We argue that future-proof TCP will need to take explicit congestion control signals (prices) from the routers, rather than be based on end-end measurements of loss or delay. We focus on wireless networks: either a single wireless link, or a broadcast channel with a single access point, and consider the problem of flow control using a window based self-clocking mechanism, as used in current versions of TCP. We introduce a control algorithm, CLAMP, that responds to explicit feedback about the state of the queue at the access point, and targets an average queue size at the access point. We analyze the delay stability using fluid equations, and provide a stochastic analysis for the single link case. Simulation results comparing CLAMP with standard TCP Reno in the broadcast scenario demonstrate the potential gains from the explicit pricing approach.

Stephen Hanly is an Associate Professor in Electrical Engineering at the University of Melbourne, Australia. His PhD in mathematics was obtained in 1994 at Cambridge University, followed by postdoctoral experience at AT&T Bell Laboratories in Murray Hill, New Jersey. Since 1996 he has been at Melbourne University. His research interests include information theory and networking, with a focus on wireless networks.