HLR Replication Protocols for Global Mobility Management in PCS Networks

The new trend for PCS networks is to provide mobile users with large-scalemobile capability across many service areas. In this scenario, global databasemanagement for PCS networks has become an increasingly important researchissue.In this paper, we examined two replicated database strategies,single-replica (SR) and multiple-replica (MR), for large-scalemobility of per-user data management in personal communicationnetworks. The SR strategy uses a single replica approach of HLR.The MR strategy replicates the per-user data of HLR in manyregions. The two strategies are based a partial replicationscheme, and a primary copy method is used to maintain replicas'consistency. Our numerical results show that the MR strategyoutperforms the SR strategy in most situations; however, it may beworse when the probability of a mobile user visiting a foreignregion is high and the query rates from other foreign regions arelow. Additionally, the number of replicas should be compact in theMR strategy in order to achieve a reasonable query response time.Therefore, we propose an adaptive multiple replication protocol tochoose a suitable replication strategy and to decide the optimizednumber of replicas.