Compared with the conventional preamble-only pilot design, equally-spaced pilot (ESP) design provides a significant improvement in terms of estimation accuracy, whereas it suffers from the increased threshold effects of the signal-to-noise rate (SNR). The relationship between the pilot placement and the estimation range of the frequency is analyzed, and then a novel maximum-likelihood estimator is proposed, which is based on ESP. The frequency region and the SNR threshold region are derived for the new estimator. The analysis is validated by computer simulations. It is shown that, compared with the traditional estimator based on ESP, the accuracy of the new estimator at low SNR is improved about 17 dB without additional channel source, if the carrier frequency offset (CFO) is located in [-0. 45, 0. 45] rad.%与传统的连续导频符号设置相比,等间隔导频符号设置的最大似然载波频偏佑计具有更高的估计精度,但低信噪比门限也较高.在分析导频符号位置对频偏佑计范围影响的基础上,提出了一种新的基于等间隔导频符号的最大似然载波频偏估计方法,推导了该方法的频偏估计范围和低信噪比门限,并对理论分析结果进行了计算机仿真验证.结果表明当载波频率偏移介于[-0.45,0.45]rad时,该方法可以在不增加导频开销的前提下,将低信噪比条件下的载波频偏佑计精度提高近17 dB.
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