Game-theoretic End-to-end Throughput Optimisation in Wireless Sensor Networks Evangelos D. Spyrou and Dimitrios K. Mitrakos School of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Egnatia Street, Thessaloniki, Greece Keywords: Transmission Power, Expected Transmission Count (ETX), Throughput, Fictitious Play, Lyapunov, Potential Game. Abstract: 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. 1 INTRODUCTION End-to-end throughput (Li et al., 2001) is a major is- sue in Wireless Sensor Networks (WSN)s. A WSN comprises a set of links formed by nodes that trans- mit their packets, in order to reach a basestation. However, nodes experience interference during their transmission, thereby making the transmission diffi- cult. Furthermore, the delay of the transmission of the packet increases, since the interfered node has to do an exponential backoff (Committee et al., 1997) and retransmit the packet. At the same time, this node may be receiving packets making its link quality with the sender to increase. Thereafter, the messages enter a queue and need to be serviced with the minimum delay, thus impacting the capacity of the link (Jun and Sichitiu, 2003). One approach to enhance the link quality between nodes forming links, which expand to the network’s reliability of communication is to increase the radio transmission power level, in order to strengthen the signal strength. Link quality is directly related to throughput, as we can see in the novel paper present- ing the Expected Transmission Count (ETX) metric (De Couto et al., 2005). However, raising the trans- mission power may result in packets being lost due to the complexities of the wireless channel. An in- crease in transmission power might cause an increase in interference and collisions, decreasing the number of packets received; hence, the end-to-end through- put of the network. On the other hand, as we see in (Spyrou and Mitrakos, 2015b), if the distance be- tween the transmitter-receiver and interferer-receiver is difference by approximately a factor of 2, interfer- ence does not cause packet loss. This indicates that a node may select a high transmission power level, in order to strengthen its signal, without suffering from packet loss. Moreover, packets using different trans- mission powers may result in their packets simulta- neously transmitted successfully, depending on their distance and transmission power level (Moscibroda et al., 2006). There is a sweet spot in ETX related to transmis- sion power levels that can keep throughput to a high level, while not using a larger transmission power level than necessary. The transmission power also affects the energy consumption of the node, directly influencing the lifetime of the WSN (Antonopou- los et al., 2009). In order to handle this trade- off, we present a finite strategy distributed game- Spyrou, E. and Mitrakos, D. Game-theoretic End-to-end Throughput Optimisation in Wireless Sensor Networks. DOI: 10.5220/0006399400170026 In Proceedings of the 14th International Joint Conference on e-Business and Telecommunications (ICETE 2017) - Volume 6: WINSYS, pages 17-26 ISBN: 978-989-758-261-5 Copyright © 2017 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved 17