基于车载信息的多普勒频移估计方法研究

摘要

列车高速移动带来的多普勒频移问题增大了无线通信系统的误码率.经典Fitz估计算法已经无法适应高速环境下频偏大且变化速率大的特点.提出基于车载信息的多普勒频移估计方法,首先推导列车在不同行驶条件下的多普勒频偏公式,然后获取实时车载信息估计出多普勒频偏,最后结合改进Fitz估计算法进行第二次精确估计.通过构建无线信道传输误码率的仿真模型,利用matlab的simulink工具箱对列车行驶过程中误码率进行仿真.结果表明联合估计算法可以精确、实时估计列车高速移动带来的多普勒频偏,并且间接地增大了改进Fitz算法频偏估计范围.%Doppler shift caused by high-speed train increases error rate of the wireless communication system. The classic Fitz shift estimation algorithm hasn't been adapted to the high-speed environment where frequency offset is large and has large variation rate. A Doppler frequency shift estimation algorithm based on the in-vehicle information is proposed. First when the train drives in different conditions, it derives the formula of Doppler frequency offset, then estimates the Doppler frequency offset through obtaining the real-time vehicle information, and then combines with the improved Fitz shift estimation algorithm to accurate estimation. Simulation model of error rate for wireless channel transmission is constructed, by using the simulink toolbox of matlab to simulate the error rate. The results show that the proposed estimation algorithm can estimate Doppler frequency offset that caused by high-speed train in real-time, and indirectly increases range of the estimation for improved Fitz shift estimation algorithm.