Research On Cell Search Algorithm Of TDD-LTE

The synchronization precess of LTE includes Cell Search and Random Acess.The main puporse of Cell Search is for UE to check the Cell ID, and then read the cell configuration information in PBCH. Cell Search is the first step of whole synchronization process, the performance of Cell Search algorithm also affects the RA for uplink and the maintaining synchroniation process. Therefore, the designing for Cell Search algorithm must have high precision for time and frequency offset. It is also reliable and robust for the cell search procedure, i.e. the procedure to detect neighbouring cells that can be used as potential handover candidates.In order to design a robust cell search scheme for LTE.We firstly descirb some fundmental theory for OFDM synchronization. According to the simulation, we give the range of the frequency offset estimation accuracy requirements for LTE. Then, a comprehensive summary and analysis of the OFDM synchronization field is described.On this basis, according to the current LTE standard, physical layer parameters are defined on the model. And a cell search scheme for TDD-LTE is designed. This scheme includes PSS detection module, cyclic prefix type detection module and second sync signal detection module.The main viewpoints of this scheme are as follows:(1) Maximum likelihood detection is adopted for the initial 5ms timing acquisition, while a high frequency error exsits. (2) The traditional frequency domain method has some limitations for integer frequency offset estimation, when the time error is taken into account. Differential correlation method should be used to eliminate the phase in frequency domain casued by timing synchronization error. (3) Coherent detect and non-coherent detect method can be both used to design the SSS sequence detection module, for TDD-LTE, non-coherent detect should be adopted.Each module can be realized and provided the algorithm. The algorithm designed is meeting the current centralized multi-antenna scenario. Finally, in the low SNR and high-speed environment, the simulation results certisfy that Cell Search scheme has good performance and can be implemented.