Papers by Petros Nicopolitidis
This paper proposes a novel method for providing performance fairness in adaptive wireless data b... more This paper proposes a novel method for providing performance fairness in adaptive wireless data broadcasting environments of push nature. In such environments, the performance of an application that runs on client devices and receives items from the broadcast channel is affected by both the number of these items and the pattern via which these are demanded by the application. The novelty of the proposed approach lies in the fact that, irrespective of the above parameters, all applications run by the client will receive a fair allocation of bandwidth and thus will enjoy the same performance. It requires additional functionality only at the Broadcast Server and can thus constitute a simple and effective means for wireless data broadcasting providers to support performance fairness.
International Journal of Communication Systems, Nov 1, 2014
Overview Fueled by the increasing popularity of the Internet and evermore bandwidth-hungry servic... more Overview Fueled by the increasing popularity of the Internet and evermore bandwidth-hungry services, networking technologies constitute one of the most fast growing areas in the field of the IT industry. This fast growth has led to a point where the energy expenditure of networking infrastructure constitutes a significant portion of the total energy expenditure and moreover, the trend is towards an additional increase. Thus, the development of energy efficient networking technologies for the various segments (backbone and access parts) of today's Internet has recently emerged as a significant research area. The primary focus of such green technologies, is towards reduction of the energy footprint of the networking infrastructure, thus enabling sustainable development, low operational costs and environmental safety. The objective of this special issue is to report state-of-the art results in energy-efficient networking protocols by welcoming contributions originating from both academic and industrial research. These should be original contributions solicited in relevant areas of energy-efficient networking protocols.
Biological nanonetworks have unique properties that can be exploited so as to develop relative co... more Biological nanonetworks have unique properties that can be exploited so as to develop relative communication paradigms. The aim of this work is to examine the use of the chemotaxis phenomenon to speed up the delivery of a message by directing bacteria cells towards the node that is the intended destination. Thus, the use of chemotaxis results to a transmission process that resembles that of directional transmission in traditional radio-based wireless environments. We study the way the system evolves by a concentration-dependent message encoding protocol. The results reveal that this new paradigm can successfully enhance the message delivery process in a chemotaxis-based biological nanonetwork.
IEEE Access, 2020
The flexible nature of elastic optical networks (EONs) effectively uses spectral resources for op... more The flexible nature of elastic optical networks (EONs) effectively uses spectral resources for optical communication by allocating the minimum required bandwidth to network connections. Since the energy consumption of such networks scales with the magnitude of bandwidth demand, addressing the issue of energy wastage is important. This fact has a profound impact on the design of efficient schemes for energy aware optical networks, and adaptivity arises as one of the most important properties of these networks. Learning Automata are Artificial Intelligence tools that have been used in networking algorithms, when adaptivity to the characteristics of the network environment can result in significantly improved network performance. In this work, a new adaptive power-aware algorithm is introduced, which selectively switches off bandwidth-variable optical transponders (BVTs) under low utilization conditions, to achieve energy efficiency. A novel adaptive scheme, which makes use of Learning Automata to significantly reduce the total energy consumption, while at the same time avoiding the onset of congestion, is proposed. The proposed scheme monitors network congestion, in terms of Bandwidth Blocking Probability (BBP), and the learning mechanism finds the optimal amount of energy-saving so that congestion is avoided, while at the same time significant energy savings are achieved. The proposed Learning Energy-Saving Algorithm (LESA) is evaluated via extensive simulation results, which indicate that it achieves an energy saving of up to 50%, compared to other energy efficient solutions. INDEX TERMS Adaptivity, elastic optical networks, energy-efficiency, learning automata, metropolitan networks.
Multi-Channel Cognitive MAC Protocol for adhoc cognitive networks that uses a distributed learnin... more 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.
Wireless Communications and Mobile Computing, 2017
Research in Optical Networking has recently focused on Elastic Optical Network architectures, tha... more Research in Optical Networking has recently focused on Elastic Optical Network architectures, that support elastic band connections to increase spectrum availability, support high transmission rates and reduce network costs. Elastic optical networks offer flexibility in the way capacity is assigned to connections and are considered the most prevalent solution for the next generation metro/backbone networks. Reduction in energy consumption is an important issue in such networks. In this work, a new power aware algorithm is introduced, which selectively switches off network links under low utilization scenarios supporting energy efficiency. A new power-aware scheme is proposed, which reduces the total energy consumption, while maintaining a low blocking probability under dynamic traffic. Extensive simulation results are presented, which indicate that the proposed heuristic algorithm achieves a power saving of up to 9%, compared to a simple energy unaware dynamic RSA algorithm.
