中文摘要：

针对IEEE 802.11标准中引用的传统的二进制指数退避算法（BEB）在解决信道接入冲突时,网络碰撞概率较大且站点公平性较差的问题,提出一种基于同步竞争窗口的退避算法（SCW）。该算法中,网络内所有站点跟踪当前网络的传输情况,当检测到信道状态发生变化时,各站点停止退避并根据信道当前监测到的信道状态自适应地调整竞争窗口大小,然后通过重置该竞争窗口使得所有站点在下一次信道竞争时具有相同竞争窗口大小,即所有站点的信道介入概率相同。仿真结果表明,随着站点个数的变化,SCW算法的公平性指数接近于1且一直保持稳定;而且当网络站点个数较多（36个左右）时,SCW算法的网络吞吐率比传统BEB算法提高了约11%,时延降低了6%。所提算法能够有效地提高了网络吞吐率和时延性能,同时具有更高的网络公平性,因此有利于实际应用中对传输速率和时延有较高需要的业务的传输,尤其适用于节点密集部署的高速率无线网络中。

英文摘要：

In order to solve the problem that the Binary Exponential Backoff（ BEB） presented in IEEE 802.11 standard has a large collision probability and a poor fairness,a novel backoff algorithm with Synchronized Contention Window（ SCW）was proposed.In SCW algorithm,each station（ STA） tracks the transmission cases of the network and when the channel state is changed,the Contention Window（ CW） of each station which participates in the competition is synchronized by resetting the CW,which makes each station get the medium access grant with the same probability in next channel contention.The experimental results show that that with the increase of the number of the stations,the fairness index of the SCW algorithm is nearly equal to 1 and always keeps stable,and when the number of stations is large（ nearly 36）,the throughput and delay of the network are respectively increased and reduced by nearly 11% and 6% than the conventional BEB algorithm.The proposed algorithm can effectively improve the performance of throughput and delay,and it has an excellent fairness of network,therefore it is beneficial to the traffic transmission with the demand of high rate and low delay,and it is especially suitable for the wireless networks with the dense station deployment.