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IntroductionWith the development of science and technology ,it has been the most important technology task which draw much attention in the sanitation system and electron industry inside our country and overseas that the use of multimedia computer technology , the use of advanced communication equipments and the use of internet technology in telemedicine service .Telemedicine uses elite of modern communication technology ,of computer network technology and of modern medicine to form a network system consist of medical treatment ,education ,information .Telemedicine indeed make it come true that people in the remote and poor mountainous area ,and more other people enjoy medicine education resources ,expert resources ,technology equipment resources ,medicine technology productions and information resources .Our country as the largest developing country in the world ,there are a lot of people in the remote areas and in the countryside are accepting unenlightened medical treatment and health care , the number of doctors and nurses is rather small compared to the total population ,people in the remote area are difficult in seeing a doctor .Telemedicine could make diagnosis and treat be done without the doctor seeing the patient ,so it could become true that the patient in the remote area would enjoy the same medical treatment service with the patient in the city .The precondition to make those come true is the deeply development of network technology and communication technology ,while it is more difficult in the remote area and undeveloped area than in the city and developed area .If "telephone walking into each village" of " the tenth five-year-plan" came true ,Broad band (such as ADSL)walking into each village would not be difficult .Thus telemedicine will gain big and practical development .At the same time ,the fast development of wireless communication technology breaks the limit of time and space for the people to gain telemedicine service ,extends the traditional concept of telemedicine .It can be forecast that telemedicine based on wireless communication will be a future development aspect ,it is worth to researching and bringing forward a scheme technically or economically. SIP is developed by IETF, based on internet standard such as HTTP and SMTP .Thus ,once developed ,SIP is compatible with internet and supports many other communication form ,such as IM ,video conference pointed once ,chat room ,presence(the ability to share real time state information among group member),cooperation ,and "one number is ok" intelligent service based on equipment which has been logged on .For the terminal device has been intelligentized ,the characteristics of SIP will gain fast ,conveniently development .In another words ,there is little to do about the network ,just the reliable connection .UAC could make an audio call ,or a video call ,or an audio and video call without any especial configuration or many network support .In fact ,if user wants to add other participants to make video conference ,he will send invitation using mouse to select .SIP is the first protocol which can make multi-user session without considering media type .SIP define how one or several participants' UA to setup ,modify ,terminate a connection in spite of the content(audio ,video ,data ,or application based on WEB). The most important thing is that all functions of SIP could be combined, through corresponding gateway span various network, forming different kinds of more large scale no-slot communication service network.Because SIP has so many advantages and good future, lots of companies are researching and producing related productions.SIP has come out of laboratory and are entering market at present .It is believed that SIP will apply into nowadays networks .For all the reasons above, the telemedicine system based on SIP don't need to spend on basic networks, the only thing has to do is develop different kinds of UA, saving large number of time and money, cost will be reduced. The feasibility of the system is high。2. Research ContentThe telemedicine system based on SIP is a network system framework based on SIP, including UA, proxy, registrar, location server and redirection server, and data server,in the very future, these kinds of server should be layed by operator when service relevant to SIP is provided, thus,only UA and data service need be developed. For the reason of time, only the system framework diagram has been brought forward and UA has been implemented. 1. Five open-code SIP inns which are often used have been compared, oSIP is selected for the reason that it is mini structure, stable, flexible.The code of oSIP is rather concision, its size is so small that it is can be used not only to implement SIP-enabled soft telephone, but also to be used in embedded SIP software.There are three components in oSIP, those are: FSM model, parser model and facility model. FSM is used to complete the record of a special transaction, and spring the corresponding transaction or callback function;the parser model is used to parse SIP message,SDP message and URI;the facility model is used to deal with SDP,diaglog management etc.2. Discussion is made on SIP is adapt to construct telemedicine system, and the system has a good future, will gain widely development.The framework of telemedicine based on SIP is brought out, the operation of the system is to is discussed.3. The UA is developed in VC++6.0 under the Windows XP operating system. The UA could create, modify, terminate a dialog, could transfer audio and video data real time.The UA is consist of application program model,signal model,multimedia model,network model and timer.The application model could complete various initialization ,spring call and response,exchange information with signal model,multimedia model;the signal model could create,modify, terminate a dialog;the network model could complete message and data transfer;the timer provide retransfer timer management. Using the test software, it is proved that the multimedia session is created and terminated by SIP.3. ConclusionUA works well on two computers installed Windows XP operation system within LAN .Since the real-time transfer of audio and video has been implemented ,other assistant function ,such as file transfer ,white board ,IM will be implemented soon .In the future ,A telemedicine system UA with various kinds of functions ,and convenient to use should come true ,it helps to resolve problems in our country's medical treatment area. |
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