A Comparative Cost Analysis of Degradable Location Management Algorithms in Wireless Networks

In this paper, we develop a uniform framework to provide a cost analysis of location update and search operations for a class of degradable location management algorithms in personal communication service (PCS) networks for tracking mobile users in the two-tier HLR (Home Location Register)–VLR (Visitor Location Register) structure. Depending on the algorithm employed, the PCS may be in a degraded state in maintaining the location of a mobile user. We classify existing location management algorithms based on how well the location information is maintained in terms of the costs associated with location updates and develop a two-level hierarchical modeling framework to analyze the performance characteristics of these algorithms. Specifically, the high-level model calculates the total cost incurred to the PCS network as a result of location-update and call-delivery operations during the period between two consecutive calls. The low-level model is a stochastic model that estimates the values of high-level model parameters. We show that by utilizing simple Markov models at the low level, we can assess and compare the performance characteristics of degradable location management algorithms easily. The basic scheme used in the standard IS-41 and GSM protocols, the paging and location updating algorithm (PLA), the forwarding and resetting algorithm (FRA) and the local anchoring algorithm (LAA) are used as examples to demonstrate the applicability of our approach. We also show how the modeling approach developed can be extended to the analysis of algorithms for handling service handoffs in the two-tier HLR–VLR architecture.