A forwarding pointer-based cache scheme for reducing location management cost in PCS networks

This paper proposes a forwarding pointer-based cache scheme (PB-Cache scheme) that can reduce the signaling cost for location management in PCS networks. In the existing cache scheme, the use of cache information can effectively reduce the signaling traffic for locating frequently called mobile users. However, when the cache information is obsolete, it results in much more signaling traffic than that of the IS-41. Inorder to solve this problem, we propose a new location cache scheme called the PB-Cache scheme, which exploits a user's movement locality as well as call locality. Even if the cached information is not up-to-date, the called user can be found by tracing forwarding pointers starting from that VLR pointed in the cache instead of querying the HLR. Thus, the PB-Cache scheme can effectively reduce the frequent access to the HLR and the signaling traffic for location management. Moreover, it distributes the signaling and database access load on the HLR to the VLR's. Analytical results indicate that the PB-Cache scheme significantly outperforms the other schemes when a user's call-to-mobility ratio is high or the signaling traffic to the HLR is heavy.