International Journal of Security and Networks, 2019
The performance of a push-based system relies heavily on the proper scheduling of the broadcast d... more The performance of a push-based system relies heavily on the proper scheduling of the broadcast data. To this end, the Broadcast Disks method is most commonly employed. It defines a procedure consisting of four separate algorithms: one to provide and handle the clients’ feedback, another to group the data objects into disks, a third one to define their spinning velocities, and finally a Broadcast Sequence constructor algorithm. In this article we introduce and evaluate Clustering-Driven Wireless Data Broadcasting (CWDB), a complete instantiation of the Broadcast Disks method. The proposed CWDB procedure addresses the major omissions of preceding schemes, including the total lack of feedback mechanisms, extremely limited variety of spinning velocity definition algorithms, and no thorough and realistic testing of complete combinations of algorithms under various client configurations. A new efficient clustering-driven data grouping algorithm is also introduced. Extensive simulation results are presented, which indicate that the proposed CWDB is absolutely dominant over other classical methods in the vast majority of the test cases and led to very important conclusions that were previously overlooked.
Computer Communications, Aug 1, 2016
Medium access control (MAC) protocol Simple polling adaptive protocol Multipoint control protocol... more Medium access control (MAC) protocol Simple polling adaptive protocol Multipoint control protocol(MPCP) Wavelength division multiplexing ethernet passive optical network (WDM-EPON) Bottleneck Radio-over-fiber (RoF) network 60 GHz wireless network Best-fit algorithm a b s t r a c t Users' rapidly increasing demands for bandwidth and mobility in conjunction with the surge of delaysensitive 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.
2022 IEEE Conference on Standards for Communications and Networking (CSCN)
Electronics
Solar power (SP) passive optical network (PON)-based fiber-wireless (FiWi) access systems are bec... more Solar power (SP) passive optical network (PON)-based fiber-wireless (FiWi) access systems are becoming increasingly popular as they provide coverage to rural and urban areas where no power grid exists. Secure operation of such networks which includes solar- and/or battery-powered devices, is crucial for anticipating potential network issues and prolong the life of the network operation. Since optical network units (ONUs) may be powered by SP-charged batteries, energy awareness becomes an important issue, particularly when it comes to reducing ONUs’ energy consumption and allowing them to operate in off-grid remote areas. With the PON as the fixed part of these networks, the optical line terminal (OLT) informs the ONUs through a message exchange mechanism when no traffic is present, allowing them to transition to a low-power-consumption sleep mode. However, man-in-the-middle (MITM) attacks pose a serious threat to the message exchange mechanisms, which can eventually drain the energy...
IEEE Access
Low Power Wide Area Networks have emerged as a leading communications technology in the field of ... more Low Power Wide Area Networks have emerged as a leading communications technology in the field of Internet of Things sensor and monitoring networks. In such networks, uplink traffic is characterized as a combination of periodic data reports and event-triggered alarm reports. When an many devices detect an event in a short timespan, a burst of concurrent transmissions can occur, leading to a surge of collisions, and thus severe data delivery performance degradation. In this paper, a hybrid random/scheduled access strategy is proposed for mitigating the impact of traffic-triggering events on network performance. Under periodic report traffic the LoRaWAN standard Class A protocol is in effect, but after an event a TDMA scheme is applied. Three implementations of this strategy are described. The first is a pair of novel MACs for LoRaWAN, allowing (a) synchronization of end devices with the network using the event detection as a crude synchronization point, and (b) the dynamic scheduling of groups of devices. The other two implementations build upon a single-hop and a two-hop previously proposed LoRaWAN-based wake-up architectures, respectively. The above approaches are validated and studied through extensive simulation. The results show improved packet delivery ratio over the Class A MAC. The effect is more prominent as the event propagation velocity increases. The proposed approach also surpasses LoRaWAN in energy per delivered bit for high event propagation velocities. Finally, the novel protocol has a lower hardware and deployment complexity than the wake up radio based alternatives, at the cost of higher energy consumption. INDEX TERMS Internet of Things, LPWAN, LoRaWAN, MAC protocol, synchronization, TDMA, event triggered traffic, event response. I. INTRODUCTION 19 In Internet of Things monitoring sensor networks, some cases 20 may arise in which events, with causes external to the net-21 work, can be detected almost simultaneously by the devices 22 in the network. In networks with random access upstream 23 protocols, such as LoRaWAN, this can cause a burst of simul-24 taneous transmissions, which can lead to serious congestion, 25 increased number of collisions, and performance degradation 26 more generally. Thus, there is a need for an appropriate 27 The associate editor coordinating the review of this manuscript and approving it for publication was Hosam El-Ocla. response to such conditions at the medium access control 28 (MAC) layer. 29 Depending on the nature of the event and the applica-30 tion, the collection of event reports from the sensors may 31 be of critical operational importance. The above statement 32 is particularly true in applications such as forest monitoring 33 for management and fire prevention and detection. Another 34 relevant application is smart metering, including power grid 35 and water supply grid monitoring for failures. In such applica-36 tions, the ability of the network to facilitate swift event report 37 data transfer is directly linked to monitoring performance, 38 and can ultimately have an impact on operational functions. 39 VOLUME 10, 2022 This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License. For more information, see https://creativecommons.org/licenses/by-nc-nd/4.0/ 157 cycled MAC ensures the LPWAN requirements under that 158 scenario. However, the standard protocol is not as well suited 159 for the case where end device transmissions are triggered 160 almost simultaneously due to some external occurrence, such as a power outage. In this scenario, as a result of the random 162 access MAC, a high number of collisions occur resulting in 163 severe performance degradation [6].
