Capacity Enhancement and Reliability of Wireless Mesh Networks

Wireless mesh networks (WMNs) have gained considerable interest in expanding IEEE 802.11 networks to large-scale enterprise and community scenarios, primarily because its capability of providing wide-band ubiquitous network access to a significant number of users. However, the mesh nodes are typically limited in resources such as bandwidth, computation power and memory. Moreover, the shared wireless medium introduces the interference. All these result in unsatisfactory network performance. In this dissertation, we tackle several issues related to the system performance of the wireless mesh networks. In the context of the network capacity enhancement, we focus on using the techniques of multi-channel multi-radio (MCMR) and partially overlapped channels (POC) respectively; In the context of network reliability, we focus on the measurement-based analysis and prediction of reliability in an experimental way. Capacity limitation is one of the fundamental issues in wireless mesh networks. We start our investigation by addressing capacity improvement enabled by multiple radios and channels with a centralized scheduling approach. In a MCMR network, our objective is to find both dynamic and static channel assignments and corresponding link schedules that maximize the network capacity. We focus on determining the highest gain we can achieve from increasing the number of radios and channels under certain traffic demands. When the number of orthogonal channel is few or multiple radios are not available, the use of partially overlapped channels is explored to enhance the capacity in wireless mesh networks. We investigate how the interference can be useful for communication when POC is properly utilized. We propose novel channel allocation and link scheduling algorithms in the MAC layer to enhance network performance. Due to different traffic characteristics in multi-hop WMNs compared to those in one-hop 802.11 networks, we perform our optimization based on end-to-end flow requirement, instead of the sum of link capacity. In addition, we discuss other factors affecting the performance of POC, including topology, node density, and distribution. To better understand how reliable a wireless mesh network performs, we perform