Integration of media point system in UMTS to provide session handover for SIP-based multimedia services

This paper describes a proposal for the tight-coupling integration of WLAN-based media points and 3GPP/UMTS systems. The approach extends the SIP based session management and mobility management proposed for a standalone media point network by connecting it to the UMTS network. The integration aims to provide seamless continuity for SIP-based services when performing vertical radio handover from UMTS to WLAN. The proposed solution builds largely on existing procedures, like the standard UMTS control plane protocols and the IETF CTP (context transfer protocol). Session continuity is provided by keeping the current local IP address in the user terminal after handover. In order to save battery the usage of 3GPP location service mechanisms is proposed, which allow switching off WLAN modules outside the WLAN coverage area