新TCP拥塞窗口调整策略

New adjustment strategy of TCP cwnd

互联网的稳定性和鲁棒性离不开拥塞控制,然而目前TCP传输中广泛使用的AIMD算法因窗口波动剧烈,致使丢包明显、系统吞吐量及带宽利用率偏低。为此提出了一种新的TCP拥塞窗口调整策略A-Cwnd。该策略依据RTT采样值构建正态分布函数式,动态更新下一拥塞窗口值,能较好地适应网络实时变化特点,具有不错的响应性。从数学角度对新策略的合理性与可行性进行了分析证明。NS3仿真结果表明新策略可有效稳定窗口波动、增大发送速率、降低丢包率,同时对系统吞吐量及带宽利用率的提高也有一定贡献。

The stability and robustness of the Internet depends on congestion control. However,the AIMD algorithm widely used in TCP transmission is subject to severe window fluctuation,resulting in significant packet loss,low system throughput and bandwidth utilization. In this paper,we propose a new TCP congestion window adjustment strategy named A-Cwnd. The strategy constructs a normal distribution function based on the RTT sampling value,dynamically updates the next congestion window value,can adapt to the real-time change characteristics of the network,and has good responsiveness. The article also proves the rationality and feasibility of the new strategy from the mathematical point of view. Finally,NS3 simulation results show that the new strategy can effectively stabilize the window fluctuation,increase the transmission rate,and reduce the packet loss rate,while the system throughput and bandwidth utilization has contributed to the increase.