| Summary: | 博士 === 國立中山大學 === 電機工程學系研究所 === 95 === The promising development of wireless technologies has brought in an increasing demand of multimedia traffic. Since various types of traffic are inherently distinct in bandwidth requirements, delay sensitivities, and error tolerances, an adequate bandwidth allocation scheme is essential for the limited radio resource to fulfill different QoS (quality of service) requirements in mobile wireless networks. In this dissertation, we present a generalized channel preemption scheme (the GCPM) and a jamming-based medium access control with dynamic priority adjustment (the JMDPA) for the two different medium access models of a mobile wireless network, grant/request-based and contention-based, respectively.
In the proposed GCPM, a mobile call is identified by four parameters, call type, traffic class, channel requirement, and preemption ratio. To effectively reduce dropping probability, high-priority handoff calls are allowed to fully or partially preempt low-priority ongoing calls when the mobile network becomes congested. An analytical model with multi-dimensional Markov chains is introduced to simultaneously investigate the effect of full and partial preemptions on the performance of a mobile wireless network. On the other hand, the proposed JMDPA scheme prioritizes a mobile node with two priorities, local and global; both of the local and global priorities can be dynamically changed based on the outcome in every contention round. Thus, any possible starvation of low-priority traffic or any ineffective contention of high-priority traffic can be avoided. A multi-dimensional Markov model, together with the scalability analysis, is introduced to evaluate the performance of the proposed JMDPA. The analytical results provide very useful guidelines to tune the QoS parameters for supporting prioritized multimedia traffic.
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