关键词: 正文频分复用（OFDM）, 全相位OFDM, 时域自相关算法, 全相位频率估计器, 快速傅里叶交换（FFT）, 全相位FFT

Abstract: Carrier Frequency Offset（CFO） mitigation is critical for Orthogonal Frequency Division Multiplexing（OFDM） because even small CFO per-transmitter may lead to serious performance loss.Making use of the character of all-phase OFDM frame，this paper proposes the correlation algorithm for frequency estimation in time domain.It is accomplished in one frame period with the advantage of fast convergence.Phase error can not affect the algorithm.This paper also proposes the frequency estimation algorithm based on all-phase FFT.The difference between FFT and all-phase FFT is used in it.Moreover，the relationship between the signal group delay and frequency is used，too.Finally，the paper obtains the accurate signal frequency.It is robust in fast fading channel and lightly impacted by frequency offset.

Key words: Orthogonal Frequency Division Multiplexing（OFDM）, all-phase OFDM, correlation algorithm in time domain, all-phase frequency estimator, Fast Fourier Transform（FFT）, all-phase FFT