An Adaptive Backoff Algorithm Based on Channel Utilization for IEEE 802.11
Though the binary exponential backoff (BEB) is a popular algorithm of collision avoidance in the IEEE 802.11 MAC protocol due to simple implementation, it causes the short-term unfair problem. Another popular algorithm is the history based adaptive backoff (HBAB), HBAB has better performance than conventional backoff algorithm by taking the channel states of past trials into account, where the length of its contention window (CW) is set artificially based on the prior knowledge of channel states. However, the length of CW in HBAB cannot be dynamically allocated and it often diverges from the optimal value. Therefore the application of HBAB will be limited in practical scenarios. In this paper, based on HBAB, we propose a new backoff algorithm which can control the length of CW according to the channel utilization ratio adaptively. The proposed algorithm is simple to implementation and can offer higher throughput and lower delay, compared with BEB and HBAB. Simulation results validate the superiority of the proposed algorithm.
backoff algorithm beb mac hbab throughput delay