| Summary: | 碩士 === 國立交通大學 === 資訊科學與工程研究所 === 94 === IEEE 802.11e standard is developed for quality of service (QoS) provisioning in wireless local area networks. However, it is still difficult to achieve satisfactory quality for multimedia applications, such as voice over IP (VoIP). The motivation of this thesis is to provision reliable QoS, including jitter, delay and throughput, for real-time traffic through a simple modification to EDCA. We propose a centralized scheme in which access point (AP) globally manages EDCA transmission parameters, including arbitration interframe space number (AIFSN) and contention window (CW) size, based on number of active QoS access categories (AC), as well as performs admission control based on the volume of admitted delay-sensitive flows. Besides, in order to guarantee strict priority contention between stations, AP will work with two EDCA configurations, unique AIFSN assignment (UAA) and contention window partitioning (CWP), which can be applied to cope with different volume of QoS ACs. Our proposed scheme avoids complex polling mechanism and is able to reduce the jitter of real-time traffic significantly. The simulation results show that up to 50 percent reduction in standard deviation of jitter delay can be achieved comparing with using IEEE 802.11e EDCA.
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