A forwarding strategy to reduce network impacts of PCS

We propose a per-user forwarding strategy for locating users who move from place to place while using personal communications services (PCS). The forwarding strategy augments the basic location strategy proposed in existing standards such as GSM and IS-41, with the objective of reducing network signalling and database loads in exchange for increased CPU processing and memory costs. With the forwarding strategy, calls to a given user will first query the user's home location register (HLR) to determine the first visitor location register (VLR) which the user was registered at, and then follow a chain of forwarding pointers to the user's current VLR. This strategy is useful for those users who receive calls infrequently relative to the rate at which they change registration areas. We use a reference PCS architecture and the notion of a user's call-to-mobility ratio (CMR) to quantify the costs and benefits of using forwarding and classes of users for whom it would be beneficial. We show that sender a variety of assumptions forwarding is likely to yield significant net benefits for certain classes of users, in exchange (possibly) for a small increase in mean call setup time. For instance, under certain cost assumptions, for users with CMR<1 forwarding can result in 20-60% savings over the basic strategy, with no increase in mean call setup time.