Breaking Limits of Line-of-Sight MIMO Capacity in 6G Wireless Communications

TL;DR

This paper introduces a novel QF-UCA antenna structure for LOS MIMO in 6G, significantly enhancing capacity by exploiting LOS channel properties with low complexity schemes.

Contribution

It proposes the QF-UCA antenna design and discusses its advantages and challenges for improving LOS MIMO capacity in future wireless systems.

Findings

QF-UCA enhances LOS MIMO capacity

Low complexity demodulation schemes are effective

Potential solutions for transceiver alignment and channel matrix issues

Abstract

Multiple-input-multiple-output (MIMO) has been proved its success for the fourth generation (4G) long term evolution (LTE) and is one of the key technical enablers for evolved mobile broadband (eMBB) in the fifth generation (5G) wireless communications. However, along with the number of antennas eventually increased to be extremely large and one-hop communication distance gradually reduced, how to significantly increase the capacity for line-of-sight (LOS) MIMO becomes more and more urgent. In this article, we introduce the quasi-fractal uniform circular array (QF-UCA) antenna structure based MIMO wireless communications, which can adequately exploit the potential of MIMO in LOS channel and greatly increase the capacity with low complexity demodulation schemes. Specifically, three advantages regarding QF-UCA based LOS MIMO are reviewed. Then, research challenges on transceiver alignment, low-rank channel matrix, extended dimensions of QF-UCA, maximum number of orthogonal streams, and the corresponding potential solutions are discussed. Compared with traditional scattering-depended MIMO communications, the QF-UCA based LOS MIMO wireless communication can achieve high-efficient transmission in LOS channel.