Novel TCP congestion control scheme and its performance evaluation

A novel self-tuning proportional and derivative (ST-PD) control based TCP congestion control scheme is proposed. The new scheme approaches the congestion control problem from a control-theoretical perspective and overcomes several important limitations associated with existing TCP congestion control schemes, which are heuristic based. In the proposed scheme, a PD controller is employed to keep the buffer occupancy of the bottleneck node on the connection path at an ideal operating level, and it adjusts the TCP window accordingly. The control gains of the PD controller are tuned online by a fuzzy logic controller based on the perceived bandwidth-delay product of the TCP connection. This scheme gives ST-PD TCP several advantages over current TCP implementations. These include rapid response to bandwidth variations, insensitivity to buffer sizes, and significant improvement of TCP throughput over lossy links by decoupling congestion control and error control functions of TCP.