Fuzzy logic based 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 the viewpoint of control theory, it is rational to regard AQM as a typical regulation system. Although PI controller for AQM outperforms RED algorithm, the mismatches in simplified TCP flow model inevitably degrades the performance of controller designed with classic control theory. In this paper, a novel fuzzy logic based sliding mode controller is designed for Active Queue Management (AQM) in TCP/AQM networks. This type of controller is insensitive to noise and variance of the parameters, thus it is suitable to time varying network systems. Recently many AQM algorithms have been proposed to address performance degradations of end-to-end congestion control. However, these AQM algorithms show weaknesses to detect and control congestion under dynamically changing network situations. 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. © Springer-Verlag 2004.