文章对几种常用的基于循环前缀(CP)的最大似然同步算法进行了分析，并对其频偏估计方差进行了比较；同

时针对基于CP 的同步算法在多径衰落信道下性能较差的情况，提出了一种改进的CP 同步算法并进行了仿真，结果表明相比

于原ML 算法，文中算法在多径信道下可有效提高频偏估计性能。-】This paper does some research on multiple maximum-likelihood (ML) algorithms based on cyclic prefix

(CP) and compares variances of frequency-offset estimation　After the analysis of the bad performance of CP based

algorithms in multi-path fading channels, an improved CP algorithm is proposed and the simulation shows that this

algorithm can improve its performance effectively in multi-path fading channels.