Air pollution is a major problem in the everyday life of citizens, especially air pollution in th... more Air pollution is a major problem in the everyday life of citizens, especially air pollution in the transport domain. Ships play a significant role in coastal air pollution, in conjunction with transport mobility in the broader area of ports. As such, ports should be monitored in order to assess air pollution levels and act accordingly. In this paper, we obtain CO values from environmental sensors that were installed in the broader area of the port of Igoumenitsa in Greece. Initially, we analysed the CO values and we have identified some extreme values in the dataset that showed a potential event. Thereafter, we separated the dataset into 6-h intervals and showed that we have an extremely high rise in certain hours. We transformed the dataset to a moving average dataset, with the objective being the reduction of the extremely high values. We utilised a machine-learning algorithm, namely the univariate long short-term memory (LSTM) algorithm to provide the predicted outcome of the tim...
Routing of vehicles is an important procedure, whereby there is the necessity to reach a destinat... more Routing of vehicles is an important procedure, whereby there is the necessity to reach a destination in a timely manner. As such, networking of vehicles is undertaken using wireless and telecommunication capabilities, in order to promote such a service. In this paper, we present two subsystems, namely a vehicle and a traffic light subsystem aiming to interconnect them, in order to provide a routing service in a distributed manner. We show the deployment of the traffic light and vehicle subsystem in a real world application and we provide results on the capturing and counting of vehicles, the acquisition of the GPS signal of the vehicles as well as their speed. The aforementioned metrics reach a dedicated server. Finally, we employ an electric vehicle, which we use to visit a set of customers and we utilise an off-the-shelf GPS logger to obtain metrics such as speed and location. The aim is to show its applicability, when we are going to employ it with our built subsystem, for future...
Optimization of the transmission power and rate allocation is a significant problem in wireless n... more Optimization of the transmission power and rate allocation is a significant problem in wireless networks with mobile nodes. Due to mobility, the vehicles establishing wireless networks may exhibit severe fluctuations of their link quality, affecting their connection reliability and throughput. In Vehicular Ad-hoc Networks (VANETS), the IEEE 802.11p standard provides a practical metric for the Packet Reception Ratio (PRR), which is related with the transmission power and rate. Finding a global strategy for optimizing PRR for all mobile nodes can be treated as a potential game where each vehicle is considered as a selfish player, aiming to maximise its transmission reliability while rate constraints are satisfied. To this end, we propose a game-theoretic approach that converges to a Nash equilibrium. The main contributions of this work include: (i) identification of the best case equilibrium, for two cases of interference: diminished or kept stable, and (ii) verification of the equili...
Proceedings of the 14th International Joint Conference on e-Business and Telecommunications, 2017
One of the most important problems in the Wireless Sensor Network community is the enhancement of... more One of the most important problems in the Wireless Sensor Network community is the enhancement of the end-to-end throughput that strengthens the reliability of the network. Transmission power adjustment may play a key role in accomplishing better throughput. Increasing transmission power to make the signal strength better is the intuitive solution; however, this may introduce certain problems such as interference and more energy consumption. However, decreasing the transmission power may result in a weak signal strength that may result in unreliable links, which also affect throughput significantly. One of the most important metrics for link reliability is the Expected Transmission Count (ETX). We take the additive ETX from the basestation to every node and we aim to optimise the route throughput by setting the transmission power accordingly. We address these trade-offs and we propose a game-theoretic solution that aims to maximize the end-to-end throughput between network nodes, while using the optimal transmission power. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium. We show that our algorithm converges to the global optimum and that it is Lyapunov stable. We provide evidence that our algorithm converges to the best response dynamics under the fictitious play learning algorithm. Spyrou, E. and Mitrakos, D. Game-theoretic End-to-end Throughput Optimisation in Wireless Sensor Networks.
Proceedings of the Seventh International Symposium on Business Modeling and Software Design, 2017
Business processes are essential for the successful growth of an organisation. Business models ai... more Business processes are essential for the successful growth of an organisation. Business models aim to organise such processes and invoke the necessary processes for particular tasks. Such a mechanism is responsible for the appropriate response and time management of the business strategy of a corporation. To this end, we formulate a scenario where business processes need to be invoked according to the expenditures of their operation, in order to complete a transaction in a market model. We model such a mechanism using game theory and we produce a characteristic function that we maximise, in order to reduce the cost of the business processes. We employ the well-known assignment game to form business process coalitions and minimise the business operation cost in the market.
