the most special feature of this paper, compared to other survey and tutorial works, is the thorough presentation of the inner schemes and mechanisms of the network protocols subject to IPv6. Compatibility, interoperability, and configuration issues of the existing and the emerging protocols and schemes are discussed based on the recent advanced of IPv6. Moreover, open networking challenges such as security, scalability, mobility, and energy management are presented in relation to their corresponding features. Lastly, the trends of the networking mechanisms in the IoT domain are discussed in detail, highlighting future challenges. © 2018 Anna Triantafyllou et al.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Moysiadis2018, title = {Towards Distributed Data Management in Fog Computing}, author = { V. Moysiadis and P. Sarigiannidis and I. Moscholios}, url = {https://www.researchgate.net/publication/327391000_Towards_Distributed_Data_Management_in_Fog_Computing?_sg=L1JqFa31HOQbDile7T5EX8FfEzBaoDUc8yMYt53GRdTd7uyRnSdLRu4DYgE0It-PnIvC7T6ah4cZvvg}, doi = {10.1155/2018/7597686}, year = {2018}, date = {2018-01-01}, journal = {Wireless Communications and Mobile Computing}, volume = {2018}, abstract = {In the emerging area of the Internet of Things (IoT), the exponential growth of the number of smart devices leads to a growing need for efficient data storage mechanisms. Cloud Computing was an efficient solution so far to store and manipulate such huge amount of data. However, in the next years it is expected that Cloud Computing will be unable to handle the huge amount of the IoT devices efficiently due to bandwidth limitations. An arising technology which promises to overwhelm many drawbacks in large-scale networks in IoT is Fog Computing. Fog Computing provides high-quality Cloud services in the physical proximity of mobile users. Computational power and storage capacity could be offered from the Fog, with low latency and high bandwidth. This survey discusses the main features of Fog Computing, introduces representative simulators and tools, highlights the benefits of Fog Computing in line with the applications of large-scale IoT networks, and identifies various aspects of issues we may encounter when designing and implementing social IoT systems in the context of the Fog Computing paradigm. The rationale behind this work lies in the data storage discussion which is performed by taking into account the importance of storage capabilities in modern Fog Computing systems. In addition, we provide a comprehensive comparison among previously developed distributed data storage systems which consist of a promising solution for data storage allocation in Fog Computing. © 2018 Vasileios Moysiadis et al.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Fountoukidis2018, title = {MIMO antenna selection using biogeography-based optimization with nonlinear migration models}, author = { K.C. Fountoukidis and C. Kalialakis and K.E. Psannis and K. Siakavara and S.K. Goudos and P. Sarigiannidis and M. Obaidat}, url = {https://www.researchgate.net/publication/327201674_MIMO_Antenna_Selection_Using_Biogeography_Based_Optimization_with_Non-Linear_Migration_Models}, doi = {10.1002/dac.3813}, year = {2018}, date = {2018-01-01}, journal = {International Journal of Communication Systems}, volume = {31}, number = {17}, abstract = {This papers deals with the problem of antenna selection (AS) for a multiple-input multiple-output (MIMO) wireless system under the constraint of the channel capacity maximization. The biogeography-based optimization (BBO) algorithm is applied on the joint transmitter and receiver AS problem. Moreover, the performance of different BBO migration models is compared with a real valued genetic algorithm (RVGA) as well as with the ant colony optimization (ACO). Representative simulation scenarios are provided in detail, involving selection of 2 × 4,3 × 5,4 × 6,8 × 8 antennas in a 16 × 16 MIMO system. The numerical results demonstrate the efficiency and the applicability of the BBO algorithm in modern MIMO wireless systems. © 2018 John Wiley & Sons, Ltd.}, keywords = {ant colony optimization, antenna selection, biogeography-based optimization, evolutionaryr algorithms, genetic algorithm, multiple-input multiple-output systems}, pubstate = {published}, tppubtype = {article} } @article{Lagkas2018b, title = {UAV IoT framework views and challenges: Towards protecting drones as “things”}, author = { T. Lagkas and V. Argyriou and S. Bibi and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/328968155_UAV_IoT_Framework_Views_and_Challenges_Towards_Protecting_Drones_as_Things}, doi = {10.3390/s18114015}, year = {2018}, date = {2018-01-01}, journal = {Sensors (Switzerland)}, volume = {18}, number = {11}, abstract = {Unmanned aerial vehicles (UAVs) have enormous potential in enabling new applications in various areas, ranging from military, security, medicine, and surveillance to traffic-monitoring applications. Lately, there has been heavy investment in the development of UAVs and multi-UAVs systems that can collaborate and complete missions more efficiently and economically. Emerging technologies such as 4G/5G networks have significant potential on UAVs equipped with cameras, sensors, and GPS receivers in delivering Internet of Things (IoT) services from great heights, creating an airborne domain of the IoT. However, there are many issues to be resolved before the effective use of UAVs can be made, including security, privacy, and management. As such, in this paper we review new UAV application areas enabled by the IoT and 5G technologies, analyze the sensor requirements, and overview solutions for fleet management over aerial-networking, privacy, and security challenges. Finally, we propose a framework that supports and enables these technologies on UAVs. The introduced framework provisions a holistic IoT architecture that enables the protection of UAVs as “flying” things in a collaborative networked environment. © 2018 by the authors. Licensee MDPI, Basel, Switzerland.}, keywords = {Drones, IoT, Privacy, security, UAV}, pubstate = {published}, tppubtype = {article} } @conference{Avdullahi2017, title = {QoS supportive MAC Protocols for WSNs: Review and Evaluation}, author = { A. Avdullahi and T. Lagkas and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/320116483_QoS_Supportive_MAC_Protocols_for_WSNs_Review_and_Evaluation}, doi = {10.1145/3136273.3136282}, year = {2017}, date = {2017-01-01}, journal = {ACM International Conference Proceeding Series}, volume = {Part F130953}, abstract = {The use of wireless sensor networks technology is growing in different applications of monitoring. Since it is a relatively new technology, the interest of researchers to improve the network performance and behaviour has been enormous. In this context, new resource allocation scheme that takes into account traffic priority and load has been introduced. The evaluation of this scheme is intended to be achieved by implementing a custom simulator. This report discusses and evaluates all the important concerns needed to be considered during the development of this project. Moreover, this work also reviews the related literature in order to afford optimisations to the scheme. © 2017 Association for Computing Machinery.}, keywords = {MAC, Resource Allocation., Sensors, Wireless Sensor Networks (WSN)}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2017, title = {Connectivity and coverage in machine-type communications}, author = { P. Sarigiannidis and T. Zygiridis and A. Sarigiannidis and T.D. Lagkas and M. Obaidat and N. Kantartzis}, url = {https://www.researchgate.net/publication/315857425_Connectivity_and_Coverage_in_Machine-Type_Communications}, doi = {10.1109/ICC.2017.7996897}, year = {2017}, date = {2017-01-01}, journal = {IEEE International Conference on Communications}, abstract = {Machine-type communication (MTC) provides a potential playground for deploying machine-to-machine (M2M), IP-enabled 'things' and wireless sensor networks (WSNs) that support modern, added-value services and applications. 4G/5G technology can facilitate the connectivity and the coverage of the MTC entities and elements by providing M2M-enabled gateways and base stations for carrying traffic streams to/from the backbone network. For example, the latest releases of long-term evolution (LTE) such as LTE-Advanced (LTE-A) are being transformed to support the migration of M2M devices. MTC-oriented technical definitions and requirements are defined to support the emerging M2M proliferation. ETSI describes three types of MTC access methods, namely a) the direct access, b) the gateway access and c) the coordinator access. This work is focused on studying coverage aspects when a gateway access takes place. A deployment planar field is considered where a number of M2M devices are randomly deployed, e.g., a hospital where body sensor networks form a M2M infrastructure. An analytical framework is devised that computes the average number of connected M2M devices when a M2C gateway is randomly placed for supporting connectivity access to the M2M devices. The introduced analytical framework is verified by simulation and numerical results. © 2017 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Radoglou-Grammatikis2017, title = {Flow anomaly based intrusion detection system for Android mobile devices}, author = { P.I. Radoglou-Grammatikis and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/316691657_Flow_Anomaly_Based_Intrusion_Detection_System_for_Android_Mobile_Devices}, doi = {10.1109/MOCAST.2017.7937625}, year = {2017}, date = {2017-01-01}, journal = {2017 6th International Conference on Modern Circuits and Systems Technologies, MOCAST 2017}, abstract = {The penetration of the modern mobile devices is progressively gaining ground in today's cognitive applications and services. Several applications have become part of the smartphone capabilities such as e-mail monitoring, Internet browsing, social networks activities, etc. However, the increased computation and storage capabilities of smartphones have attracted more and more cyber attacks in terms of writing mobile malware for various purposes. In this paper, we present an intrusion detection system (IDS) for detecting the anomaly behaviors in Android mobile devices. The IDS continuously monitors the network traffic of the mobile device and collects various features of the NetFlows. An artificial neural network (ANN) gathers the data flows and determines whether there is an invasion or not. The proposed IDS is demonstrated in realistic conditions, where the accuracy of the systems reaches 85%. © 2017 IEEE.}, keywords = {Android, Artificial Neural Networks, intrusion detection system, Mobile, NetFlows, security}, pubstate = {published}, tppubtype = {conference} } @conference{Salis2017, title = {A stochastic FDTD approach for assessing random media uncertainties in polar coordinates}, author = { C. Salis and T. Zygiridis and P. Sarigiannidis and N. Kantartzis}, url = {https://www.researchgate.net/publication/317298765_A_stochastic_FDTD_approach_for_assessing_random_media_uncertainties_in_polar_coordinates}, doi = {10.1109/MOCAST.2017.7937648}, year = {2017}, date = {2017-01-01}, journal = {2017 6th International Conference on Modern Circuits and Systems Technologies, MOCAST 2017}, abstract = {Deterministic schemes are usually unable to predict random media uncertainties and as a result produce unreliable outcomes in this kind of problems. In this work, we present a novel finite difference time domain (FDTD) technique that manages to calculate the statistics of the involved field quantities, considering that the variability of random media is known. The proposed method is applied in polar grids and can efficiently deal with such cases in a single realization. Comparisons with the Monte Carlo method show that reliable results may be obtained, thus making our proposed technique much more faster. © 2017 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Magganopoulou2017, title = {Performance improvement of various antennas using inclusions of split-ring resonators}, author = { E. Magganopoulou and T. Zygiridis and P. Sarigiannidis and N. Kantartzis}, url = {https://www.researchgate.net/publication/317298607_Performance_improvement_of_various_antennas_using_inclusions_of_split-ring_resonators}, doi = {10.1109/MOCAST.2017.7937681}, year = {2017}, date = {2017-01-01}, journal = {2017 6th International Conference on Modern Circuits and Systems Technologies, MOCAST 2017}, abstract = {Split-ring resonators (SRRs) are fundamental elements of metamaterials, which exhibit attractive properties and find various electromagnetic applications. In this paper, we consider the inclusion of SRRs for improving the performance of various antennas, with respect to their radiation patterns, electrical size or wideband response. The provided results verify that incorporating SRRs in the radiator design provides an efficient and cost-effective solution for upgrading the characteristics of standard antenna elements, without resorting to more complex or costly alternative solutions. © 2017 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Pelekanidis2017, title = {Circular and square SRR exploitation as a means for wireless power transfer}, author = { A.G. Pelekanidis and A.X. Lalas and N.V. Kantartzis and T.T. Zygiridis and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/317293814_Circular_and_square_SRR_exploitation_as_a_means_for_wireless_power_transfer}, doi = {10.1109/MOCAST.2017.7937646}, year = {2017}, date = {2017-01-01}, journal = {2017 6th International Conference on Modern Circuits and Systems Technologies, MOCAST 2017}, abstract = {As wireless power transfer (WPT) systems emerge, the efficiency and achievable transmitting distance are two constraining factors for their prevalence over wired ones. In this paper, two split ring resonator (SRR)-based WPT configurations, with circular and square SRRs, as their transmitting and receiving elements, are investigated for various frequencies and distances. The efficiency is found to be very satisfactory in both cases, exceeding 98% for certain sets of parameters. Thus, the general response of both arrangements seems to be promising for effective power transfer over distances of a few centimeters. © 2017 IEEE.}, keywords = {Electromagnetic resonance, metamaterials, negative permeability, split ring resonators, wireless power transfer}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2017b, title = {Direct and indirect access in machine type communications: An analytical approach invited paper}, author = { P. Sarigiannidis and D. Pliatsios}, url = {https://www.researchgate.net/publication/311675523_Direct_and_Indirect_Access_in_Machine_Type_Communications_An_Analytical_Approach}, doi = {10.4108/eai.15-12-2016.2267736}, year = {2017}, date = {2017-01-01}, journal = {BodyNets International Conference on Body Area Networks}, abstract = {Machine-to-machine (M2M) communications have emerged as a cost-effective, flexible and efficient solution of facilitating the penetration of independent 'things' and machines in local networks and systems. the latest releases of long-term evolution (LTE) such as LTE-Advanced (LTE-A) are being transformed to support the migration of M2M devices to end terminals. 3GPP supports the definition of technical requirements and functional specifications that allows the adapting of existing technologies to support machine type communications (MTC) and the optimization of the design of advanced standards (e.g., LTE-A) for efficient data delivery. According to ETSI M2M architecture three types of MTC access methods are supported, the direct access, the gateway access and the coordinator access. An MTC can access an evolved NodeB (eNB) with or without relay nodes. Hence coverage and connectivity issues appear on designing and deploying MTC architectures. This work is focused on studying and analyzing the probability of having at least k machine devices connected in modern cellular network, where the deployedM2Mdevices are directly or indirectly connected to the eNB node.e provided analytic framework is verified by simulation results that indicate suitable deployment conditions in specific MTC scenarios. © 2017 EAI.}, keywords = {Coverage, Deployment, LTE, M2M, Relay}, pubstate = {published}, tppubtype = {conference} } @conference{moscholios2017fixed, title = {On the Fixed Channel Reservation Policy in LEO Mobile Satellite Systems}, author = { I. Moscholios and V. Vassilakis and N. Sagias and P. Sarigiannidis and M. Logothetis}, url = {https://www.researchgate.net/publication/322703709_On_Channel_Sharing_Policies_in_LEO_Mobile_Satellite_Systems?_sg=NiVSuHdgJEs-U1GYCMhvVAA1pSknXuL2iuKIhL13AWicipCRTxnjsyFpCEmf_AXwLBolEaLOf97D1LQ}, year = {2017}, date = {2017-01-01}, journal = {IEICE Information and Communication Technology Forum (ICTF)}, volume = {50}, publisher = {The Institute of Electronics, Information and Communication Engineers}, address = {Poznan, Poland}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sarigiannidis2017c, title = {An adaptive energy-efficient framework for time-constrained optical backbone networks}, author = { P. Sarigiannidis and V. Kakali and M. Fragakis}, url = {https://www.researchgate.net/publication/275219667_An_adaptive_energy-efficient_framework_for_time-constrained_optical_backbone_networks_AN_ADAPTIVE_ENERGY-EFFICIENT_FRAMEWORK}, doi = {10.1002/dac.2972}, year = {2017}, date = {2017-01-01}, journal = {International Journal of Communication Systems}, volume = {30}, number = {3}, abstract = {Power management has emerged as a challenge of paramount importance having strong social and financial impact in the community. The rapid growth of information and communication technologies made backbone networks a serious energy consumer. Concurrently, backbone networking is deemed as one of the most promising areas to apply energy efficient frameworks. One of the most popular energy efficient techniques, in the context of backbone networks, is to intentionally switch off nodes and links that are monitored underutilized. Having in mind that optical technology has thoroughly dominated modern backbone networks, the function of switching off techniques entails fast operation and rigorous decision-making because of the tremendous speed of the underlying optical media. This paper addresses this challenge by introducing a novel, adaptive, and efficient power management scheme for large-scale backbone networks. The proposed framework exploits traffic patterns and dynamics in order to effectively switch off the set of network entities in a periodic fashion. An adaptive decision-making algorithm is presented to maximize the network energy gains with respect to time constraints as well as QoS guarantees. The conducted simulation results reveal considerable improvements when applying the proposed framework compared with other inflexible energy efficient schemes. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.}, keywords = {adaptive algorithms, backbone networks, energy efficiency, optical networks, power consumption}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis2017d, title = {Towards power consumption in optical networks: a cognitive prediction-based technique}, author = { P.G. