Research And Design Of Smart Terminal Trunk Communication System Based On SIP

In recent years, with the rapid development of the mobile communications techniques, more and more services are applied to the intelligent terminals. Digital trunking system is a type of special mobile communication system which is used for dispatching and emergency communications, and users in system can realize one to many call. With the advent of the voice change era, HD IP voice communication in mobile intelligent terminal has been achieved, Vo LTE and VoWiFi has begun commercial use. The most popular IP voice communication technology is SIP protocol. SIP protocol is simplicity, agility and facilitates the expansion, so it loved by the majority of developers. Based on the features of IP voice communication and trunking communication system, combined with the Android platform, this article designed and implemented an intelligent terminal trunking communication system based on SIP.This thesis firstly detailed research and analysis SIP protocol. Including overview, system structure, message structure and session flow about SIP protocol. Then through the analysis and comparison of different SIP protocol stack, the android SIP stack is selected as the present system SIP stack, and conducted in-depth study for this SIP stack in android source. Next, introduced the system requirements analysis and designed a system framework according to needs analysis. Finally, I had implementation for this system.The designed trunking system includes four modules: the wireless communication module, register and login module, cluster intercom module, location module. The wireless communication module implements the related function about data transmission beween client and server; register and login module implements the function about register and login authentication with server, including registration about personal account and SIP service.;cluster intercom module implements the function of intercom in group, including establishing the SIP session and transferring the voice data; location module implements the function of locating member’s position in group. The system also implements search and modify user information functions except realizes the basic functions of SIP trunck system.Moreover, consider the usage scenarios like outdoor emergency and network outages, this thesis made some improvements for this SIP trunking communication system, integrated the server and client together, and can networking using the wifi hotspots in Android to realize LAN cluster intercom.In the end of this article, we made some test for this trunk communication system and shows that it can realize all the functions in needs analysis and run in all kinds of android platform stably. Also it is extensive and more function could be implemented further based on current version.