A novel deregistration strategy for mobile networks

In this paper a novel deregistration scheme-lazy deregistration-for mobile systems is proposed. In the proposed scheme, instead of sending a registration cancellation message to the old visitor location register (VLR) right after each registration, the home location register (HLR) keeps the identification of the mobile terminal (MT) in a list associated with the old VLR. When the next registration from the old VLR arrives, the MT identifications maintained in the list are sent to the old VLR along with the registration acknowledgement message. The old VLR then deregisters these MTs that have left its service area since the last registration from this VLR. Compared to the standard scheme deployed in existing systems, the proposed scheme greatly reduces both the signaling traffic and the database access rate due to deregistration. Compared to other proposed deregistration schemes, in our scheme no valid records in the VLR are deleted and no storage increase in the VLR is required