Registration Procedure Improvements for IMS Core Networks via Satcom Access

There is a growing interest in combination of Mobile Satellite Systems (MSS) and IP Multimedia Subsystem (IMS) network. MSS could provide larger range and flexible manner for subscribers to access IMS networks, but it is difficult to provide the equivalent quality of service (QoS) as the terrestrial communication system due to the high propagation delay and low data rate. This situation will bring long time delay to the IMS signaling flows. In this paper, a solution that could improve the Satellite-IMS (SAT-IMS) registration and reregistration mechanism is proposed. We add SAT-IMS Gateway (SIGW) as a registration and re-registration proxy in satellite gateway station, and make some modifications to the IMS registration signaling flows, then calculate the time delay of registration procedure before and after modification. The result shows that this solution could reduce the registration time delay of SAT-IMS the same level with terrestrial access network.