一种高动态卫星网络的拥塞控制算法

A Congestion Control Algorithm for High Dynamic Satellite Networks

针对卫星网络通信路径发生改变引起往返时延突变,导致现有的拥塞控制机制中超时重传时间估计不准确,并对拥塞窗口计算产生不利影响的问题,提出一种基于链路长度的带宽估计TCPW-BLC算法。该算法通过计算通信链路长度合理调整拥塞窗口、慢启动阈值及超时重传定时器中相关参数的增益因子,使拥塞控制算法在往返时延突变情况下仍保持较高吞吐量,适应卫星网络动态环境特性。NS2仿真结果表明,TCPW-BLC算法相比TCPW算法在卫星网络中吞吐量性能提高了2.8%,有效降低了时延突变给拥塞控制机制造成的不利影响。

In satellite networks, round-trip time delay changes suddenly due to communication path changes have an adverse impact on retransmission time out estimation and congestion window calculation. A new congestion control algorithm named TCPW-BLC is proposed, which implements bandwidth estimation based on length of communication path. TCPW-BLC provides a method for setting properly the congestion window, the slow start threshold and gain factors of parameters related to retransmission time out timer by calculating the length of communication path, in order to keep the algorithm high throughput and performance in the satellite network environment when round-trip time changes suddenly. NS2 simulation results show that TCPW-BLC outperforms the rest of TCP versions, the throughput is improved by 2.8% compared with that of TCP westwood ＋, and the effect of abrupt time delay changes on congestion control mechanism over satellite networks is alleviated effectively.