Fast coarse frequency offset estimation for OFDM systems by using differentially modulated subcarriers

In this paper, we propose a fast coarse estimation method of carrier frequency offset for orthogonal frequency division multiplexing (OFDM) systems using a burst mode transmission. In the proposed method, we use two OFDM symbols for a training sequence, where the subcarriers of each training symbol are differentially modulated in phase. By exploiting the phase difference between two adjacent subcarriers of the received signal, which is proportional to the frequency offset, we estimate the even integer part of relative frequency offset (RFO). The proposed scheme has much lower computational load compared to the conventional cross-correlation-based methods. Simulation results show that the failure rate of the proposed coarse estimator is sufficiently low and the total estimator combined with a fine estimator reveals similar estimation performance to the case of conventional cross-correlation-based method at practical range of signal-to-noise ratio (SNR).