| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 94 === Wireless local area networks have gained a lot of popularity in recent years due to its ease of installment, low cost and high data rate compared to 3G networks. One standard family of the popular wireless local area networks is the IEEE 802.11 series. The legacy IEEE 802.11 utilizes CSMA/CA with binary exponential backoff as its Medium Access Control (MAC) protocol. CSMA/CA is contention-based, and does not provide any priority schemes and thus service differentiation. As more and more real-time voice and video other than non-real-time data are expected in wireless domain, IEEE 802.11e is proposed to support service differentiation. One of the access scheme of IEEE 802.11e is the enhanced distributed channel access (EDCA). In this thesis, we study the performance of EDCA under different traffic scenarios via computer simulation. Instead of the saturated traffic scenario that is often assumed, we consider more realistic traffic models, e.g., Poisson and Markov Modulated Poisson Process (MMPP) traffic models. To emphasize on the self-similarity of internet traffic, ON and OFF periods of MMPP processes are assumed to be not only exponentially distributed but also Weibull distributed. We study the RTS/CTS access mechanism. Furthermore, each station is assumed to have a finite queue. The performance measures of interest are throughput, mean access delay, queueing delay, and packet losses due to both access failure and buffer overflow.
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