Observer-Based Robust Controller Design for Active Queue Management

In this paper, an observer–based controller is designed for the problem of congestion control . In TCP/IP networks, the packets-dropping probability function is considered as a control input. Therefore, the work described here is to design robust observer controller, which is aimed at robust stabilization of network system with uncertainties, input delay and a saturated input. The controller is used to estimate online the average trasmission window and achieve the desired queue length. By applying the LyapunovKrasovskii function approach and the linear matrix inequality technique, control law is derived. Simulation experiments have been carrier out and the results demonstrate this scheme can achieve transient and steady-state responses. The results also show that this scheme outperformance the tradition PI controller.