Designing Robust PID Congestion Controller Supporting TCP Flows Based on H_∞ Optimal Control Theory

摘要

A robust PID controller for active queue management (AQM) based on modern H_∞ optimal control theory is presented in this paper. Taken both robustness and closed loop performance into consideration, most desirable parameters value can be gotten through some straightforward analytical formulas. Our robust PID controller is determined only by one parameter, other than traditional PID controller is by three or more. Additionally, this new parameters determining method can not only be extended to other AQM controller based on classical control theory or optimal control theory, but also be easily understood and implementation. We evaluate the performances of the controller extensively. The results show that the robust PID congestion controller outperform the existing controller, such as PI, RED, on keeping the router queue size at the target value. The most obvious property of the controller is that it takes on robustness such that it can adapt the network dynamic.