Blind synchronization for OFDM systems in multipath channels

In this paper we consider the problem of blind feedforward carrier-frequency offset (CFO) and symbol timing estimation for orthogonal frequency-division multiplexing systems in multipath channels. At first, a closed-form blind CFO estimator based on the least-squares (LS) approach is derived under the assumption that the start position of the FFT window is within the lock-in interval. Then, this assumption is removed and, a joint CFO and symbol timing LS estimator is obtained. Specifically, the proposed joint LS estimator does not require the knowledge of the channel impulse response and/or the insertion of virtual subcarriers. Computer simulation results show that the proposed estimators can outperform several blind CFO and symbol timing estimators previously proposed in the literature.