LTE-R应用于铁路通信多径衰落信道下的时频同步研究

LTE-R(Long Term Evolution-Railway,长期演进)作为下一代铁路无移动通信系统,采用OFDM(正交频分复用)的调制方式来提高频谱利用率。铁路无线通信系统易受到多径衰落和突发干扰的影响,严重影响铁路的行车安全和运输效率。因此研究符号定时同步和载波频率同步对铁路无线通信系统具有很重要的意义。采用重复共轭结构训练符号的自适应符号同步算法,首先确定训练符号的符号定时同步、载波频率同步以及信道参数,再经过迭代递推把符号定时同步起始位置调到FFT窗口的理想位置和对载波频偏进行补偿。仿真结果表明,该方法在多径衰落信道下有很好的符号定时同步估计和对载波频偏的补偿,信噪比越高符号定时同步估计精度也越高。

Research on Time and Frequency Synchronization Estimation of Railway Communication with LTE-R under Multipath Fading Channel

As the next generation of railway mobile communication system, LTE-R( Long Term Evolution) uses OFDM modulation mode to improve spectrum efficiency. The railway wireless communication system is susceptible to the influence of multipath fading and sudden disturbance,which seriously impact normal train operation traffic efficiency. Thus, the study on symbol timing synchronization and carrier frequency synchronization for railway wireless communication system is of vital significance. The self-adaptive symbol synchronization algorithm of repetition conjugate structure training symbol is used to determine the symbol timing synchronization of the training symbol,carrier frequency synchronization and channel parameters,and then the starting position of symbol timing synchronization is tuned to the ideal FFT window location and the carrier frequency offset is compensated through iterative recursion. The simulation results show that this method is effective in symbol timing synchronization estimation and compensation of carrier frequency offset under multipath fading channel with high signal-to-noise ratio and high precision of symbol timing synchronization estimation.