A speed-adaptive strategy for location management cost reduction in cellular networks

A speed adaptive location management scheme will greatly reduce the cost of tracking mobile stations, because mobile stations can travel at a wide range of speeds. Recently, an elegant distance- and time-based scheme has been proposed. The scheme uses a look-up table which describes the relationship between the distance and the time: the distance decreases while the time increases. In the scheme, the paging area for a mobile station will be automatically reduced if the mobile station does not update its location over a certain time period. Therefore, the scheme performs well when a mobile station travels at a low speed. However, it does not perform well when the incoming call arrival rate is high or when the speed of a mobile station is high. To overcome those drawbacks, a novel speed-adaptive scheme is proposed in this paper. The proposed scheme uses an enhanced look-up table that consists of two parts: the distance in the first part increases while the time increases; in the second part, the distance decreases with the increasing time. By introducing the first part, the proposed scheme reduces the paging cost for a call arriving shortly after a location update, and adapts to the speed range of a mobile station. To reduce the paging cost further, a paging angle is introduced for high-speed mobile stations. Numerical simulations using various activity-based models and random walk models show that the proposed scheme performs well for mobile stations traveling at both high and low speeds.