Bandwidth reservation strategies for mobility support of wireless connections with QoS guarantees

摘要

This paper examines QoS guarantees for bandwidth in mobile wireless networks, with a focus on reducing dropped connections on handoff. We can achieve this by reserving bandwidth for connections that might move into a cell from a neighbouring one. We develop a novel framework for analysing issues relevant to handoff. The principal novelty of this framework is the use of an arbitrary planar graph (network) to model the adjacency relationships of cells in the network. Mobility patterns of the mobile stations are then captured by simple probabilities for moving to a neighbouring cell, leading to a notion of a shadow cluster that is very easy to implement. Three strategies for bandwidth reservations are then proposed and investigated. They range from simple (used as a baseline for comparison) to more complex ones using the shadow cluster concept. We study these strategies by simulation and attempt to determine important parameters and quantify what is gained by added complexity and other variations. Our results show that the topology has an important influence on the results of a reservation policy. However, one of our strategies (the optimistic one) appears to be uniformly superior, because it adapts to changing network topologies as well as movement patterns.