A Dynamic Anti-windup AQM for Congestion Control in Internet

Abstract

This paper addresses the design of anti-windup gains for obtaining stability for linear systems with discrete time varying delay and saturating inputs delay. Considering that a dynamic output feedback has been designed to stabilize the AQM system (without saturation), a method is proposed for designing an anti-windup gain which relates the saturation of the queue when congestion, which is inevitable in networks. It is shown that the closed-loop system obtained from the controller plus the anti-windup gain can be modeled by a linear system with a dead zone nonlinearity. A modified sector condition is then used to obtain stability conditions based on Lyapunov functions. Differently from previous works these conditions are directly in linear matrix inequality form. Resulting in a new AQM which will be simulated in MATLAB and compared to RED.