| Summary: | 碩士 === 長庚大學 === 資訊工程研究所 === 92 === In wireless local area networks (WLANs), the IEEE 802.11 medium access control (MAC) protocol has been the main element that determines the efficiency of sharing the limited communication bandwidth of the wireless channel. The performance of the IEEE 802.11 protocol could be improved by using an appropriate turning of the backoff algorithm to approach a theoretical throughput limit. However, in real case, a mobile node would not exactly know the information of network and load configurations (e.g., number of active nodes). Hence, in this thesis, we propose a novel and efficient selection of backoff window size mechanism using fuzzy reasoning approach named the fuzzy backoff controller (FBC) to achieve the system throughput
limit. This mechanism is developed on the following ideas: by observing the busy degree of medium and the number of neighbors, the proposed FBC could generate a proper backoff window thus reduce the probability of collisions and enhance the
throughput. The obtained simulation results show that the proposed FBC not only significantly improves the performance of the IEEE 802.11 protocol but also achieves the fairness of accessing medium between nodes well.
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