ONE-STEP POINTER FORWARDING STRATEGY FOR LOCATION TRACKING IN DISTRIBUTED HLR ENVIRONMENT

One of the main challenges in personal communication service (PCS) is to locate many mobiles that may move frequently from place to place. S uch a system operation is called location tracking, Many network signa ls flow, and database queries are required to achieve such a task. In addition to the two-level hierarchical strategy in IS-41 and GSM, seve ral strategies have been proposed to improve the efficiency of locatio n tracking, Pointer forwarding was used to reduce the expensive home l ocation register (HLR) accesses, Previously, the distributed HLR schem e was proposed to prevent HLR from becoming a bottleneck in the signal ing network, However, the length of a forwarding pointer chain may be lengthened in a distributed HLR environment, In this paper, we propose a more efficient strategy to overcome this potential problem, This st rategy attempts to migrate the locating chains in a distributed HLR sy stem when a mobile issues a registration operation, As a consequence, the length of any forwarding pointer chain does not exceed one in our strategy, Simulation results indicate that our strategy significantly decreases the locating cost, In fact, this strategy provides an upper bound of location tracking time owing to the fact that the length of a ny locating path does not exceed one. Furthermore, obsolete entries in local databases visiter location registers can be reclaimed in this s trategy.