Abstract:

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.