摘要
In this paper, the authors investigate the overload problem of a congested router in TCP （Transmission Control Protocol） networks, with a design of an AQM （Active Queue Management） controller based on control theory. The model of TCP/AQM is converted into a second-order system with time delay, the stability of the closed-loop AQM system is described in terms of a characteristic quasi-polynomial. The authors focus on the synthesis of first-order AQM controller. The authors＇ approach consists of determining the stabilizing regions in the parameter space of the first-order controller, then choosing controller＇s parameters within these regions. Finally, the authors illustrate the proposed methodology with an example and simulations using NS-2 simulator.
