Research And Implementation On Downlink Mac Layer Control Mechanism In LTE-A

The Chinese government will issue the Fourth Generation license by the end of the year in order to promote the commercial development of LTE in the China market. As the evolution of LTE technology, LTE-A can not only provide higher data rates and spectrum efficiency, greater coverage, but also can reduce the business delay and support multiple wireless access technology, which will promote operators to launch more real-time and high-rate services.Amongthe key technologies of Fourth Generation, the software radio technology plays a important role in its process. Software defined radio technology can improve the flexibility and scalability of LTE-A soft base station design, and shorten the time to be put into use.Therefore, in the development of LTE-A soft base station, it is a very important part tostudy and realize the radio air interface of LTE-A.This paper mainly studies the control mechanism of LTE-A downlink MAC layer and realizes the MAC layer function with software. This paper firstly describes the key technology and performance of LTE-A system, as well as the development of software defined radio. Then give an overview of LTE-A radio air interface protocol, and put forward an overall design scheme for the protocol stackand an overall plan for MAC layer function implementation. Then it focuses on the study of control mechanism of basic function modules in LTE-A downlink MAC layer protocol.This paper mainly includes the design and implementation of HARQ module, random access module and the scheduling module, the design of module function process, interface and state machine in MAC layer. The ultimate goal is to realize the basic function modules of MAC layer by C++programming language. Later perform functional testing for each function module, integration testing, as well as system simulation and optimization. Eventually, the testing and simulation results show that the downlink MAC layer function is implemented, and the design goalsare achieved. At the same time, after the downlink scheduling simulation, the system can satisfy user fairness and maximize system throughput at the meantime.The software finished by this paper, when compared to the hardware implementation, has more flexibility and convenience, low cost, strong scalability, reduces overall investment of development and maintenance, which is beneficial for soft base station deployment and network coverage.