Softswitch Based Design Of Call Control Unit In Digital Trunking System

With the progress of our economy, society and the technology of radio, the radio has developed greatly, especially the mobile radio industry. As a new industry, the digital trunked radio communication attracts attention in China. TETRA (Terrestrial Trunked Radio) digital trunked radio communication system is a kind of advanced private mobile communication system and is a radio directed communication system, which can share resource, expenditure and channel equipments, provide kinds of services and have high efficiency. Because our traditional analogue trunked radio communication system takes use of analogue module, it has many shortages such as uncomfortable improving capacity and difficult connection with the other digital devices. And the Key technology of NGN, softswitch has been the thesis being heavily researched in current stage, with features of separated call control function and easily supporting new services, softswitch is the basic technology of merging different networks. Consequently it is more and more necessary that our country researches and develops our own digital trunked radio communication system. Based on the study of the private communication system, especially on the most important part of the control center and the protocol of the V+D air interface, the design project based on softswitch is proposed.First of all, the development of the digital trunked communication system is summarized, and the technical characteristics of several prevail worldly digital trunked communication systems are compared. In view of the domestic situation, the TETRA digital trunked radio communication system is chosen as the studying and developing model. With the study of control technology of softswitch , the protocol of the V+D air interface and the multiple use of channel is analyzed, the base station control unit of the digital trunked communication system is discussed, the calling control flow is designed. And then this paper analyzes stressedly the course of control and the signalling flow of calling control in switch control unit of TETRA system. According to the task requirement, the communication is realized by using VC++ general programming language on LAN based on the TCP/IP transmission protocol. With the TETRA air interface...