基于D稳定域和ITAE准则的主动队列管理算法

主动队列管理(active queue management,简称AQM)是网络拥塞控制的研究热点之一,其中的关键问题是如何设计反馈控制策略.提出一种新的基于D稳定域和时间乘以误差绝对值乘积积分(integral of time-weighted absolute error,简称ITAE)性能准则的比例-积分-微分(proportional-integral-differential,简称PID)优化设计方法(简称DITAE-PID),并用于AQM控制器的设计,控制闭环系统的理想动态性能.首先在复平面上设定一组理想的D稳定域,然后以ITAE为目标函数,通过数值优化算法求出控制器的参数,使得闭环系统的所有特征根都在D稳定域内,以降低排队延时,提高有效吞吐量.对比仿真实验结果表明,该算法能够预先探测和控制拥塞,有较好的鲁棒性,链路利用率更高,丢包率更小,平均队列长度更趋于期望值,同时,趋于期望队列长度的时间更短,其综合性能明显优于典型的随机早期探测(random early detection,简称RED)和比例-积分(proportional-integral,简称PI)算法.

Optimal Design of AQM Routers with D-Stable Regions Based on ITAE Performance

Active queue management(AQM) is a hotspot in the current studies on network congestion control. Moreover,the feedback control strategy is the most pivotal.This paper applies a optimization method for proportional-integral-differential(PID) controller design with D-stable regions based on the integral of time-weighted absolute error(ITAE) performance to AQM routers that permits the designer to control the desired dynamic performance of a closed-loop system.A set of desired D-stable regions in the complex plane is first specified and then a numerical optimization algorithm based on ITAE performance is run to find the controller parameters such that all the roots of the closed-loop system are within the specified regions.This controller for AQM routers can detect and control the congestion effectively and predictively.Compared with the random early detection(RED) and proportional-integral(PI) algorithms via experimental simulations,the proposed method, called DITAE-PID method,is indeed more efficient and robust in achieving the lower packet loss rate and higher link utilization.