Analytical design of PI controller for AQM with robustness adjustability

Abstract

Based on a linearized TCP/AQM model, a new proportional integral (PI) controller design approach is proposed. This analytical approach applies H_∞ optimization and internal model control (IMC) theory to design active queue management (AQM) routers that support transmission control protocol (TCP) flows. The most important feature of the proposed scheme lies in that it can be explicitly tuned with a single parameter for the trade-off between performance and stability of the AQM control system. It is thus flexible and easy to use in design. The proposed method and the designed PI controller are verified and compared with other existing AQM schemes using ns-2 simulator. The results show the advantages of the new PI controller design approach for AQM routers supporting TCP flows.

Keywords

active queue management (AQM) / proportional integral (PI) controller / transmission control protocol (TCP) / time delay / robustness