| SIP (Session Initiation Protocol) is a new generation protocol for multimedia communication framework by IETF. It features simple service logic control, flexible usage and supports seamless transition from wired to wireless networks, which makes it the core protocol in NGN. SIP in mobile networks and its embedded implementation is one of the hot research topics on SIP. The thesis concentrates the critical issues related to SIP in wireless environment and implements the SIP backbone based on TI's DSP platform, thus to support the SIP modules for next generation of embedded multimedia communication terminals.The layered structure, functional entry, message syntax, working routine, extended mechanisms and various application modes in NGN related to SIP were investigated in detail. A SIP wireless application model was proposed based on SIP wired network application framework, in which the tough issues were discussed, such as registrar mechanism, terminal mobility and so on. Then the SIP UA (User Agent) of the wireless application model was developed on the basis of oSIP (an open source software package) , including the basic modules such as event scheduler, dialog management, callback function, resource management and so on, complying with the specifications RFC3261, RFC3265 and RFC3428. Based on DSP/BIOS, the SIP UA codes were embeddedly implemented by code transplanting and optimizing. Combining other software modules, that is, video acquisition, video codec and network transmission modules, the SIP communication software was finished and tested.The embedded SIP UA was developed according to the modularization principle, which makes it easy to implement other extended mechanism and... |
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