Research And Development Of Upper MAC Protocol For Digital Trunked Mobile Station In Direct Mode

Digital trunked system is a kind of advanced appropriative mobile communication system. It can not only provide personal mobile communication services, but also control and implement communication between individuals and groups. Abundant wireless conduct applications are provided by this system. As direct mode operation is flexible, convenient and quick-networking, it plays an irreplaceable role in disaster and emergency. Digital trunked direct mode operation is a part of Digital trunked system.Media Access Control (MAC) layer is an important part of digital trunked Direct Mode (DM) protocol stack. It’s mainly responsible for the management of wireless resource and the access of wireless channel. Upper MAC is one sub-layer of MAC, and it’s mainly responsible for the management of address, synchronization of mobile station, random access control, DM channel monitor and so on. So functions of upper MAC layer is the key of the development of digital trunked DM protocol stack.First of all, the development status of DM for digital trunked system at home and abroad are summarized in this paper. Based on analysing work model and air interface protocol stack of digital trunked DM, the structure and functions of upper MAC layer and DM channel are further researched. Then, PDU of upper MAC layer, primitives between upper MAC and Direct Mode Call Control (DMCC) and primitives between upper MAC and lower MAC are described, and the upper MAC work process such as state changeover, transmission and reception of the signaling, frame count down mechanism, random access control, establishment and release of the channel are described in detail. At last, based on Tornado integrated development environment, DM functions of upper MAC layer are implemented by using C language, and the program of upper MAC is tested through simulation testing and actual testing, and the test result satisfies the requirements of user.