Abstract: OFDM underwater acoustic communication system is very sensitive to the carrier offset.System performance will degrade dramatically with little carrier offset.In this paper，the interference among the multi-carrier is analyzed and regarded as degradation of SNR.To eliminate the imprecision of carrier frequency offset estimation using the cyclic prefix，a fitting method based on LS algorithm（CPLS） is proposed，which can dramatically improve the estimation precision.Simulation results show that compared with the method using cyclic prefix，OFDM underwater acoustic communication system using CPLS can work well under an even lower SNR.

Key words: cyclic prefix, LS fitting, estimation precision

摘要： OFDM水声通信系统对载波频率偏移非常敏感，很小的频率偏移就会使系统的性能显著下降。首先分析了由载波引起的载波间干扰，将其等效为系统信噪比的降低。针对OFDM系统利用循环前缀的频率偏移估计精度不高的问题，提出了一种基于循环前缀的频偏估计LS拟合算法（CPLS），该算法可显著提高频率偏移的估计精度。研究结果表明，同利用循环前缀的频率偏移估计方法相比，基于循环前缀频率偏移LS拟合算法的OFDM水声通信系统能够工作在更低的信噪比情况下。

关键词: 循环前缀, LS拟合, 估计精度