Multi-user Downlink Beamforming using Uplink Downlink Duality with 1-bit Converters

The increased power consumption of high-resolution data converters at higher carrier frequencies and larger band-widths is becoming a bottleneck for communication systems. In this paper, we consider a fully digital base station equipped with 1-bit analog-to-digital (in uplink) and digital-to-analog (in downlink) converters on each radio frequency chain. The base station communicates with multiple single antenna users with individual SINR constraints. We present a linear solution to the multi-user downlink beamforming problem based on the uplink down-link duality principle. The proposed solution takes into account the hardware constraints and jointly optimizes the downlink beamformers and the power allocated to each user. Detailed simulations carried out using 3GPP channel models generated from Quadriga show that our proposed solution outperforms state of the art solutions in terms of the ergodic sum and minimum capacity especially when the number of users is large.