基于模数的WiMAX网络高负载自适应冲突解决算法

Module Based Self-adaptive Contention Resolution Scheme for WiMAX Network with Heavy Traffic

根据现有的部分研究结果发现,IEEE 802.16标准中使用的截断二进制指数后退算法在解决网络冲突时效率很低;并且当网络的负载增多时,该算法的运行性能更差。在此基础上,提出了一种基于模数的自适应冲突解决算法来优化WiMAX网络的冲突解决过程。该算法将所有用户站按照当前时间帧内的传输机会数量分为多个小组,并且要求用户站只能通过特定的传输机会发送请求。与此同时,为了保证整个网络的高性能,本算法要求基站和用户站根据上一轮请求过程中的平均冲突概率和传输机会使用率来调整当前时间帧内的传输机会数量,以及挑选部分用户站参与带宽请求,保证了WiMAX网络在高负载情况下的运行性能。模拟结果表明,本算法在WiMAX网络运行过程中能够较好地解决请求过程中的冲突,对网络性能提高较大。

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 Stations sending bandwidth request will be self-adaptively updated by Base Station and Subscriber Station respectively according to the average collision probability and transmission opportunity utilization present during last frame. The results of analysis and simulation show our scheme can improve the performance of the whole network remarkably.