One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generatio... more One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generation of topologies that maximize transmission reliability and guarantee network connectivity while also maximizing the network’s lifetime. Transmission power settings have a large impact on the aforementioned factors. Increasing transmission power to provide coverage is the intuitive solution yet with it may come with lower packet reception and shorter network lifetime. However, decreasing the transmission power may result in the network being disconnected. To balance these trade-offs we propose a discrete strategy game-theoretic solution, which we call TopGame that aims to maximize the reliability between nodes while using the most appropriate level of transmission power that guarantees connectivity. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium as well as experimental results. Here we show, using the Indriya WSN testbed, that TopG...
At 2010, we are at the effective end of the first decade of Wireless Sensor Network (WSN) researc... more At 2010, we are at the effective end of the first decade of Wireless Sensor Network (WSN) research and that the aspects such as energy efficient routing have pretty much had their day as the sensing, computing and energy technologies have now moved on. There now seems to be a consensus in the field as to what the next challenges are. This paper will describe some of those challenges for the next decade and discuss some of the key impediments hindering WSN research. From this we report a small experiment whereby we try to take on board some of the critiques we put forward to see what we come up with. To this end, we indeed show how a simple solution can help to solve many of the problems we list, and in doing so, highlight some of the difficulties in keeping to our own recommendations regarding the future direction of WSN research.
SCIREA Journal of Traffic and Transportation, 2021
This report presents Open Science initiatives in Greece and proposes modern services with respect... more This report presents Open Science initiatives in Greece and proposes modern services with respect to different challenges that stakeholders in transport may face. The focus is given on how Greece responded to the modern movement of openness promoted by the European Commission for increasing transparency, integrity and reproducibility of data, information and results. Different initiatives of Open Science are presented covering infrastructures, portals, data and other services. Finally, a modern system is proposed for the transport sector in an attempt to exploit previous research work and speed up the path from research to innovation and promote stakeholders' engagement.
Structural health monitoring (SHM) has been extensively used in the railway industry, with applic... more Structural health monitoring (SHM) has been extensively used in the railway industry, with applications ranging from railway infrastructures to carbody shells. An SHM method that dominates monitoring procedures is Acoustic Emissions (AE). The utilisation of the AE method could use a significantly large amount of data, collected and forwarded to terminal computers using wireless communications. Nowadays, the use of 5G is taking over traditional wireless such as Wi-Fi and 4G telecommunications. However, errors in the transmission due to noisy channels may be experienced. The SHM system may result in the wrong detection of a potential defect in a railway infrastructure with dangerous consequences, such as derailment. Hence, methods for adequately dealing with these errors need to be established, such as Forward Error Correction (FEC) codes. In this paper, we suggest the use of the wireless FEC codes applied to a number of deployed AE devices, in order to perform correction at the trans...
Recently, the transport industry has been substituting metal with composite parts due to their pr... more Recently, the transport industry has been substituting metal with composite parts due to their properties, such as increased strength, stiffness and lightweightness. Inspection and monitoring are very important tools that detect, identify and measure occurred damage or deterioration state of transport means and infrastructure. Acousto-ultrasonics is an non-destructive testing technique, which is essentially a combination of acoustic emission methodology with ultrasonic simulation of stress waves to assess defect states in certain materials. In this paper, we perform initial experiments with composite specimens, attempting to detect defects. In particular, the attenuation of simulated acoustic emission events are measured in order to further investigate the phenomenon of edge reflections from small composite specimens. Furthermore, the detection of two different types of defects is shown using only two features extracted from the signal.
Metal parts have recently been substituted with composite in the transport industry due to their ... more Metal parts have recently been substituted with composite in the transport industry due to their characteristics, which include increased strength, stiffness and reduced weight. Acoustoultrasonics is an inspection technique, which combines the acoustic emission methodology with ultrasonic simulation of stress waves to assess defect states in materials. Acousto-ultrasonics belong to the family of inspection tools, which emerge to identify and measure occurred damage or decay state of transportation modes and infrastructure. In this paper, we attempt to detect defects by performing initial experiments with composite specimens. Specifically, the attenuation of simulated acoustic emission events are measured aiming to further investigate the phenomenon of edge reflections from small composite specimens. Also, only two features from the signal can be used to detect two different types of faults. Finally, a new triangular–like larger specimen is introduced and assessed using the two senso...
