An H_∞ approach to congestion control design for AQM routers supporting TCP flows in wireless access networks

In this paper, we aim at developing an H_∞ approach, from control-theoretic viewpoint, to the design of an active queue management (AQM) based congestion control algorithm for wireless networks supporting the Internet Protocol. We study networks in which the backbone is a traditional wired network supporting Internet TCP, while end user access is via wireless. First, a dynamic model for the congestion control problem of wireless networks is built up, which enables the application of modern control theory on time-delay systems to this problem. Second, an H_∞ design approach for general time-delay systems is presented. Finally, the proposed approach is applied to the congestion control algorithm design of wireless networks, yielding an effective and systematic way for the design problem. Simulation results are provided to illustrate the design procedure and the effectiveness of the proposed method. Our design method is described by linear matrix inequalities (LMI), which can be solved very efficiently by LMI toolbox in Matlab.