中文摘要：

提出一种适用于DCF（distributed coordination function）机制的自适应优化算法．该算法基于网络节点侦听信道得到的网络状态信息进行相关参数的自适应调整以获得最优的网络性能，称为CSB（channel sensing backoff）算法,算法采用了对节点的信道接入请求以概率参数P_T进行过滤的方法控制节点竞争接入信道的激烈程度．不同于已有的DCF机制优化方法，CSB算法的特点在于，在优化调整过程中不需要进行计算复杂的网络节点数量估计，并且可以在不同网络状态下始终围绕确定的优化目标进行参数优化调整．仿真实验结果表明，算法能够针对网络节点数量和分组大小改变等网络状态变化作出自适应的网络优化调整，并获得了系统吞吐量、碰撞概率、延迟、延迟抖动、公平性等多方面的性能改善．

英文摘要：

In this paper, an adaptive optimization scheme for DCF （distributed coordination function） is proposed to enhance the network performance. The scheme is based on the channel sensing result for network state information and thus it is named CSB （channel sensing backoff）. The key idea to approach optimal performance dynamically in the proposed scheme is that the transmission attempt from the DCF is filtered by an adjustable probability P T, which is dynamically adapted to reflect the current channel competing level among the network stations. Unlike other proposals for the DCF optimization, CSB does not need to perform complex on-line estimation of the number of active stations in the network, and can make adaptive tuning always toward a certain optimization object under various network states. Detailed performance evaluation of the scheme is carried out through NS-2 simulation. Simulation results show that the scheme can effectively adapt to both network size and packet length changes in the network, and simultaneously achieve performance improvements in several aspects including system throughput, collision probability, delay, delay jitter, fairness and so on.