Research And Design For STB Videophone System Based On Softswitch

STB(Set-Top Box)is a household appliances which is designed to expand the function of TV set,it can supplye multiple services since it has enough IP network access to bandwidth and a powerful capability of multimedia processing.Videophone system is one of the kinds of the software service. Video communication system is a kind of business software which can be loaded into set-top box.This paper begins with contradiction between the Telecommunication technologies and the rapid development of the current communication networks, analyzes the background of the NGN(next generation networks) in detail,then provides a detailed study of the basic definition, the main functions and the main characteristics of SoftSwitch. SIP(Session Initiation Protocol)is a control protocol over application layer in SoftSwitch network,SIP can be used to create, modify and end multimedia sessions. At present, the most of the video communication systems are based on the H.323 protocol,but, due to the SIP protocol plays an important role in the evolution process of the existing Network to the NGN.After comparing the two protocols,this paper uses SIP as the signaling protocol.Consequently a comprehensive study of SIP is given.Based on the study of the key technologies of videophone system, the paper gives a kind of design proposal of IP videophone system in STB based on SoftSwitch. And designes the architecture syetem of the hardware and software. From the function and the application of the system,the paper provides a design from bottom to top with hierarchical,carries out the system structure and the design of each function module. Finally, a specific research and design of the calling process of the communication is provided. It relized the co-existence STB of two software modules which are the communication system and the control of IPTV. The two software modules resolved the problem of system resource management and control effectively, which arises from the co-existence of videophone services and IPTV/VOD.