Research And Development Of Random Access And Reserved Access In Upper MAC Protocol Of Digital Trunked Base Station

As digital trunked system can provide secure, reliable and high-speed voice and data communications, it emerges rapid development across the world. Nowadays, foreign technologies of digital trunked system are relatively mature, but the price is very high, and the systems lack security and confidentiality. Digital trunked systems in China started fairly late. They are not mature enough and also need more time to make themselves perfect. So it is significant to develop digital trunked systems with independent intellectual property rights of our own.Media Access Control (MAC) protocol layer is one of the important parts of digital trunked system protocol stack. Radio channel access is controlled and radio resources management is conducted in MAC layer. Upper MAC layer is one of the two sublayers in MAC protocol layer. Physical channels and different logical channel groups are provided for MS, and access ways of random access and reserved access and periodic broadcasts which help MS acquire cell synchronous information and network information are also provided in upper MAC. Random access and reserved access are the foremost access control function in upper MAC protocol, so they are keys of the development of upper MAC protocol stack.First of all, the major functions of access control in upper MAC and developing situation of it at home and abroad are summarized in this paper, and the significance of this subject is analysed. After that, based on the analysis of digital trunked air interface protocol stack, the structure and major functions of upper MAC layer are described. Then, functions of random access and reserved access in upper MAC layer are described respectively. Meanwhile, the developing language, developing and debugging tools and implement methods of protocol stack are given after analyzing and comparing several protocol stack developing languages and methods that are used recently. At last, based on Tornado integrated development environment, the functions of random access and reserved access in upper MAC protocol layer are implemented by using C language. The programs are transplanted and debuged in CVT_PXA270 platform loading VxWorks embedded system, and the results satisfy the design requirements.