| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 96 === Mobile WiMAX followed the 802.16e standards provides broadband services with high mobility capability under wireless environment. Handover is an essential function for every mobile communication systems and users suffer handover failure due to handover process and channel resource. WiMAX operates under two modes : PMP (Point to Multi-point) mode and Mesh mode. Mesh mode provide the networks with larger data coverage, subscriber stations and Base stations in mesh mode have self-configured and self-organized capabilities. Mesh mode in WiMAX reduce the cost of constructing a network in metropolitan area or in rural area due to its radio access characteristic for Base stations. In this thesis, we only focus on the environment with mesh base stations, the mobile subscriber stations use PMP mode to access services. In this way, the handover procedures are extended to execute routing process to the base stations which connect to Internet after the regular handover procedures finished. Therefore the handover time will be longer to increase the failure rate. Different handover mechanism (hard handover and soft handover) are discussed in this thesis, we founded that routing delay due to mesh base stations environment dominates the handover failure rate in some handover types. There is a comparison of handover performance in standard environment and in mesh base stations environment. To reduce the effect of routing delay, this thesis propose a simple method to make the neighbor base stations do the routing procedure in advance, and the simulation result show it works.
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