Policy-Based Access Control Mechanism Of IMS

IP Multimedia Subsystem (IMS ) is proposed by 3rd Generation Partnership Project based on Release 5 for supporting the IP multimedia services. IMS provides the convergence of IP and mobile communication. It supports access independence and separation of control function and bearer etc. However, as the most promising core network scheme of the next-generation network, it is a pity that the present IMS standard is short of through thought and deep research into the solutions to muti-access mode, so the theoretical research and design of policy-based access control mechanism in this thesis has great meaning for the understanding and generalization of IMS network.The thesis aims to implement the policy-based access control mechanism with the key module called policy control entity in order to support the access independence in IMS. Firstly this thesis introduces the IMS background, and explains policy-based QoS managerment of IMS. Secondly it researches and describes the implementation of policy control mechanism of IMS from GPRS access defined in 3GPP R5 and from WLAN access defined in 3GPP R6. Thirdly, by referring the two aboved mechanisms, the thesis proposes a new policy-based access control mechanism of IMS from fixed (xDSL) access. Then the detailed application of the technology is offered by taking the VoIP streaming service for example. Forthly, the thesis designs the construction of policy control which supports muti-access mode through the standard results integration of 3GPP and TISPAN. In addition, the thesis introduces the thinking of hierarchical policy control to the muti-access control mechanism. A common solution access bearer control based on policy is innovatively put forward. And this solution is applied to a case in the new convergence construction, in order to implement the QoS negotiation between different access domains. At last, the areas studied are briefly reviewed, along with some issues that need further studies.