Throughput, robustness, and security of wireless mesh networks

Abstract

Wireless Mesh Networks (WMNs) are viewed as the key technology of the next generation wireless communication system. They feature cost-effectiveness, easy deployment, and extended range of wireless Internet access, whereas many research challenges still exist in the development of WMNs. In this thesis, the issues of network throughput, network robustness, and routing security in WMNs are studied. In WMNs, Mesh Points (MPs) are used to serve as the Internet gateways for the wireless clients. The traffic forwarded to the MPs in a WMN is based on a routing protocol commonly agreed in the network, and the loading conditions of the MPs directly affect the overall throughput of a WMN. To enhance the overall throughput, this thesis presents an efficient MP placement strategy, taking into account routing protocol used in the network. In the analysis, the total aggregated traffic of each wireless node in the network will be first investigated. After that, the upper bounds of network throughput, under different combinations of the placements of MPs, can be calculated. Analysis and simulation show that the placements of MPs and the routing protocol used in the network play critical roles in determining the throughput in a WMN. Wireless nodes in a WMN are interconnected to support multi-hop transmission, making a much larger network feasible. The trade off is isolated clusters if some nodes are fail. Consequently, the network reliability and overall throughput are reduced. In order to measure the connectivity robustness of a WMN, this thesis investigates the largest cluster size and the drop in network throughput after the network suffers from random node failure. The study shows that the largest cluster size and the overall throughput dropped as a function of node failure. To mitigate the opportunity of network failure, an alternative routing architecture for improving routing security of WMNs is proposed. As routing messages are transmitted among the wireless nodes via air, it is not difficult for attackers to capture the messages and make use of them to launch various kinds of attacks to the network. To address this problem, our proposed routing architecture introduces powerlines as the medium for routing messages. Since powerlines have a better physical protection than air, it reduces the risk of being attacked in the WMN. Three routing protocols for this architecture are also discussed in this thesis.

Date of Award	15 Jul 2010
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Kai Hau Alan YEUNG (Supervisor)