UMTS: Alive and Well - 4G Americas

VPLMNHPLMNCSGList SrvHSSC1 (OMA DM /OTA)S6aUELTE-UuHeNBS1-MMEHeNBGWS1-US1-MMEMMES-GWS11Figure 6.11. Variant 3 with HeNB GW for C-Plane.6.3.2 IMS SERVICE CONTINUITYWork on functionality to provide aspects of Service Continuity has been underway in 3GPP forseveral releases. Rel-7 saw the definition of Voice Call Continuity (VCC) and Rel-8 built on this todefine Service Continuity (SC) and VCC for Single Radio systems (SRVCC). Rel-9 has addedfurther enhancements to these features.In Rel-8, Service Continuity allows a user’s entire session to be continued seamlessly as theuser’s device moves from one access network to another. In Rel-9, this functionality has beenenhanced to allow components of a user’s session to be transferred to, and retrieved from,different devices belonging to the user. For example, a video call or video stream in progress on amobile device could be transferred to a laptop, or even a large-screen TV (assuming both can beprovided with an IMS appearance in the network), for an enhanced user experience and then, ifnecessary, retrieved to the mobile device.As well as transferring existing media, the user can add or remove media associated with asession on multiple devices, all controlled from a single device. These devices may be ondifferent 3GPP, or non-3GPP, access networks.6.3.3 IMS CENTRALIZED SERVICESIMS Centralized Services (ICS) feature was developed in Rel-8 and provides voice services andservice control via IMS mechanisms and enablers, while providing voice media bearers via CSaccess. Users, therefore, subscribe to IMS services and can receive those services regardless ofwhether the voice media is carried over PS access or CS access. Within the limitations of the CSaccess capabilities, the user has the same experience of the services.www.3GAmericas.org February 2010 Page 74