LOCATION TRACKING WITH DISTRIBUTED HLRS AND POINTER FORWARDING

Location tracking operations in a personal communications services (PC S's) network are expensive. A location tracking algorithm called point er forwarding has been proposed to reduce the location update cost, Th e key observation behind forwarding is that if users change PCS regist ration areas (RA's) frequently, but receive calls relatively infrequen tly, it should be possible to avoid registrations at the home-location register (HLR) database by simply setting up a forwarding pointer fro m the previous visitor-location register (VLR), Calls to a given user will first query the user's HLR to determine the first VLR, which the user was registered at, and then follow a chain of forwarding pointers to the user's current VLR. To reduce the ''find'' cost in call delive ry, the PCS service provider may distribute HLR databases in the netwo rk. This paper integrates the concept of distributed HLR's with pointe r forwarding, and the new scheme is referred to as the pointer forward ing with distributed HLR (PFDHLR). Since no registration to the HLR is performed in the pointer forwarding scheme when a user moves to the n ew locations, the cost of updating multiple HLR's is eliminated in PFD HLR. Our study indicates that PFDHLR may significantly reduce the mobi lity management cost compared with the single HLR approach.