Hybrid Analog-Digital Precoding for Interference Exploitation

TL;DR

This paper introduces a hybrid analog-digital precoding scheme for multi-user massive MIMO systems with low-cost 1-bit DACs, exploiting constructive interference to improve downlink transmission efficiency.

Contribution

It proposes a novel hybrid precoding method using SVD-based analog precoding and direct digital signal design exploiting constructive interference, with an efficient linear programming solution.

Findings

Proposed scheme outperforms existing methods in simulations.

Relaxed optimization is efficiently solvable as linear programming.

Numerical results confirm improved system performance.

Abstract

We study the multi-user massive multiple-input-single-output (MISO) and focus on the downlink systems where the base station (BS) employs hybrid analog-digital precoding with low-cost 1-bit digital-to-analog converters (DACs). In this paper, we propose a hybrid downlink transmission scheme where the analog precoder is formed based on the SVD decomposition. In the digital domain, instead of designing a linear transmit precoding matrix, we directly design the transmit signals by exploiting the concept of constructive interference. The optimization problem is then formulated based on the geometry of the modulation constellations and is shown to be non-convex. We relax the above optimization and show that the relaxed optimization can be transformed into a linear programming that can be efficiently solved. Numerical results validate the superiority of the proposed scheme for the hybrid massive MIMO downlink systems.