Ad hoc网络PI队列管理算法稳定性分析

主动队列管理PI算法的稳定性是拥塞控制研究的重要内容。目前PI-AQM设计大多基于经验,缺乏稳定性的理论分析。针对Ad hoc网络的时滞特点,利用泰勒级数展开,将时滞系统线性化,分析了PI算法在时延无线网络中的稳定性,推导了时滞对象的稳定条件,以便进一步优化设计PI控制器。通过Matlab和NS2仿真,结果表明,选择kp=0.01,ki=0.04,的PI控制器能较好地稳定TCP/AQM时滞系统;与传统的去尾算法相比,PI控制器取得了较好的控制效果,队列长度维持在理想值附近。

Analysis of Stability of PI Queue Management in Ad hoc Network

The stability of PI algorithm in active queue management(AQM) is important for the congestion control.Now,PI-AQM design lacks the theoretical analysis of stability mostly based on experience.This paper uses Taylor series expansion to linearize the delay system and analyzes the stability characterization of PI-AQM in wireless Ad hoc network because of large-delay.Finally,we give the stability condition of PI controllers in Ad hoc network.So the design of PI controllers can be improved.By using Matlab and NS2 simulations,the result proves that PI controllers with kp=0.01,ki=0.04 can steady TCP/AQM delay system well.Compared with traditional drop-tail algorithm,PI controller has gotten better control effect for the queue length keeps its ideal value nearby.