MIMO-OFDM Precoder for Minimizing BER Upper Bound of MLD under Imperfect CSI

This paper proposes a minimum BER (MBER) based precoder that is robust to imperfect channel state information (CSI) for MIMO-OFDM mobile communications. The proposed MBER precoding aims to minimize BER of the maximum likelihood detection (MLD), on the condition that the transmitter can obtain only imperfect CSI owing to channel estimation and quantization errors of the feedback CSI. The proposed scheme controls its precoding parameters under a transmit power constraint by minimizing an upper bound of BER which is derived from the pairwise error probability and then averaged with respect to the CSI error. Computer simulations demonstrate that the proposed precoding method outperforms a conventional nonrobust MBER precoder and a conventional robust power allocation MBER precoder.