Optimal Design of AQM Routers with D-Stable Regions Based on ITAE Performance

This paper applies a novel optimization method for Proportional-Integral-Differential (PID) controller design with D-stable regions based on Integral of Time-weighted Absolute Error (ITAE) performance to Active Queue Management (AQM) routers that permits the designer to control the desired dynamic performance of a closed-loop system. A set of desired D-stable regions in the complex plane is first specified and then a numerical optimization algorithm based on ITAE performance is run to find the controller parameters such that all the roots of the closed-loop system are within the specified regions. This controller for AQM routers can detect and control the congestion effectively and predictively. Compared with the Random Early Detection (RED) and Proportional-Integral (PI) algorithms via experimental simulations in Network Simulator Version 2 (NS2), the proposed method, called DITAE-PID method, is indeed more efficient and robust in achieving the smaller queuing delay and higher throughput of an AQM router.