Speed up the Responsiveness of Active Queue Management System

Fengyuan REN  Chuang LIN  

IEICE TRANSACTIONS on Communications   Vol.E86-B   No.2   pp.630-636
Publication Date: 2003/02/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Internet Technology III)
Category: Packet Transmission
AQM,  PID controller,  delay,  stability margin,  flow control,  

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As an enhancement mechanism for the end-to-end congestion control, AQM (Active Queue Management) can keep smaller queuing delay and higher throughput by purposefully dropping the packets at the intermediate nodes. Comparing with RED algorithm, although the PI (Proportional-Integral) controller for AQM designed by C. Hollot improves the stability, it seems unscientific to tune the controller parameters through trial-error, moreover the transient performance of the PI controller is not perfect, such as the regulating time is too long. In order to overcome this drawback, in this paper, the PID (Proportional-Integral-Differential) controller is proposed to speed up the responsiveness of AQM system. The controller parameters are tuned based on the determined gain and phase margins. The simulation results show that the integrated performance of the PID controller is obviously superior to that of the PI controller.