The Research And Implementation Of TD-LTE Cell Search And Time-frequency Synchronization Technology

TD-LTE(Time Division Long Term Evolution)is a standard of China’s leading and deploying for mobile communication.It has a very optimistic development prospect in the transmission rate,network delay,bandwidth allocation,etc.However,it also meets a lot of technical challenges.As the premise of the communication between UE and network in TD-LTE,the synchronization of cell and decoding of control information need to be obtained,which is called cell search.The algorithm’s performance of cell search is of crucial importance,which will directly affect the normal communication.The paper mainly focuses on the research and realization of the cell search and synchronization technology.Firstly,the paper starts with the technology in TD-LTE,and elaborates the background of the TD-LTE research,including the related principles and technologies of TD-LTE physical layer,synchronous signal,OFDM,etc,which forms a base for further research and realization.Then,the paper focuses on the algorithm of cell search and time-frequency synchronization process.Through the research and analysis of cell search process,cell identification and synchronization signals,the paper designs the whole scheme for cell search process.Based on the time and frequency synchronization process,the paper proposed several algorithms,they are the symbol synchronization algorithm,5ms timing of Primary Synchronization Signal detection algorithm,10ms timing of Secondary Synchronization Signal detection algorithm,frequency offset detection and compensation algorithm.At the same time,the paper uses diversity method which can further improve the performance.All the algorithms are simulated by MATLAB under different channel which have tested and evaluated their performance.In addition,in the case of the situation that the up-link and down-link signal is difficult to confirm in the initial search,the corresponding algorithm is designed to identify and distinguish the signal,which has improved the accuracy of the algorithm.In order to meet the high performance and real time requirement,an improved coarse timing scheme with low complexity is proposed,which is based on the matched filter and down-sampling.By using the matched filter and down-sampling process,which is combined with cyclic convolution method,the detection of the Primary Synchronization Signal has the advantages of low complexity and fast acquisition process.Finally,based on the general purpose processor platform for software radio,the paper carries out all the algorithms in the down-link synchronization process,and uses parallel processing and fixed-point processing to improve the whole performance of the realization at the same time.The realization results show that the proposed algorithm has completed the process of cell search and time-frequency synchronization,and the performance can achieve the desired results.