Research Of The Digital Mobile Centraless System Using Multi-Channel Access Techniques

Nowadays, according to the dispatch method, there are three classes of system in the field of private network communication: the Walkie and Talkie system without the dispatch function, the Trunked system with the dispatch function by a base station and the Centraless system( communication system without a central control) which realizes the dispatch function by itself. Under the trendancy to communication system being digitized overall, there is dPMR protocol in the Walkie and Talkie system, and TETRA protocol in the Trunked system. Although, there is no appropriate protocol in the Centraless system. This paper brings up a complete Digital Centraless Communication System using multi-channel access techniques on the base of anolog centraless system and digital Walkie-Talkie system. The design idea of the structure of this protocol stack originates from OSI layered model. the traditional seven layers model is simplifed to three layers, they are, the Call Control Layer(CCL), the Data Link Layer(DLL) and the Physical Layer(PL).In the CCL protocol, this paper designs two sets of communication signalling, for the common user and the supervisor respectively. Then, it brings up the basic calling procedure and designs the state shift process of the protocol on the base of the extended finite state machine (EFSM).In the DLL protocol, the transmitted logical frame format and the frame parameters are provided. When the channel coding algorithms are researched, it is proved that the algorithms are able to be realized through the experiment, and it is valued that the algorithms have a good error control ability. In the end, the allotment of the frequence and the access of the channel and the radio call number distribute solution are introduced.In the PL protocol, after comparing the national standard with the international standard, 4FSK modulation and main radio frequence parameter are given for the physical base of the whole protocol stack.