Location updating and paging strategies in a cellular system

The problem of locating a mobile user in a cellular system is addressed. The mobility of a user is modelled by a two-dimensional directional random walk process. A location updating scheme based on overlapping location areas (LA's) is presented for keeping track of the LA a user is in. Two LA paging schemes, namely spread paging and selective paging, are proposed and are compared to a conventional flood paging scheme in which all cells in the LA are paged simultaneously. It is found that both spread paging and selective paging can yield typical paging traffic reductions of more than 50%. The cost is a small increase in the average paging delay. Selective paging performs better than spread paging in terms of both average paging delay and average paging traffic, but is more complex to implement. An LA sectorization technique is applied to spread paging and selective paging to further reduce paging traffic. Two sectorization patterns are examined. The results show that sectorization can yield typical average paging traffic reductions of about 50%. The resulting increases in paging delay are negligible for both patterns. The sensitivity of spread paging and selective paging to uncertainty in user mobility parameter values, such as the angular deviation parameter, mean speed, mean velocity hold time and mean trip length, is studied. It is found that spread paging is most sensitive to the mean trip length of a user while selective paging is most sensitive to uncertainty in user mean speed.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat