Massive MIMO is a Reality - What is Next? Five Promising Research Directions for Antenna Arrays

By Emil Björnson, Luca Sanguinetti, Henk Wymeersch, Jakob Hoydis, T. Marzetta. arXiv.org, 2019

791 citations recorded by the source corpus.

Massive MIMO (multiple-input multiple-output) is no longer a "wild" or "promising" concept for future cellular networks - in 2018 it became a reality. Base stations (BSs) with 64 fully digital transceiver chains were commercially deployed in several countries, the key ingredients of Massive MIMO have made it into the 5G standard, the signal processing methods required to achieve unprecedented spectral efficiency have been developed, and the limitation due to pilot contamination has been resolved. Even the development of fully digital Massive MIMO arrays for mmWave frequencies - once viewed prohibitively complicated and costly - is well underway. In a few years, Massive MIMO with fully digital transceivers will be a mainstream feature at both sub-6 GHz and mmWave frequencies. In this paper, we explain how the first chapter of the Massive MIMO research saga has come to an end, while the story has just begun. The coming wide-scale deployment of BSs with massive antenna arrays opens the door to a brand new world where spatial processing capabilities are omnipresent. In addition to mobile broadband services, the antennas can be used for other communication applications, such as low-power machine-type or ultra-reliable communications, as well as non-communication applications such as radar, sensing and positioning. We outline five new Massive MIMO related research directions: Extremely large aperture arrays, Holographic Massive MIMO, Six-dimensional positioning, Large-scale MIMO radar, and Intelligent Massive MIMO.

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/8eabd71300b0c4357586259070dc326ee866c7d4

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Citations in the corpus

Reconfigurable Intelligent Surfaces: A signal processing perspective with wireless applications (2021, neutral): “The RIS technology appears under different names, such as software-controlled metasurfaces [6], intelligent reflecting surfaces [18], and a few others [2].”
A Tutorial on Environment-Aware Communications via Channel Knowledge Map for 6G (2023, methodology): “For example, by further dramatically increasing the array size beyond massive MIMO, extremely large-scale MIMO (XL-MIMO) [17]–[21] or extremely largescale aperture array (ELAA) [15] is expected to achieve super spatial resolution, beamforming gain, and ultra-high”
Dynamic Metasurface Antennas for 6G Extreme Massive MIMO Communications (2020, background): “The ability to stack a large number of elements in a limited surface area allows metasurfaces to achieve highly directed signalling enabling holographic beamforming [2].”
6G and Beyond: The Future of Wireless Communications Systems (2020, background): “the originally densely-packed antenna array set with a few hundred elements at the BS is distributed in a fairly large area in the form of smaller sets with fewer than 10 antenna elements, while still serving a similar number of users in the same area [156].”
Renew (2022, background): “Therefore, one of the big questions in C-RAN standardization groups, such as O-RAN [17], is whether the current processors can handle the large computational cost associated with mMIMO, especially as the number of base station antennas is predicted to reach hundreds of antennas, if not more, in the ”
Twelve Scientific Challenges for 6G: Rethinking the Foundations of Communications Theory (2022, background): “In [19], the effect of the laws of electromagnetism on the MIMO channel capacity was investigated.”
Toward Massive MIMO 2.0: Understanding Spatial Correlation, Interference Suppression, and Pilot Contamination (2019, background): “Different embodiments of this concept has recently appeared under the names large intelligent surfaces [55], extremely large aperture arrays [56], and holographic Massive MIMO [57].”
Holographic MIMO Communications: Theoretical Foundations, Enabling Technologies, and Future Directions (2022, background): “In [34], the authors outlined several new research directions beyond mMIMO, in which HMIMOS”
Prospective Multiple Antenna Technologies for Beyond 5G (2019, background): “5) Identifying a “Killer Application”: There is a series of survey papers that speculate on how an IRS can be used in future networks [14], [15], [166], [167], but there is a need to demonstrate a “killer application” or a metric for which IRS-aided transmission makes a paradigm shift in…”
Reconfigurable Intelligent Surfaces for Wireless Communications: Principles, Challenges, and Opportunities (2020, result): “Accurate modeling of the path loss through the RIS is critical in assessing the performance of RIS-assisted communication links, especially as compared to other techniques [20].”
A Tutorial on Near-Field XL-MIMO Communications Toward 6G (2023, neutral): “For instance, in outdoor environments, XL-MIMO mounted on the facades of buildings is capable of sensing the surrounding environment, e.g., pedes-trians, vehicles and buildings, or tracking the position and velocity of objects, and thus a higher level of autonomous driving is expected.”
A Survey of Rate-Optimal Power Domain NOMA With Enabling Technologies of Future Wireless Networks (2019, methodology): “However, in mMIMO systems, supervised learning algorithms have been studied for channel feedback and estimation, MIMO detection, and other related problems [105], [322].”
Communicating With Extremely Large-Scale Array/Surface: Unified Modeling and Performance Analysis (2021, neutral): “…technologies have attracted fast-growing interest recently, such as extremely large-scale multiple-input multiple-output (XL-MIMO) communication [6], [7], Terahertz communication [8], [9], intelligent reﬂecting surface (IRS) or reconﬁgurable intelligent surface (RIS)-assisted communications…”
The Road Towards 6G: A Comprehensive Survey (2021, background): “To pave the way towards the realization of massive MIMO in beyond 5G and 6G mobile networks, the authors in [122] and [123] have outlined a number of research challenges including the (i) deployment of extremely large aperture arrays; (ii) limitation in channel prediction; (iii) implementation of…”