Joint MMSE precoder and equalizer for massive MIMO using 1-bit quantization

We present a novel linear minimum-mean-squared-error (MMSE) joint precoding and equalization technique for a downlink (DL) massive multiple-input-multiple-output (MIMO) scenario. To lower the power consumption, the computational and the design complexity, 1-bit digital to analog converters (DACs) and analog to digital converters (ADCs) are used at the transmitter and at the receiver antennas. These economical and computational gains come at the cost of a performance loss which can be recovered by the large number of antennas deployed at the base station and by implementing appropriate precoders and equalizers which can mitigate the coarse quantization effects. The proposed technique implements a two-stage digital and an analog precoder with a digital equalizer, both of which take into account the effects of the 1-bit quantizers. The simulation results indicate the superiority of the novel joint precoder and equalizer design to the previously proposed linear precoders and equalizers not only in terms of the uncoded bit error rate (BER) performance but also in terms of the robustness to errors in the estimation of channel state information at the transmitter (CSIT).