Sip Protocol Application And Implementation Of A Wifi Phone

The development of network technology and multimedia technology has greatly boosted the communication technology to be sythetical, digital, intelligent and customizable. This makes it possible to realize multi-services such as audio, data, video, etc., on a single network platform. The VoIP, which integrates network technology and multimedia technology, emerged in such a background and has developed fast to be a competitive technology in voice communication field. Apart from those advantages such as packet switching, effectively utilization of the bandwidth and cost-effective, VoIP can realize various kind of ancillary services, and can combine with multimedia technology. This is the key for it competitiveness and its prospective market. Although currently the quality of the voice of VoIP telephone is not good, it is paid high attention by the communication practitioner. Many international standard organization are proposing new related standards, focusing no only on the VoIP telephone itself, but also on future IP multimedia multi-point communication and various kind of VoIP ancillary services.SIP (Session Initiation Protocol) is one of application-layer control signaling protocols in VoIP technology proposed by IETF (Internet Engineering Task Force). Based on SIP, traditional voice and its added service can be integraed, and some new real time service andvideo service over IP network can be provided. This can offer a standard and highly scalable platform for more added services providers. This platform is totally based on distributed Internet architecture, and hence is highly flexible and scalable. This thesis focuses on the study on the key technology of SIP protocol and its application on WiFi cell phone terminal. The thesis first introduces the technical background of the VoIP and WiFi, then elaborates several key technologies, and then describes the related protocols. Next, the definition, functionalities, components, message and protocol architecture of SIP isintroduced. According to the function of the VoIP terminal, SIP protocol stack is designed to implement WiFi wireless voice functionality (VoWLAN). The necessary functional modules are designed, incnluding the user agent, real-time transport and the management of the system's resource, among which the user agent module is paid more attention. Then, on the basis of modular...