Hierarchical mobility database overflow control

Abstract

AbstractIn a 3G cellular network, the gateway location registers (GLRs), the visitor location registers (VLRs) and the home location registers (HLRs) form a three‐level mobility database structure. An HLR database is used to record mobile users' permanent subscription information. A VLR database is used to temporarily hold the subscription information of the roaming users who visit the service area of the VLR. A GLR is deployed at the edge of a visited network handling the location management of a roaming subscriber in a visited network without involving the HLR, and holding users' temporary subscription information when the mobile user is within the service area of the GLR. When users leave the GLR/VLR service area, the corresponding records in the GLR/VLR are deleted. Owing to mobility, a GLR/VLR database may overflow at some time periods when the number of visitors significantly increases in the GLR/VLR area. If the GLR/VLR is full, the registration procedure fails and the system cannot deliver services to incoming users under the existing cellular technology. This issue is called GLR/VLR overflow.In this paper, we propose a hierarchical database overflow control mechanism in 3G cellular networks to effectively eliminate the GLR/VLR overflow problem, and incoming users can continuously use the service with insignificant extra overhead. An analytic model is proposed to investigate the performance of the hierarchical database overflow control scheme. Our study not only shows that the probability of VLR overflow is very small but also shows that among the VLR overflow cases, there is a very small probability of GLR overflow. In other words, the overhead in terms of causing both local and remote/international signaling traffic by exercising our approach is very small. Copyright © 2003 John Wiley & Sons, Ltd.