Robust congestion control for TCP/AQM using integral backstepping control

In this paper, a novel active queue management scheme is proposed to control the congestion in the networks using TCP/IP protocol for transport layer. Active queue management (AQM) is a complement protocol to TCP/IP which provides feedback to the TCP sources in order to perform close loop congestion control. We use the nonlinear model of TCP/AQM system and build our controller on this realistic model. The control parameter is the drop probability of AQM technique. Our controller is designed based on integral backstepping technique. The main advantage of our AQM technique compared to other is the robustness of the algorithm with respect to changes in the system parameters such as the number of sources of the round trip time. Next, we provide conditions which guarantee that the control input which is the packet dropping probability falls between 0 and 1. Finally, we evaluate the performance of our proposed scheme for various network conditions and parameters. Compared to the other AQM controllers, the simulation results obtained with Simulink, demonstrate the effectiveness of the proposed method.