Design And Implementation Of Integrate Communication Terminal Based On SIP

With development of Packet Switching and computer technology, softswitch will gradually replace circuitswitch and become the future of telecommunication network. In the softswitch environment, telecommunication net can provide not only voice service, but also video,data and intelligent services. This will give out new requirements for users'terminals. In new generation net, users'terminals must be able to access into Packet net, exchange signal with component of softswitch and receive all kinds of digital services provided by softswitch net.The paper designed and realized a kind of desktop terminal base on SIP protocol to satisfy the requirement of softswitch net. The terminal mainly realized IP video phone function. It used SIP protocol to exchange signal with softswitch network, used RTP to realize media stream real time transmission. The lecture first analysed and discussed the communication theory of SIP network and key technologies then discussed detailed process of terminal's software and hardware design.In theory part, paper lucubrated SIP protocol and discussed detailedly entities of SIP network,layered structure of SIP protocol,structure of SIP message,process of session building,mechanism of media negotiation and several other key technologies used by SIP terminal: signal,media codec,RTP and QoS.The paper's key chapters were focused on embedded system design of the terminal. Here it not only emphasized on realization of design but also design method. In these chapters, lecture first introduced design method simply then introduced whole process of software and hardware design detailedly. Hardware design which put XScale PXA270 processor as its core described the constructing hardware platform according to power system,core system and peripheral interface these three design steps. Software design can divide into two stages. First stage named constructing software platform is foundation of second stage, which contained Linux kernel porting, driver program design and root filesystem's building. Second stage named application design could be divided into five modules which were main control module,SIP stack,RTP stack,media codec and media device control. Paper designed these five modules according to function of their definition,relationship of each other and Linux its own property.Paper make test for the terminal in the end. There were two kinds test, one for terminal communicating with other components in network, another for quality of terminal's communication. The test results revealed that terminal communicated well with other network components and its voice quality is good but video quality is common.