An efficient blind estimator of carrier frequency offset for MIMO-OFDM systems

In this paper, we propose a new efficient blind carrier frequency offset (CFO) estimator for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems. A cost function is carefully designed which can be exactly expressed as a superposition of very few harmonically related cosine waves even with the effect of noise. By using this property, the minimization of the designed cost function can be solved in a quite computationally efficient manner without any exhausted grid searching procedure. We provide numerical results to corroborate the proposed studies. It is seen that the proposed estimator can achieve comparable estimation performance with existing competitors with substantially reduced computational burden.

I. Introduction

The technique of multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) has been drawing substantial research interests. MIMO can exploit spatial domain resources and provide high capacity, while OFDM is immune to frequency-selective fading. However, these advantages depend heavily on the precise estimation and compensation of the carrier frequency offset (CFO) between the transceivers. During the past few years, intensive studies have been carried out on the CFO estimation for OFDM systems. In this paper, we mainly focus on the blind estimation that has attracted a large amount of attentions due to its improved spectral efficiency. Different kinds of blind estimators have been proposed, which can be based on the kurtosis-type criterion [1], diagonality criterion [2], null subcarriers [3], [4], [5], oversampling [7], [8] or constant modulus constellations [6].