IMS core and access integration — evaluation of alternative SDO architectures

The primary objective of 3GPP IMS was to define architectural components and interfaces of a session management core that is transparent to the underlying access technology and user device connected to it. To meet this objective, it has worked on defining an abstraction of the Access Plane by identifying the interaction requirements between IMS core and access plane and defining interfaces between the two. However, while it was working on this objective, other SDOs, specifically those, that define standards for access technologies, looked at the problem of integrating their access technology with IMS core. They evolved their existing architectures to add IMS components and define interfaces to the access plane elements. These parallel efforts have resulted in multiple architecture definitions that meet the same objectives but differ in their own subtle ways. This has caused reasonable amount of confusion in the "operator" community with regard to the path to follow for IMS deployment. This paper compares and contrasts the architectures proposed by PacketCable, ETSI-TISPAN, multi-service forum (MSF) and 3GPP .