Hierarchical implicit deregistration with forced registrations in 3G wireless networks

Deregistration due to the departures of mobile users from their current visiting registration area may cause significant traffic in the wireless cellular networks. In this paper, we propose a hierarchical implicit deregistration scheme with forced registration in third-generation wireless cellular networks to reduce the remote/international roaming signaling traffic when home-location registers (HLRs), gateway-location registers (GLRs), and the visitor-location registers (VLRs) form a three-level database hierarchy. In this scheme, if a mobile phone arrives and the GLR/VLR is full, a random record is deleted and the reclaimed storage is reassigned to the new arriving mobile phone. When a call arrives and the callee´s record is missing in the GLR/VLR, forced registration is executed to restore the GLR/VLR record before the call-setup operation proceeds. An analytic model is proposed to carry out the performance evaluation for the proposed scheme. Our results show that the proposed scheme not only reduces the local deregistration traffic between the GLR and the VLR, but also reduces the remote/international deregistration traffic between the HLR and the GLR, especially when the ratio of the cost of the remote/international traffic between GLR and HLR to the cost of local traffic between the VLR and the GLR is high.