卫星移动通信多普勒频移补偿研究

Compensation of Doppler frequency satellite mobile communication

针对卫星通信系统中,多普勒频移过大对通信过程造成严重影响的问题。在传统多普勒频移补偿思想的基础上,通过分析信号传输过程中影响多普勒频移估计值的因素。提出了一种改进的多普勒频移补偿方案。该方案通过使用最大似然估计法对用户链路上的收发信号进行多普勒频移估计。并使用该方案对Iridium系统,GEO(geostationary earth orbit)系统的反向通信链路上的多普勒频移进行计算,得出频率补偿误差。仿真结果表明,当统计点数N=3 500,信噪比SNR=8 dB时,经改进后,频率补偿方案在Iridium系统与GEO系统中的频率估计误差与传统频率补偿方案中的频率估计误差相比较,分别降低了50%与42%。因此,改进后的频率补偿方案与传统频率补偿方案相比,多普勒频率估计精度更高,更有利于卫星信号的精确跟踪和解调。

Doppler frequency offset is so large that it even affects the communication process. It is really a problem in the satellite communication system. In this paper, we analyze the factors of the influence of Doppler signal transmission in frequency estimation and propose an improved Doppler frequency shift compensation scheme, and use the maximum likelihood estimation method to estimate the compensation technique, and to estimate the Doppler frequency shift and calculate the frequency estimation error in the reverse communication link of Iridium and geostationary earth orbit system, The simulation result shows that when the statistical point N = 3 500 , SNR = 8 dB, in Iridium and GEO systems ,the frequency estimation error in the improved frequency compensation scheme compared with the traditional frequency compensation scheme is reduced by 50% and 42%. So the algorithm is superior to the traditional Doppler frequency compensation algorithm, It is useful for satellite signal to track and demodulate aecurately.