802.11 WLAN中一种基于竞争窗口的分组调度算法

IEEE 802.11 MAC层中的分布式协调功能DCF（distributed coordination function）使用随机退避机制来解决信道竞争问题，导致信道资源不能充分利用.特别是在高负载的网络系统中，信道带宽在碰撞状态下浪费严重.本文提出了基于竞争窗口的分组调度算法，通过增加一个竞争窗口将节点间的竞争划分为两个阶段进行，其中只有通过第一退避阶段的节点才能进入下一个退避阶段，完成第二退避阶段的节点才能开始访问信道.根据具体网络情况，选择合适的第二阶段的最小窗口值，得到相应的网络性能.仿真结果表明该算法在高负载的网络中能够提高信道带宽利用率.

Packet scheduling algorithm based on a contention window for IEEE 802.11 WLAN

The way in which IEEE 802.11 DCF uses the random backoff scheme to resolve the channel contention leads to inefficient utilization of the channel bandwidth resource.Especially in a highly loaded network,the portion of channel bandwidth wasted in collision state is significantly high.A packet scheduling algorithm was proposed based on a contention window which adds one contention window to divide the contention stage into two parts.The nodes finishing the first stage of contention resolution can proceed to the second stage.Those nodes finishing the second stage of contention resolution will begin to access the channel.According to the load situation of the network,proper contention window value of the second stage of contention resolution can be chosen.Simulation results show that this algorithm improves the utilization of channel bandwidth in a highly loaded network.