Design And Realization Of Media Gateway Based On H.248 Agreement

With the rapid development of broadband access and NGN technology becoming more mature,the user demand in communications has shifted from voice-centric communications to the direction of the means of communication integration such as Instant messaging,voice,video,conferencing and so on.NGN and soft switch technology came into being,it can be said that NGN is a milestone in the history of communication.It can provide voice,data and multimedia services and so on.The unique network architecture in it not only make network convergence come true,but also make business integration come true.Soft switch technology is a platform that based on distributed switching and control of software.It make the relatively more independent business system come true by the separation of business and call control,the separation between call control and bearer.The separation brings great benefit to the rapid introduction of new business and that is the main idea of soft switch technology.Media gateway is an important part of the soft switch device,and MGCP is a standard interface protocol in soft switch network between soft switch device in control layer and kinds of media gateways in access layer,such as H.248.H.248 not only inherits all the advantages of conventional media protocol,but also has a powerful description of the function,and it provides better support for application layer.Besides,the management and implementation of H.248 is more simply,it can control media bearer better.This paper combines upgrading project that the author was involved in,first,it describes the background and significance of the paper,the development at home and abroad and the target of this project's research.Then,in the second chapter,it has a brief description of media gateway and media gateway controller,and it also describes the technology protocol of media gateway and media gateway controller in the current trend of technological development.In the third chapter,the author makes a overall design of the media gateway which based on H.248 protocol.The author makes a detailed design of the media gateway that based on H.248,and a difference between G.729 and G.723about the result of time delay,And then,the author gives us the process between media gateway and other access network devices that through command and descriptor of H.248 protocol,and it also has flow chart and program of the process.At last,to illustrate the use of media gateway that based on H.248 has Practical feasibility,the author expands the discussion of media gateway's external features such as change user's numbers and permissions or accounting function and obtains the test results.