Abstract: In order to improve the network performance in congestion status and to achieve or approach the optimum performance in different network scales, a self-adaptive backoff algorithm named SAOP is proposed based on Optimum Parameter approaching. By taking the approximate invariability character of the optimum sending load(ratio of count in collision and success sending), every WLAN station adjusts the self minimum contention window periodically, making current sending load approach the optimum value, to improve the network congestion status. Simulation proves that SAOP can enhances the IEEE 802.11 WLAN saturation throughput by 48%, decreases the delay by 31% when the network scale is 80 stations in the basic access mode, and is close to the theoretical max throughput in the network scale-throughput curve (98% the max throughput on average).

Key words: self-adaptive backoff algorithm, optimum parameter, minimum contention window