Design of a stabilizing AQM controller for large-delay networks based on internal model control

We focus on the problem of the stability of congestion control for networks with large round-trip communication delays. Nearly all the existing AQM schemes neglect the impact large communication delay has on system behavior, such as stability, robustness and convergence. The drastic queue oscillations in large delay networks of PI, REM and DC-AQM decrease link utilization and introduce avoidable delay jitter. To address this problem, we propose a robust IMC-PID congestion controller based on the internal model control principle to restrict the negative impact of the stability caused by large delay. Simulation results demonstrate that the integrated performance of our proposed scheme outperforms others as communication delay increases, and achieves high link utilization and small delay jitter. 2007 Elsevier B.V. All rights reserved.