Mathematical Problems in Engineering
Volume 2005 (2005), Issue 5, Pages 477-489
Suboptimal feedback control of TCP flows in computer network using random early discard (RED) mechanism
School of Information Technology and Engineering, University of Ottawa, Ottawa K1N 6N5, ON, Canada
Received 8 February 2005
Copyright © 2005 N. U. Ahmed and Cheng Li. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We consider a dynamic model that simulates the interaction of TCP
sources with active queue management system (AQM). We propose a
modified version of an earlier dynamic model called RED. This is
governed by a system of stochastic differential equations driven
by a doubly stochastic point process with intensity as the
control. The feedback control law proposed observes the router
(queue) status and controls the intensity by sending congestion
signals (warnings) to the sources for adjustment of their
transmission rates. The (feedback) control laws used are of
polynomial type (including linear) with adjustable coefficients.
They are optimized by use of genetic algorithm (GA) and random
recursive search (RRS) technique. The numerical results
demonstrate that the proposed model and the method can improve the
system performance significantly.