Single-Carrier Modulation versus OFDM for Millimeter-Wave Wireless MIMO

TL;DR

This study compares single-carrier and OFDM modulation schemes for millimeter-wave MIMO systems in 5G, highlighting that single-carrier with time-domain equalization offers superior spectral and energy efficiency under certain conditions.

Contribution

It provides a comprehensive analysis of single-carrier versus OFDM modulation in mmWave MIMO, considering practical factors like non-linearities and hybrid beamforming, which was not extensively studied before.

Findings

Single-carrier with time-domain equalization outperforms OFDM in spectral efficiency.

Performance degrades significantly beyond 90-100 meters link length.

Non-linearities of power amplifiers impact system performance notably.

Abstract

This paper presents results on the achievable spectral efficiency and on the energy efficiency for a wireless multiple-input-multiple-output (MIMO) link operating at millimeter wave frequencies (mmWave) in a typical 5G scenario. Two different single-carrier modem schemes are considered, i.e., a traditional modulation scheme with linear equalization at the receiver, and a single-carrier modulation with cyclic prefix, frequency-domain equalization and FFT-based processing at the receiver; these two schemes are compared with a conventional MIMO-OFDM transceiver structure. Our analysis jointly takes into account the peculiar characteristics of MIMO channels at mmWave frequencies, the use of hybrid (analog-digital) pre-coding and post-coding beamformers, the finite cardinality of the modulation structure, and the non-linear behavior of the transmitter power amplifiers. Our results show that the best performance is achieved by single-carrier modulation with time-domain equalization, which exhibits the smallest loss due to the non-linear distortion, and whose performance can be further improved by using advanced equalization schemes. Results also confirm that performance gets severely degraded when the link length exceeds 90-100 meters and the transmit power falls below 0 dBW.