Performance analyses of three geography-based location strategies for PCS networks

Although many location schemes have been proposed and analyzed, the tradeoff among the location registration and the call delivery of different schemes and the relative performance of them are not studied extensively. In this paper, IS-41, pointer-forwarding strategy, and one-step forwarding strategy are analyzed and compared. We first describe how to model location updates and call deliveries. We show that call delivery costs of pointer-forwarding strategy and one-step forwarding strategy can be computed by Markov chains. Because of the accuracy of models, results of mathematical models and simulations are not distinguishable. We compare different schemes by varying relative signaling costs. Simulation results show although IS-41 has the lowest call delivery costs, it has a very high location update costs and thus total costs. Interestingly, both call delivery costs and location update costs of one-step forwarding strategy are lower than pointer-forwarding strategy. For total costs, one-step forwarding strategy is in general better than the other two strategies and pointer-forwarding strategy is usually better than IS-41 except when call-to-mobility ratio is high. For pointer-forwarding strategy, we prefer to have a lower threshold when call-to-mobility ratio (CMR) is high and a larger threshold when CMR is low.