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos}, url = {https://www.researchgate.net/publication/276509099_Towards_power_consumption_in_optical_networks_A_cognitive_prediction-based_technique}, doi = {10.1002/dac.2981}, year = {2017}, date = {2017-01-01}, journal = {International Journal of Communication Systems}, volume = {30}, number = {7}, abstract = {Modern backbone, optical networks have developed into large, massive networks, which consist of numerous intermediate and terminal nodes as well as final users. These networks serve uninterruptedly multitude of users at the expense of considerable power consumption. Many research efforts are aimed at reducing energy consumption in large-scale optical networks, however, this objective is deemed laborious: the operation of such networks has to continuously remain in good levels without disruptions. One of the most compelling techniques to remedy this situation is to switch off redundant links and devices at specific (short) periods. These links and devices remain idle as long as the network can cope with the underlying traffic demands. Hence, a power mechanism is required to manage how and when underutilized network elements may be silent during network operation. Nevertheless, this management entails fast processing and efficient decision making. While many research efforts neglect this serious factor, the problem of reducing the power consumption still threats the development of today's backbone network. In this work, an effective, cognitive power management technique is proposed by enhancing the decision making with traffic prediction. Traffic capacity is estimated in each link within the network supporting, thus, more efficient decisions on switching off underutilized or even idle network elements a priori. The technique introduced succeeds high accuracy levels, while it offers energy savings up to 30% lower than other energy-aware schemes. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.}, keywords = {backbone networks, energy efficiency, optical networks, power consumption, prediction}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis2017e, title = {DIANA: A Machine Learning Mechanism for Adjusting the TDD Uplink-Downlink Configuration in XG-PON-LTE Systems}, author = { P. Sarigiannidis and A. Sarigiannidis and I. Moscholios and P. Zwierzykowski}, url = {https://www.researchgate.net/publication/317359158_DIANA_A_Machine_Learning_Mechanism_for_Adjusting_the_TDD_Uplink-Downlink_Configuration_in_XG-PON-LTE_Systems}, doi = {10.1155/2017/8198017}, year = {2017}, date = {2017-01-01}, journal = {Mobile Information Systems}, volume = {2017}, abstract = {Modern broadband hybrid optical-wireless access networks have gained the attention of academia and industry due to their strategic advantages (cost-efficiency, huge bandwidth, flexibility, and mobility). At the same time, the proliferation of Software Defined Networking (SDN) enables the efficient reconfiguration of the underlying network components dynamically using SDN controllers. Hence, effective traffic-aware schemes are feasible in dynamically determining suitable configuration parameters for advancing the network performance. To this end, a novel machine learning mechanism is proposed for an SDN-enabled hybrid optical-wireless network. The proposed architecture consists of a 10-gigabit-capable passive optical network (XG-PON) in the network backhaul and multiple Long Term Evolution (LTE) radio access networks in the fronthaul. The proposed mechanism receives traffic-aware knowledge from the SDN controllers and applies an adjustment on the uplink-downlink configuration in the LTE radio communication. This traffic-aware mechanism is capable of determining the most suitable configuration based on the traffic dynamics in the whole hybrid network. The introduced scheme is evaluated in a realistic environment using real traffic traces such as Voice over IP (VoIP), real-time video, and streaming video. According to the obtained numerical results, the proposed mechanism offers significant improvements in the network performance in terms of latency and jitter. © 2017 Panagiotis Sarigiannidis et al.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis20171964, title = {Modeling the Internet of Things under Attack: A G-network Approach}, author = { P. Sarigiannidis and E. Karapistoli and A.A. Economides}, url = {https://www.researchgate.net/publication/317867935_Modelling_the_Internet_of_Things_Under_Attack_A_G-network_Approach?_sg=nQGxFUwlDGkq6bJAkluGr9ICZ80minya34gpJdFzE990HU4AFYuPRV760oFW4FmaMbAYtNSeFztuzGo}, doi = {10.1109/JIOT.2017.2719623}, year = {2017}, date = {2017-01-01}, journal = {IEEE Internet of Things Journal}, volume = {4}, number = {6}, pages = {1964-1977}, abstract = {This paper introduces a novel, analytic framework for modeling security attacks in Internet of Things (IoT) infrastructures. The devised model is quite generic, and as such, it could flexibly be adapted to various IoT architectures. Its flexibility lies in the underlying theory, it is based on a dynamic G-network, where the positive arrivals denote the data streams that originated from the various data collection networks (e.g., sensor networks), while the negative arrivals denote the securit attacks that result in data losses (e.g., jamming attacks). In addition, we take into account the intensity of an attack by considering both light and heavy attacks. The light attack implies simple losses of traffic data, while the heavy attack causes massive data loss. The introduced model is solved subject to the arrival and departure rates in terms of: 1) average number of data packets in the application domain and 2) attack impact (loss rate). A comprehensive verification discussion accompanied by numerous numerical results verify the accuracy of the proposed model. Moreover, the assessment of the presented model highlights notable operation characteristics of the underlying IoT system under light and heavy attacks. © 2017 IEEE.}, keywords = {G-networks, Internet of Things (IoT), Modeling, queuing theory, security}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis2017141, title = {Hybrid 5G optical-wireless SDN-based networks, challenges and open issues}, author = { P. Sarigiannidis and T. Lagkas and S. Bibi and A. Ampatzoglou and P. Bellavista}, url = {https://www.researchgate.net/publication/318827251_Hybrid_5G_Optical-wireless_SDN-based_Networks_Challenges_and_Open_Issues?_sg=6dvVjsRNgmeZ3ZzZ_5ioBwj6i70LRmLGAAuPQH3MBXyLOm6dDRmMD9Qdi8DHYcOSDOVhRx5NNm-crtI}, doi = {10.1049/iet-net.2017.0069}, year = {2017}, date = {2017-01-01}, journal = {IET Networks}, volume = {6}, number = {6}, pages = {141-148}, abstract = {The fifth-generation (5G) mobile networks are expected to bring higher capacity, higher density of mobile devices, lower battery consumption and improved coverage. 5G entails the convergence of wireless and wired communications in a unified and efficient architecture. Mobile nodes, as defined in fourth-generation era, are transformed in heterogeneous networks to make the front-haul wireless domains flexible and intelligent. This work highlights a set of critical challenges in advancing 5G networks, fuelled by the utilisation of the network function virtualisation, the software defined radio and the software defined networks techniques. Furthermore, a novel conceptual model is presented in terms of control and management planes, where the inner architectural components are introduced in detail. © The Institution of Engineering and Technology 2017.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2016, title = {Analysing indirect Sybil attacks in randomly deployed Wireless Sensor Networks}, author = { P. Sarigiannidis and E. Karapistoli and A.A. Economides}, url = {https://www.researchgate.net/publication/304900761_Analysing_Indirect_Sybil_Attacks_in_Randomly_Deployed_Wireless_Sensor_Networks}, doi = {10.1109/PIMRC.2016.7794866}, year = {2016}, date = {2016-01-01}, journal = {IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC}, abstract = {Wireless Sensor Networks (WSNs) have been established as a valuable tool in a wide variety of applications, systems and paradigms. Many application, such as surveillance of a military region, entail unattended operation, where sensor nodes are randomly deployed in an area, known as sensor area. Such a sensor network may be vulnerable to several harmful threats such as wormhole, blackhole, selective forwarding, hello flood, and Sybil attack. One of the most complicated threat is the Sybil attack, where one or more malicious nodes illegitimately declare multiple identities. Additionally, the attack could be even more arduous, if the malicious node(s) declare that the Sybil nodes are directly connected to them. The so-called indirect Sybil attack is the main focus of this study. A performance analysis is devised, where the expected potential number of indirect Sybil nodes in randomly deployed WSNs is computed. Moreover, the probability of an (indirect) Sybil-free sensor network is calculated subject to the number of sensor nodes and the sensor area intensity. The analysis is thoroughly validated by simulation results. © 2016 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Tsitsiroudi2016103, title = {EyeSim: A mobile application for visual-Assisted wormhole attack detection in IoT-enabled WSNs}, author = { N. Tsitsiroudi and P. Sarigiannidis and E. Karapistoli and A.A. Economides}, url = {https://www.researchgate.net/publication/303673629_EyeSim_A_Mobile_Application_for_Visual-Assisted_Wormhole_Attack_Detection_in_IoT-enabled_WSNs?_sg=6v05L1WmYu6pcSk-SkfsPuc92kUAnhZEstNgT6cvRQf2JmXQp7-va2N_ockkec6Q3M8pxbEaKbz4F-w}, doi = {10.1109/WMNC.2016.7543976}, year = {2016}, date = {2016-01-01}, journal = {2016 9th IFIP Wireless and Mobile Networking Conference, WMNC 2016}, pages = {103-109}, abstract = {Internet of Things (IoT) have emerged as a valuable, flexible, and interoperable network of devices, objects, items, and electronics. Fuelled by recent advances in networking, communications, computation, software, and hardware technologies, IoT has stepped out of its infancy and is considered as the next breakthrough technology in transforming the Internet into a fully integrated Future Internet. Wireless Sensor Networks (WSNs) are utilized by IoT to collect, exchange, and deliver data remotely leveraging the potential of IoT in practical applications and services. However, delivering data remotely might be threatened by various and serious security attacks. This work focuses on developing a visual-Assisted tool for exposing security threats in IP-enabled WSNs. The proposed tool, called EyeSim, is a human-interactive visual-based anomaly detection system that is capable of monitoring and promptly alerting for the presence of wormhole links. In addition, it is capable of indicating the malicious nodes that form the wormhole link. EyeSim may expose adversaries by conducting cognitive network data analysis based on dynamic routing information. The efficacy of EyeSim is assessed in terms of detection accuracy. The simulation results show that EyeSim has the capabilities to accurately detect multiple wormhole attacks in real-Time. © 2016 IEEE.}, keywords = {IoT-enabled Wireless Sensor Networks, visual-Assisted wormhole detection, wormholes}, pubstate = {published}, tppubtype = {conference} } @conference{Lagkas2016, title = {The effect of group mobility on the efficacy of routing in next generation mobile networks}, author = { T.D. Lagkas and A. Lamproudi and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/304664872_The_effect_of_group_mobility_on_the_efficacy_of_routing_in_next_generation_mobile_networks?_sg=3u9z6RpXPn4TkPO4FsylL25lYsJy-VYd-Ty_whZqNcW-uPlgKOpMzVzGbBaKnyRuymqptI9KqqFy8Bg}, doi = {10.1109/ICT.2016.7500424}, year = {2016}, date = {2016-01-01}, journal = {2016 23rd International Conference on Telecommunications, ICT 2016}, abstract = {A key challenge in next generation mobile networks is ensuring effective routing that efficiently adapts to the special characteristics of the various mobility schemes. The purpose of this paper is to study and illustrate how group mobility affects the network performance of a wireless ad hoc network depending on the type of movement, in a space with or without obstacles. In the scope of this paper, we created a simulator of a MANET that uses AODV routing protocol, while the entities of the network move according to the chosen group mobility model. Despite the fact that the routing protocol supports mobility in general, the results greatly vary depending on the specific mobility scenario. The strong connection between mobility properties and network performance is revealed. © 2016 IEEE.}, keywords = {AODV, group mobility, MANETs, mobile routing, next generation networks, WMNs}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2016b, title = {DAMA: A data mining forecasting DBA scheme for XG-PONs}, author = { P. Sarigiannidis and D. Pliatsios and T. Zygiridis and N. Kantartzis}, url = {https://www.researchgate.net/publication/300413104_DAMA_A_data_mining_forecasting_DBA_scheme_for_XG-PONs}, doi = {10.1109/MOCAST.2016.7495169}, year = {2016}, date = {2016-01-01}, journal = {2016 5th International Conference on Modern Circuits and Systems Technologies, MOCAST 2016}, abstract = {The latest new generation passive optical network (NG-PON) standard, known as 10-gigabit-capable passive optical network (XG-PON), enables a very promising architecture that offers 10 Gbps nominal data delivery ratio in the downstream direction. The optical line terminal (OLT) is located within the CO and constitutes the main decision-making tank of the PON. OLT applies a dynamic bandwidth allocation (DBA) scheme for coordinating the transmission opportunities, especially in the upstream direction. According to the standard, a differential fibre distance of 40 km, between ONUs and OLT, is allowed. This outspread deployment implies high propagation delays which should be taken into account of designing the bandwidth allocation. This work is focused on proposing a cognitive DBA scheme which is capable of forecasting the additional bandwidth, which arrives in ONUs, during the transmission coordination between OLT and ONUs. The k-nearest neighbors (k-NN) algorithm is applied for forecasting the additional bandwidth requests of each ONU. In addition, the adopted algorithm is enhanced with an adaptive learning-based method which efficiently selects the most appropriate k value based on the traffic dynamics. © 2016 IEEE.}, keywords = {bandwidth allocation, k-nearest neighbors, Passive optical networks, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Salis2016, title = {Unconditionally-stable time-domain approach for uncertainty assessment in transmission lines}, author = { C. Salis and T. Zygiridis and P. Sarigiannidis and N. Kantartzis}, url = {https://www.researchgate.net/publication/303112364_Unconditionally-Stable_Time-Domain_Approach_for_Uncertainty_Assessment_in_Transmission_Lines}, doi = {10.1109/MOCAST.2016.7495151}, year = {2016}, date = {2016-01-01}, journal = {2016 5th International Conference on Modern Circuits and Systems Technologies, MOCAST 2016}, abstract = {Uncertainties characterizing the per-unit-length parameters of transmission lines (TL) may have a significant impact on the properties of the propagating voltage and current waves that deterministic models tend to overlook. In this paper, we present an unconditionally-stable finite-difference time-domain (FDTD) algorithm that calculates the statistics of the involved field quantities, provided that the variability of the line characteristics is known. Being free from time-step restrictions, the proposed scheme is an extension of the standard stochastic FDTD method and exhibits better efficiency, esp. in densely discretized computational domains. Indicative results verify that uncertainty quantification in TL problems is possible in a reliable manner, even when larger than usual time-steps are selected. © 2016 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Papadimopoulos2016, title = {Statistical analysis of microwave components through a 3-D stochastic-FDTD technique}, author = { A. Papadimopoulos and V. Alreem and T. Zygiridis and P. Sarigiannidis and N. Kantartzis and C. Antonopoulos}, url = {https://www.researchgate.net/publication/304456910_Statistical_analysis_of_microwave_components_through_a_3-D_stochastic-FDTD_technique}, doi = {10.1109/MOCAST.2016.7495163}, year = {2016}, date = {2016-01-01}, journal = {2016 5th International Conference on Modern Circuits and Systems Technologies, MOCAST 2016}, abstract = {The consistent modeling of microwave components with random fluctuations regarding their electromagnetic material parameters is performed in this paper via a 3-D stochastic finite-difference time-domain method. The featured formulation provides precise numerical results with a considerably smaller computational cost compared to the extensively resource-consuming Monte Carlo approach. Numerical simulations of microstrip transmission lines with media uncertainties are conducted in order to verify the accuracy of the proposed technique along with its effectiveness to investigate the operation of complicated microwave structures in a stochastic environment. © 2016 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{10.5555/3068615.3068657, title = {Direct and Indirect Access in Machine Type Communications: An Analytical Approach}, author = { P. Sarigiannidis and D. Pliatsios}, url = {https://www.researchgate.net/publication/311675523_Direct_and_Indirect_Access_in_Machine_Type_Communications_An_Analytical_Approach}, isbn = {9781631901324}, year = {2016}, date = {2016-01-01}, booktitle = {Proceedings of the 11th EAI International Conference on Body Area Networks}, pages = {191–195}, publisher = {ICST (Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering)}, address = {Turin, Italy}, series = {BodyNets '16}, abstract = {Machine-to-machine (M2M) communications have emerged as a cost-effective, flexible and efficient solution of facilitating the penetration of independent 'things' and machines in local networks and systems. The latest releases of long-term evolution (LTE) such as LTE-Advanced (LTE-A) are being transformed to support the migration of M2M devices to end terminals. 3GPP supports the definition of technical requirements and functional specifications that allows the adapting of existing technologies to support machine type communications (MTC) and the optimization of the design of advanced standards (e.g., LTE-A) for efficient data delivery. According to ETSI M2M architecture three types of MTC access methods are supported, the direct access, the gateway access and the coordinator access. An MTC can access an evolved NodeB (eNB) with or without relay nodes. Hence coverage and connectivity issues appear on designing and deploying MTC architectures. This work is focused on studying and analyzing the probability of having at least k machine devices connected in modern cellular network, where the deployed M2M devices are directly or indirectly connected to the eNB node. The provided analytic framework is verified by simulation results that indicate suitable deployment conditions in specific MTC scenarios.}, keywords = {Coverage, Deployment, LTE, M2M, Relay}, pubstate = {published}, tppubtype = {conference} } @article{Vasileiou201645, title = {An effective resource allocation medium access control protocol for radio-over-fiber access networks based on wavelength reuse}, author = { G. Vasileiou and G.I. Papadimitriou and P. Nicopolitidis and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/302919670_An_Effective_Resource_Allocation_Medium_Access_Control_Protocol_for_Radio-Over-Fiber_Access_Networks_Based_on_Wavelength_Reuse}, doi = {10.1016/j.comcom.2016.05.001}, year = {2016}, date = {2016-01-01}, journal = {Computer Communications}, volume = {88}, pages = {45-56}, abstract = {Users' rapidly increasing demands for bandwidth and mobility in conjunction with the surge of delay-sensitive applications, creates the necessity for further research and development of new energy- and cost-effective technologies such as radio-over-fiber (RoF) and radio-and-fiber (R&F). The research community is dealing with medium access control (MAC) protocol design for RoF networks, so that it can support bandwidth-demanding multimedia services such as voice over IP, video on demand, video conferencing, etc. In this work, a novel MAC protocol for RoF access networks is proposed, which is based on a modification of the multipoint control protocol (MPCP). The network's decision centre receives detailed feedback from the mobile client queues via MPCP's GATE/REPORT mechanism so as to efficiently allocate the bandwidth and the wavelength resources in a dynamic manner. The novelty of this protocol is that since wavelength reuse is achieved a single wavelength can be used by more than one remote antenna unit (Rau). The proposed MAC protocol also adapts its operation according to the clients' actual traffic demands and manages to exploit the huge capacity that the optical medium provides. Furthermore, a best-fit algorithm is applied in order to achieve further optimization. Simulation results reveal the superior performance and the better scalability of the proposed protocol compared with similar proposals reported in the literature. © 2016 Elsevier B.V.