OFDM系统定时偏差补偿算法

Timing offset compensation algorithm for OFDM system

为了消除正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)符号定时偏差对信道估计的影响,提出了一种补偿算法.理论分析表明相移可以被看作是信道统计特性的变化,并且在使用线性插值的信道估计方法时估计误差会扩大.该算法利用符号定时偏差会引起子载波相位旋转的特点,对信道估计进行补偿.仿真结果表明,在多径信道下,在信噪比为20 dB定时位置位于循环前缀中点时,使用该算法后信道估计均方误差是通常线性插值算法的25%,因此新算法缩小了信道估计均方误差.实验结果表明,该算法提高了接收机的性能.

To eliminate the effect of orthogonal frequency division multiplexing（OFDM） system symbol timing offset on channel estimation,a compensation algorithm was presented.The theoretical analysis shows the phase shift is calculated as the change of statistical properties and the channel estimation error is extended when the linear interpolation is used in the channel estimation.The presented algorithm compensates the channel estimation using the characteristic of subcarrier phase shift caused by symbol timing offset.The simulation results show that,in multipath fading channel,the channel estimation mean square error of the new algorithm is 25% that of normal linear interpolation algorithm when the signal to noise ratio is 20 dB and the timing position is the middle of the cyclic prefix,so the new algorithm can shorten the mean-square error of channel estimation.The experimental results show the algorithm can improve the performance of receiver.