Reconfigurable Intelligent Surfaces: Three Myths and Two Critical Questions

By Emil Björnson, Özgecan Özdogan, Erik G. Larsson. IEEE Communications Magazine, 2020

344 citations recorded by the source corpus.

The search for physical layer technologies that can play a key role in beyond 5G systems has started. One option is reconfigurable intelligent surfaces (RISs), which can collect wireless signals from a transmitter and passively beamform them toward the receiver. The technology has exciting prospects and is quickly gaining traction in the communication community, but in the current hype we have witnessed how several myths and overstatements are spreading in the literature. In this article, we take a neutral look at the RIS technology. We first review the fundamentals and then explain specific features that can be easily misinterpreted. In particular, we debunk three myths: 1) current network technology can only control the transmitter and receiver, not the environment in between; 2) a better asymptotic array gain is achieved than with conventional beamforming; 3) the path loss is the same as with anomalous mirrors. To inspire further research, we conclude by identifying two critical questions that must be answered for RIS to become a successful technology: 1) What is a convincing use case for RIS?; 2) How can we estimate channels and control an RIS in real time?

Subfields: Aerospace Engineering, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/890c82d9ab8bd8b46955ed3659b3419bc4422afc

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Citations in the corpus

Power Scaling Laws and Near-Field Behaviors of Massive MIMO and Intelligent Reflecting Surfaces (2020, methodology): “While the first generation of mMIMO technology is commercially available, the IRS technology is in its infancy which makes it impossible to quantify its cost and energy consumption [23].”
Reconfigurable Intelligent Surfaces: A signal processing perspective with wireless applications (2021, positive): “More importantly, the near field enables the RIS to focus signals not only in a particular direction but at a certain point in that direction, thereby making a flat RIS better than a flat mirror [5].”
Intelligent Reflecting Surface-Aided Wireless Communications: A Tutorial (2020, neutral): “[10], [21]–[23], [35]–[42], which are sum-”
RIS-Aided Wireless Communications: Prototyping, Adaptive Beamforming, and Indoor/Outdoor Field Trials (2021, methodology): “MN iterations required for estimating unstructured channels [8].”