Low RF-Complexity Technologies to Enable Millimeter-Wave MIMO with Large Antenna Array for 5G Wireless Communications

TL;DR

This paper reviews low RF-complexity technologies for millimeter-wave MIMO systems with large antenna arrays, focusing on phased array and lens array hybrid precoding to reduce hardware costs and power consumption.

Contribution

It provides a comprehensive review and comparison of two promising low RF-complexity technologies, phased array based and lens array based hybrid precoding, for mmWave MIMO systems.

Findings

Phased array based hybrid precoding offers flexible beamforming.

Lens array based hybrid precoding reduces hardware complexity.

Performance comparison provides insights for practical deployment.

Abstract

Millimeter-wave (mmWave) MIMO with large antenna array has attracted considerable interests from academic and industry communities, as it can provide larger bandwidth and higher spectrum efficiency. However, with hundreds of antennas, the number of radio frequency (RF) chains required by mmWave MIMO is also huge, leading to unaffordable hardware cost and power consumption in practice. In this paper, we investigate low RF-complexity technologies to solve this bottleneck. We first review the evolution of low RF-complexity technologies from microwave frequencies to mmWave frequencies. Then, we discuss two promising low RF-complexity technologies for mmWave MIMO systems in detail, i.e., phased array based hybrid precoding (PAHP) and lens array based hybrid precoding (LAHP), including their principles, advantages, challenges, and recent results. We compare the performance of these two technologies to draw some insights about how they can be deployed in practice. Finally, we conclude this paper and point out some future research directions in this area.