Robust stability analysis for uncertain state and input delay TCP/AQM network systems

In this paper, an active queue management (AQM) controller is designed for the problem of congestion control. In TCP networks, the packet-dropping probability function is considered as a control input. Thus, a TCP/AQM controller is modeled as a time-delay system with a saturated input. The robust observer-based controller is designed to achieve the desired queue size and guarantee the asymptotic stability of the operating point. For the particular TCP network mode, the Lyapunov-Krasovskii function is defined, and the system can be stabilize with the obtained observer and the state feedback control law by using linear matrix inequality (LMI). Simulation results show that the derived control strategy is validated.