}, keywords = {60 GHz wireless network, Best-fit algorithm, Bottleneck, Medium access control (MAC) protocol, Multipoint control protocol(MPCP), Radio-over-fiber (RoF) network, Simple polling adaptive protocol, Wavelength division multiplexing ethernet passive optical network (WDM-EPON)}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis201671, title = {Three-phase Cooperative Jamming Based Improving PHY Security for Multicast Network with an Untrusted Relay}, author = { X Fu and Li A. and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/312343020_Three-phase_Cooperative_Jamming_Based_Improving_PHY_Security_for_Multicast_Network_with_an_Untrusted_Relay}, doi = {10.1049/iet-net.2015.0087}, year = {2016}, date = {2016-01-01}, journal = {International Journal of Future Generation Communication and Networking}, volume = {9}, number = {12}, pages = {87-96}, abstract = {The standardisation of the 10 GB-capable passive optical network (XG-PON) system is accompanied by a rigorous set of recommendations. Power reduction in XG-PONs is considered a quite important topic by the telecommunication standardisation sector (ITU-T), thus, with importance of energy saving, XG-PON recommendation describes power management processes in detail. The core power management process comprises distinct states representing the desired power management transitions, while two modes: namely, the doze and the cyclic sleep mode, are defined. This study provides an analytical model for power consumption computation of an optical network unit (ONU), assuming that the two modes are enabled in the ONU operation. The presented analytical findings are verified by conducting extensive simulation experiments. Concurrently, the average time spent on doze and cyclic sleep states is provided. © The Institution of Engineering and Technology 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis201671b, title = {Analysing the optical network unit power consumption in the 10 GB-capable passive optical network systems}, author = { P. Sarigiannidis and M. Louta and G. Papadimitriou and M. Theologou}, url = {https://www.researchgate.net/publication/301824855_Analysing_the_optical_network_unit_power_consumption_in_the_10_GB-capable_passive_optical_network_systems}, doi = {10.1049/iet-net.2015.0087}, year = {2016}, date = {2016-01-01}, journal = {IET Networks}, volume = {5}, number = {3}, pages = {71-79}, abstract = {The standardisation of the 10 GB-capable passive optical network (XG-PON) system is accompanied by a rigorous set of recommendations. Power reduction in XG-PONs is considered a quite important topic by the telecommunication standardisation sector (ITU-T), thus, with importance of energy saving, XG-PON recommendation describes power management processes in detail. The core power management process comprises distinct states representing the desired power management transitions, while two modes: namely, the doze and the cyclic sleep mode, are defined. This study provides an analytical model for power consumption computation of an optical network unit (ONU), assuming that the two modes are enabled in the ONU operation. The presented analytical findings are verified by conducting extensive simulation experiments. Concurrently, the average time spent on doze and cyclic sleep states is provided. © The Institution of Engineering and Technology 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2016c, title = {A metaheuristic bandwidth allocation scheme for FiWi networks using Ant Colony Optimization}, author = { P. Sarigiannidis and M. Louta and G. Papadimitriou and P. Nicopolitidis and K. Diamantaras and I. Tinnirello and C. Verikoukis}, url = {https://www.researchgate.net/publication/303819245_A_Metaheuristic_Bandwidth_Allocation_Scheme_for_FiWi_Networks_Using_Ant_Colony_Optimization}, doi = {10.1109/SCVT.2015.7374242}, year = {2015}, date = {2015-11-01}, booktitle = {2015 IEEE Symposium on Communications and Vehicular Technology in the Benelux (SCVT)}, journal = {2015 IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT 2015}, publisher = {IEEE}, abstract = {Optical-wireless access networks constitute a quite attractive solution to meet the ever-increasing bandwidth requirements of end-users, offering significant benefits such as ubiquitous coverage in the wireless domain and huge bandwidth in the optical domain. However, converging optical and wireless networking technologies, with Passive Optical Networks (PONs) and 4G wireless standards, such as the Worldwide Interoperability for Microwave Access (WiMAX) and the Long Term Evolution (LTE), entails major challenges that need to be addressed. In this context, designing an efficient and fair bandwidth distribution with Quality of Service (QoS) support is a difficult task due to the interdependence of resource allocation process to both optical and wireless domains. Specifically, the bandwidth distribution in the optical domain has to be aware of the mobile user heterogeneity in the wireless domain, while in the wireless domain the allocation process depends on the optical transmission grant opportunities. In this work a metaheuristic approach to govern the bandwidth allocation in modern Fiber Wireless (FiWi) networks is proposed. The Ant Colony Optimization (ACO) method is effectively employed in order to optimize the bandwidth report process of Mobile Subscribers (MSs). Simulation results reveal the effectiveness of the proposed approach in terms of latency and network throughput. © 2015 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis201545, title = {Alleviating the high propagation delays in FiWi networks: A prediction-based DBA scheme for 10G-EPON-WiMAX systems}, author = { P. Sarigiannidis and M. Louta and G. Papadimitriou and I. Moscholios and A. Boucouvalas and D. Kleftouris}, url = {https://www.researchgate.net/publication/308463668_Alleviating_the_high_propagation_delays_in_FiWi_networks_a_prediction-based_DBA_scheme_for_10G-EPON-WiMAX_systems}, doi = {10.1109/FOAN.2015.7320478}, year = {2015}, date = {2015-01-01}, journal = {2015 International Workshop on Fiber Optics in Access Network, FOAN 2015}, pages = {45-50}, abstract = {Fiber Wireless (FiWi) networks constitute a very promising, cost-effective solution to cope with modern demanding services and applications in access networks. One of the most challenging objective lies in the design of a robust, efficient and effective bandwidth allocation. The design of such a Dynamic Bandwidth Allocation (DBA) scheme should take into account the large propagation delays between mobile users and the Central Office (CO). In this work, we endeavor to address this challenge by proposing a prediction-aware DBA scheme for FiWi networks, where the optical domain is implemented by a 10Gbps Ethernet PON (10G-EPON) and the wireless domain is supported by WiMAX access stations. In order to ensure an effective DBA scheme a hidden Markov chain model is devised for estimating the surplus traffic requests of each mobile user during the coordination message exchange between the optical and the wireless domains. In addition, a fair bandwidth distribution is applied based on the results of the prediction module. Based on the obtained simulation results the proposed scheme presents a good network performance in terms of prediction accuracy and packet delay. © 2015 IEEE.}, keywords = {bandwidth allocation, FiWi, hidden Markov chains, prediction}, pubstate = {published}, tppubtype = {conference} } @conference{Lagkas20156037, title = {The impact of mobility patterns on the efficiency of data forwarding in MANETs}, author = { T.D. Lagkas and A. Lamproudi and P. Sarigiannidis and C. Skianis}, url = {https://www.researchgate.net/publication/299059764_The_Impact_of_Mobility_Patterns_on_the_Efficiency_of_Data_Forwarding_in_MANETs?_sg=X4co3ZwV7lD6S05ooJl0svikpTH0l3RqlLvNVNr9B5knlpmvwYTLH5rBuJjPDE9LtPD6tGC7jyYUb1I}, doi = {10.1109/ICC.2015.7249284}, year = {2015}, date = {2015-01-01}, journal = {IEEE International Conference on Communications}, volume = {2015-September}, pages = {6037-6042}, abstract = {One of the most challenging requirements in cutting-edge Mobile Ad hoc Networks is the need for adaptive and efficient routing. Networks capable of adapting their behavior based on current conditions are often characterized as self-organizing networks, which are lately considered very promising for future applications. This work examines the impact of the different mobility properties on the performance of self-organizing networks. For that purpose, a simulator was developed to model different mobility patterns and study the way they affect the effectiveness of the well-known AODV routing protocol. Particularly, this paper focuses on the effect of the different mobility schemes on network topology and consequently to the overall network performance. The results reveal the tight correlations between node mobility characteristics and network metrics. © 2015 IEEE.}, keywords = {AODV, MANETs, mobile routing, mobility patterns, self-organizing networks, WMNs}, pubstate = {published}, tppubtype = {conference} } @conference{Kakalou20155608, title = {A Reinforcement learning-based cognitive MAC protocol}, author = { I. Kakalou and G.I. Papadimitriou and P. Nicopolitidis and P.G. Sarigiannidis and M.S. Obaidat}, url = {https://www.researchgate.net/publication/308872233_A_Reinforcement_learning-based_cognitive_MAC_protocol}, doi = {10.1109/ICC.2015.7249216}, year = {2015}, date = {2015-01-01}, journal = {IEEE International Conference on Communications}, volume = {2015-September}, pages = {5608-5613}, abstract = {A Multi-Channel Cognitive MAC Protocol for adhoc cognitive networks that uses a distributed learning reinforcement scheme is proposed in this paper. The proposed protocol learns the Primary User (PU) traffic characteristics and then selects the best channel to transmit. The scheme, whichaddresses overlay cognitive networks,avoids collision with the PU nodes and manages toexceed the performance of the less adaptive statistical channel selection schemesin normal and especially bursty traffic environments. The simulation analysis results have shown that the performance of our proposed scheme outperforms that of the CREAM-MAC scheme. © 2015 IEEE.}, keywords = {ad-hoc, Cognitive, MAC, next generation networks, Reinforcement Learning}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis20152633, title = {VisIoT: A threat visualisation tool for IoT systems security}, author = { P. Sarigiannidis and E. Karapistoli and A.A. Economides}, url = {https://www.researchgate.net/publication/308806248_VisIoT_A_threat_visualisation_tool_for_IoT_systems_security?_sg=NezuGqHQMVXGmBsVHyG1xWgeBJW5mNW4DseaUoLexWmOeJrK8BV7uWLHbTs0kTuCEd3OwI54tauCI8w}, doi = {10.1109/ICCW.2015.7247576}, year = {2015}, date = {2015-01-01}, journal = {2015 IEEE International Conference on Communication Workshop, ICCW 2015}, pages = {2633-2638}, abstract = {Without doubt, the Internet of Things (IoT) is changing the way people and technology interact. Fuelled by recent advances in networking, communications, computation, software, and hardware technologies, IoT has stepped out of its infancy and is considered as the next breakthrough technology in transforming the Internet into a fully integrated Future Internet. However, realising a network of physical objects accessed through the Internet brings a potential threat in the shadow of the numerous benefits. The threat is 'security'. Given that Wireless Sensor Networks (WSNs) leverage the potential of IoT quite efficiently, this paper faces the challenge of security attention on a particular, yet broad, context of IP-enabled WSNs. In particular, it proposes a novel threat visualisation tool for such networks, called VisIoT. VisIoT is a human-interactive visual-based anomaly detection system that is capable of monitoring and promptly detecting several devastating forms of security attacks, including wormhole attacks, and Sybil attacks. Based on a rigorous, radial visualisation design, VisIoT may expose adversaries conducting one or multiple concurrent attacks against IP-enabled WSNs. The system's visual and anomaly detection efficacy in exposing complex security threats is demonstrated through a number of simulated attack scenarios. © 2015 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis201514, title = {Time synchronization in XG-PON systems: An error analysis}, author = { P. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos and M. Louta}, url = {https://www.researchgate.net/publication/300095707_Time_Synchronization_in_XG-PON_Systems_An_Error_Analysis}, doi = {10.5220/0005577600140021}, year = {2015}, date = {2015-01-01}, journal = {OPTICS 2015 - 6th International Conference on Optical Communication Systems, Proceedings, Part of 12th International Joint Conference on e-Business and Telecommunications, ICETE 2015}, pages = {14-21}, abstract = {Synchronization in modern optical systems is of paramount importance. The sharing of a common time between different network components constitutes a crucial factor towards system stability. Latest advancements in optical access networks, such as Passive Optical Networks (PONs), allow transmission rates of 10 Gbps. Hence, a very accurate synchronization method is required in order to keep the network free of blocking and collisions. In this work, we focus on 10-gigabit-capable passive optical network (XG-PON) systems, one of the most popular standards for PONs. A rigorous analytic approach is devised so as to investigate the required precision of underlying synchronization method. Closed equations for computing the no blocking and blocking probabilities are developed. The devised analytic framework is verified using simulation methods.}, keywords = {Analysis, Passive optical networks, Synchronization, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{, title = {A Novel Fair and Efficient Bandwidth Allocation Scheme for FiWi Networks}, author = { A. Sarigiannidis and P. Nicopolitidis and G. Papadimitriou and P. Sarigiannidis}, editor = { Proceedings of IEEE Symposium on Computers and Communication (ISCC 2015)}, year = {2015}, date = {2015-01-01}, booktitle = {Proceedings of IEEE Symposium on Computers and Communication (ISCC 2015)}, address = {Larnaca, Cyprus}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sarigiannidis2015651, title = {On the use of learning automata in tuning the channel split ratio of WiMAX networks}, author = { A.G. Sarigiannidis and P. Nicopolitidis and G.I. Papadimitriou and P.G. Sarigiannidis and M.D. Louta and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/259965818_On_the_Use_of_Learning_Automata_in_Tuning_the_Channel_Split_Ratio_of_WiMAX_Networks?_sg=n136X9gc9StHToProYGXLZS-jwpMWkwXOcutOZjrnuvav1Dkx2j8jDAYH2U1EttqBO-qyvaiEoSFzSk}, doi = {10.1109/JSYST.2013.2282032}, year = {2015}, date = {2015-01-01}, journal = {IEEE Systems Journal}, volume = {9}, number = {3}, pages = {651-663}, abstract = {The Worldwide Interoperability for Microwave Access (WiMAX) family of standards have introduced a flexible, efficient, and robust wireless interface. Among other interesting features, WiMAX access networks bring into play a flexible determination of the ratio between the downlink and uplink directions, allowing a relation width from 3: 1 to 1: 1, respectively. However, this promising feature is not properly utilized, since hitherto scheduling and mapping schemes proposed neglect it. In this paper, this challenging issue is effectively addressed by proposing an adaptive model that attempts to adequately adjust the downlink-to-uplink subframe width ratio according to the current traffic conditions. In the context of a mobile WiMAX wireless access network, the base station is enhanced with an error-aware learning automaton in order to be able to identify the magnitude of the incoming and outgoing traffic flows and, in turn, to suitably define the ratio on a frame-by-frame basis. The model designed is extensively evaluated under realistic and dynamic scenarios, and the results indicate that its performance is clearly improved compared with schemes having predefined and fixed ratio values. © 2007-2012 IEEE.}, keywords = {IEEE 802.16, learning automata (LA), mapping, orthogonal frequency-division multiple access (OFDMA), Worldwide Interoperability for Microwave Access (WiMAX)}, pubstate = {published}, tppubtype = {article} } @article{Kraounakis2015878, title = {A Robust Reputation-Based Computational Model for Trust Establishment in Pervasive Systems}, author = { S. Kraounakis and I.N. Demetropoulos and A. Michalas and M.S. Obaidat and P.G. Sarigiannidis and M.D. Louta}, url = {https://www.researchgate.net/publication/278737556_A_Robust_Reputation-Based_Computational_Model_for_Trust_Establishment_in_Pervasive_Systems}, doi = {10.1109/JSYST.2014.2345912}, year = {2015}, date = {2015-01-01}, journal = {IEEE Systems Journal}, volume = {9}, number = {3}, pages = {878-891}, abstract = {Distributed systems built in open competitive and highly dynamic pervasive environments are composed of autonomous entities that act and interact in an intelligent and flexible manner so as to achieve their own goals and aims. System entities may be classified into two main categories that are, in principle, in conflict. These are the service resource requestors (SRRs) wishing to use services and/or exploit resources offered by the other system entities and the service resource providers (SRPs) that offer the services/resources requested. Seeking for the maximization of their welfare, entities may misbehave, thus leading to a significant deterioration of system's performance. The scope of this paper is to present a computational model for trust establishment based on a reputation mechanism, which incorporates direct SRRs' experiences and information disseminated from witness SRRs on the basis of their past experiences with SRPs. The designed mechanism discriminates between unfair feedback ratings intentionally and unintentionally provided, takes into consideration potential changes to providers' behavior, and weighs more recent events in the evaluation of the overall reputation ratings. The proposed model has been extensively evaluated through simulation experiments. It exhibits good performance, as the reputation computation error introduced due to false feedback provision decreases significantly. © 2007-2012 IEEE.}, keywords = {Collaborative reputation mechanism, intelligent multiagent systems, pervasive systems, trust management systems}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis2015427, title = {Architectures and Bandwidth Allocation Schemes for Hybrid Wireless-Optical Networks}, author = { A.G. Sarigiannidis and M. Iloridou and P. Nicopolitidis and G. Papadimitriou and F.-N. Pavlidou and P.G. Sarigiannidis and M.D. Louta and V. Vitsas}, url = {https://www.researchgate.net/publication/273792922_Architectures_and_Bandwidth_Allocation_Schemes_for_Hybrid_Wireless-Optical_Networks?