Massive MIMO Downlink 1-Bit Precoding for Frequency Selective Channels

Quantized massive multiple-input-multiple-output (MIMO) systems are gaining more interest due to their power efficiency. We present a new precoding technique in a quantized downlink multi-user (MU) multiple-input-single-output (MISO) system with frequency selective channels. This work is restricted to 1-bit quantization at the transmitter and receiving PSK modulation schemes. The transmit signal vector is optimized for every desired received vector taking into account the 1-bit quantization. The optimization is based on maximizing the safety margin to the decision thresholds of the PSK modulation. This optimization is applied for the following three cases: symbol wise processing as well as block-wise processing without and with cyclic prefix. Simulation results show a significant gain in terms of the uncoded bit-error-ratio (BER) compared to existing linear precoding techniques.