Research And Design Of High Layer Protocol In DMR Trunking System

Digital Trunking Communication System can integrate command scheduling, telephone, data transmission and other functions in one, and has a wide range of applications. Along with the international and domestic telecommunications environment changes, including rapid command scheduling, security and emergency communications growth, the importance of Digital Trunking Communication System becomes increasingly prominent. It will effectively improve and enhance the country's armed forces, public security, railways, civil aviation, water conservancy departments, and other technical equipment.The main research in this paper is the analysis of DMR trunking system interface protocol which was developed by the European Telecommunications Standards Institute. The structure and the functions of the layers of DMR system interface protocol stack are also studied. In this paper, we firstly give the technical characteristics of DMR Trunking system, TDMA frame structure and time slot information format. Then, we analyze the layered structure of system stack and describe the data link layer protocol structure and function. Also, channel coding of Trunking Communication system is in our research.Secondly, we have an in-depth research to channel access protocol, analyze a wide range of random channel access protocol and give an improved algorithm. Improvement is based on the slot ALOHA algorithm. It uses dynamic estimates of the collision slot, then constantly changes, so that it make the length of frame equal to the number of calls. Then, it may work when the system meets the maximum throughput work. From the simulation result, the method has greatly enhanced the system's stability.This paper also designs the call control protocol. Taking basic call and packet data transmission process as an example, we also describe the process protocol.In short, through the technical characteristics of digital trunking system and the in-depth analysis of protocol structure, we can see that the digital trunking system has many advantages such as fast follow, good error correction capability and confidentiality. All of these make it has a wide range of applications in command scheduling and emergency communication systems.