A Fast Pointer Forwarding Strategy for Location Tracking in Distributed HLR Environment

Cheng-Ming WENG  Chen-Hung CHU  

IEICE TRANSACTIONS on Communications   Vol.E85-B   No.9   pp.1706-1713
Publication Date: 2002/09/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Switching
PCS,  location tracking,  pointer forwarding,  

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Location management is crucial for mobile systems. A mobile must be located whenever a connection is established. Thus, mobile systems must cope with frequent location updates and queries. In addition to the HLR/VLR scheme in IS-41 and GSM, the feasibility of reducing the network load caused by locating mobile users has received considerable attention. One user location algorithm called "Pointer Forwarding with Single HLR," was proposed to reduce location update cost. Thereafter, the distributed HLR scheme was proposed to prevent HLR from becoming a signal bottleneck in the signaling network. This approach eliminates the cost of updating multiple HLRs, vastly reducing the database access delay, but also introduces long pointer chain traverse that may cause large location tracking costs and long call delivery times/costs. This study proposes a efficient location tracking strategy, named, "Fast Pointer Forwarding Strategy with Distributed HLR. " This strategy ensures that the pointer chain length never exceeds one. In fact, this strategy provides an upper bound on location tracking time. Its performance is numerically analyzed. Results in this study demonstrate that our strategy can considerably reduce the complexity of implementation and the call delivery time/cost.