Waveforms for the Massive MIMO Downlink: Amplifier Efficiency, Distortion and Performance

TL;DR

This paper compares transmission schemes in massive MIMO, showing that low-PAR precoding with either OFDM or single-carrier transmission offers similar power efficiency benefits, enabling simpler hardware design.

Contribution

It demonstrates that low-PAR precoding achieves comparable power efficiency to conventional methods, simplifying hardware requirements in massive MIMO systems.

Findings

OFDM and single-carrier have similar performance in massive MIMO

Low-PAR precoding reduces amplifier power consumption

Low-PAR signals enable cheaper hardware design

Abstract

In massive MIMO, most precoders result in downlink signals that suffer from high PAR, independently of modulation order and whether single-carrier or OFDM transmission is used. The high PAR lowers the power efficiency of the base station amplifiers. To increase power efficiency, low-PAR precoders have been proposed. In this article, we compare different transmission schemes for massive MIMO in terms of the power consumed by the amplifiers. It is found that (i) OFDM and single-carrier transmission have the same performance over a hardened massive MIMO channel and (ii) when the higher amplifier power efficiency of low-PAR precoding is taken into account, conventional and low-PAR precoders lead to approximately the same power consumption. Since downlink signals with low PAR allow for simpler and cheaper hardware, than signals with high PAR, therefore, the results suggest that low-PAR precoding with either single-carrier or OFDM transmission should be used in a massive MIMO base station.