Location management techniques and teletraffic modeling for large wireless communications networks
Donald C. Cox, Derek Lam · 1998
A wireless communications network maintains per-user information about each subscriber in user profiles that are stored in databases connected to the signaling network. When a person makes a call, the network must perform a location lookup to obtain the callee's current location from a copy of the user profile. When a user moves from one region to another, the network must modify information in the user profile to track the person's new location. This dissertation addresses the location management problem--the efficient retrieval and maintenance of location information in user profiles--for large wireless communications networks. Location management standards in cellular mobile systems, IS-41 and GSM, are limited to geographical phone numbers, i.e., users cannot maintain the same phone numbers if they have relocated or changed service providers. A lifelong permanent phone number is a highly attractive feature that has been proposed for future wireless communications services. This dissertation presents two location management techniques, Hierarchical ProfilE Replication (HIPER) and Hierarchical Online Parametric ProfilE Replication (HOPPER), that were developed for supporting lifelong numbering in a scalable and efficient manner. Research into a modeling framework for realistic performance evaluation of location management techniques in wireless networks is lacking. Since user calling and mobility patterns are not well understood, performance studies in the literature have used over-simplified models that incompletely characterize user behavior. A realistic teletraffic modeling framework for large wireless communications networks based on actual call traffic traces, vehicle and airplane traffic data, and government transportation surveys, is presented. Large-scale network simulations, based on the teletraffic and mobility research, are presented to compare the performance between HIPER, HOPPER, and other proposed location management techniques. The simulation results show that both HIPER and HOPPER have better location lookup performance than the current location management standard modified for lifelong numbering. Particularly, HOPPER has the best lookup performance, requiring 23% fewer database lookups compared to the modified location management standard. HOPPER also incurs the lowest total database access and network signaling loads while requiring 57% more memory than the modified location management standard.