| Summary: | 碩士 === 國立中興大學 === 電機工程學系所 === 95 === The development of 802.11 wireless local area networks makes our life more convenient. In order to provide Quality of Service (Qos), IEEE 802.11 working group has defined a new standard called IEEE 802.11e. It includes a contention-window based access control algorithm called enhanced distributed channel access (EDCA). In EDCA, the collision rate increases when the number of stations increases. In addition, backoff time results in the waste of the available transmission time. To reduce collision rate as the number of stations increases, adaptive EDCF (AEDCF) was proposed.
In the thesis, we proposed a new solution called Weibull-based EDCA. In our algorithm, we use Weibull distribution probability to find the best contention window value corresponding to the current network state. The parameters in the distribution can be dynamically adjusted according to the number of stations and the average collision rate.
Finally, we used Network Simulator Version 2 (NS2) to simulate our algorithms and compare them with EDCA and AEDCF. We found WEDCA provides better network fairness and adaptively adjust parameters of WEDCA was better than fixed parameters
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