An enhanced caching strategy for location tracking in PCS networks

Abstract

In a Personal Communication Service (PCS) network, the user location tracking strategy plays a critical role in ensuring successful mobile communication for users at any place and any time. The current standard location tracking schemes include the IS-41 scheme in North America and the MAP of the GSM system in Europe. A number of user location tracking strategies, categorized as caching and pointer forwarding strategies, have been proposed to reduce the network communication cost for these two basic schemes. The caching strategies aim to reduce the cost occurring upon call delivery; the pointer forwarding strategies are intended to reduce the cost due to registration. This paper presents a new caching strategy which enhances the caching strategy with forwarding pointers to locate a user who makes frequent moves while using a PCS. The proposed caching strategy is able to reduce the cost resulting from registration, cache hits but invalid, and cache misses by using the forwarding pointers to replace the updated information of a user's location. On call delivery, we explore the feature that a user tends to revisit previous registration areas to update the cache records, resulting in higher cache hit and valid ratios. Extensive simulation runs are conducted to further demonstrate the favorable performance and reduced cost of our caching strategy. © Springer-Verlag Berlin Heidelberg 2004.