On the sliding mode control of uncertain time-delay TCP/AQM system

For the transmission control protocol (TCP) linear dynamic systems with input time-delay and unmatched uncertainties, a special linear transformation was done to transform an uncertain time-delay system into a delay-free system. Then, an active queue management (AQM) algorithm based on sliding mode control (SMC) was designed in the new coordinate system. A new SMC strategy is proposed satisfying the sliding mode reaching conditions, and LMI-based method was given to design the robust sliding hyperplane so as to verify the system stabilization via Lyapunov function. Simulation results showed that the algorithm enable the queue length to converge to its set value quickly and keep the queue oscillation small. The simulation also showed that the algorithm outperforms the conventional SMC strategies with its high robustness and accurate trackability in case the network conditions change.