Novel Database Architecture and Signaling Scheme for IP-Based Heterogeneous Wireless Access Interworking

Next generation heterogeneous wireless networks are expected to interwork with IP-based infrastructures. The IP Multimedia Subsystem (IMS) is an open, standard based solution that merges the Internet with Third Generation (3G) cellular networks. Attainment of a unified logical database is one of the key aspects that promote deployment of IMS. Home Subscriber Server (HSS) as an evolved version of Home Location Register (HLR) is one of the key components of IMS. In deploying HSS as a central repository database, in a fully overlapped heterogeneous network setting, changes of access mode are very frequent and conveying this information to HSS imposes excessive signaling load and delay. In our proposed scheme we introduce an Interface Agent (IA) for each location area that that caches the location and information about the access mode through which a user can be reached. This method results in significant amount of signaling cost savings, hence a better delay performance.