In wireless mobile networks, particularly in PCS networks, new calls to a portable may be lost due to the incorrect location information in the mobility database, which leads to a database failure. Such database failure can be recovered either through the portable's registration initiation, the deregistration when it crosses the location area boundary or the active location update. In this paper, we analyze the active location update scheme under several different mobile traffic distributions for failure restoration. We present analytical results for cost analysis. We find that under certain conditions there exists an optimal choice of location update period to minimize the total cost which represents the tradeoff between the location update and call loss. Our results provide a general framework for evaluating active database failure recovery schemes in wireless networks.

When the location information for a mobile user in the Home Location Register (HLR) is corrupted or obsolete, the new arriving calls to the user may be lost. In order to minimize the effect of such HLR mobility database failure, a location update scheme called period location updating is proposed, and the cost analysis is performed. Analytical results for the failure recovery time distribution and the average number of call losses, which are crucial for cost analysis, are presented. The optimal location update period is given analytically as a function of other traffic parameters. This optimal choice of location update period lays the foundation for the adaptive adjustment of the location update period in failure restoration for PCS networks.