2019 15th International Conference on Distributed Computing in Sensor Systems (DCOSS), 2019
There is a considerable degree of uncertainty regarding the precise role of the board of director... more There is a considerable degree of uncertainty regarding the precise role of the board of directors in corporate strategic planning. With reference to the South African Company Law and practice the objectives of this paper are (i) to isolate and categorize possible alternative relationships between top management and the board of directors in matters of corporate strategy; (ii) to identify the level at which the board should become involved in corporate strategy; (iii) to suggest which elements of strategy should be the legitimate concern of the board; (iv) to propose procedural guidelines which will facilitate optimal board involvement in corporate strategy. The author concludes that the board of directors, in terms of its mandate, should not only become involved in strategy evaluation but also in the formulation and implementation of strategic plans. This is particularly true within the context of the current socio-economic and political environment in South Africa. The implications of this conclusion for the composition of the board and for the conducting of board affairs are discussed.
Transmission power has a major impact on link and communication reliability and network lifetime ... more Transmission power has a major impact on link and communication reliability and network lifetime in Wireless Sensor Networks. We study power control in a multi-hop Wireless Sensor Network where nodes' communication interfere with each other. Our objective is to determine each node's transmission power level that will reduce the communication interference and keep energy consumption to a minimum. We propose a potential game approach to obtain the unique equilibrium of the network transmission power allocation. The unique equilibrium is located in a continuous domain. However, radio transceivers accept only discrete values for transmission power level setting. We study the viability and performance of mapping the continuous solution from the potential game to the discrete domain required by the radio. We demonstrate the success of our approach through TOSSIM simulation when nodes use the Collection Tree Protocol for routing the data. Also, we show results of our method from th...
A MIMO system is a wireless system, which employs multiple antennas at the transmitter and the re... more A MIMO system is a wireless system, which employs multiple antennas at the transmitter and the receiver. MIMO is an acronym for "multiple-input multiple-output". Its main objective is the transmission and reception of signals at the physical layer of the wireless stack. Currently, MIMO have been made commercial, with examples being WiMAX and LTE, as well as WiFi and 802.11n. However, there is significant research to be undertaken with respect to handling interference.. Interference has been neglected in point-to-point MIMO as far as concurrent transmissions are concerned; thus, we are given the facts that MIMO offered the possibility of increased reliability through diversity and combination of gains. A technique to handle concurrent transmissions id cognitive radio, where nodes are separated to primary and secondary users competing for the channel medium. In this paper we provide a recent review on cog-nitive radio for MIMO.
The asymmetric and dynamic properties of the wireless channel required the derivation of a pletho... more The asymmetric and dynamic properties of the wireless channel required the derivation of a plethora of link quality metrics that assisted in the enhancement of wireless link reliability. Expected Transmission Count is a robust link quality metric used in most of the state-of-the-art works, due to its consideration of bidirectional links. Transmission power plays a key role to mitigate interference, which affects link quality. Power control problems, often exhibit non-convex behaviour and can not be solved using traditional methods. In this paper, we optimise transmission power taking onboard the Expected Transmission Count metric. We construct our game-theoretic model with pricing and show that it can reach Pareto-dominant equilibrium. Finally, we create a learning algorithm using logit dynamics and show that it guarantees probabilistic convergence of the joint action to the potential function maximisers.
Wireless Sensor networks comprise of nodes that act in order to transmit their packets in the mos... more Wireless Sensor networks comprise of nodes that act in order to transmit their packets in the most efficient way. Various metrics exist that target the enhancement of link quality upon these transmissions. We use the Expected Transmission Count metric to establish a characteristic function that aims to the cooperation of nodes in a coalition that gets the best worth of link quality. A node may have the incentive to cooperate or to directly transmit the packet to the upstream node. To this end, we establish a cooperative relay selection game that we formulate as a combinatorial game of coalition formation. We reduce the problem to a well known assignment game that may be solved with Linear Programming. We provide solid mathematical proof that indicates the link quality enhancement in the network. We also provide evidence that a cooperative selection game is effective, which we show in simulations.
Electric vehicles emerged in the transport industry due to the clean energy that they incorporate... more Electric vehicles emerged in the transport industry due to the clean energy that they incorporate and promote. Routing is essential in electric vehicles, since their battery has a limit and there are not enough chargers in a city; thus, making optimal routing a challenging and important problem to address. Many solutions incorporate the use of wireless systems to perform a car-to-car communication. We take onboard the scenario of distributed route planning and propose a fault detection mechanism that will ensure that there will not be a deficiency in the electric vehicle routing process, in terms of wireless communication. We employ the Byzantine Generals algorithm to detect possible faulty wireless mediums in cars or traffic lights, in order to fix or exclude them from the routing process. We show how our approach is capable to detect faulty wireless mediums and we provide an alternative if the consensus cannot be satisfied.
Electric vehicles (EVs) emerged in the transport domain, due to their energy efficiency and clean... more Electric vehicles (EVs) emerged in the transport domain, due to their energy efficiency and clean energy that they utilise. The electric vehicle routing problem is essentially a problem of selecting a set of minimum cost routes, while the demand of the customers is achieved. In this work, we model the electric vehicle routing problem using a wireless network methodology, namely the backpressure framework. Every route is imposed with a penalty, which includes the driving time of each road. We derive a weight as a function of the road queue backpressure and the driving time of a car. The next route for our EV is the one that has the highest weight. We show that this methodology leads to faster routes in that there are often roads with accidents or traffic jams. Also, we propose a fault detection mechanism that will ensure that there will be not deficiency in the electric vehicle routing process, in terms of wireless communication. We employ the Byzantine Generals algorithm to detect p...
One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generatio... more One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generation of topologies that maximize transmission reliability and guarantee network connectivity while also maximising the network's lifetime. Transmission power settings have a large impact on the aforementioned factors. Increasing transmission power to provide coverage is the intuitive solution yet with it may come with lower packet reception and shorter network lifetime. However, decreasing the transmission power may result in the network being disconnected. To balance these trade-offs we propose a discrete strategy game-theoretic solution, which we call TopGame that aims to maximize the reliability between nodes while using the most appropriate level of transmission power that guarantees connectivity. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium as well as experimental results. Here we show, using the Indriya WSN testbed, that ...
Air pollution is a major problem in the everyday life of citizens, especially air pollution in th... more Air pollution is a major problem in the everyday life of citizens, especially air pollution in the transport domain. Ships play a significant role in coastal air pollution, in conjunction with transport mobility in the broader area of ports. As such, ports should be monitored in order to assess air pollution levels and act accordingly. In this paper, we obtain CO values from environmental sensors that were installed in the broader area of the port of Igoumenitsa in Greece. Initially, we analysed the CO values and we have identified some extreme values in the dataset that showed a potential event. Thereafter, we separated the dataset into 6-h intervals and showed that we have an extremely high rise in certain hours. We transformed the dataset to a moving average dataset, with the objective being the reduction of the extremely high values. We utilised a machine-learning algorithm, namely the univariate long short-term memory (LSTM) algorithm to provide the predicted outcome of the tim...
Routing of vehicles is an important procedure, whereby there is the necessity to reach a destinat... more Routing of vehicles is an important procedure, whereby there is the necessity to reach a destination in a timely manner. As such, networking of vehicles is undertaken using wireless and telecommunication capabilities, in order to promote such a service. In this paper, we present two subsystems, namely a vehicle and a traffic light subsystem aiming to interconnect them, in order to provide a routing service in a distributed manner. We show the deployment of the traffic light and vehicle subsystem in a real world application and we provide results on the capturing and counting of vehicles, the acquisition of the GPS signal of the vehicles as well as their speed. The aforementioned metrics reach a dedicated server. Finally, we employ an electric vehicle, which we use to visit a set of customers and we utilise an off-the-shelf GPS logger to obtain metrics such as speed and location. The aim is to show its applicability, when we are going to employ it with our built subsystem, for future...
Optimization of the transmission power and rate allocation is a significant problem in wireless n... more Optimization of the transmission power and rate allocation is a significant problem in wireless networks with mobile nodes. Due to mobility, the vehicles establishing wireless networks may exhibit severe fluctuations of their link quality, affecting their connection reliability and throughput. In Vehicular Ad-hoc Networks (VANETS), the IEEE 802.11p standard provides a practical metric for the Packet Reception Ratio (PRR), which is related with the transmission power and rate. Finding a global strategy for optimizing PRR for all mobile nodes can be treated as a potential game where each vehicle is considered as a selfish player, aiming to maximise its transmission reliability while rate constraints are satisfied. To this end, we propose a game-theoretic approach that converges to a Nash equilibrium. The main contributions of this work include: (i) identification of the best case equilibrium, for two cases of interference: diminished or kept stable, and (ii) verification of the equili...
