Energy efficiency of mmWave massive MIMO precoding with low-resolution DACs

TL;DR

This paper evaluates the energy efficiency of mmWave massive MIMO precoding with low-resolution DACs, comparing hybrid and digital methods, and explores how phase-shifter topology impacts efficiency and data rates.

Contribution

It introduces a realistic system model for quantized hybrid precoders and compares their energy efficiency to digital precoders under various configurations.

Findings

Partially-connected hybrid precoders are more energy-efficient than digital precoders.

Fully-connected hybrid precoders generally have poor energy efficiency.

Active phase-shifters enable higher data rates, passive phase-shifters improve energy efficiency.

Abstract

With the congestion of the sub-6 GHz spectrum, the interest in massive multiple-input multiple-output (MIMO) systems operating on millimeter wave spectrum grows. In order to reduce the power consumption of such massive MIMO systems, hybrid analog/digital transceivers and application of low-resolution digital-to-analog/analog-to-digital converters have been recently proposed. In this work, we investigate the energy efficiency of quantized hybrid transmitters equipped with a fully/partially-connected phase-shifting network composed of active/passive phase-shifters and compare it to that of quantized digital precoders. We introduce a quantized single-user MIMO system model based on an additive quantization noise approximation considering realistic power consumption and loss models to evaluate the spectral and energy efficiencies of the transmit precoding methods. Simulation results show that partially-connected hybrid precoders can be more energy-efficient compared to digital precoders, while fully-connected hybrid precoders exhibit poor energy efficiency in general. Also, the topology of phase-shifting components offers an energy-spectral efficiency trade-off: active phase-shifters provide higher data rates, while passive phase-shifters maintain better energy efficiency.