Location management for mobile cellular communications.

摘要

Mobile cellular communications support a large number of mobile users that are free to move in the service area. As a mobile user moves, its network access node changes. In order to find a particular mobile user when an incoming call arrives, location management schemes are used to track and locate mobile users. In this dissertation, several new location management schemes for mobile cellular communications are proposed and their performances are characterized.Firstly, we propose an efficient distributed location tracking scheme which aims at reducing the signaling traffic generated by location management on the wireline links of the backbone network. In this scheme, the databases in the system are logically organized into multiple steps of two kinds of sets, write sets and read sets . Write sets are used to store location information of mobile users. Read sets are used in retrieval of location information of mobile users. The sizes of write sets and read sets at different steps are different. The scheme accounts for mobility and call-arrival-rate of mobile users and dynamically changes the step of write sets and read sets to which a mobile user registers.Secondly, we investigate two proposed location update strategies aimed at reducing the signaling traffic incurred by location management on the wireless links: location update scheme using overlapping location areas, and location update scheme using dynamic location areas. A location area (LA) consists of a cluster of cells. In the first of these, the location areas are arranged in an overlapped fashion to reduce the required location update signaling. The latter scheme utilizes the physical geographical limitations and the fact that the movements of most mobile users have some regularity to reduce the combined signaling cost for location update and paging.All proposed schemes allow for the analytical computation of performance characteristics. A variety of system parameters are considered. These parameters include mobile user mobility and call activity. Relevant performance measures include: location update cost, location query cost, paging cost, combined cost of location update and query, combined cost of location update and paging.