Location update and paging optimization in wireless Personal Communication Systems

摘要

An important operation in Personal Communication Systems is mobility tracking.The service area is divided into Location Registration(LR)areas,and a mobile subscriber(MS)sends a location update(LU)whenever it enters a new LR area.To alert this MS to an incoming call,it is paged in the LR area it last sent an LU.Location update and paging constitute additional load(or overhead)on the wireless network.Various factors affect this overhead,including the mobility and call patterns of the individual MS,the shape,size and orientation of the LR areas,and the method of searching for the MS within the LR areas.We exploit information on the mobility pattern of the MS to design dynamic LR areas which maximize the number of cells traversed by the MS between two successive LUs.Using the shortest distance model for vehicular MS mobility patterns the LR optimization problem is formulated and proved to be NP-complete.Approximate solution to the LR area optimization problem was obtained using a heuristic optimization technique.A dynamic selective paging strategy that exploits the mobility pattern and incoming call rates of the MS to minimize the paging cost subject to a constraint on the delay in locating the MS is also proposed.This strategy divides the LR area into several partitions,which are paged sequentially until the MS is found.