K-step pointer forwarding strategy for location tracking in distributed HLR environment

Abstract

Managing the location of mobile systems is crucial. The location of a mobile must be determined whenever a connection is established. Thus, mobile systems need to be able to cope with frequent location updates and queries. In addition to the HLR/VLR strategy in IS-41 and GSM, the feasibility of reducing the network load imposed by locating mobile users has attracted considerable attention. One user location algorithm, called ‘pointer forwarding with single HLR’ was proposed to reduce the location update cost. The distributed HLR strategy was then presented to prevent HLR from becoming a signal bottleneck in the signalling network. Although this approach eliminates the cost of updating multiple HLRs, greatly reducing the database access delay, it also introduces a long pointer chain that may involve a large locating cost and long call delivery time. The study proposes a more efficient location tracking strategy, named the ‘K-step pointer forwarding strategy with distributed HLR’. This strategy guarantees that the pointer chain length never exceeds K. Its performance is studied by numerical analysis. The results demonstrate that the strategy can considerably reduce the call delivery time.