IEEE802．11 MAC层退避算法的一种改进方案

An Improved Solution for 802.11 Backoff Algorithm

通过对IEEE 802.11 DCF模式下的马尔可夫链模型的研究发现,目前普遍采用的二进制退避算法存在着由于选择时隙得不到均匀分布而造成竞争节点数量过多时碰撞概率增大、系统吞吐量下降的问题.针对这些问题,提出了一种对部分节点采取延缓其重置进程的方法,其本质就是要通过降低节点对初始窗口的选择概率,来达到退避记数器选择退避数分布均匀的目的.仿真结果表明,该方法能有效地提高系统的吞吐量.

When the Markov process of IEEE 802.11 DCF mechanism is studied, it can be found that system throughput decreases and its collision probability increases if the station number increases because the binary backoff algorithm adopted can not provide even distribution for chosen time interval. This paper pro- poses an improved backoff algorithm which adopts the method of deferring the station reset action, so that the distribution of the chosen backoff window is made more evenly by reducing selection probability of nodes for initial windows. Simulation result shows the new method can improve system throughput significantly.