Adaptive fuzzy queue management and congestion avoidance in TCP/AQM networks

Abstract

Active Queue Management (AQM) takes a trade-off between link utilization and delay experienced by data packets. From control point of view, it is rational to regard AQM as a typical regulation system. Recently many AQM algorithms have been proposed to address performance degradations of end-toend congestion control. However, these AQM algorithms show weaknesses to detect and control congestion under dynamically changing network situations. In this paper, an adaptive fuzzy AQM is designed to congestion avoidance in TCP/AQM networks. This kind of control action has robust performance, which is suitable for time varying and complex systems such as computer and communication networks. A candidate Lyapunov function is employed in the adaptive law synthesis to ensure convergence. A simulation study over a wide range of IP traffic conditions shows the effectiveness of the proposed controller in terms of the queue length dynamics, the packet loss rates, and the link utilization. Also, a complete comparison between the proposed fuzzy adaptive controller and classic Proportional-Integral (PI) controller is made, which the former has superior performance. © Springer-Verlag 2004.