_sg=Ubu-c9MVnMKQCG9WEfRFKa3Wd26kQdcSp4_xLD8X1dD_RizLK1cy2D7cEwMylTdpH03-cKk38_B5pT0}, doi = {10.1109/COMST.2014.2356640}, year = {2015}, date = {2015-01-01}, journal = {IEEE Communications Surveys and Tutorials}, volume = {17}, number = {1}, pages = {427-468}, abstract = {The combination of the most prestigious optical and wireless technologies for implementing a modern broadband integrated access network has been progressively gaining ground. By extending the network coverage in a cost-efficient way, hybrid wireless-optical networks are able to enclose a larger number of potential subscribers than standalone access architectures. Hence, they are capable of increasing revenue levels and facilitating commercial penetration to the telecom market. At the same time, hybrid wireless-optical networks pose an ambitious, alternative, and efficient solution to coping with new bandwidth-hungry user applications. Hybrid wireless-optical networks incorporate sophisticated modules, fabrics, and network entities to effectively provide adequate quality of service (QoS) provisioning. This survey endeavors to classify the main features of wireless-optical integration. We provide a comprehensive compilation of the latest architectures, integrated technologies, QoS features, and dynamic bandwidth allocation (DBA) schemes. In addition, new trends towards wireless-optical convergence are presented. Moreover, as the up-to-date hybrid network standards remain under development, since there is not yet an integrated standard for approving hybrid network access platforms, we accompany this survey with detailed challenges indicating potential avenues of future research. © 1998-2012 IEEE.}, keywords = {Access networks, DBA, FiWi, hybrid wireless-optical, integrated architectures, LTE, Passive optical networks, WiFi, WiMAX}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis20157560, title = {Detecting Sybil attacks in wireless sensor networks using UWB ranging-based information}, author = { P. Sarigiannidis and E. Karapistoli and A.A. Economides}, url = {https://www.researchgate.net/publication/279153588_Detecting_Sybil_Attacks_in_Wireless_Sensor_Networks_using_UWB_Ranging-based_Information?_sg=8HafLwH09h8CvldAKWBSwxdP1uPr4CVat2Xutl6381pf9s5GybAmhWbTDwL3Y4fLD9wOI6trjwQ6MWI}, doi = {10.1016/j.eswa.2015.05.057}, year = {2015}, date = {2015-01-01}, journal = {Expert Systems with Applications}, volume = {42}, number = {21}, pages = {7560-7572}, abstract = {Security is becoming a major concern for many mission-critical applications wireless sensor networks (WSNs) are envisaged to support. The inherently vulnerable characteristics of WSNs appoint them susceptible to various types of attacks. This work restrains its focus on how to defend against a particularly harmful form of attack, the Sybil attack. Sybil attacks can severely deteriorate the network performance and compromise the security by disrupting many networking protocols. This paper presents a rule-based anomaly detection system, called RADS, which monitors and timely detects Sybil attacks in large-scale WSNs. At its core, the proposed expert system relies on an ultra-wideband (UWB) ranging-based detection algorithm that operates in a distributed manner requiring no cooperation or information sharing between the sensor nodes in order to perform the anomaly detection tasks. The feasibility of the proposed approach is proven analytically, while the performance of RADS in exposing Sybil attacks is extensively assessed both mathematically and numerically. The obtained results demonstrate that RADS achieves high detection accuracy and low false alarm rate appointing it a promising ADS candidate for this class of wireless networks. © 2015 Elsevier Ltd. All rights reserved.}, keywords = {Detection probability analysis, Rule-based anomaly detection system, Ultra-wideband (UWB) radio technology, UWB ranging-based Sybil attack detection, wireless sensor networks}, pubstate = {published}, tppubtype = {article} } @article{Mavridopoulos2015470, title = {Broadcast Levels: Efficient and Lightweight Schedule Construction for Push-Based Data Broadcasting Systems}, author = { S. Mavridopoulos and P. Nicopolitidis and G. Papadimitriou and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/279770864_Broadcast_Levels_Efficient_and_Lightweight_Schedule_Construction_for_Push-Based_Data_Broadcasting_Systems?_sg=0j_ejC8-35oRtU2DLJIJKl7iGe88YpazLBtSgzLPGJ8-cvUO2V89ykQQXbEwvStZzzVlda7jumqwv90}, doi = {10.1109/TBC.2015.2444334}, year = {2015}, date = {2015-01-01}, journal = {IEEE Transactions on Broadcasting}, volume = {61}, number = {3}, pages = {470-481}, abstract = {In wireless push-based systems traffic is asymmetric meaning that the server has much more bandwidth available, as compared to the clients. Since it is often not possible or desirable for the clients to send any requests, the server should broadcast the data periodically. The performance of this system relies heavily on the proper scheduling of the broadcast data. The well known algorithm proposed by Vaidya and Hameed battles this challenge and achieves state-of-the-art performance. However, this performance comes with a computational complexity linear to the number of data items that are broadcast. Furthermore, Vaidya's and Hameed's proposed solution for this time complexity degenerates performance. This paper proposes a scheduling algorithm for wireless push-based data broadcasting systems, which performs near optimal and has low computational complexity. Performance evaluation results are presented to demonstrate its efficient performance despite its low computational demands. © 1963-12012 IEEE.}, keywords = {adaptive, Broadcast, low computational complexity, multiple channels, push-based system, wireless}, pubstate = {published}, tppubtype = {article} } @article{Panagiotakis20151628, title = {Performance Increase for Highly-Loaded RoF Access Networks}, author = { A. Panagiotakis and P. Nicopolitidis and G.I. Papadimitriou and P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/281768938_Performance_Increase_for_Highly-Loaded_RoF_Access_Networks}, doi = {10.1109/LCOMM.2015.2456911}, year = {2015}, date = {2015-01-01}, journal = {IEEE Communications Letters}, volume = {19}, number = {9}, pages = {1628-1631}, abstract = {This letter presents a medium access control (MAC) mechanism that allows for the effective use of the bandwidth of highly loaded 60 GHz Radio-over-Fiber (RoF) networks. We extend a previous approach proposed in the literature which is shown to have problems in highly-loaded cases. We propose a protocol that makes use of a memory buffer at the Central Office (CO) at the providers side that allows for the reduction of the number of polling packets required to identify all the active wireless nodes that need to transmit data. This greatly increases the overall throughput of the network at a maximum percentage of 42% for the examined configurations. The high throughput provided by our proposal is achieved without the need to update current infrastructure and only needs a trivial amount of memory at the provider's side. © 1997-2012 IEEE.}, keywords = {MAC protocols, Radio over Fiber, Wireless networking}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis20142580, title = {On forecasting the ONU sleep period in XG-PON systems using exponential smoothing techniques}, author = { P. Sarigiannidis and A. Gkaliouris and V. Kakali and M. Louta and G. Papadimitriou and P. Nicopolitidis and M. Obaidat}, url = {https://www.researchgate.net/publication/282688355_On_forecasting_the_ONU_sleep_period_in_XG-PON_systems_using_exponential_smoothing_techniques}, doi = {10.1109/GLOCOM.2014.7037196}, year = {2014}, date = {2014-01-01}, journal = {2014 IEEE Global Communications Conference, GLOBECOM 2014}, pages = {2580-2585}, abstract = {Power management has been advanced on a crucial factor in the design of modern access networks. Furthermore, the proliferation of optical networking in the last mile led major Telecom unions, such as the International Telecommunication Union (ITU), to emerge energy consumption as a critical objective of the next generation passive optical networks (NG-PONs). In particular, the standardization of the 10-gigabit-capable PON (XG-PON) entails well-defined specifications towards power management and energy reduction, especially regarding the power control of optical terminal devices such as the optical network units (ONUs). In this way, the optical line terminator (OLT) along with ONUs are able to cooperate with each other in order to succeed energy reduction, by applying doze or cyclic sleep periods to idle ONUs. However, the sleep period determination remains a quite challenging research area. In this study, we endeavor to provide XG-PON networks with an effective forecasting mechanism that is capable of estimating the time duration of the forthcoming sleep session. To this end, we apply the exponential smoothing technique to best estimate the sleep duration based on the monitoring time series observations. The obtained evaluation results sound quite promising, since the proposed model accomplishes to advance the trade-off between the energy reduction and network efficiency. © 2014 IEEE.}, keywords = {bandwidth allocation, energy efficiency, exponential smoothing, Passive optical networks, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis20145, title = {HYRA: An efficient hybrid reporting method for XG-PON upstream resource allocation}, author = { P. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos and K. Yiannopoulos}, url = {https://www.researchgate.net/publication/301390310_HYRA_An_Efficient_Hybrid_Reporting_Method_for_XG-PON_Upstream_Resource_Allocation}, doi = {10.5220/0005048200050014}, year = {2014}, date = {2014-01-01}, journal = {OPTICS 2014 - Proceedings of the 5th International Conference on Optical Communication Systems, Part of ICETE 2014 - 11th International Joint Conference on e-Business and Telecommunications}, pages = {5-14}, abstract = {The dynamic bandwidth allocation (DBA) process in the modern passive optical networks (PONs) is crucial since it greatly influences the whole network performance. Recently, the latest new generation PON (NGPON) standard, known as 10-gigabit-capable passive optical network (XG-PON), standardized by the international telecommunication union telecommunication standardization sector (ITU-T), emerges as one of the most efficient access networking framework to cope with the demanding needs of the fiber to the x (FTTX) paradigm, where x stands for home (FTTH), bulding (FTTB), or curve (FTTC). Motivated by the fact that the ITU-T specifications leave the bandwidth allocation process open for development by both industry and academia, we propose a novel DBA scheme for effectively delivering data in the upstream direction. Our idea is based on a subtle suggestion induced by the XG-PON specifications, each developed DBA method should combine both status reporting (SR) and traffic monitoring (TM) techniques. This means that a XGPON framework should be cognitive enough in order to be able either to request bandwidth reporting from the connected users or estimate users' bandwidth demands or both. In this article we cover this gap by proposing a robust learning from experience method by utilizing a powerful yet simple tool, the learning automata (LAs). By combining SR and TM methods, the proposed hybrid scheme, called hybrid reporting allocation (HYRA), is capable of taking efficient decisions on deciding when SR or TM method should be employed so as to maximize the efficacy of the bandwidth allocation process. Simulation results reveal the superiority of our scheme in terms of average packet delay offering up to 33% improvement.}, keywords = {Dynamic bandwidth allocation, Learning automata, Passive optical networks, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2014341, title = {Predicting multimedia traffic in wireless networks: A performance evaluation of cognitive techniques}, author = { P. Sarigiannidis and K. Aproikidis and M. Louta and P. Angelidis and T. Lagkas}, url = {https://www.researchgate.net/publication/267210651_Predicting_Multimedia_Traffic_in_Wireless_Networks_A_Performance_Evaluation_of_Cognitive_Techniques}, doi = {10.1109/IISA.2014.6878802}, year = {2014}, date = {2014-01-01}, journal = {IISA 2014 - 5th International Conference on Information, Intelligence, Systems and Applications}, pages = {341-346}, abstract = {Traffic engineering in networking is defined as the process that incorporates sophisticated methods in order to ensure optimization and high network performance. One of the most constructive tools employed by the traffic engineering concept is the traffic prediction. Having in mind the heterogeneous traffic patterns originated by various modern services and network platforms, the need of a robust, cognitive, and error-free prediction technique becomes even more pressing. This work focuses on the prediction concept as an autonomous, functional, and efficient process, where multiple cutting-edge methods are presented, modeled, and thoroughly assessed. To this purpose, real traffic traces have been captured, including multiple multimedia traffic flows, so as to comparatively assess widely used methods in terms of accuracy. © 2014 IEEE.}, keywords = {automata, extrapolation, markov chains, prediction, wireless networks}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis201449, title = {Towards a fair and efficient downlink bandwidth distribution in XG-PON frameworks}, author = { P. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos and K. Yiannopoulos}, url = {https://www.researchgate.net/publication/269305724_Towards_a_fair_and_efficient_downlink_bandwidth_distribution_in_XG-PON_frameworks}, doi = {10.1109/MELCON.2014.6820505}, year = {2014}, date = {2014-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {49-53}, abstract = {Fairness assurance in modern access networks constitutes a focal point of interest since it dramatically affects the quality of the provided services to the final users. Traffic balancing entails fair bandwidth distribution along with efficient service provisioning, inaugurating a challenging tradeoff between the system throughput and fairness. In this paper, the downlink scheduling effectiveness in modern passive optical networks (PONs) is examined, adopting the ten-gigabit passive optical network (XG-PON) architecture deployed in a tree topology. Considering that the tree topology implies a broadcast nature of data delivering in the downlink direction, the tradeoff between the efficiency and fairness becomes even more compelling, bearing in mind that the distance the broadcast data propagate between the source and users' destination is highly differentiated. In order to remedy this situation two effective scheduling schemes are proposed, namely the shortest propagation processing time (SPPT) and the shortest weighted propagation processing time (SWPPT). Both algorithms are extensively assessed, while the obtained results indicate that the proposed algorithms assure a fair and effective downlink schedule. © 2014 IEEE.}, keywords = {downstream, Fairness, Passive optical networks, round trip time, Scheduling, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis20147, title = {IFAISTOS: A fair and flexible resource allocation policy for next-generation passive optical networks}, author = { P. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos and M. Louta and V. Kakali}, url = {https://www.researchgate.net/publication/282320629_IFAISTOS_A_fair_and_flexible_resource_allocation_policy_for_next-generation_passive_optical_networks}, doi = {10.1109/ICUMT.2014.7002071}, year = {2014}, date = {2014-01-01}, journal = {International Congress on Ultra Modern Telecommunications and Control Systems and Workshops}, volume = {2015-January}, number = {January}, pages = {7-14}, abstract = {In modern, competitive, and dynamic access networks the underlying bandwidth distribution mechanism has to be capable of understanding user requirements, meeting stringent quality of service (QoS) demands, and satisfying a broad spectrum of user traffic dynamics. Undoubtedly, optical fiber is the dominant transmission medium enabling practical and cost-effective optical infrastructures in the last mile. Passive optical networks (PONs) represent one of the most promising player towards the fiber to the home (FTTH) vision allowing users to experience high quality, demanding multimedia services and applications. The 10-gigabit-capable passive optical network (XG-PON), one of the latest PON standard, incorporates a set of profound conditions a contemporary PON should ensure. Fairness provisioning constitutes one of the most critical features a PON should provide. However, ensuring fairness in an access network with numerous different users, requesting multiple traffic flows in any time, is not a straightforward task. In this work, we focus on the fairness issue by devising an adaptive, efficient, and fair dynamic bandwidth allocation (DBA) scheme called Insistent FAIr STrategy prOcesS (IFAISTOS). IFAISTOS investigates and maintains user traffic profiles. Overloaded users are carefully treated by gaining greater granting windows than other users, however bandwidth monopolization is prevented. Fairness is ensured for all users in terms of traffic load and average delay. A steering, adaptive mechanism records user traffic profiles by changing and defining bandwidth weights proportional to individual traffic needs. Extensive simulation results reveal the efficacy of the proposed DBA in terms of fairness and average packet delay. © 2014 IEEE.}, keywords = {Dynamic bandwidth allocation, Fairness, Learning automata, Passive optical networks, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2014f, title = {An adaptive power management scheme for Ethernet Passive Optical Networks}, author = { P. Sarigiannidis and K. Anastasiou and E. Karapistoli and V. Kakali and M. Louta and P. Angelidis}, url = {https://www.researchgate.net/publication/286812658_An_adaptive_power_management_scheme_for_Ethernet_Passive_Optical_Networks?_sg=9Zz2iY14mUeTZMc-phRI6wlWdfdweiaLCUVbz0BGxvUSnU_GRkZWSEFJrAzLqjctJX0s3ulybPAE6OQ}, doi = {10.1109/ISCC.2014.6912460}, year = {2014}, date = {2014-01-01}, journal = {Proceedings - International Symposium on Computers and Communications}, abstract = {Undoubtedly, energy consumption in communication networks poses a significant threat to the environmental stability. Access networks contribute to this consumption by being composed of numerous energy inefficient devices and network equipment. Passive Optical Networks (PONs), one of the most promising candidates in the field of access networking, should avoid this bottleneck in the backhaul power consumption by lowering the energy use of the optical devices. In this paper, we move towards that direction by introducing an energy efficient power management scheme that encompasses two major goals: a) to reduce the energy consumption by allowing the optical devices to enter the sleep mode longer, and b) to concurrently maintain the network performance. To this end, we focus on the energy consumed by the optical network units (ONUs). The intelligence of the ONUs is stimulated by enhancing the decision making in determining the duration of the sleep period with learning from experience mechanism. Learning automata (LAs) are charged to address this challenge. The evaluation of the proposed enhanced power management scheme reveals considerable improvements in terms of energy savings, while at the same time the network performance remains in high levels. © 2014 IEEE.