Abstract: The latest wireless network access technology, IEEE 802. 16 provides broadband Internet connection to user.However, it was found that the mandatory contention resolution scheme in IEEE 802. 16 which is based on truncated binary exponential backoff algorithm can not run perfectly in most cases, especially when the traffic is heavy. A novel selfadaptive contention resolution scheme was proposed, which divides all Subscriber Stations into several groups according to the available transmission opportunities in each frame and requires each Subscriber Station send bandwidth request during its group time. Meanwhile, the number of available transmission opportunities and the number of Subscriber Stadons sending bandwidth request will be self-adaptively updated by Base Station and Subscriber Station respectively according to the average collision probability and transmission opportunity utilisation present during last frame. The results of analysis and simulation show our scheme can improve the performance of the whole network remarkably.

Key words: WiMAX, Contention resolution, Self-adaptive, Module