Efficient call admission control scheme in wireless multimedia networks

Abstract

This thesis investigates three problems in related with call admission control in wireless multimedia networks. We present formulation of the problems and the algorithms, and study the capacity analysis and derive the admission criterion. First, under wireless ATM networks we propose a new handoff scheme called Enhanced Anchor Rerouting (EAR) scheme, which is a modification of AR scheme. Our scheme reserves periodically wired bandwidth between each pair of neighboring switches for future possible inter-switch handoffs. If an inter-switch handoff actually becomes necessary, then we use the reserved bandwidth for the wired path to the new switch and follow the usual AR scheme. Since a wired path already determined is used and no path setup procedure is needed, we can save preparation time of the inter-switch handoff. We expect that this procedure can significantly reduce handoff latency of the inter-switch handoff. The amount of reserved wired bandwidth between each pair of switches is determined based on the inter-switch handoff rate and the available bandwidth of the wired path between the neighboring switches, which are measured at each switch periodically. Our simulation tests show that our proposed handoff scheme has much better performance than the existing schemes especially in terms of handoff latency. Second, we study the bandwidth adaptation process. When some bandwidth becomes available due to the termination of an ongoing call, the bandwidth is optimally allocated to ongoing calls which need more bandwidth. If a call is allocated with more bandwidth, then the user of the call feels more satisfaction. Bandwidth allocation is performed in a way to maximize the satisfaction degree of users. This optimization problem can be formulated as a binary linear integer program. Since the optimization should be performed in real time, we present a computationally efficient algorithm for the integer program based on the Lagrangean relaxation procedure. With limited...