Per-User Pro le Replication in Mobile Environments: Algorithms, Analysis, and Simulation Results

We consider per-user pro le replication as a mechanism for faster location lookup of mobile users in a Personal Communications Service system. We present a minimum-cost maximumow based algorithm to compute the set of sites at which a user pro le should be replicated given known calling and user mobility patterns. We then present schemes for replication plans that gracefully adapt to changes in the calling and mobility patterns. We show the costs and bene ts of our replication algorithm against previous location lookup approaches through analysis. We also simulate our algorithm against other location lookup algorithms on a realistic model of a geographical area to evaluate critical system performance measures. A notable aspect of our simulations is that we use well-validated models of user calling and mobility patterns.