Linear Precoder Design in Massive MIMO under Realistic Power Amplifier Consumption Constraint

TL;DR

This paper investigates energy-efficient precoder designs for massive MIMO systems considering realistic power amplifier consumption, proposing new precoders that optimize for amplifier power rather than transmit power.

Contribution

It introduces power consumption-based precoders that account for amplifier non-linearities, fundamentally changing antenna activation strategies for energy efficiency.

Findings

Fewer antennas should be active to minimize amplifier power consumption.

Traditional precoders activate all antennas to minimize transmit power.

New precoders significantly reduce power amplifier energy use.

Abstract

The energy consumption of wireless networks is a growing concern. In massive MIMO systems, which are being increasingly deployed as part of the 5G roll-out, the power amplifiers in the base stations have a large impact in terms of power demands. Most of the current massive MIMO precoders are designed to minimize the transmit power. However, the efficiency of the power amplifiers depend on their operating regime with respect to their saturation regime, and the consumed power proves to be non-linearly related to the transmit power. Power consumption-based equivalents of maximum ratio transmission, zero-forcing, and regularized zero-forcing precoders are therefore proposed. We show how the structure of the solutions radically changes. While all antennas should be active in order to minimize the transmit power, we find on the contrary that a smaller number of antennas should be activated if the objective is the power consumed by the power amplifiers.