}, keywords = {bandwidth allocation, energy efficiency, Learning automata, Passive optical networks}, pubstate = {published}, tppubtype = {conference} } @conference{Karapistoli2014, title = {Wormhole Attack Detection in Wireless Sensor Networks based on Visual Analytics}, author = { E. Karapistoli and P. Sarigiannidis and A.A. Economides}, editor = { Proceedings of the 10th International Conference on Security and Privacy in Communication Networks (SecureComm’14)}, year = {2014}, date = {2014-01-01}, booktitle = {Proceedings of the 10th International Conference on Security and Privacy in Communication Networks (SecureComm’14)}, address = {Beijing, China}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Louta2014173, title = {RLAM: A dynamic and efficient reinforcement learning-based adaptive mapping scheme in mobile WiMAX networks}, author = { M. Louta and P. Sarigiannidis and S. Misra and P. Nicopolitidis and G. Papadimitriou}, url = {https://www.researchgate.net/publication/259965632_RLAM_A_Dynamic_and_Efficient_Reinforcement_Learning-based_Adaptive_Mapping_Scheme_in_Mobile_WiMAX_Networks}, doi = {10.3233/MIS-130177}, year = {2014}, date = {2014-01-01}, journal = {Mobile Information Systems}, volume = {10}, number = {2}, pages = {173-196}, abstract = {WiMAX (Worldwide Interoperability for Microwave Access) constitutes a candidate networking technology towards the 4G vision realization. By adopting the Orthogonal Frequency Division Multiple Access (OFDMA) technique, the latest IEEE 802.16x amendments manage to provide QoS-aware access services with full mobility support. A number of interesting scheduling and mapping schemes have been proposed in research literature. However, they neglect a considerable asset of the OFDMA-based wireless systems: the dynamic adjustment of the downlink-to-uplink width ratio. In order to fully exploit the supported mobile WiMAX features, we design, develop, and evaluate a rigorous adaptive model, which inherits its main aspects from the reinforcement learning field. The model proposed endeavours to efficiently determine the downlink-to-uplink width ratio, on a frame-by-frame basis, taking into account both the downlink and uplink traffic in the Base Station (BS). Extensive evaluation results indicate that the model proposed succeeds in providing quite accurate estimations, keeping the average error rate below 15% with respect to the optimal sub-frame configurations. Additionally, it presents improved performance compared to other learning methods (e.g., learning automata) and notable improvements compared to static schemes that maintain a fixed predefined ratio in terms of service ratio and resource utilization. © 2014-IOS Press.}, keywords = {channel allocation ratio, IEEE 802.16, Learning, mapping, OFDMA, WiMAX}, pubstate = {published}, tppubtype = {article} } @article{Lagkas20141117, title = {Analyzing the mobile WiMAX system resource exploitation of the downlink direction}, author = { T.D. Lagkas and P. Sarigiannidis and M. Louta}, url = {https://www.researchgate.net/publication/259442681_Analyzing_the_Mobile_WiMAX_System_Resource_Exploitation_of_the_Downlink_Direction}, doi = {10.1007/s11277-013-1557-2}, year = {2014}, date = {2014-01-01}, journal = {Wireless Personal Communications}, volume = {77}, number = {2}, pages = {1117-1127}, abstract = {Worldwide interoperability for microwave access (WiMAX) constitutes a viable networking technology, providing wireless connectivity in an efficient mannerIn this work, on the grounds of the defined frame structure, a novel performance analysis of the mobile WiMAX standard in terms of the downlink resource utilization is presentedThe analysis is validated via simulation, the results of which are also provided along with numerical results, studying the effectiveness of the OFDMA-based downlink mappingThe results reveal the relationship among the frame dimensions, the mapped request size, and the number of unexploited OFDMA slots. © 2013 Springer Science+Business Media New York.}, keywords = {IEEE 802.16e, mapping, OFDMA, Performance analysis, Resource utilization, Simulation, WiMAX}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2013, title = {Ensuring fair downlink allocation in modern access networks: The XG-PON framework}, author = { P. Sarigiannidis and G. Papadimitriou and P. Nicopolitidis and E. Varvarigos}, url = {https://www.researchgate.net/publication/271556110_Ensuring_fair_downlink_allocation_in_modern_access_networks_The_XG-PON_framework}, doi = {10.1109/SCVT.2013.6736006}, year = {2013}, date = {2013-01-01}, journal = {IEEE SCVT 2013 - Proceedings of 20th IEEE Symposium on Communications and Vehicular Technology in the BeNeLux}, abstract = {The fairness aspect on handling user data flows in modern broadband telecommunication networks is of paramount importance since it strongly affects the quality of the provided services. In this work, the fairness provisioning is investigated in a competitive telecommunication field such as the passive optical networks (PONs). Intending to resolve unequal resource allocation in the downstream data delivery, a fair bandwidth assignment scheme is devised and evaluated. The Max-Min fairness concept is applied in order to determine the best effort (BE) bandwidth allocation of each optical network unit (ONU) in the optical line terminal (OLT) side. Simulation results indicate the benefits of utilizing the proposed resource allocation technique in terms of fair bandwidth distribution. © 2013 IEEE.}, keywords = {downstream, Fairness, Max-Min fairness, Passive optical networks, XG-PON}, pubstate = {published}, tppubtype = {conference} } @conference{Karapistoli201349, title = {SRNET: A real-time, cross-based anomaly detection and visualization system for wireless sensor networks}, author = { E. Karapistoli and P. Sarigiannidis and A.A. Economides}, url = {https://www.researchgate.net/publication/262347500_SRNET_A_real-time_cross-based_anomaly_detection_and_visualization_system_for_wireless_sensor_networks?_sg=KDdCBpLRuPqrORtOxHP4P38HAPGocREt6hya_JuOcjZ4M1vhmZ-JbGRQWfXjdL1x1Y-q1yQxIBrvu1w}, doi = {10.1145/2517957.2517964}, year = {2013}, date = {2013-01-01}, journal = {ACM International Conference Proceeding Series}, pages = {49-56}, abstract = {Security concerns are a major deterrent in many applications wireless sensor networks are envisaged to support. To date, various security mechanisms have been proposed for these networks dealing with either Medium Access Control (MAC) layer or network layer security issues, or key management problems. Security visualization is the latest weapon that has been added in the arsenal of a security officer who is tasked with detecting network anomalies by analyzing large amounts of audit data. This paper proposes a novel security visualization system for analyzing and detecting complex patterns of sensor network attacks, called SRNET. Both selective forwarding and jamming attacks are identified through visualizing and analyzing network traffic data on multiple coordinated views, namely the multidimensional crossed view, the crossed view perspective, and the track area view. Through simulations, we demonstrate that SRNET is able to help detect and further identify the root cause of the aforementioned sensor network attacks. Copyright 2013 ACM.}, keywords = {Cross-based anomaly detection and visualization, Detection of selective forwarding and jamming attacks, Wireless sensor network security visualization}, pubstate = {published}, tppubtype = {conference} } @conference{Yiannopoulos2013335, title = {PANDA: Asymmetric passive optical network for xDSL and FTTH access}, author = { K. Yiannopoulos and E. Varvarigos and D. Klonidis and I. Tomkos and M. Spyropoulou and I. Lazarou and P. Bakopoulos and H. Avramopoulos and G. Heliotis and L.-P. Dimos and G. Agapiou and Th. Oikonomou and D. Kritharidis and Sp. Spyridakis and M. Dalakidis and G. Synnefakis and D. Reisis and G. Papastergiou and I. Koukouvinos and A. Orfanoudakis and G.I. Papadimitriou and P. Sarigiannidis and C. Liaskos}, url = {https://www.researchgate.net/publication/258963505_PANDA_asymmetric_passive_optical_network_for_xDSL_and_FTTH_access}, doi = {10.1145/2491845.2491885}, year = {2013}, date = {2013-01-01}, journal = {ACM International Conference Proceeding Series}, pages = {335-342}, abstract = {In this paper, we present an "Asymmetric Passive Optical Network for xDSL and FTTH Access" (PANDA) architecture that is suitable for providing end-users with broadband connections in a cost-effective and non-disruptive fashion. We first describe the need for expanding the current ADSL access to VDSL (and ultimately FTTH), as well as the network upgrades that will be required to perform this expansion. We then introduce the PANDA architecture, a multiwavelength passive optical network (PON) that implements a fiber-to-the cabinet (FTTC) access scheme and provides multi-ten Mb/s access to VDSL2 end-users. We also derive the PANDA capacity in terms of number of users and spatial coverage and show that PANDA is well capable of meeting the broadband needs in the Greece for the short and medium term. We conclude this work with a scalability study of PANDA in view of the goals set in the EU Digital Agenda. Copyright © 2013 ACM.}, keywords = {Broadband access, Digital subscriber loop, Medium Access Control, Network scalability, Passive optical networks}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2013470, title = {Adaptive sensing policies for cognitive wireless networks using learning automata}, author = { P. Sarigiannidis and M. Louta and E. Balasa and T. Lagkas}, url = {https://www.researchgate.net/publication/267210747_Adaptive_Sensing_Policies_for_Cognitive_Wireless_Networks_using_Learning_Automata}, doi = {10.1109/ISCC.2013.6754991}, year = {2013}, date = {2013-01-01}, journal = {Proceedings - International Symposium on Computers and Communications}, pages = {470-475}, abstract = {This paper introduces an adaptive spectrum sensing method for cognitive radio wireless networks. The proposed method enhances previously proposed random-based sensing policies, effectively selecting the licensed channels to be sensed by accurately estimating channels' availability, resulting, thus, to high system's resources utilization. The core mechanism of the adaptive method is an enhanced learning automaton, which efficiently interacts with the environment and provides accurate decisions on selecting the channel to be sensed on behalf of the secondary users. A thorough description of the introduced method is provided, while the performance of the enhanced sensing policies is verified through extensive simulation experiment. © 2013 IEEE.}, keywords = {cognitive radio, Learning automata, multi-channel MAC, wireless networks}, pubstate = {published}, tppubtype = {conference} } @article{Lagkas2013547, title = {Exploring the intra-frame energy conservation capabilities of the horizontal simple packing algorithm in IEEE 802.16e networks: An analytical approach}, author = { T.D. Lagkas and P.G. Sarigiannidis and M. Louta and P. Chatzimisios}, url = {https://www.researchgate.net/publication/233790502_Exploring_the_Intra-frame_Energy_Conservation_Capabilities_of_the_Horizontal_Packing_Algorithm_in_IEEE_80216e_Networks_An_Analytical_Approach?_sg=xykvdNc2j2UIG3_dglWCsetpRGt2s_iN1MnAZp-u4XzbkRQzKBvx-0FNuyh9t-g3KiaDHPuvDEJYkEk}, doi = {10.1007/s11276-012-0484-6}, year = {2013}, date = {2013-01-01}, journal = {Wireless Networks}, volume = {19}, number = {4}, pages = {547-558}, abstract = {The power saving capabilities of the mobile devices in broadband wireless networks constitute a challenging research topic that has attracted the attention of researchers recently, while it needs to be addressed at multiple layers. This work provides a novel analysis of the intra-frame energy conservation potentials of the IEEE 802.16e network. Specifically, the power saving capabilities of the worldwide interoperability for microwave access downlink sub-frame are thoroughly studied, employing the well-known simple packing algorithm as the mapping technique of the data requests. The accurate mathematical model, cross-validated via simulation, reveals the significant ability to conserve energy in this intra-frame fashion under different scenarios. To the best of our knowledge, this is the first work providing intra-frame power-saving potentials of IEEE 802.16 networks. Additionally, this is the first study following an analytic approach. © 2012 Springer Science+Business Media, LLC.}, keywords = {Downlink mapping, IEEE 802.16, Intra-frame power saving, Sleep slots, WiMAX}, pubstate = {published}, tppubtype = {article} } @article{Lagkas20131656, title = {On analyzing the intra-frame power saving potentials of the IEEE 802.16e downlink vertical mapping}, author = { T.D. Lagkas and P. Sarigiannidis and M. Louta}, url = {https://www.researchgate.net/publication/235951767_On_Analyzing_the_Intra-Frame_Power_Saving_Potentials_of_tbe_IEEE_80216e_Downlink_Vertical_Mapping?_sg=KDoKqCiIgJLlPGKSofBFyHQ3ib8pUfmddqW_QvQLtz4xtG6Kfcbr2Rl_HcoguK0bm06CHKY6zG5ljWM}, doi = {10.1016/j.comnet.2013.02.015}, year = {2013}, date = {2013-01-01}, journal = {Computer Networks}, volume = {57}, number = {7}, pages = {1656-1673}, abstract = {Worldwide Interoperability for Microwave Access (WiMAX) is generally considered as a competitive candidate networking technology for the realization of the 4G vision. Among the key factors towards its successful and widespread deployment are the effective support of mobility and the provision of mechanisms for enabling service access at a high quality level in an efficient and cost-effective manner. Nonetheless, this effort should take into account and adequately address strict and severe energy limitations that the mobile devices are currently facing. Power saving constitutes an issue of vital importance, as mobile terminals continue to incorporate more and more functionalities and energy-hungry features in order to support the ever increasing user requirements and demands. The standard employs variations of power saving classes in a frame-to-frame basis, while recent power saving mechanisms proposed in related research literature limit their activity in whole frames, neglecting, thus, the intra-frame power saving capabilities. In this work, the intra-frame energy conservation potentials of the mobile WiMAX network are studied and a novel analytical approach is provided, focusing on the downlink direction where the bandwidth allocation involves idle intervals and dynamic inactivity periods. Specifically, we endeavour to accurately analyse the potential energy conservation capabilities in an intra-frame point of view, applying the well-known simple packing algorithm to distribute the available bandwidth to the various subscribers. Our analytical findings are thoroughly cross-validated via simulation, providing clear insights into the intra-frame energy reduction capabilities. © 2013 Elsevier B.V.}, keywords = {Downlink mapping, IEEE 802.16, Intra-frame power saving, Sleep slots, WiMAX}, pubstate = {published}, tppubtype = {article} } @conference{Louta20124909, title = {Design of an effective QoS-aware mapping scheme using persistent allocation probing}, author = { M. Louta and P. Sarigiannidis and P. Nicopolitidis and G. Papadimitriou and M. Obaidat}, doi = {10.1109/ICC.2012.6364291}, year = {2012}, date = {2012-01-01}, journal = {IEEE International Conference on Communications}, pages = {4909-4913}, abstract = {Mobile Worldwide Interoperability for Microwave Access (WiMAX) constitutes an attractive trademark for supporting wireless access to Intranets and the Internet. Scheduling and mapping processes are of paramount importance since they dramatically affect the network performance. This work endeavors to provide a robust mapping scheme for the downlink sub-frame with respect to various Quality of Service (QoS) constraints. Each downlink request creates rectangular regions, called Horizons, and the mapping technique applies a persistent probing of the Horizons recorded. The evaluation experiments conducted indicate that the scheme designed beneficially affects the system performance. © 2012 IEEE.}, keywords = {IEEE 802.16, mapping, OFDMA, QoS, WiMAX}, pubstate = {published}, tppubtype = {conference} } @conference{Vasileiou20122671, title = {A novel medium access Control Protocol for radio-over-fiber access networks}, author = { G. Vasileiou and G.I. Papadimitriou and P. Nicopolitidis and P.G. Sarigiannidis and M. Louta and M.S. Obaidat}, url = {https://www.researchgate.net/publication/261046625_A_novel_medium_access_Control_Protocol_for_radio-over-fiber_access_networks}, doi = {10.1109/GLOCOM.2012.6503520}, year = {2012}, date = {2012-01-01}, journal = {GLOBECOM - IEEE Global Telecommunications Conference}, pages = {2671-2676}, abstract = {Radio over fiber (RoF) technology is considered as an energy and cost-effective solution to cover the users' rapidly increasing demands for bandwidth and mobility. However, integration of a wireless and an optical network into a hybrid one needs the design of new protocols. In this work, a novel MAC protocol based on the MultiPoint Control Protocol (MPCP) is proposed. The network's decision center receives feedback from the mobile clients via MPCP's GATE/REPORT mechanism so as to efficiently allocate the bandwidth and the wavelength resources in a dynamic manner. The proposed MAC protocol adapts its operation according to the actual client traffic demands. Simulation results reveal the superior performance of the proposed protocol compared to other similar competing proposals reported in the literature. © 2012 IEEE.}, keywords = {60 GHz wireless network, Medium access control (MAC) protocol, MPCP, Passive Optical Network (PON), Radio-over-fiber (RoF) network, Simple polling adaptive protocol}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2011139, title = {On effectively determining the downlink-to-uplink sub-frame width ratio for mobile WiMAX networks using spline extrapolation}, author = { P. Sarigiannidis and M. Louta and A. Michalas}, url = {https://www.researchgate.net/publication/221565459_On_Effectively_Determining_the_Downlink-to-Uplink_Sub-frame_Width_Ratio_for_Mobile_WiMAX_Networks_Using_Spline_Extrapolation}, doi = {10.1109/PCI.2011.44}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - 2011 Panhellenic Conference on Informatics, PCI 2011}, pages = {139-143}, abstract = {One of the most valuable design issues of the Worldwide Interoperability for Microwave Access (WiMAX) standard is its flexibility. It allows multiple downlink-to-uplink duration definitions concerning the width of the corresponding sub-frames, thus, the telecommunication companies and businesses are able to define the downlink-to-uplink width from 3:1 to 1:1 respectively to meet the traffic demands of the connected subscribers. However, the decision on defining the most appropriate ratio is not yet solved, since current efforts on developing scheduling and mapping schemes consider it as fixed. In this work, a novel adaptive mapping approach - based on cubic spline extrapolation - is proposed in order to dynamically determine the most appropriate downlink-touplink width ratio in accordance to the downlink and uplink traffic demands. The method proposed is evaluated through realistic simulation scenarios, whereas its performance is compared with static approaches maintaining a fixed ratio. The results indicate that the approach suggested succeeds noticeable improvements in terms of network service capabilities and bandwidth utilization. © 2011 IEEE.}, keywords = {extrapolation, IEEE 802.16, mapping, OFDMA, Splines, WiMAX}, pubstate = {published}, tppubtype = {conference} } @conference{Skondras2011199, title = {A personalized audio web service using mpeg-7 and mpeg-21 standards}, author = { E. Skondras and M. Louta and P. Sarigiannidis}, url = {https://www.researchgate.net/publication/221565401_A_Personalized_Audio_Web_Service_Using_MPEG-7_and_MPEG-21_Standards}, doi = {10.1109/PCI.2011.29}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - 2011 Panhellenic Conference on Informatics, PCI 2011}, pages = {199-204}, abstract = {This paper presents a web service which delivers personalized audio information. The personalization process is automated and decentralized. The metadata which support personalization are separated in two categories: the metadata describing user preferences stored at each user and the resource adaptation metadata stored at the web service host. The multimedia models MPEG-21 and MPEG-7 are used to describe metadata information and the Web Ontology Language (OWL) to produce and manipulate ontological descriptions. SPARQL is used for querying the OWL ontologies. The MPEG Query Format (MPQF) is also used, providing a wellknown framework for applying queries to the metadata and to the ontologies. © 2011 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2011391, title = {Towards an effective energy efficient passive optical network}, author = { P.G. Sarigiannidis and V.D. Pechlivanidou and M.D. Louta and P. Angelidis}, url = {https://www.researchgate.net/publication/221504359_Towards_an_effective_energy_efficient_passive_optical_network}, doi = {10.1109/ISCC.2011.5983869}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - IEEE Symposium on Computers and Communications}, pages = {391-396}, abstract = {Communication networks' energy consumption poses a considerable threat to the environment stability. The expansion of access networks, which constitute the main playground of the Internet backhaul, is accompanied by numerous energy inefficient devices and equipments. Passive optical networks (PONs) is a potential dominant technology on the field of access networking, hence the reduction of the consumed energy of the optical devices forms a critical issue. In this paper, an efficient green PON is introduced, having two main targets: a) to reduce the energy consumption, by allowing optical devices to operate longer in sleep mode, and b) to maintain PON's good performance. Beyond the green provisioning, the proposed scheme is able to increase occasionally the network performance in terms of mean packet delay and packet drop ratio. This is accomplished by reducing the amount of control messages between subscribers, operating in sleep mode, and central office, allowing more bandwidth to be allocated for data delivering. © 2011 IEEE.