Zero-padded symmetric conjugate technique for intercarrier interference cancellation in MIMO-OFDM systems

This paper proposes a zero-padded symmetric conjugate self-cancellation technique in orthogonal frequency division multiplexing (OFDM) systems by padding zero in between two consecutive symbols for mitigating intercarrier interference (ICI) caused by a frequency offset in MIMO systems. The proposed system is not limited to the real-value channels as required in applying ICI cancellation technique in Alamouti-coded MIMO systems. The proposed system offers advantages of a symmetric conjugate cancellation scheme and MIMO systems such as efficiently mitigating ICI and enhancement of a diversity gain. The property of symmetric conjugate cancellation is investigated, a technique for ICI cancelling and diversity combining is proposed. Simulation results show that the proposed scheme achieves a lower bit error rate (BER) compared to the ordinary zero-padded MIMO-OFDM systems in AWGN channel. In Rayleigh fading channels, when frequency offset is 1-10%, the proposed system performance, i.e. BER, is significantly improved over the zero-padded conjugate cancellation in MIMO-OFDM systems when the frequency offset is not greater than 10% of subcarrier frequency spacing.