Proceedings of the 14th International Joint Conference on e-Business and Telecommunications, 2017
One of the most important problems in the Wireless Sensor Network community is the enhancement of... more One of the most important problems in the Wireless Sensor Network community is the enhancement of the end-to-end throughput that strengthens the reliability of the network. Transmission power adjustment may play a key role in accomplishing better throughput. Increasing transmission power to make the signal strength better is the intuitive solution; however, this may introduce certain problems such as interference and more energy consumption. However, decreasing the transmission power may result in a weak signal strength that may result in unreliable links, which also affect throughput significantly. One of the most important metrics for link reliability is the Expected Transmission Count (ETX). We take the additive ETX from the basestation to every node and we aim to optimise the route throughput by setting the transmission power accordingly. We address these trade-offs and we propose a game-theoretic solution that aims to maximize the end-to-end throughput between network nodes, while using the optimal transmission power. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium. We show that our algorithm converges to the global optimum and that it is Lyapunov stable. We provide evidence that our algorithm converges to the best response dynamics under the fictitious play learning algorithm. Spyrou, E. and Mitrakos, D. Game-theoretic End-to-end Throughput Optimisation in Wireless Sensor Networks.
Proceedings of the Seventh International Symposium on Business Modeling and Software Design, 2017
Business processes are essential for the successful growth of an organisation. Business models ai... more Business processes are essential for the successful growth of an organisation. Business models aim to organise such processes and invoke the necessary processes for particular tasks. Such a mechanism is responsible for the appropriate response and time management of the business strategy of a corporation. To this end, we formulate a scenario where business processes need to be invoked according to the expenditures of their operation, in order to complete a transaction in a market model. We model such a mechanism using game theory and we produce a characteristic function that we maximise, in order to reduce the cost of the business processes. We employ the well-known assignment game to form business process coalitions and minimise the business operation cost in the market.
One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generatio... more One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generation of topologies that maximize transmission reliability and guarantee network connectivity while also maximizing the network’s lifetime. Transmission power settings have a large impact on the aforementioned factors. Increasing transmission power to provide coverage is the intuitive solution yet with it may come with lower packet reception and shorter network lifetime. However, decreasing the transmission power may result in the network being disconnected. To balance these trade-offs we propose a discrete strategy game-theoretic solution, which we call TopGame that aims to maximize the reliability between nodes while using the most appropriate level of transmission power that guarantees connectivity. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium as well as experimental results. Here we show, using the Indriya WSN testbed, that TopG...
At 2010, we are at the effective end of the first decade of Wireless Sensor Network (WSN) researc... more At 2010, we are at the effective end of the first decade of Wireless Sensor Network (WSN) research and that the aspects such as energy efficient routing have pretty much had their day as the sensing, computing and energy technologies have now moved on. There now seems to be a consensus in the field as to what the next challenges are. This paper will describe some of those challenges for the next decade and discuss some of the key impediments hindering WSN research. From this we report a small experiment whereby we try to take on board some of the critiques we put forward to see what we come up with. To this end, we indeed show how a simple solution can help to solve many of the problems we list, and in doing so, highlight some of the difficulties in keeping to our own recommendations regarding the future direction of WSN research.
SCIREA Journal of Traffic and Transportation, 2021
This report presents Open Science initiatives in Greece and proposes modern services with respect... more This report presents Open Science initiatives in Greece and proposes modern services with respect to different challenges that stakeholders in transport may face. The focus is given on how Greece responded to the modern movement of openness promoted by the European Commission for increasing transparency, integrity and reproducibility of data, information and results. Different initiatives of Open Science are presented covering infrastructures, portals, data and other services. Finally, a modern system is proposed for the transport sector in an attempt to exploit previous research work and speed up the path from research to innovation and promote stakeholders' engagement.
