Comparison of replication of the user mobility profile with caching for reduction of HLR accesses

The widespread deployment of mobile personal communication services will lead to a tremendous increase in the number of real time updates and queries to the network databases. The centralised home location register (HLR) in GSM can be a potential bottleneck. Most users have regular calling and mobility patterns (or profiles) which can be used to reduce database accesses. Selective replication of the user mobility profiles (SRP) at the source-MSC/VLR can reduce HLR queries. Using GSM as the reference, this paper studies the cost of replicating user mobility profiles and compares its performance with caching the VLR number. It is shown that SRP performs better for a mobile which has a higher mobility rate compared to the incoming call rate from a switch. The paper also suggests a combined scheme with better overall performance.