ML estimation of carrier frequency offset for multicarrier signals in Rayleigh fading channels

In this paper, we present a new maximum likelihood estimator (MLE) of carrier frequency offset for multicarrier signals in a frequency-selective Rayleigh fading channel. The proposed MLE is able to achieve wider estimation range of frequency offset with higher accuracy than previous blind approaches by exploiting the intrinsic structure of multicarrier signals. Simulations show that the estimation accuracy is close to the Cramér-Rao bound. In order to reduce the complexity of the proposed MLE, a suboptimum technique is presented that enables simple implementation. The bit error rate performance of the suboptimum technique with two or three symbols averaged is close to the theoretical bound. An important feature of both the MLE and the suboptimum method is the capability to correct the frequency offset in a feedforward approach that makes it possible to perform fast acquisition and tracking of the frequency offset.