Congestion Control for Networks in Challenged

CONGESTION CONTROL FOR NETWORKS IN CHALLENGED ENVIRONMENTS GUOHUA ZHANG, Ph.D. The University of Texas at Arlington, 2008 Supervising Professor: Yonghe Liu Congestion occurs when resource demands exceed the capacity of a network. The goal of congestion control is to use the network as efficiently as possible. While extensive efforts have been devoted to providing optimization based, distributed congestion control schemes for efficient bandwidth utilization and fair allocation in the Internet and wireless networks, little consideration was given to congestion control for networks in challenged environments, specifically for networks with time-varying link capacities and networks that intermittently communicate. In this dissertation, we explore optimal congestion control strategies for such networks based on optimization techniques and repeated game model. For networks with time varying link capacities, we explicitly model link capacities to be time varying and investigate the corresponding optimal congestion control strategies. In particular we propose a primal-dual congestion control algorithm which is proved to be trajectory stable in the absence of feedback delay. Different from system stability around a single equilibrium point, trajectory stability guarantees the system is stable around a time varying reference trajectory. Moreover, we obtain suf-