Research And Design Of IMS Core Function For NGN Core Network

Along with communication service diversification develop market requirement, ITU-T led by the concept of NGN .for consistent with the NGN goal, 3GPP defined the IMS (IP multimedia subsystems) in the 3GPP R5 edition. in FMC under trend of development , in June, 2004 ITU-T had integrated IMS in the NGN core network, The core network located on Packet Switched (PS) Domain , has provided the integrated data service,and chose SIP (Session Initiation Protocal) has taken IMS the signaling controlling protocol. It has realized on PSTN/ISDN and the INTERNET pronunciation or the multimedia service calls processes.This article conducts the research in view of 3GPP IMS and the ITU-TFGNGN related standard. First, introduced the mobile network's evolution draws out the IMS system concept, and was introducing in detail IMS in the domestic and foreign development's situation, plans the topic primary mission. Next, in the deep research 3GPP IMS the layered approach to architectutal design, including service layer, control layer, access layer.using the software engineering the theory and the technology, has with drawn the IMS service subsystem, the call session control subsystem and the Radio Access subsystem. Thus proposed the IMS core function concept construction, and analyzes its feasibility. Finally, using the UML modeling technology, from the logical construction and the physical construction angle, and between them the news carries on the design alternately to the IMS core functional module. Thus completes the IMS core function, controls including the call, the Packet Domain of QoS guarantees, IMS security system and the roaming task of design. And opens the source take FOKUS IMS protocol stack API and SER as the foundation, realizes the NGN core network IMS system platform, has provided the platform of the Telecommunications software's teaching and studies for the Beijing University of Posts and Telecommunications Software Institute.