无线网络中基于自适应带宽估计的跨层拥塞控制算法

The congestion control mechanism in wireless networks by cross-layer optimization based on the adaptive bandwidth estimation

TCP是一种主动探索网络可用带宽的传输层协议,在无线网路中,实时准确地探测链路可用带宽,动态调节TCP拥塞控制机制,是提高无线通信系统性能的有效方法之一。本文基于带宽测量技术,提出了一种无线环境下跨层TCP拥塞控制机制,通过探测TCP确认信号ACK返回速率和往返时间RTT,结合链路拥塞和物理层突发错误分布,实时探测可用带宽,对拥塞滑动窗口大小进行动态控制,并根据当前网络状态,动态设置慢启动阀值,保证网络资源的有效利用。仿真结果证明,此算法能有效地降低误码丢包率,提高系统的可靠性。

TCP is the transmission layer protocol which actively explores available network bandwidth.One of the ways of TCP modification is based on estimation of the available bandwidth and adjustment of the transmission window.In this paper,a novel TCP congestion control mechanism is proposed using adaptive bandwidth estimation in wireless networks which continuously measures the bandwidth via monitoring the rate of ACKs and RTT values.Based on the estimation of the available bandwidth,this scheme dynamically adjusts the congestion window and realizes the adaptive parameter setting of the slow start threshold.Simulation results show that the probability of multi-packet loss has been significantly decreased and TCP performance has been effectively improved by implementation of this scheme.