}, keywords = {bandwidth allocation, energy consumption, passive optical network}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2011353, title = {Using learning automata for adaptively adjusting the downlink-to-uplink ratio in IEEE 802.16e wireless networks}, author = { A. Sarigiannidis and P. Nicopolitidis and G. Papadimitriou and P. Sarigiannidis and M. Louta}, url = {https://www.researchgate.net/publication/221504931_Using_learning_automata_for_adaptively_adjusting_the_downlink-to-uplink_ratio_in_IEEE_80216e_wireless_networks}, doi = {10.1109/ISCC.2011.5983863}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - IEEE Symposium on Computers and Communications}, pages = {353-358}, abstract = {IEEE 802.16e allows for flexibly defining the relation of the downlink and uplink sub-frames' width from 3:1 to 1:1, respectively. However, the determination of the most suitable ratio is left open to the network designers and the research community. Existing scheduling and mapping schemes are inflexibly designed. In this paper, a novel adaptive mapping scheme is proposed aiming to dynamically adjust the downlink-to-uplink ratio, following adequately the modification of the load requests with respect to both downlink and uplink directions. A learning automaton is exploited in order to sense the performance of the downlink and uplink mapping processes and to determine the most appropriate length ratio of both sub-frames in order to maximize the network performance. The suggested ratio determination scheme is evaluated through realistic scenarios and it is compared with static schemes that maintain a fixed ratio. The results show that our proposed scheme introduces considerable improvement, increasing the network's service ratio and reducing the bandwidth waste. © 2011 IEEE.}, keywords = {IEEE 802.16, Learning automata, mapping, OFDMA, WiMAX}, pubstate = {published}, tppubtype = {conference} } @conference{Louta2011472, title = {Towards realization of the ABC vision: A comparative survey of Access Network Selection}, author = { M. Louta and P. Zournatzis and S. Kraounaws and P. Sarigiannidis and I. Demetropoulos}, url = {https://www.researchgate.net/publication/221505821_Towards_realization_of_the_ABC_vision_A_comparative_survey_of_Access_Network_Selection}, doi = {10.1109/ISCC.2011.5983882}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - IEEE Symposium on Computers and Communications}, pages = {472-477}, abstract = {Access Network Selection (ANS) providing the most appropriate networking technology for accessing and using services in a heterogeneous wireless environment constitutes the heart of the overall handover management procedure. The aim of this paper is to survey representative vertical handover schemes proposed in related research literature with emphasis laid on the design of the ANS mechanism. Schemes' distinct features are analyzed and the authors discuss on their relative merits and weaknesses. © 2011 IEEE.}, keywords = {access network selection, always best connectivity, vertical handover}, pubstate = {published}, tppubtype = {conference} } @conference{Lagkas2011185, title = {Load dependent resource allocation in cooperative multiservice wireless networks: Throughput and delay analysis}, author = { T. Lagkas and D.G. Stratogiannis and G.I. Tsiropoulos and P. Sarigiannidis and M. Louta}, url = {https://www.researchgate.net/publication/221505003_Load_dependent_resource_allocation_in_cooperative_multiservice_wireless_networks_Throughput_and_delay_analysis}, doi = {10.1109/ISCC.2011.5983838}, year = {2011}, date = {2011-01-01}, journal = {Proceedings - IEEE Symposium on Computers and Communications}, pages = {185-190}, abstract = {Cooperative wireless networks supporting multiple services necessitate the application of a robust bandwidth allocation policy to ensure Quality of Service (QoS) provision to different applications. In this work, a load dependent bandwidth allocation technique is presented considering traffic priority and buffer load in the relay nodes of a cooperative communication network. An analytical approach for bandwidth sharing is provided along with a delay analysis, verifying that the proposed scheme can efficiently provide traffic differentiation, satisfying, also, the QoS requirements in terms of bandwidth, packet transmission rate and delay. The results obtained by the analysis are validated via simulations, confirming the improved network performance in terms of throughput and delay. © 2011 IEEE.}, keywords = {Buffer load, Cooperative wireless network, delay, MAC, QoS, Simulation}, pubstate = {published}, tppubtype = {conference} } @conference{Christidis2011, title = {Utilizing locality of demand for lower response times in underwater data broadcasting}, author = { K. Christidis and P. Nicopolitidis and G.I. Papadimitriou and P.G. Sarigiannidis and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/221641077_Utilizing_Locality_of_Demand_for_Lower_Response_Times_in_Underwater_Data_Broadcasting}, doi = {10.1109/VETECS.2011.5956160}, year = {2011}, date = {2011-01-01}, journal = {IEEE Vehicular Technology Conference}, abstract = {Despite being a fundamental networking primitive, data broadcasting has so far received little attention in underwater networks. This paper proposes an adaptive push system for data broadcasting in underwater acoustic wireless networks with locality of client demands. It achieves adaptation of its broadcast schedule according to the a-priori unknown needs of the clients, it efficiently combats the problem of high latency of the underwater acoustic wireless environment and it exploits the bandwidth-distance relationship of this environment in order to improve performance in topologies with locality of client demands. Simulation results show superior performance of the proposed approach compared to existing systems. © 2011 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Kakali2011591, title = {A novel adaptive framework for wireless push systems based on distributed learning automata}, author = { V.L. Kakali and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/233846012_A_Novel_Adaptive_Framework_for_Wireless_Push_Systems_Based_on_Distributed_Learning_Automata?_sg=Ym015TvpDlDVKlU13wezchacetj4IV-v5ySnGHJ45BUx860oyjTpYKK8o2HHFXt_QuecNyPhZlw5IEE}, doi = {10.1007/s11277-009-9863-4}, year = {2011}, date = {2011-01-01}, journal = {Wireless Personal Communications}, volume = {57}, number = {4}, pages = {591-606}, abstract = {A novel adaptive scheme for wireless push systems is presented in this paper. In this wireless environment two entities play the most important role: the server side and the client side that is connected to the system. The server side is responsible to broadcast an item per transmission in order to satisfy the clients' requests. The performance of the server side depends on item selections. Hence, the server broadcasts an item and the clients are satisfied if the transmitted item was the desired one. In this work, a set of learning automata try to estimate the client demands in a distributed manner. More specifically, an autonomous learning automaton is utilized on each client group, since the clients are gathered into groups based on their location. The output of each automaton is combined in order to produce a well-performed transmission schedule. Concurrently, a round robin phase is adopted, giving the opportunity to the non-popular items to be transmitted. In this manner, the various client demands are treated fairly. The introduced technique is compared with a centralized adaptive scheme and the results indicate that the proposed scheduling framework outperforms the centralized one, in terms of response time and fairness. © 2009 Springer Science+Business Media, LLC.}, keywords = {Distributed learning automata, Fairness, Locality of demand, Wireless push systems}, pubstate = {published}, tppubtype = {article} } @article{Kakali2011474, title = {A novel HMM-based learning framework for improving dynamic wireless push system performance}, author = { V.L. Kakali and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/220511276_A_novel_HMM-based_learning_framework_for_improving_dynamic_wireless_push_system_performance}, doi = {10.1016/j.camwa.2011.05.028}, year = {2011}, date = {2011-01-01}, journal = {Computers and Mathematics with Applications}, volume = {62}, number = {1}, pages = {474-485}, abstract = {A new machine learning framework is introduced in this paper, based on the hidden Markov model (HMM), designed to provide scheduling in dynamic wireless push systems. In realistic wireless systems, the clients' intentions change dynamically, hence a cognitive scheduling scheme is needed to estimate the desirability of the connected clients. The proposed scheduling scheme is enhanced with self-organized HMMs, supporting the network with an estimated expectation of the clients' intentions, since the system's environment characteristics alter dynamically and the base station (server side) has no a priori knowledge of such changes. Compared to the original pure scheme, the proposed machine learning framework succeeds in predicting the clients' information desires and overcomes the limitation of the original static scheme, in terms of mean delay and system efficiency. © 2011 Elsevier Ltd. All rights reserved.}, keywords = {Hidden Markov models, machine learning, Scheduling, wireless networks}, pubstate = {published}, tppubtype = {article} } @article{Nicopolitidis201175, title = {Adaptive Wireless Networks Using Learning Automata}, author = { P. Nicopolitidis and G.I. Papadimitriou and A.S. Pomportsis and P. Sarigiannidis and M.S. Obaidat}, url = {https://www.researchgate.net/publication/224230435_Adaptive_wireless_networks_using_learning_automata}, doi = {10.1109/MWC.2011.5751299}, year = {2011}, date = {2011-01-01}, journal = {IEEE Wireless Communications}, volume = {18}, number = {2}, pages = {75-81}, abstract = {Wireless networks operate in environments with unknown and time-varying characteristics. The changing nature of many of these characteristics will significantly affect network performance. This fact has a profound impact on the design of efficient protocols for wireless networks and as a result adaptivity arises as one of the most important properties of these protocols. Learning automata are artificial intelligence tools that have been used in many areas where adaptivity to the characteristics of the wireless environment can result in a significant increase in network performance. This article reviews state of the art approaches in using learning automata to provide adaptivity to wireless networking. © 2011 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {article} } @article{Nicopolitidis2011285, title = {Performance evaluation of acoustic underwater data broadcasting exploiting the bandwidth-distance relationship}, author = { P. Nicopolitidis and K. Christidis and G.I. Papadimitriou and P.G. Sarigiannidis and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/220056798_Performance_Evaluation_of_Acoustic_Underwater_Data_Broadcasting_Exploiting_the_Bandwidth-Distance_Relationship}, doi = {10.3233/MIS-2011-0123}, year = {2011}, date = {2011-01-01}, journal = {Mobile Information Systems}, volume = {7}, number = {4}, pages = {285-298}, abstract = {Despite being a fundamental networking primitive, data broadcasting has so far received little attention in the context of underwater networks. This paper proposes an adaptive push system for data broadcasting in underwater acoustic wireless networks with locality of client demands. The proposed system exploits the characteristic relationship between the bandwidth of an underwater acoustic link and the transmitter-receiver distance in order to improve performance in environments with locality of client demands. Simulation results show superior performance of the proposed approach in the underwater environment compared to existing systems. © 2011 - IOS Press and the authors. All rights reserved.}, keywords = {acoustic communications, data broadcasting, Locality of demand, Underwater networks}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2010763, title = {A novel fair mapping scheme for IEEE 802.16 downlink sub-frame}, author = { P.G. Sarigiannidis and M.D. Louta and P. Chatzimisios}, url = {https://www.researchgate.net/publication/221003449_A_novel_fair_mapping_scheme_for_IEEE_80216_downlink_sub-frame}, doi = {10.1109/ICUMT.2010.5676550}, year = {2010}, date = {2010-01-01}, journal = {2010 International Congress on Ultra Modern Telecommunications and Control Systems and Workshops, ICUMT 2010}, pages = {763-768}, abstract = {A novel fair mapping scheme is proposed in this paper for the IEEE 802.16 downlink sub-frame. The mapping process is critical since it allocates the users' requests into the downlink sub-frame in order to be sent to the mobile stations. One of the most noticeable issues in this area lies on the fairness aspect. Giving that the mapping process defines the order and the way that the users' requests are being serviced, some users may be treated unfairly. In this work this issue is considered and a new mapping scheme is introduced. The proposed scheme encloses fair and more efficient mapping process, compared to the leading scheme, according to the presented simulation results. ©2010 IEEE.}, keywords = {Fairness, IEEE 802.16, mapping, OFDMA, Simulation}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis20101243, title = {Towards a QoS-aware IEEE 802.16 downlink sub-frame mapping scheme}, author = { P.G. Sarigiannidis and M. Louta and D.G. Stratogiannis and G.I. Tsiropoulos}, url = {https://www.researchgate.net/publication/233833066_Towards_a_QoS-Aware_IEEE_80216_downlink_sub-frame_mapping_scheme}, doi = {10.1109/GLOCOMW.2010.5700136}, year = {2010}, date = {2010-01-01}, journal = {2010 IEEE Globecom Workshops, GC'10}, pages = {1243-1247}, abstract = {IEEE 802.16 (WiMAX) is considered as one of the most promising wireless access technologies supporting high-capacity and long-distance communications as well as user mobility. A problem that should be addressed in the context of multi-access communications is the efficient accommodation of traffic requests to the downlink subframe. The allocation operation in downlink sub-frame is not standardized, while only restrictions on the usage of downlink sub-frame's bandwidth are defined. The most noticeable restriction is the rectangular restriction, requiring all downlink allocations to be mapped in a two-dimensions rectangular shaping. This study is a first step towards defining a QoS-aware mapping scheme, prioritizing traffic requests in accordance with the strict delay requirements they pose. The mapping scheme applies horizon scheduling, permitting bursts to be scheduled efficiently and in a simple way, following the horizons as pilots. The QoS-aware mapping scheme is evaluated by means of simulation experiments, which indicate that the proposed scheme operates effectively and efficiently, by reducing the number of unserviced users and traffic requests, and the portion of the dropped real-time traffic. ©2010 IEEE.}, keywords = {Downlink mapping, IEEE 802.16, OFDMA, QoS, Simulation}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2010c, title = {A novel adaptive mapping scheme for IEEE 802.16 mobile downlink framing}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and P. Nicopolitidis and M.S. Obaidat and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/221288841_A_Novel_Adaptive_Mapping_Scheme_for_IEEE_80216_Mobile_Downlink_Framing}, doi = {10.1109/GLOCOM.2010.5683645}, year = {2010}, date = {2010-01-01}, journal = {GLOBECOM - IEEE Global Telecommunications Conference}, abstract = {IEEE 802.16 (WiMAX) constitutes one of the most promising broadband access technologies for high-capacity and high-distance wireless access networks, supporting user mobility. The contribution of this paper is twofold. Firstly, a novel mapping scheme for IEEE 802.16 Mobile standard is introduced, applying horizon mapping. Secondly, an efficient adaptive prediction-based scheme is devised, which is able to adjust the downlink sub-frame capacity, accordingly to the traffic load, since the standard allows the downlink-to-uplink subframe ratio to be changeable from 3:1 to 1:1. The novel adaptive horizon burst mapping (AHBM) scheme is evaluated by simulation experiments, which indicate that the proposed scheme operates effectively and efficiently, by reducing the number of unserved users, the number of unserved traffic requests, and the portion of wasted bandwidth. ©2010 IEEE.