Research On The SIP Extension And Its Application In The IP Multimedia Subsystem

The IP Multimedia Subsystem (IMS) is the solution to the core network of NGN defined by the 3GPP. It divides the core network into four planes, including the application plane, session control plane, data transport plane and access plane. Therefore the independence of the planes makes the services development and provision, and the networks management more convenient. In Addition, the independenance of the core network from various access networks is implemented by separating the functions of access and session control. All the features mentioned above will make the legacy networks evolve into the NGN core networks based on IMS. Therefore, providing multi-point vedio conference (MPVC) services will become a hotspot of the academe and service provider in the future.This dissertation first introduces the IMS architecture and its working principle. The detailed description is the SIP of the core call control protocol used in IMS, including its architecture, message structure, work principle and extensions in IMS.Discussing the multi-point multimedia conference scheme provided by 3GPP, and analyzing the problem of this scheme, the solution to the MPVC is proposed in this dissertation, which is a layered model and based on IMS. To meet the requirements of the MPVC the emphasis is on the extension to SIP. This dissertation also investigates on the design and implemention of the session control software for the MPVC prototype, and performs this software validation in the laboratory environment. The efforts made in this dissertation provide a technical foundation for developing MPVC software in the future.