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

This paper proposes a zero-padded conjugate cancellation technique in orthogonal frequency division multiplexing (OFDM) systems by padding zero between two consecutive symbols in order to effectively mitigate intercarrier interference (ICI) caused by a frequency offset in MIMO systems. The channels of the proposed system are not limited to the real-value channels as required in Alamouti-coded MIMO systems combined with ICI cancellation technique. The proposed system offers advantages of a conjugate cancellation scheme and MIMO systems such as backward compatibility with the MIMO-OFDM system, low receiver complexity, and offering a diversity of four. Simulation results show that the proposed scheme achieves a lower bit error rate (BER) compared with the ordinary zero-padded MIMO-OFDM systems in both AWGN (when frequency offset = 1-20%) and Rayleigh fading channels (when frequency offset = 1-10%), and outperforms the repetition-coded conjugate cancellation in SISO-OFDM systems when the frequency offset is not greater than 10% of subcarrier frequency spacing.