Robust discrete-time sliding mode control algorithm for TCP networks congestion control

For solving the problem of congestion control in transmission control protocol (TCP) networks, we propose a new active queue management (AQM) algorithm based on discrete-time sliding mode control (DSMC) theory. We use a discrete-time system model with uncertainties to decipt the time-varying TCP networks. Based on the model, an asymptotically stable sliding surface is designed by linear matrix inequality (LMI). The design of sliding surface compensates for the disadvantageous effect of uncertainties. Therefore, the robustness of the algorithm is good. The proposed controller can guarantee the controlled object, namely, the queue length in router to converge to the desired value quickly and constrain oscillation of the queue length effectively. The simulation results certify the validity of the algorithm.