OFDM系统中基于插值的频率同步

发送端和接收端时钟振荡器的不匹配以及多普勒偏移导致了载波频率偏差.在正交频分复用(OFDM)系统中,这种频率偏移会使信号产生很大的误差,严重影响系统的性能.因此在收发两端进行载波频率同步减小这种偏移是非常必要的.文中提出了一种OFDM系统中基于插值的载波频率同步算法,该算法仅需要一个OFDM训练符号,采用最大似然估计,完成频率偏移的捕获,在算法实现中,插值操作通过频域的循环卷积来完成.基于插值的同步算法独立于可能发生的载波相位偏移,具有很高的稳定性.仿真结果表明,作为一种捕获阶段的同步算法,能够给跟踪阶段一个很好的起点,从而改善系统整体性能.

Interpolation Based Frequency Synchronization in OFDM System

The mismatch of the oscillators in transmitter and receiver and the Doppler shift,introduce an offset in the expected carrier frequency.In orthogonal frequency-division multiplexing(OFDM) systems,this frequency offset causes large errors in the signal values.Therefore,it is very important to correct the offset.In this paper,an interpolation-based algorithm is proposed for carrier frequency offset synchronization in OFDM systems.This algorithm is based on maximum-likelihood estimation,for acquisition purpose,only uses one OFDM symbol block.And,because the algorithm is dependent on system phase offset,it is more robust.As an synchronization algorithm for acquisition phase,it gives a very good start of tracking phase,then general BER performance will be improved.