Researches On Theories And Technologies Of Capacity And Channel Assignment In Wireless Mesh Networks (WMNs)

Wireless Mesh Network (WMN) is a new promising broadband wireless networking technology for numerous applications. With the rapid development of WMN technology, more and more commercial products and even solutions are provided in trial applications. However, a lot of difficulties still exist in the protocol design, performance analysis, and application of wireless mesh networks.In this dissertation, firstly the derivation and development of WMNs are presented. Several important issues of WMNs are discussed and summarized, which include definitions, characteristics, applications, critical factors influencing network performance, etc.Secondly, the throughput capacity of a hybrid WMN is analyzed in details. Meanwhile, NS2-based simulation results are presented to get some quantitative estimate of the throughput capacity in hybrid WMNs. The performances of hybrid WMNs adopting different backbone schemes are compared. From the results, some guidelines are provided for protocol development, planning, deployment and operation of the network.Thirdly, we study the channel assignment problem in wireless mesh networks from more practical aspects. The Channel Assignment Tool (CAT) designed for the optimized backhaul networking of Multi-Radio Multi-Channel (MRMC) WMNs is presented. Through the local test taken on pc, the functions of CAT are verified, while through the outdoor test taken on the test-bed consisting of commercial wireless mesh routers, the optimal channel assignment scheme figured out by the CAT is verified to perform best in the real MRMC WMN.Fourthly, we study the complexity of channel assignment problems both in general and in practice. By conclusions in the combinatorics, complexities of three types of channel assignment problems are figured out. Furthermore, the theoretical results are verified through practical tests. The results show that complexity of the practical problem is much smaller than that of the general problem and it is feasible to solve channel assignment problems in large-scale WMNs by heuristic algorithms instead of exhaustive search algorithms.Finally, we describe a typical WMN project, i.e. the WMN on the Haiyun campus of Xiamen University.