Robust anti-windup compensation for TCP/RED network congestion control

Abstract

In designing congestion control of TCP/RED network, it is very important to take into account two points. One is packet drop probability which is our control input restricted to the range between 0 and 1. The other is robustness of control against fluctuation of network dynamics caused by variation in the number of TCP connections and so forth. In this paper, we propose an approach to designing a congestion controller to be implemented in a RED router. The proposed control system consists of an H-infinity controller achieving the robustness, and an anti-windup compensator maintaining the robustness even in the presence of the input constraints. The effectiveness is illustrated by some numerical comparisons.