Distributed group location tracking based on several RIDs and virtual VLRs for transportation systems

To efficiently support mobility of users on transportation systems, we propose a distributed group location tracking (DGLT) scheme based on several virtual visitor location registers (VVLRs) and representative identities. We analyze the DGLT scheme in view of the database (DB) access cost and the signaling cost under a one-dimensional network architecture. Compared with the IS-41 scheme, the DGLT scheme using distributed group management has a lower signaling cost as well as a lower DB access cost. As the user mobility-increases or the number of users on a TS increases, the outperformance of the DGLT scheme increases. Generally, the DGLT scheme in which a corresponding home location register selects an optimum VVLR among several VVLRs has a lower signaling cost, although a DB access cost is increased slightly compared with the GLT scheme.