| LTE-A system uses OFDM technology. And the OFDM system is sensitive to time synchronization error and frequency offset. The performances of receivers are reduced by inter-symbol interference cause by time synchronization error and inter-subcarrier interference because of frequency offset. Therefore, synchronization is a key technical problem in OFDM system, including time synchronization and frequency offset estimation, and it is cell searching in downlink and random access in uplink. The work of this paper is to determine the synchronization scheme for LTE-A system and design the synchronization scheme on the GPP platform.This paper design a cell search algorithm with down-sampling and two steps for PSS detection based on the traditional algorithm. Firstly, finish the PSS detection with the down-sampling signal. Then do the detection with original signal using the symbol boundary detected in first step. Finally, complete the frame synchronization and frequency offset estimation. Also, a random access signal detection algorithm based on down-sampling and detection threshold is proposed. And the algorithm is lower computational complexity and ensures the signal detection performance.Signal processing simulation system based on GPP platform has good portability, and to facilitate the development and upgrading. Some optimization methods are tried to meet the real-time requirement in the uplink and downlink synchronization process of the signal processing simulation system. Simulate and analysis the performance and efficiency of the synchronization algorithms. Finally we obtain4-10times efficiency improvement compared with traditional GPP signal processing. |
