Key Technology Research Of Next Generation IP Mobile Communication Network

The proposal of next generation net (NGN) brings a revolution of communication network technology. NGN is not a special type of network, however, it is a new network architecture. This architecture supporting voice,data,multimedia services etc focus on IP. The ITU-T definition of NGN includes: it offers unrestricted access by users to different service providers, and it supports generalized mobility which will allow consistent and ubiquitous provision of services to users. As describe above, NGN is the aim of communication network evolution, but IMS is crucial technology in next generation network convergence.IMS (IP multimedia subsystem) is a subsystem supporting IP multimedia, which was proposed by 3GPP in version R5. Its main characters includes: It employs SIP protocol and independence of access type. IMS provides future multimedia application with a common service platform, which is an important step towards entire IP network service. In the trend of network convergence, A solution of network convergence based on IMS has being studied by 3GPP,ETSI and ITU-T. The target of this study is that IMS will become a common platform based on SIP and support fixed and mobile access mode to converge fixed network and mobile network. IP multimedia core network system is composed of all core network function entities providing multimedia service, which comprises sets of function entities relevant to signaling and bearing. IP multimedia services is based on IETF definition of session control capability and uses multimedia bearing in PS domainTo meet the target of independence of access and smooth of wireless endpoint and internet interoperation, thus, IP multimedia subsystem employs as possibly as internet protocol in accordance with IETF protocol and also its port protocol. For example, IETF SIP protocol.So far, IMS is still in a development and far away from grown. Therefore, there still exists many problems. In order to improve IMS, present paper analyzes IMS from many aspects and researches these relevant problems.Present paper analyzes in detail problems comprising: the session establishment that is important in IMS architecture,media negotiation,equipment addressing and routing,NAT/FW traversal,error control of channel encoding. Present paper resolves problems described above by using mathematics or other methods.(1) Analyzing the signaling process of session establishment including multiple entities in IMS architecture and researching the process of early media negotiation. Finding out a fault of offer/answer mode supplied by SIP specification for media negotiation when this mode is applied to early media negotiation. This fault is described below: In some conditions, the offer/answer signaling for media negotiation will be unmatched. Present paper also analyzes present solution and point out its drawback. Proposing a new solution resolving the problem that offer/answer is unmatched in original offer/answer mode of early media negotiation. This solution resolves the problem from two aspects including SDP message content and SIP signaling integrity.(2) Analyzing the characters and properties of endpoint to endpoint in IMS architecture and equipment addressing in instance that one user has multiple equipments. Extending the SIP message structure, moreover, Proposing a new solution resolving the problem about equipment addressing from three aspects comprising register process,structure of SIP message head and user privacy protection. This solution improves the process of endpoint to endpoint service.(3) Analyzing and researching the some scenarios and reasons of that SIP message can not traverse a NAT/FW. Proposing a new solution combines the method of equipment addressing to resolve the problem about NAT/FW traversal of SIP signaling, which results in that equipments behind NAT/FW may communicate with external equipments.(4) Analyzing the error control and error detection (error correction) mechanism of next generation network data communication and researching the burst error catching algorithm of cyclic code used in wide. Pointing out the substance of this detection (error correction) mechanism. Proposing a new burst error detection (error correction) mechanism of cyclic code based on study and met the necessary of real time communication. This mechanism improves original burst error detection (error correction) algorithm and enhance the efficiency and speed of burst error detection (error correction) of cyclic code.