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

Abstract

SUMMARY A novel frequency domain training sequence and the corresponding carrier frequency offset (CFO) estimator are proposed for orthogonal frequency division multiplexing (OFDM) systems over frequency-selective fading channels. The proposed frequency domain training sequence comprises two types of pilot tones, namely distinctively spaced pilot tones with high energies and uniformly spaced ones with low energies. Based on the distinctively spaced pilot tones, integer CFO estimation is accomplished. After the subcarriers occupied by the distinctively spaced pilot tones and their adjacent subcarriers are nulled for the sake of interference cancellation, fractional CFO estimation is executed according to the uniformly spaced pilot tones. By exploiting a predefined lookup table making the best of the structure of the distinctively spaced pilot tones, computational complexity of the proposed CFO estimator can be decreased considerably. With the aid of the uniformly spaced pilot tones generated from Chu sequence with cyclically orthogonal property, the ability of the proposed estimator to combat multipath effect is enhanced to a great extent. Simulation results illustrate the good performance of the proposed CFO estimator.

Improved Frequency Offset Estimation Based on the DRM System

“…Aiming at the OFDM system of frequency-selective fading channels, Jiang et al proposed a frequency offset estimator based on a frequency-domain training sequence [10]. Chin proposed a time-domain non-data-assisted maximum likelihood (ML) estimation method based on the Doppler frequency for OFDM on doubly selective fading channels [11].…”