一种自组织网络MAC层退避算法

A BACKOFF ALGORITHM OF MAC PROTOCOL IN AD HOC NETWORKS

针对IEEE 802.11 DCF通信机制所使用的二进制退避算法存在的问题,提出了S-BEB退避算法。该算法利用了DCF机制MAC层中的两个参数,保持了二进制退避算法简单高效的特点,动态调整节点在发送数据包冲突时竞争窗口增大的幅度,同时也加大了节点成功发送数据包后的竞争窗口以减小下一轮竞争的冲突。利用OPNET软件实现了该退避算法的仿真并进行了分析。研究结果表明,无论在网络延时、吞吐量还是公平性方面,S-BEB算法的网络性能均好于经典二进制退避算法。

The backoff algorithm of S-BEB is presented in allusion to the deficiencies of binary exponential backoff（BEB） algorithm the IEEE 802.11 DCF communication mechanism used.To keep simple and efficient which the BEB possesses as its feature,S-BEB employs two parameters in MAC protocol of DCF,dynamically modifies the increasing extent of contention window（CW） when the nodes conflicting during data packet transmission,while enlarges the CW after a successful transmission of data packet completed by nodes to reduce the conflict of contention in next turn.Simulation of the S-BEB is implemented by using OPNET software together with the analyses.Studying results show that the network performances of S-BEB algorithm are better than the classical BEB＇s no matter in delay,throughput or fairness.