Queue Length Based Internet Congestion Control

In this paper we present a new queue length based Internet congestion control protocol which is shown through simulations to work effectively. The control objective is to regulate the queue size at each link so that it tracks a reference queue size chosen by the designer. To achieve the latter, the protocol implements at each link a certainty equivalent proportional controller which utilizes estimates of the effective number of users utilizing the link. These estimates are generated online using a novel estimation algorithm which is based on online parameter identification techniques. The protocol utilizes an explicit multi-bit feedback scheme and does not require maintenance of per flow states within the network. Extensive simulations indicate that the protocol is able to guide the network to a stable equilibrium which is characterized by max-min fairness, high utilization, queue sizes close to the reference value and no observable packet drops. In addition, it is found to be scalable with respect to changing bandwidths, delays and number of users utilizing the network. The protocol also exhibits nice transient properties such as smooth responses with no oscillations and fast convergence.