The technique of IMS Sh interface and its NGN LBS application

In this paper, the technique of IP Multimedia Subsystem (IMS) Sh interface (Diameter) is introduced. The architecture for service provision of IMS is shown. The messages and user data on the Sh interface are presented. Then the Location-Based Services (LBS) in the IMS/NGN Network of Chunghwa Telecom Labs. of Taiwan, R.O.C. are illustrated. At first, the location information is obtained by PANI SIP header for the caller and by TLS/SSL (https) to the Connectivity Session Location and Repository Function (CLF) via outbound for the callee. Next, an alternative way of it is by Sh interface to look up the related data of IMS user identity from the Home Subscriber Server (HSS). Because it is via inbound and in the IMS core network only; moreover, it is better in retrieving any specified location information regardless session case of the caller or callee. Hence it is an efficient application for the fixed User Equipment (UE).