Implicit deregistration in 3G cellular networks

In a 3G cellular network, the visitor location registers (VLRs), the gateway location registers (GLRs), and the home location registers (HLRs) form a three-level mobility database structure. When users leave a GLR/VLR service area, deregistration with a GLR/VLR is required. Deregistration may create significant traffic in the network, especially the traffic between a GLR and a HLR, which is the remote/international traffic. In this paper, we propose a hierarchical implicit deregistration scheme with a first/subsequent registration in 3G cellular networks to effectively eliminate deregistration traffic. An analytic model is proposed to carry out the performance of the proposed scheme. Our study shows 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. This is especially true when the ratio of the cost of the remote/international traffic between the GLR and the HLR to the cost of local traffic between the VLR and the GLR is high.