}, keywords = {Downlink mapping, IEEE 802.16, OFDMA, prediction}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis20101406, title = {Applying quality of service prediction in WDM optical networks}, author = { P.G. Sarigiannidis}, url = {https://www.researchgate.net/publication/233835727_Applying_Quality_of_Service_Prediction_in_WDM_Optical_Networks}, doi = {10.1109/MELCON.2010.5476023}, year = {2010}, date = {2010-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {1406-1410}, abstract = {A dynamic prediction scheme is presented in this paper, named PROPHET. The purpose of the proposed technique is to predict, given two different classes of quality of service (QoS), the total amount of the demanded transmission requests per QoS class. PROPHET is constructed based on Hidden Markov Chains (HMC), modeled by an ergodic framework. The prediction objective is to reduce the amount of time spent in computing the transmission schedule by predicting traffic requests. The evaluation of the predictor is realized in a Wavelength Division Multiplexing (WDM) single-hop network with star topology. Furthermore, PROPHET is compared to a previous prediction-based scheme, called POSA. Simulation results indicate that the novel technique supports efficient predictable QoS, since it operates more accurately than POSA. © 2010 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis201064, title = {A new approach to the design of MAC protocols for WDM-EPONs}, author = { P.G. Sarigiannidis and S.G. Petridou and G.I. Papadimitriou and M.S. Obaidat}, url = {https://www.researchgate.net/publication/233835732_A_new_approach_to_the_design_of_MAC_protocols_for_WDM-EPONs}, doi = {10.1109/MELCON.2010.5476337}, year = {2010}, date = {2010-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {64-67}, abstract = {Medium Access Control (MAC) protocols for WDM Ethernet passive optical networks (WDM-EPONs) suffer from low performance when the users' round trip times are different. In this paper a new MAC protocol for WDM-EPONs is introduced which overcomes the above limitation by filling the gaps in the scheduling program. Moreover, the proposed scheme favors the requests that present a burst-like behavior, by altering the nodes' service order in such a way that further eliminating the aforementioned gaps. The performance of the proposed scheme is being studied via simulation results which indicate that it achieves a significantly lower delay and packet loss ratio in relation to the well-known WDM IPACT protocol. © 2010 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Kakali20101263, title = {Speeding up the adaptation process in adaptive wireless push systems by applying spline interpolation technique}, author = { V.L. Kakali and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/224142711_Speeding_Up_the_Adaptation_Process_in_Adaptive_Wireless_Push_Systems_by_Applying_Spline_Interpolation_Technique}, doi = {10.1109/MELCON.2010.5475939}, year = {2010}, date = {2010-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {1263-1268}, abstract = {In wireless push systems, the server schedules the broadcasts of its information items aiming at satisfying the clients' preferences efficiently. Latest research efforts have proposed adaptive push systems, enhanced with a learning automaton, in which the server has the ability to update its estimated item demand probability vector. This vector indicates the level of the items' desirability. Even though the adaptive push systems are capable of operating in dynamic environments, where the item demand probability distribution changes periodically, the time that the learning automaton needs to adapt its estimated probability vector to a new demand probability distribution leads to degradation of the system's performance. This work addresses this problem, by applying the spline interpolation method to produce an estimation of the changed desirability immediately after this change takes place. A set of indicative feedback samples are collected by the server and the new item demand probability distribution function is approximated, providing the learning automaton with estimated item probabilities, as initial probabilities. Extensive simulation results indicate the superiority of the proposed scheme, in terms of mean response time © 2010 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Papazoglou2010187, title = {The use of a triangular estimator to improve scheduling in optical burst switched networks}, author = { C. Papazoglou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/220548314_The_use_of_a_triangular_estimator_to_improve_scheduling_in_optical_burst_switched_networks}, doi = {10.1002/dac.1060}, year = {2010}, date = {2010-01-01}, journal = {International Journal of Communication Systems}, volume = {23}, number = {2}, pages = {187-203}, abstract = {In an optical burst switched network, variable-sized data bursts are switched on the fly using bandwidth previously reserved by their control packets. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, that is, the scheduling of bursts. This paper proposes a new class of burst scheduling algorithms based on a triangular estimator. The proposed tool reduces the complexity of the scheduling scheme (measured in channel checks) without compromising its performance (measured by the burst drop ratio). Simulation results demonstrate both the accuracy and the efficiency of the estimator in a variety of scenarios and under self-similar network traffic. Copyright © 2009 John Wiley & Sons, Ltd.}, keywords = {Burst scheduling, Bursty traffic, Horizon, Latest available unused channel with void filling, Optical burst switching}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis201049, title = {IGFS: A new MAC protocol exploiting heterogeneous propagation delays in the dynamic bandwidth allocation on WDM-EPON}, author = { P.G. Sarigiannidis and S.G. Petridou and G.I. Papadimitriou and M.S. Obaidat}, url = {https://www.researchgate.net/publication/220544845_IGFS_A_new_MAC_protocol_exploiting_heterogeneous_propagation_delays_in_the_dynamic_bandwidth_allocation_on_WDM-EPON}, doi = {10.1109/JSYST.2009.2039886}, year = {2010}, date = {2010-01-01}, journal = {IEEE Systems Journal}, volume = {4}, number = {1}, pages = {49-56}, abstract = {One of the most challenging issues of the Ethernet passive optical networks' (EPONs) architecture is the bandwidth allocation problem. Various dynamic allocation schemes have been proposed to schedule the subscribers' demands. However, the performance of all these schemes is significantly degraded when the round-trip times (RTTs) of the optical network units (ONUs) are dissimilar, due to the large number of gaps in the transmission schedule. Unfortunately, in real networks, RTTs are usually dissimilar. In this paper a new medium access control (MAC) protocol for multichannel EPONs, namely the Intelligent Gap Filling Strategy (IGFS) is proposed. The IGFS employs two algorithms: the DissimilarityExploitation algorithm, which exploits the RTTs' dissimilarities, and the MinimumLatencyScheduling algorithm, which rearranges the ONUs' service order in order to favor the requests that cause the minimum scheduling latency. © 2010 IEEE.}, keywords = {Passive optical networks, Reservation, Scheduling, WDM-EPONs}, pubstate = {published}, tppubtype = {article} } @conference{Papazoglou200963, title = {Techniques for improved scheduling in optical burst switched networks}, author = { C. Papazoglou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, doi = {10.1109/ISADS.2009.5207359}, year = {2009}, date = {2009-01-01}, journal = {Proceedings - 2009 International Symposium on Autonomous Decentralized Systems, ISADS 2009}, pages = {63-66}, abstract = {Optical burst switching (OBS) has emerged as a viable switching alternative in backbone optical networks since it can support high data rates with an intermediate granularity compared to wavelength routing and optical packet switching. At the edges of an OBS cloud, packets are assembled to form bursts which enter the network core and are switched on the fly using bandwidth previously reserved by their control packets at each node. A key problem in OBS networks is the assignment of wavelengths to incoming bursts, i.e. the scheduling of bursts. This paper proposes two new techniques which are shown to improve burst scheduling algorithms by lowering their complexity. The first proposed technique is based on a triangular estimator that defines a "drop zone", bursts that fall into this area are considered to have a very low probability of finding a suitable wavelength and as such, no effort is made to schedule them. According to the second approach, the drop zone is defined dynamically based on the burst drop history. Simulation results show that both approaches yield burst drop rates marginally higher or identical to the LAUC-VF scheduling algorithm while reducing the number of channel or void checks and thus the algorithm complexity and execution time.}, keywords = {Burst scheduling, Bursty traffic, Drop history, Horizon, Latest available unused channel with void filling, Optical burst switching, Triangular estimator}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2009472, title = {A quality of service scheduling technique for optical LANs}, author = { P.G. Sarigiannidis and S.G. Petridou and G.I. Papadimitriou and M.S. Obaidat and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/221429798_A_Quality_of_Service_Scheduling_Technique_for_Optical_LANs}, doi = {10.1109/AICCSA.2009.5069366}, year = {2009}, date = {2009-01-01}, journal = {2009 IEEE/ACS International Conference on Computer Systems and Applications, AICCSA 2009}, pages = {472-477}, abstract = {Quality of Service (QoS) support has become a key factor in designing Media Access Control (MAC) protocols. This paper introduces a novel scheduling scheme which supports priority based QoS in Wavelength Division Multiplexing (WDM) star networks. The proposed Interval-based Prioritized Orderly Scheduling Strategy (IPOSS) employs a collision-free scheduling approach and handles variable-length data packets. In practice, it is designed to handle real-time traffic, on the basis that each node may generate high- and low-priority packets with high-priority packets being scheduled prior to low-priority ones. Moreover, the proposed scheme differentiates the packets' schedule order, by prioritizing the long-length over the short-length packets. The performance of IPOSS is evaluated under Bernoulli traffic and simulation results indicate that the novel scheme achieves a significantly high throughput-delay performance for real-time traffic, without sacrificing the performance for non-real-time traffic. © 2009 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Petridou200942, title = {A clustering-driven medium access control protocol for WDM star networks}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/233835645_A_clustering-driven_medium_access_control_protocol_for_WDM_star_networks}, doi = {10.1016/j.optlastec.2008.04.003}, year = {2009}, date = {2009-01-01}, journal = {Optics and Laser Technology}, volume = {41}, number = {1}, pages = {42-52}, abstract = {Channel assignment and nodes' service order are two key issues that have to be addressed when designing medium access control (MAC) protocols for WDM star networks. Traditional scheduling techniques consider either channel assignment or nodes' service order issues. Furthermore, they make use of information such as data channels or receivers' availability, without combining it with senders' demands. This paper introduces a novel approach to message scheduling algorithms for WDM star networks, which is driven by clustering techniques. The proposed clustering driven-minimum scheduling latency (CD-MSL) scheme combines all the aforementioned information to create groups of similar source nodes on the basis of the destination nodes of their messages, aiming at rearranging nodes' service order and improving network performance. Extensive simulation results are presented, which indicate that the proposed clustering-driven scheme leads to a significantly higher throughput-delay performance, in comparison to conventional scheduling algorithms. © 2008 Elsevier Ltd. All rights reserved.}, keywords = {Clustering, Scheduling, WDM star networks}, pubstate = {published}, tppubtype = {article} } @inbook{Papadimitriou2008, title = {Communication Privacy in Book 'Protection of Privacy in Information and Communication Technologies: Technical and Legal Issues'}, author = { G Papadimitriou and P Sarigiannidis and S Petridou and S Gritzali and A Pomportsi}, year = {2008}, date = {2008-01-01}, publisher = {Papasotiriou}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } @conference{Petridou2008222, title = {A high performance clustering-driven MAC protocol for single-hop lightwave networks}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/4368600_A_high_performance_clustering-driven_MAC_protocol_for_single-hop_lightwave_networks}, doi = {10.1109/MELCON.2008.4618438}, year = {2008}, date = {2008-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {222-227}, abstract = {A Medium Access Control (MAC) protocol for Wavelength Division Multiplexing (WDM) star networks has to handle two key issues: channel assignment and nodes' service order. Traditional scheduling techniques define the nodes transmissions and receptions, by considering either channel assignment or nodes' service order issue. Furthermore, they take into account data channels or receivers' availability, but they ignore the similarity between nodes' demands which affect the scheduling length. In this paper a novel, clustering-driven scheduling approach is introduced. The proposed Clustering Driven - Minimum Scheduling Latency (CD-MSL) scheme combines all the aforementioned information and creates groups of source nodes which present similar demands on the basis of their message destination nodes. Based on the obtained clusters, CD-MSL improves network performance by rearranging the nodes' service order. Simulation results indicate that the proposed clustering-driven scheme leads to a significantly higher throughput-delay performance, in comparison to conventional scheduling algorithms. © 2008 IEEE.}, keywords = {Clustering, Scheduling, WDM star networks}, pubstate = {published}, tppubtype = {conference} } @conference{Petridou2008252, title = {Nodes' clustering in WDM star networks with real-time traffic}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/4368607_Nodes%27_clustering_in_WDM_star_networks_with_real-time_traffic?_sg=49FeKpOhf_KQ-DjyqVqurGYS9oknXmSMnVaXKNKptTUl_QQNCmDNMuteoEPx_3tqcDKDNKFz_LUrt0Q}, doi = {10.1109/MELCON.2008.4618443}, year = {2008}, date = {2008-01-01}, journal = {Proceedings of the Mediterranean Electrotechnical Conference - MELECON}, pages = {252-257}, abstract = {This paper proposes a novel scheduling scheme, namely Node Clustering with Prioritized Scheduling (NOC-PS), which is designed to handle real-time traffic in Wavelength Division Multiplexing (WDM) star networks. NOC-PS is based on clustering techniques, while it takes into account the priority information of data packets. The clustering process aims at organizing the network nodes into groups in terms of their packets' requests per channel. Then, NOC-PS rearranges the nodes' service order beginning from the cluster with long-length requests and ending to the cluster with short-length requests. The novelty of NOC-PS is that it applies separate clustering to nodes with high and low priority packets, while it also differentiates their scheduling, since high-priority packets have the privilege of being scheduled prior to low-priority ones. The simulation results indicate that the proposed scheme leads to a significantly higher throughput-delay performance for realtime traffic, without sacrificing the performance of non-real-time traffic. © 2008 IEEE.}, keywords = {Clustering, Packet priority, Real-time traffic, Scheduling, WDM star networks}, pubstate = {published}, tppubtype = {conference} } @conference{Kakali2008, title = {A prediction-based scheme for wireless push systems, using a statistical Hidden Markov Model}, author = { V Kakali and P Sarigiannidis and G Papadimitriou and A Pomportsis}, editor = { Proceeding of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, url = {https://www.researchgate.net/publication/233835722_A_prediction-based_scheme_for_wireless_push_systems_using_a_statistical_Hidden_Markov_Model}, year = {2008}, date = {2008-01-01}, booktitle = {Proceeding of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, address = {Antwerpen, Belgium}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Kakali2008a, title = {DIAS: An adaptive Push System, based on Distributed Learning Automata}, author = { V Kakali and P Sarigiannidis and G Papadimitriou and A Pomportsis}, editor = { Proceeding of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, url = {https://www.researchgate.net/publication/233835719_DIAS_An_Adaptive_Push_System_based_on_Distributed_Learning_Automata}, year = {2008}, date = {2008-01-01}, booktitle = {Proceeding of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, address = {Antwerpen, Belgium}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sarigiannidis2008175, title = {A novel medium access control protocol for optical local networks based on data request ordering}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/223600886_A_novel_medium_access_control_protocol_for_optical_local_networks_based_on_data_request_ordering}, doi = {10.1016/j.optlastec.2007.02.004}, year = {2008}, date = {2008-01-01}, journal = {Optics and Laser Technology}, volume = {40}, number = {1}, pages = {175-193}, abstract = {The basic aim of the scheduling algorithms in wavelength division multiplexing (WDM) single-hop optical networks is to construct a short schedule, in order to support quick communication between the nodes of the network. A design of medium access control (MAC) protocol without collisions is introduced for scheduling variable-length data packets based on a broadcast and select architecture. The system includes only data channels and the coordination of the transmissions is achieved via control packets, functioning before the beginning of actual transmissions. The proposed scheme adopts a prediction mechanism in order to eliminate the possible delay introduced by the scheduling computation between the control and data phases of each cycle of transmission. The two common scheduling strategies suggested try to reorder the service sequence of the nodes, by prioritizing the nodes with long data packets, compared with the nodes with short data packets. The final schedule, formed by a scheduling matrix, seems to be much shorter and leads to an increase, in terms of channel utilization. The extensive simulation results show that the novel scheduling techniques offer more free time space for schedule and allow more data to travel on the medium for the same amount of time. Also, the mean packet delay on the queues is reduced and the relation throughput-delay is much better. © 2007 Elsevier Ltd. All rights reserved.}, keywords = {Optical WDM networks, Scheduling, Service sequence}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis200839, title = {LENA: An efficient channel eclectic algorithm for WDM optical networks}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/233835639_LENA_An_efficient_channel_eclectic_algorithm_for_WDM_optical_networks}, doi = {10.1016/j.optlastec.2007.04.001}, year = {2008}, date = {2008-01-01}, journal = {Optics and Laser Technology}, volume = {40}, number = {1}, pages = {39-51}, abstract = {Media access control (MAC) protocols are methods and ways of accessing the optical fibers, in order to support communication to the nodes of the network. One of the important themes on the design of high-efficient optical networks is the time duration of the schedule process. A good protocol supports effective scheduling methods, without significant time cost. In this work, the performance of a new pre-transmission coordination based protocol on a wavelength division multiplexing (WDM) broadcast and select optical network is studied. A novel scheduling algorithm is proposed, which maintains a prediction scheme and concurrently constructs the pre-transmission scheduling form, based on the demanded traffic of each available channel. Also, this work includes the presentation of the new algorithm, the comparison of the new algorithm with two prior predicted scheduling schemes, along with the presentation and the description of a series of graphs, which plot the results of our simulation. According to simulation results, it is realized that the proposed algorithm not only improves the output of the network but also reduces the average time delay of the packets in the buffer memories of each node. © 2007 Elsevier Ltd. All rights reserved.}, keywords = {Optical WDM networks, Scheduling, Service sequence}, pubstate = {published}, tppubtype = {article} } @article{Petridou2008863, title = {Clustering-based scheduling: A new class of scheduling algorithms for single-hop lightwave networks}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/220548025_Clustering-based_scheduling_A_new_class_of_scheduling_algorithms_for_single-hop_lightwave_networks}, doi = {10.1002/dac.929}, year = {2008}, date = {2008-01-01}, journal = {International Journal of Communication Systems}, volume = {21}, number = {8}, pages = {863-887}, abstract = {In wavelength division multiplexing (WDM) star networks, the construction of the transmission schedule is a key issue, which essentially affects the network performance. Up to now, classic scheduling techniques consider the nodes' requests in a sequential service order. However, these approaches are static and do not take into account the individual traffic pattern of each node. Owing to this major drawback, they suffer from low performance, especially when operating under asymmetric traffic. In this paper, a new class of scheduling algorithms for WDM star networks, which is based on the use of clustering techniques, is introduced. According to the proposed Clustering-Based Scheduling Algorithm (CBSA), the network's nodes are organized into clusters, based on the number of their requests per channel. Then, their transmission priority is defined beginning from the nodes belonging to clusters with higher demands and ending to the nodes of clusters with fewer requests. The main objective of the proposed scheme is to minimize the length of the schedule by rearranging the nodes' service order. Furthermore, the proposed CBSA scheme adopts a prediction mechanism to minimize the computational complexity of the scheduling algorithm. Extensive simulation results are presented, which clearly indicate that the proposed approach leads to a significantly higher throughput-delay performance when compared with conventional scheduling algorithms. We believe that the proposed clustering-based approach can be the base of a new generation of high-performance scheduling algorithms for WDM star networks.