H2Performance Limitation of Congestion Controller for TCP/AQM Network Systems

In this paper, we deal with congestion control of one bottleneck type for TCP/AQM network systems and investigate the H2control performance limitation. To this end, we first represent the dynamics of the congestion window size at source nodes and the queue length at the bottleneck link by a discrete time model. We then prove the stability of the plant and provide the Youla parametrization of all stabilizing controllers. With this parametrization, we consider an H2optimization problem of the queue length at the bottleneck link. We derive an explicit form of the best achievable H2norm and discuss the control performance limitation with respect to the ratio of the transmission time of the packets from source nodes to the link and the round trip time.