Performance analysis of a fault-tolerant scheme for location management of mobile hosts

Abstract

We consider the problem of location management of mobile users. The objective is to keep track of the mobile users in order to deliver calls. The IS-41 is a simple strategy for location management used in North America. This strategy is not efficient for some movement and call patterns. Many strategies have been proposed to address efficiently given movement and call patterns.

For mobile users who move frequently but receive relatively rare calls, a forwarding scheme has been shown to outperform the normal IS-41 location management scheme. But the forwarding scheme is more vulnerable to intermediate Visitor Location Registers (VLRs) failure than the IS-41 scheme. On the other hand, the call set-up with forwarding pointers may be costly, as a list of pointers must be traversed. We propose a simple variation to the forwarding scheme to address the fault tolerance weakness and the call set-up cost. The idea is to maintain two paths from the home location server to the last VLR with each path being of half the length of the normal forwarding path. We study and compare the performance of the normal forwarding scheme and our scheme.

Research reported is supported in part by Texas Advanced Technology Program grant 009741-052-C and National Science Foundation grant MIP-9423735.