}, keywords = {Clustering, prediction, Reservation, Scheduling, WDM star networks}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis2008525, title = {Supporting quality-of-service scheduling in a TT-FR WDM system}, author = { P.G. Sarigiannidis and S.G. Petridou and G.I. Papadimitriou and M.S. Obaidat and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/224358108_Supporting_quality-of-service_scheduling_in_a_TT-FR_WDM_system}, doi = {10.1109/JSYST.2008.2009207}, year = {2008}, date = {2008-01-01}, journal = {IEEE Systems Journal}, volume = {2}, number = {4}, pages = {525-535}, abstract = {In this paper, our recent work interval-based orderly scheduling strategy (IOSS) [1] is extended by adding quality-of-service (QoS) provisioning. A revised medium access control (MAC) protocol is introduced, which supports priority-based QoS in wavelength division multiplexing (WDM) networks with star topology. The proposed interval-based prioritized orderly scheduling strategy (IPOSS) operates in a distributed manner, and has the capability of handling channel collision and destinations conflicts in order to provide a collision-free scheduling scheme. Each node in the network is equipped with a tunable transmitter and a fixed receiver, assuring that the scheme is scalable with respect to the number of nodes and channels. Also, each node may accept high- and low-priority packet arrivals. IPOSS favors high-priority packets, without regarding packets' length or packets' destination. Moreover, the proposed scheme differentiates the packet's schedule order by prioritizing the long-length over the short-length packets. It is found that the adopted access control scheme achieves a critically high throughput-delay performance for real-time traffic. Furthermore, IPOSS presents a little bit improved throughput performance than IOSS scheme, since it handles in a different way the case in which two or more requests demand the same amount of transmission time. The traffic involved in the simulation results follows Bernoulli and Poisson distribution, regarding the arrival of the requests. © 2008 IEEE.}, keywords = {Quality-of-service (QoS), Reservation, Scheduling, Wavelength division multiplexing (WDM) star networks}, pubstate = {published}, tppubtype = {article} } @article{Petridou20082999, title = {On the use of clustering algorithms for message scheduling in WDM star networks}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/224367225_On_the_Use_of_Clustering_Algorithms_for_Message_Scheduling_in_WDM_Star_Networks}, doi = {10.1109/JLT.2008.926913}, year = {2008}, date = {2008-01-01}, journal = {Journal of Lightwave Technology}, volume = {26}, number = {17}, pages = {2999-3010}, abstract = {Scheduling algorithms in wavelength division multiplexing (WDM) single-hop networks aim at producing an effective schedule in order to improve the networks' performance. Apart from channel assignment, the message sequencing is an important issue that have to be addressed when designing media access control (MAC) protocols for WDM networks. Up until now, popular approaches have not extensively addressed the order in which the messages are scheduled even though the messages' service order can considerably contribute to the advance of network performance. This paper introduces a new approach to the design of message scheduling algorithms for WDM star networks, which is based on the use of clustering techniques. The proposed clustering oriented - earliest available time scheduling (CO-EATS) creates groups of nodes whose messages are destined to common nodes. The goal of the proposed CO-EATS scheme is to decrease the probability of scheduling messages to the same destination at successive order. The simulation results have shown that the proposed scheme improves channel utilization and as a result it leads to higher network throughput while it keeps mean packet delay at low levels in comparison with conventional scheduling algorithms. © 2008 IEEE.}, keywords = {Clustering, Optical wavelength division multiplexing (WDM) networks, Reservation, Scheduling}, pubstate = {published}, tppubtype = {article} } @conference{Petridou2007, title = {An Efficient Clustering Oriented Algorithm for Message Scheduling on WDM Star Networks}, author = { S. G. Petridou and P. G. Sarigiannidis and G. I. Papadimitriou and A. S. Pomportsis}, url = {https://www.researchgate.net/publication/4312906_An_Efficient_Clustering_Oriented_Algorithm_for_Message_Scheduling_on_WDM_Star_Networks}, doi = {10.1109/SCVT.2007.4436252}, year = {2007}, date = {2007-11-01}, booktitle = {2007 14th IEEE Symposium on Communications and Vehicular Technology in the Benelux}, journal = {2007 14th IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT}, publisher = {IEEE}, abstract = {Message sequencing and channel assignment are two important issues that have to be addressed when designing MAC protocols for optical Wavelength Division Multiplexing (WDM) networks. Up to now, popular approaches deal with channel assignment without however addressing the order in which the messages are scheduled. This paper presents a new reservation-based message scheduling algorithm for WDM star networks which is based on clustering techniques. The proposed Clustering Oriented - Earliest Available Time Scheduling (CO-EATS) creates groups of nodes whose messages are destined to common destination nodes. The goal of CO-EATS is to prevent consecutive messages from being destined to the same node. The simulation results have shown that the proposed scheme improves channel utilization and as a result it leads to higher network throughput while it keeps mean packet delay at low levels in comparison with conventional scheduling algorithms. ©2007 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Papazoglou2007, title = {A new priority scheme for WDM star networks}, author = { C. Papazoglou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/4312889_A_new_priority_scheme_for_WDM_star_networks}, doi = {10.1109/SCVT.2007.4436234}, year = {2007}, date = {2007-01-01}, journal = {2007 14th IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT}, abstract = {This paper presents a new scheduling protocol for WDM star networks. The new protocol (Priority Scheme Earliest Available Time Scheduling - PS-EATS) is based on the previously proposed EATS protocol which assigns the earliest available data channel to each node that has a message to transmit. PS-EATS modifies the order in which the nodes' requests are processed and allows long messages to be processed ahead of shorter ones. Simulation results show that PS-EATS improves network performance in terms of throughput and also marginally reduces the mean packet delay. ©2007 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Petridou2007b, title = {Clustering based scheduling: A new approach to the design of scheduling algorithms for WDM star networks}, author = { S.G. Petridou and P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/4312904_Clustering_Based_Scheduling_A_New_Approach_to_the_Design_of_Scheduling_Algorithms_for_WDM_Star_Networks}, doi = {10.1109/SCVT.2007.4436255}, year = {2007}, date = {2007-01-01}, journal = {2007 14th IEEE Symposium on Communications and Vehicular Technology in the Benelux, SCVT}, abstract = {Scheduling algorithms in Wavelength Division Multiplexing (WDM) single hope networks aim at producing an effective schedule in order to improve the networks' performance. Up to now, popular approaches schedule network traffic based on nodes' requests which are considered in a sequential service order. This paper presents a novel packet scheduling scheme for WDM star networks based on clustering techniques. Our Clustering Based Scheduling Algorithm (CBSA) organizes the nodes of a network into groups (i.e. clusters) according to the number of their requests per channel and then it defines their transmission priority beginning from the nodes belonging to the cluster with greater demands and ending to the nodes of cluster with fewer requests. The simulation results have shown that the proposed approach improves network performance since it results in higher network throughput keeping mean packet delay at low levels in comparison with conventional scheduling algorithms. ©2007 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sarigiannidis200776, title = {A high performance scheduling priority scheme for WDM star networks}, author = { P. Sarigiannidis and G. Papadimitriou and A. Pomportsis}, url = {https://www.researchgate.net/publication/3417936_A_high_performance_scheduling_priority_scheme_for_WDM_star_networks}, doi = {10.1109/LCOMM.2007.060824}, year = {2007}, date = {2007-01-01}, journal = {IEEE Communications Letters}, volume = {11}, number = {1}, pages = {76-78}, abstract = {A novel scheduling scheme for local area wavelength division multiplexing (WDM) single hop networks is introduced. The proposed protocol provides pre-transmission coordination schedule without collisions. It is based on a broadcast and select star architecture and uses a timeslot based access protocol. The proposed scheme incorporates a prediction based system, in order to reduce the amount of time spend in computing the schedule by predicting traffic requests. A series of simulation results is presented which indicates that when a specific schedule order is followed, starting from the node with the greatest demand, and completing to the node with the least demand (in transmission time) then a better network performance is achieved. Furthermore, the network throughput is higher, while the mean time packet delay at the waiting queues seems to be lower. © 2007 IEEE.}, keywords = {Optical WDM networks, Reservation, Scheduling, Traffic prediction}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2006628, title = {A high performance channel sorting scheduling algorithm based on largest packet}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/233835671_A_High_Performance_Channel_Sorting_Scheduling_Algorithm_Based_On_Largest_Packet}, year = {2006}, date = {2006-01-01}, journal = {Proceedings of CSNDSP (Communication Systems, Networks and Digital Signal Processing)}, address = {Patras, Greece}, abstract = {We present a new scheduling algorithm, which is a synthesis of all the remarkable features of pretransmission coordination-based protocols for broadcast and select star networks. The new algorithm follows a novel policy for switching, in order to improve the efficiency of the network. It is based on all notable elements of a specific family of protocols and tries to accommodate the different ways of scheduling. The protocol manages to bring some improvement, in terms of channel utilization and network throughput, which is proven by simulation results. © 2006 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2006628b, title = {SASA: A synthesis scheduling algorithm with prediction and sorting features}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/221505696_SASA_A_Synthesis_Scheduling_Algorithm_with_Prediction_and_Sorting_Features}, doi = {10.1109/ISCC.2006.140}, year = {2006}, date = {2006-01-01}, journal = {Proceedings - International Symposium on Computers and Communications}, pages = {628-633}, abstract = {We present a new scheduling algorithm, which is a synthesis of all the remarkable features of pretransmission coordination-based protocols for broadcast and select star networks. The new algorithm follows a novel policy for switching, in order to improve the efficiency of the network. It is based on all notable elements of a specific family of protocols and tries to accommodate the different ways of scheduling. The protocol manages to bring some improvement, in terms of channel utilization and network throughput, which is proven by simulation results. © 2006 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2006628c, title = {A new channel priority scheduling technique for WDM star networks}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/233835667_A_New_Channel_Priority_Scheduling_Technique_for_WDM_Star_Networks}, year = {2006}, date = {2006-01-01}, journal = {Proceedings of CSNDSP (Communication Systems, Networks and Digital Signal Processing)}, address = {Patras, Greece}, abstract = {We present a new scheduling algorithm, which is a synthesis of all the remarkable features of pretransmission coordination-based protocols for broadcast and select star networks. The new algorithm follows a novel policy for switching, in order to improve the efficiency of the network. It is based on all notable elements of a specific family of protocols and tries to accommodate the different ways of scheduling. The protocol manages to bring some improvement, in terms of channel utilization and network throughput, which is proven by simulation results. © 2006 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @article{Sarigiannidis2006211, title = {CS-POSA: A high performance scheduling algorithm for WDM star networks}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/225152613_CS-POSA_A_high_performance_scheduling_algorithm_for_WDM_star_networks}, doi = {10.1007/s11107-005-6024-x}, year = {2006}, date = {2006-01-01}, journal = {Photonic Network Communications}, volume = {11}, number = {2}, pages = {211-227}, abstract = {In this paper a new packet scheduling algorithm for WDM star networks is introduced. The protocol adopted is pre-transmission coordination-based and packet collisions have been eliminated due to predetermination of the timeslots each node transmits in a demand matrix. The requests of the transmitted packets are predicted through Markov chains in order to reduce the calculation time of the final scheduling matrix. This is accomplished by pipelining the schedule computation. The innovation that this algorithm introduces is to modify the service sequence of the node. The proposed algorithm is studied via extensive simulation results and it is proved that changing the sequence that nodes transmit, from the node with the largest number of requests to the node with the fewest requests, that there is an increase in the throughput of the network, with a minimum (almost zero) cost in mean time delay and in delay variance. © Springer Science + Business Media, Inc. 2006.}, keywords = {Optical WDM networks, Reservation, Scheduling, Star topology, Traffic prediction}, pubstate = {published}, tppubtype = {article} } @article{Sarigiannidis20064811, title = {A high-throughput scheduling technique, with idle timeslot elimination mechanism}, author = { P.G. Sarigiannidis and G.I. Papadimitriou and A.S. Pomportsis}, url = {https://www.researchgate.net/publication/3243752_A_High-Throughput_Scheduling_Technique_With_Idle_Timeslot_Elimination_Mechanism}, doi = {10.1109/JLT.2006.884992}, year = {2006}, date = {2006-01-01}, journal = {Journal of Lightwave Technology}, volume = {24}, number = {12}, pages = {4811-4827}, abstract = {A new media-access-control protocol is introduced in this paper. The authors consider a wavelength-division-multiplexing (WDM) network with star topology. A single-hop WDM system is considered, so that there is a full connectivity between every node-pair in just one hop. The protocol adopted is pretransmission coordination-based, so the protocol coordinates nodes before the actual transmission. The coordination is achieved with one demand (or traffic) matrix, which saves the predetermination of the timeslots each node transmits. Each transmission frame (or cycle) has two phases: the control phase and the data phase. In order to eliminate the possible delay added by the schedule computation between the two phases of each frame, they consider a traffic prediction scheme, which is based upon the hidden Markov chain model. The control phase functions as a learning period in which the predictor is trained. The training is based on the traffic of the network. During the data phase, each station transmits its packets based on the predicted reservations, which are the predictor's output. In the same frame, the predictor computes the reservations for the next frame. They show that their protocol, although suffering from small packet delay loss, introduces a new method of computing the reservations of the demand matrix and brings some performance improvement in terms of channel utilization and results in higher network throughput, which is proven by extensive simulations. © 2006 IEEE.}, keywords = {Demand matrix, Optical wavelength-division-multiplexing (WDM) networks, Reservation, Scheduling, Traffic prediction}, pubstate = {published}, tppubtype = {article} } @conference{Sarigiannidis2005a, title = {WFF: A High Performance Scheduling Algorithm for WDM Star Networks that Minimizes Idle Timeslots}, author = { PG Sarigiannidis and GI Papadimitriou and AS Pomportsis}, editor = { Proceedings of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, url = {https://www.researchgate.net/publication/233835661_WFF_A_High_Performance_Scheduling_Algorithm_for_WDM_Star_Networks_that_Minimizes_Idle_Timeslots}, year = {2005}, date = {2005-01-01}, booktitle = {Proceedings of IEEE/SCVT (Symposium on Communications and Vehicular Technology}, address = {Enschede, the Netherlands}, abstract = {This paper introduces a new packet scheduling algorithm for WDM star networks, named CS-POSA. This algorithm utilizes Markov chains in order to predict the transmission requests of the network nodes and thus reduce the calculation time of the final scheduling matrix. The resulting protocol is pre-transmission coordination-based without packet collisions. The proposed algorithm pipelines the schedule computation process and introduces a new order in which nodes’ requests are processed. This innovative feature is shown to increase network throughput with negligible impact on the mean delay and the delay variance.}, keywords = {}, pubstate = {published}, tppubtype = {conference} } @conference{Sarigiannidis2005b, title = {A New Prediction and Channel Sorting Based Scheduling Algorithm for WDM Star Networks}, author = { PG Sarigiannidis and GI Papadimitriou and AS Pomportsis}, editor = { Proceedings of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, url = {https://www.researchgate.net/publication/233835660_A_New_Prediction_and_Channel_Sorting_Based_Scheduling_Algorithm_for_WDM_Star_Networks}, year = {2005}, date = {2005-01-01}, booktitle = {Proceedings of IEEE/SCVT (Symposium on Communications and Vehicular Technology)}, address = {Enschede, the Netherlands}, abstract = {This paper introduces a new packet scheduling algorithm for WDM star networks, named CS-POSA. This algorithm utilizes Markov chains in order to predict the transmission requests of the network nodes and thus reduce the calculation time of the final scheduling matrix. The resulting protocol is pre-transmission coordination-based without packet collisions. The proposed algorithm pipelines the schedule computation process and introduces a new order in which nodes’ requests are processed. This innovative feature is shown to increase network throughput with negligible impact on the mean delay and the delay variance.}, keywords = {}, pubstate = {published}, tppubtype = {conference} }