Frequency Offset Estimation for OFDM Systems with a Novel Frequency Domain Training Sequence

摘要

A novel frequency domain training sequence and the corresponding carrierfrequency offset (CFO) estimator are proposed for orthogonal frequency divisionmultiplexing (OFDM) systems over frequency-selective fading channels. Theproposed frequency domain training sequence comprises two types of pilot tones,namely distinctively spaced pilot tones with high energies and uniformly spacedones with low energies. Based on the distinctively spaced pilot tones, integerCFO estimation is accomplished. After the subcarriers occupied by thedistinctively spaced pilot tones and their adjacent subcarriers are nulled forthe sake of interference cancellation, fractional CFO estimation is executedaccording to the uniformly spaced pilot tones. By exploiting a predefinedlookup table making the best of the structure of the distinctively spaced pilottones, computational complexity of the proposed CFO estimator can be decreasedconsiderably. With the aid of the uniformly spaced pilot tones generated fromChu sequence with cyclically orthogonal property, the ability of the proposedestimator to combat multipath effect is enhanced to a great extent. Simulationresults illustrate the good performance of the proposed CFO estimator.