Cell-Free Massive MIMO: A New Next-Generation Paradigm

By Jiayi Zhang, Shuaifei Chen, Yan Lin, Jiakang Zheng, Bo Ai, Lajos Hanzo. IEEE Access, 2019

455 citations recorded by the source corpus.

Cell-free (CF) massive multiple-input-multiple-output (MIMO) systems have a large number of individually controllable antennas distributed over a wide area for simultaneously serving a small number of user equipments (UEs). This solution has been considered as a promising next-generation technology due to its ability to offer a similar quality of service to all UEs despite its low-complexity signal processing. In this paper, we provide a comprehensive survey of CF massive MIMO systems. To be more specific, the benefit of the so-called channel hardening and the favorable propagation conditions are exploited. Furthermore, we quantify the advantages of CF massive MIMO systems in terms of their energy- and cost-efficiency. Additionally, the signal processing techniques invoked for reducing the fronthaul burden for joint channel estimation and for transmit precoding are analyzed. Finally, the open research challenges in both its deployment and network management are highlighted.

Subfields: Aerospace Engineering, Computer Networks and Communications, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/8e0c7bf51e58f3262feae2bd32722a328a560a70

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Citations in the corpus

Prospective Multiple Antenna Technologies for Beyond 5G (2019, background): “Early experiments with cell-free networks are described in [33], but it is ﬁrst in recent years that the concept has gained signiﬁcant traction from academia [34], [35], where the name cell-free massive MIMO has been coined [36]–[38].”
Massive Access for 5G and Beyond (2020, methodology): “In practice, the APs equipped with independent RF chains are connected to the CPU by high-capacity optical fibers.”
Intelligent Reflecting Surface Aided MIMO Broadcasting for Simultaneous Wireless Information and Power Transfer (2019, background): “In contrast to conventional physical layer techniques that are designed for accommodating the hostile time-varying wireless channels [5], [6], IRSs constitute a new paradigm capable of ‘reprogramming’ the wireless propagation environment into a more favorable transmission medium.”
Foundations of User-Centric Cell-Free Massive MIMO (2020, background): “A cell-free network is an attempt to move beyond those limits [49], [83], [126], [208], [210].”
A Survey of Rate-Optimal Power Domain NOMA With Enabling Technologies of Future Wireless Networks (2019, background): “One such low-cost solution that is an extension of the current mMIMO, is the concept of cell-free mMIMO (CF-mMIMO) [100].”
5G Key Technologies for Smart Railways (2020, background): “One of the promising solutions to tackle these key challenges is to utilize a distributed massive MIMO architecture called cell-free massive MIMO [127].”
A Comprehensive Survey on Millimeter Wave Communications for Fifth-Generation Wireless Networks: Feasibility and Challenges (2020, background): “…networks are suboptimal as higher spectral efﬁciency (bit/s/Hz/UE) can be realized by employing multiple access points per signal co-processing [312], [313], [316]. correlation [316], and therefore, proper user grouping and user scheduling algorithms are required to reduce UEs’ spatial correlation.”