Pilot-based Fast Estimation of Frequency Offset and Channel for OFDM

A new fast algorithm is proposed for estimating the CFO based on the pilot structure in [1], [2]. The new method first identifies a coarse estimation of the CFO and then refines it by a least square (LS) method. It always gives a more accurate estimation than the multi-stage method in [2] and is better than the method in [1] at low SNR. It only slightly worse than the maximum likelihood estimator at high SNR. Furthermore, the proposed method can be used for CFO tracking. Also, in this paper, channel estimation by using the same pilot block is considered. The best values for the non-null subcarriers are found to optimize the channel estimation and peak to average power ratio (PAPR) simultaneously. Simulations demonstrate that the proposed methods are effective.