Topology control for wireless mesh networks and its effect on network performance
University of Zululand
InfrastructureWireless Mesh Networks (I-WMNs) are increasingly used to provide network connectivity and Internet access to previously under-served areas in the developing world. It is common for some of these deployments to be battery-powered due to a lack of electrical infrastructure in the targeted areas. Thus, the energy-efficiency of these networks gains additional importance. Topology Control (TC) has been previously reported to improve the energy-efficiency and network performance of wireless ad-hoc networks, including I-WMNs. However,simulation-based studies have been relied upon to reach these conclusions and the study of TC prototypes applicable to I-WMNs has largely been limited to design issues. Thus, the study of the efficacy of TC prototypes as a mechanism for improving energy-fficiency and network performance remains an open issue. The thesis addresses this knowledge gap by studying the dynamic, run-time behaviours and the network topologies created by two standards-compatible TC prototypes. This study provides unique insight into how the prototypes consume computational resources, maintain network connectivity, produce cumulative transceiver power savings and affect the workings of the routing protocol being employed. This study also documents the topology instability caused by transceiver power oscillations produced by the PlainTC prototype. A context-based solution to reduce transceiver power oscillations and the subsequent topology instability is proposed. This solution applies the Principal Component Analysis statistical method to historical network data in order to derive the weights associated with each of the identified context variables. A threshold value is defined that only permits a node to adjust its transceiver power output if the observed change in a node’s context exceeds the threshold. The threshold mechanism is incorporated into the PlainTC+ prototype and is shown to reduce topology instability whilst improving network performance when compared to PlainTC.The results obtained in this study suggest that I-WMN topologies formed by TC are able to closely match the performance of networks that do not employ TC. However, this study shows that TC negatively affects the energy efficiency of the network despite achieving cumulative transceiver power savings.
A thesis submitted to the Faculty of Science and Agriculture in fulfilment of the Degree of Doctor of Philosophy in the Department of Computer Science at the University of Zululand, 2017
network --connectivity --internet --infrastructure mesh networks --I-WMNs