2020 International Conference on Computer, Information and Telecommunication Systems (CITS)
LoRaWAN is one of the most promising standards for IoT networking. Slotted ALOHA has been recentl... more LoRaWAN is one of the most promising standards for IoT networking. Slotted ALOHA has been recently proposed as LoRaWAN MAC protocol, in an effort to achieve a performance improvement. However, as of today, the performance of backoff algorithms in a LoRaWAN environment has not been studied. Furthermore, critical performance metrics, such as queueing delay, remain to be evaluated. This paper explores the use of six backoff schemes in a Slotted-ALOHA-based LoRaWAN network. Their performance is studied via extensive simulation results, under low, medium and high load conditions by using delay, throughput and packet loss rate as performance metrics. Finally, the use of each backoff scheme in the LoRaWAN environment is extensively discussed in the light of the above simulation results and major conclusions are extracted.
Internet Technology Letters, 2021
Broadcasting the downstream traffic makes the Ethernet Passive Optical Networks (EPONs) vulnerabl... more Broadcasting the downstream traffic makes the Ethernet Passive Optical Networks (EPONs) vulnerable to eavesdropping which is typically the initial step of an active attack, such as Man in the Middle attack (MITM). A MITM attack in such a network can be implemented by employing a fake Optical Line Terminal (OLT) and overwhelm computational, bandwidth, or energy resources. The latter is of great interest since Passive Optical Networks (PONs) are estimated to be the largest energy consumers among optical networks. In this paper we use formal analysis to quantitatively assess the impact of a fake OLT attacking an EPON energy‐efficiency mechanism. Formal verification techniques, such as model checking, constitute the perfect candidate for security verification, since they can analyze systems and protocols based on rigorous model definitions. Our results show that a MITM attack increases the energy expenditure, since it enforces the Optical Network Units (ONUs) to stay in the active mode ...
Proceedings of the 17th International Joint Conference on e-Business and Telecommunications, 2020
A novel medium access control (MAC) protocol designed for healthcare environments is proposed. Th... more A novel medium access control (MAC) protocol designed for healthcare environments is proposed. The protocol is aimed to support different Classes of Service (CoS) with diverse needs, each including different kinds of medical applications. The highest priority class includes Tactile Internet applications, that require an endto-end latency of less than 1 msec, while the rest of the classes are assigned graded priorities.The proposed protocol provides the highest priority class with the required bandwidth and guaranteed low delay while the other classes, which also include critical applications, do not starve. Two protocol versions are introduced with the second version exhibiting very good performance in terms of average delay and throughput.
Studies in health technology and informatics, 2019
Recent statistics have demonstrated that Emergency Departments (EDs) in Greece lack in organizati... more Recent statistics have demonstrated that Emergency Departments (EDs) in Greece lack in organization and service. In most cases, patient prioritization is not automatically implemented. The main objective of this paper is to present IntelTriage, a smart triage system, that dynamically assigns priorities to patients in an ED and monitors their vital signs and location during their stay in the clinic through wearable biosensors. Initital scenarios and functional requirements are presented as preliminary results.
2021 International Conference on Computer, Information and Telecommunication Systems (CITS), 2021
LoRaWAN is one of the most promising standards for IoT applications. Slotted ALOHA has been propo... more LoRaWAN is one of the most promising standards for IoT applications. Slotted ALOHA has been proposed as a LoRaWAN MAC protocol, to achieve performance improvement. This paper explores the effect of using clusters in a multichannel Slotted ALOHA-based LoRaWAN network, for event detection, like forest fires, where a small part of the network nodes, at the pace of the event, produce data at a high rate. It proposes a new frequency planning for such environments, that aims to reduce the number of collisions, and consequently to reduce the mean packet delay, as the data is important to be transmitted as fast as possible. Extensive simulation results indicate a promising performance improvement in terms of throughput and mean packet delay, compared to a random frequency channel assignment to the network nodes.
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Papers by Petros Nicopolitidis