Blind maximum likelihood CFO estimation for OFDM systems via polynomial rooting

The blind carrier frequency offset estimation problem has been well studied by exploiting the virtual carriers existing in practical orthogonal frequency division multiplexing transmissions. A highly efficient approach by rooting a polynomial has been proposed in the literature. However, this rooting method is suboptimal when noise is present. In this letter, we propose an improved polynomial rooting method that is shown to be the maximum likelihood estimator for both the noisy and the noise-free case.