基于IEEE802.11的星间链路最短接入时延退避算法

A Delay-Optimal Backoff Algorithm for IEEE802.11 over Inter-Satellite Links

为满足空间信息网络低轨卫星用户多址接入骨干中继卫星的访问需求,基于IEEE 802. 11机制,提出最短接入时延退避算法(Delay-Optimal Backoff,DOB),可解决大时空尺度条件下,传统二进制退避算法(Binary Exponential Backoff,BEB)造成的网络平均接入时延高和吞吐量低的问题.根据用户卫星与中继卫星的相对位置特性,设定中继卫星通信窗口,利用通信窗口内不同用户卫星数量时用户接入时延与平均接入请求概率的变化关系,确定最短接入时延条件下用户平均接入请求概率,实现动态调整碰撞窗口大小.研究结果表明,该算法使网络接入时延较BEB算法平均降低了10s,饱和吞吐量提升一倍,归一化业务量阈值比BEB算法增加至0. 6,网络多址接入性能显著提高.

In order to meet the multiple access requirements of LEO(Low Earth Orbit)satellites when accessing to data relay satellite,the delay-optimal backoff(DOB)algorithm based on IEEE802.11scheme is proposed,which shows a better performance in access delay and throughput compared with the traditional binary exponential backoff(BEB)algorithm at large-spatial and temporal-scale inter-satellite links.In this paper,we construct the communication coverage of a data relay satellite to LEO spacecrafts based on the space position relation between LEO spacecrafts and data relay satellite.The DOB algorithm can dynamically adjust the values of backoff window depending on the access request probability which is related to the number of user satellites in the communication coverage.Research results show that average access delay of DOB algorithm is decreased by about10s,the traffic threshold is increased to0.6and the maximum throughput has doubled compared to BEB algorithm,which improves the network performance on multiple access.