Modeling and Analysis of Slow CW Decrease for IEEE 802.11 WLAN

~Ihsrruci-~rhe IEEE 802.1 I Medium Access Control (MAC) protucol provides a contention-based distributed channel access mechanism for mobile stations to share the wireless medium, which may introduce a lot of collisions i n ease of overloaded active stations. Slow Contention Window (CW) decrease scheme is a simple and efficient solution for this problem. In this paper, we use an analytical model to compare the slow CW decrease scheme t u the IEEE 802.11 MAC protocol. Several parameters are invcrtigdted such as thc number of Svations, the initial CW size. the decrease factor value. the maximum bdckoff stage and the coexistence with the RequestToSend and ClearToSend (RlSICTS) mechanism. The results show that the slow CW decl-ease scheme can efficiently improve the throughput of IEEE 802.11. a n d that the throughput gain is higher when the -decrease hctor is larger. Moreover, the initial CW size and maximum backoff stage also affect tlie performance of slow CW decrease scheme.