An observer-based robust active Queue Management scheme

Considering the characteristics of time-varying network parameters and input saturation, TCP /AQM system is described as linear state space model with state and input delay. An observer-based robust H-infinity AQM scheme is presented in this paper, where the state-observer is used to obtain the TCP window size which is immeasurable in real TCP network, in order to avoid the error by approximation. Based on Lyapunov stability theory and LMI techniques, AQM controller is designed to guarantee the robust stability of closed-loop system. Finally simulation results verify the effectiveness of the presented algorithm via NS-2 simulator.