卫星OFDM系统的同步算法研究

摘要

定时偏差和频率偏移会造成OFDM系统性能严重恶化,研究了卫星OFDM系统的同步技术,使OFDM能适应卫星信道低信噪比环境,实现天地一体化通信网络的融合.在分析了现有的卫星信道条件下OFDM符号定时同步算法和载波频率同步算法性能的基础上,根据CAZAC序列相关峰位置受定时偏差和频率偏移的影响,设计了一种新的训练序列,并依新训练序列提出了一种改进的同步算法.仿真结果表明,在卫星信道下该算法在低信噪比时依然具有较高的符号定时同步和载波频率同步性能,并且在时域信号中就可以实现同步,相比其他在频域中实现同步的算法减少了复杂度.%The timing offset and frequency offset may cause a serious performance degradation of OFDM system.This paper studies the synchronization technology of satellite OFDM system to make OFDM suitable to low signal-to-noise ratio of satellite channel for fusion of space-ground integrated communication network.By analyzing OFDM symbol timing synchronization algorithm and and carrier frequency synchronization algorithm in the existing satellite channel condition,this paper designs a novel training sequence based on influence of timing offset and frequency offset on CAZAC sequence correlation peak location,and puts forward an improved synchronization algorithm based on novel training sequence.The simulation results show that the algorithm has higher symbol timing synchronization and carrier frequency synchronization performance with the low signal to noise ratio in satellite channel,and achieve synchronization in the time domain signal synchronization is achieved,compared with other synchronization algorithms in the frequency domain,its complexity is reduced.