Structural health monitoring (SHM) has been extensively used in the railway industry, with applic... more Structural health monitoring (SHM) has been extensively used in the railway industry, with applications ranging from railway infrastructures to carbody shells. An SHM method that dominates monitoring procedures is Acoustic Emissions (AE). The utilisation of the AE method could use a significantly large amount of data, collected and forwarded to terminal computers using wireless communications. Nowadays, the use of 5G is taking over traditional wireless such as Wi-Fi and 4G telecommunications. However, errors in the transmission due to noisy channels may be experienced. The SHM system may result in the wrong detection of a potential defect in a railway infrastructure with dangerous consequences, such as derailment. Hence, methods for adequately dealing with these errors need to be established, such as Forward Error Correction (FEC) codes. In this paper, we suggest the use of the wireless FEC codes applied to a number of deployed AE devices, in order to perform correction at the trans...
Recently, the transport industry has been substituting metal with composite parts due to their pr... more Recently, the transport industry has been substituting metal with composite parts due to their properties, such as increased strength, stiffness and lightweightness. Inspection and monitoring are very important tools that detect, identify and measure occurred damage or deterioration state of transport means and infrastructure. Acousto-ultrasonics is an non-destructive testing technique, which is essentially a combination of acoustic emission methodology with ultrasonic simulation of stress waves to assess defect states in certain materials. In this paper, we perform initial experiments with composite specimens, attempting to detect defects. In particular, the attenuation of simulated acoustic emission events are measured in order to further investigate the phenomenon of edge reflections from small composite specimens. Furthermore, the detection of two different types of defects is shown using only two features extracted from the signal.
Metal parts have recently been substituted with composite in the transport industry due to their ... more Metal parts have recently been substituted with composite in the transport industry due to their characteristics, which include increased strength, stiffness and reduced weight. Acoustoultrasonics is an inspection technique, which combines the acoustic emission methodology with ultrasonic simulation of stress waves to assess defect states in materials. Acousto-ultrasonics belong to the family of inspection tools, which emerge to identify and measure occurred damage or decay state of transportation modes and infrastructure. In this paper, we attempt to detect defects by performing initial experiments with composite specimens. Specifically, the attenuation of simulated acoustic emission events are measured aiming to further investigate the phenomenon of edge reflections from small composite specimens. Also, only two features from the signal can be used to detect two different types of faults. Finally, a new triangular–like larger specimen is introduced and assessed using the two senso...
2019 15th International Conference on Distributed Computing in Sensor Systems (DCOSS), 2019
There is a considerable degree of uncertainty regarding the precise role of the board of director... more There is a considerable degree of uncertainty regarding the precise role of the board of directors in corporate strategic planning. With reference to the South African Company Law and practice the objectives of this paper are (i) to isolate and categorize possible alternative relationships between top management and the board of directors in matters of corporate strategy; (ii) to identify the level at which the board should become involved in corporate strategy; (iii) to suggest which elements of strategy should be the legitimate concern of the board; (iv) to propose procedural guidelines which will facilitate optimal board involvement in corporate strategy. The author concludes that the board of directors, in terms of its mandate, should not only become involved in strategy evaluation but also in the formulation and implementation of strategic plans. This is particularly true within the context of the current socio-economic and political environment in South Africa. The implications of this conclusion for the composition of the board and for the conducting of board affairs are discussed.
Transmission power has a major impact on link and communication reliability and network lifetime ... more Transmission power has a major impact on link and communication reliability and network lifetime in Wireless Sensor Networks. We study power control in a multi-hop Wireless Sensor Network where nodes' communication interfere with each other. Our objective is to determine each node's transmission power level that will reduce the communication interference and keep energy consumption to a minimum. We propose a potential game approach to obtain the unique equilibrium of the network transmission power allocation. The unique equilibrium is located in a continuous domain. However, radio transceivers accept only discrete values for transmission power level setting. We study the viability and performance of mapping the continuous solution from the potential game to the discrete domain required by the radio. We demonstrate the success of our approach through TOSSIM simulation when nodes use the Collection Tree Protocol for routing the data. Also, we show results of our method from th...
A MIMO system is a wireless system, which employs multiple antennas at the transmitter and the re... more A MIMO system is a wireless system, which employs multiple antennas at the transmitter and the receiver. MIMO is an acronym for "multiple-input multiple-output". Its main objective is the transmission and reception of signals at the physical layer of the wireless stack. Currently, MIMO have been made commercial, with examples being WiMAX and LTE, as well as WiFi and 802.11n. However, there is significant research to be undertaken with respect to handling interference.. Interference has been neglected in point-to-point MIMO as far as concurrent transmissions are concerned; thus, we are given the facts that MIMO offered the possibility of increased reliability through diversity and combination of gains. A technique to handle concurrent transmissions id cognitive radio, where nodes are separated to primary and secondary users competing for the channel medium. In this paper we provide a recent review on cog-nitive radio for MIMO.
