Residual Carrier Frequency Offset Estimation and Correction in OFDM MIMO Systems

This paper addresses the problem of estimating and correcting the residual carrier frequency offset in a multi-input-multi- output (MIMO) system employing orthogonal frequency division multiplexing (OFDM). The presented technique is based on the maximum likelihood criterion and exploits the pilot carriers of the OFDM modulation by assuming that no inter-carrier interference is present. Some implementation aspects of the estimator are also discussed, presenting two alternatives: the grid search and the truncated discrete Fourier transform (DFT) approaches. The evaluation of the estimator is performed by deriving and comparing the corresponding Cramer-Rao bound with the mean square error. Additional simulations are provided in terms of symbol error rate for the case of applying orthogonal space-time block coding to the data carriers.