大时滞网络拥塞控制器的设计

Design of a Stabilizing Congestion Controller for Large-Delay Networks

几乎现有的AQM算法都忽略了大时滞对网络拥塞控制系统稳定性的负面影响,以致稳定性、响应性和鲁棒性在大时滞网络中大大降低.如PI、REM等AQM算法在大时滞环境下表现出剧烈的队列震荡和频繁的空队列情况,这些现象直接导致了链路利用率的低下和延时抖动的增大.而面向大时滞网络拥塞控制的DC-AQM算法不够恰当的参数配置使得系统输出偏离了控制的目标,出现了很高的分组丢弃概率.为解决大时滞网络拥塞控制的稳定性问题,本文基于内模控制原理,提出一种新的鲁棒AQM控制器IMC-PID来补偿网络时滞对系统稳定性的影响.仿真分析表明,随着网络时滞的增大,IMC-PID在综合性能上胜过其他算法,获得了较高的链路利用率和较低的延时抖动.

This paper addresses the problem of the stability of congestion control for networks with large round-trip communication delays.Nearly all the existing AQM schemes neglect the impact on system behavior,such as stability,robustness and convergence,caused by large communication delay.The drastic queue oscillations in large delay networks of PI,REM and DC-AQM decrease the link utilization and introduce the avoidable delay jitter.To address this problem,we develop a robust IMC-PID congestion controller based on internal model control principle to restrict the negative impact on the stability caused by the large delay. Simulation results demonstrate that the integrated performance of proposed scheme outperforms others as communication delay increases,and achieves high link utilization and small delay jitter.