Multiple-antenna systems is a key technique to serve multiple users in future wireless systems. For low energy consumption and hardware complexity we first consider transmit symbols with constant magnitude and then 1-bit digital-to-analog converters. We propose precoding designs which maximize the minimum distance to the decision threshold at the receiver. The precoding design with 1-bit DAC corresponds to a discrete optimization problem, which we solve exactly with a branch-and-bound strategy. We alternatively present an approximation based on relaxation. Our results show that the proposed branch-and-bound approach has polynomial complexity. The proposed methods outperform existing precoding methods with 1-bit DAC in terms of uncoded bit error rate and sum-rate. The performance loss in comparison to infinite DAC resolution is small.
@article{arxiv.1705.00122,
title = {Branch-and-Bound Precoding for Multiuser MIMO Systems with 1-Bit Quantization},
author = {Lukas T. N. Landau and Rodrigo C. de Lamare},
journal= {arXiv preprint arXiv:1705.00122},
year = {2018}
}