The asymmetric and dynamic properties of the wireless channel required the derivation of a pletho... more The asymmetric and dynamic properties of the wireless channel required the derivation of a plethora of link quality metrics that assisted in the enhancement of wireless link reliability. Expected Transmission Count is a robust link quality metric used in most of the state-of-the-art works, due to its consideration of bidirectional links. Transmission power plays a key role to mitigate interference, which affects link quality. Power control problems, often exhibit non-convex behaviour and can not be solved using traditional methods. In this paper, we optimise transmission power taking onboard the Expected Transmission Count metric. We construct our game-theoretic model with pricing and show that it can reach Pareto-dominant equilibrium. Finally, we create a learning algorithm using logit dynamics and show that it guarantees probabilistic convergence of the joint action to the potential function maximisers.
Wireless Sensor networks comprise of nodes that act in order to transmit their packets in the mos... more Wireless Sensor networks comprise of nodes that act in order to transmit their packets in the most efficient way. Various metrics exist that target the enhancement of link quality upon these transmissions. We use the Expected Transmission Count metric to establish a characteristic function that aims to the cooperation of nodes in a coalition that gets the best worth of link quality. A node may have the incentive to cooperate or to directly transmit the packet to the upstream node. To this end, we establish a cooperative relay selection game that we formulate as a combinatorial game of coalition formation. We reduce the problem to a well known assignment game that may be solved with Linear Programming. We provide solid mathematical proof that indicates the link quality enhancement in the network. We also provide evidence that a cooperative selection game is effective, which we show in simulations.
Electric vehicles emerged in the transport industry due to the clean energy that they incorporate... more Electric vehicles emerged in the transport industry due to the clean energy that they incorporate and promote. Routing is essential in electric vehicles, since their battery has a limit and there are not enough chargers in a city; thus, making optimal routing a challenging and important problem to address. Many solutions incorporate the use of wireless systems to perform a car-to-car communication. We take onboard the scenario of distributed route planning and propose a fault detection mechanism that will ensure that there will not be a deficiency in the electric vehicle routing process, in terms of wireless communication. We employ the Byzantine Generals algorithm to detect possible faulty wireless mediums in cars or traffic lights, in order to fix or exclude them from the routing process. We show how our approach is capable to detect faulty wireless mediums and we provide an alternative if the consensus cannot be satisfied.
Electric vehicles (EVs) emerged in the transport domain, due to their energy efficiency and clean... more Electric vehicles (EVs) emerged in the transport domain, due to their energy efficiency and clean energy that they utilise. The electric vehicle routing problem is essentially a problem of selecting a set of minimum cost routes, while the demand of the customers is achieved. In this work, we model the electric vehicle routing problem using a wireless network methodology, namely the backpressure framework. Every route is imposed with a penalty, which includes the driving time of each road. We derive a weight as a function of the road queue backpressure and the driving time of a car. The next route for our EV is the one that has the highest weight. We show that this methodology leads to faster routes in that there are often roads with accidents or traffic jams. Also, we propose a fault detection mechanism that will ensure that there will be not deficiency in the electric vehicle routing process, in terms of wireless communication. We employ the Byzantine Generals algorithm to detect p...
One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generatio... more One of the most significant problems in Wireless Sensor Network (WSN) deployment is the generation of topologies that maximize transmission reliability and guarantee network connectivity while also maximising the network's lifetime. Transmission power settings have a large impact on the aforementioned factors. Increasing transmission power to provide coverage is the intuitive solution yet with it may come with lower packet reception and shorter network lifetime. However, decreasing the transmission power may result in the network being disconnected. To balance these trade-offs we propose a discrete strategy game-theoretic solution, which we call TopGame that aims to maximize the reliability between nodes while using the most appropriate level of transmission power that guarantees connectivity. In this paper, we provide the conditions for the convergence of our algorithm to a pure Nash equilibrium as well as experimental results. Here we show, using the Indriya WSN testbed, that ...
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Papers by Evangelos Spyrou