An Efficient Blind CFO Estimation Technique for MIMO-OFDM Systems Using Space-time Diversity

In this paper, a blind carrier frequency offset (CFO) estimation algorithm for multi-input multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems employing constant modulus signaling has been proposed. The CFO incorporated frequency domain received signal has been utilized for the purpose of CFO estimation in block fading channel. Thereafter, frequency domain sum and difference signals have been formulated using the received signal and the expression for corresponding signal powers have been derived. Here, a cost function has been deduced which minimizes the signal power difference between all the subcarriers in two neighbouring space-time-coded blocks. The complexity of proposed estimation algorithm has significantly been reduced by using the sinusoidal nature of the cost function. The proposed method is verffied for $2\times2$ MIMO using Alamouti codes. Simulation results have been presented to demonstrate the proposed CFO estimation algorithm. The proposed method exhibits improved performance when compared with the existing techniques over Rayleigh frequency-selective fading channels.