A predictive PID controller for AQM router supporting TCP with ECN

Active queue management (AQM) can keep smaller queuing delay and higher throughput by purposefully dropping the packets at the intermediate routers. Comparing with RED algorithm, although the PID (proportional-integral-differential) controller for AQM improves the stability. It is no systematic method in selecting a group of parameters for these controllers to guarantee the transient performance, and the case is much worse especially when the network parameters are time-varying. We use generalized predictive control to propose a predictive PID (PPID) controller for AQM router supporting TCP with slightly modified ECN to improve the robustness and transient performance of the PID controller. The simulation results show that the integrated performance of the controller is obviously superior to those of PID controller.