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Reconfigurable Intelligent Surfaces for Programmable Wireless Environments

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21 personnes membres du GdR ISIS, et 58 personnes non membres du GdR, sont inscrits à cette réunion.
Capacité de la salle : 80 personnes.

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Link: https://cnrs.zoom.us/j/95160168815

Password: GQW5mP

Future wireless networks will be as pervasive as the air we breathe, not only connecting us but embracing us through a web of systems that support personal and societal well-being. That is, the ubiquity, speed and low latency of such networks will allow currently disparate devices and services to become a distributed intelligent communications, sensing, and computing platform.

Small cells, massive multiple-input-multiple-output (MIMO), millimeter-wave communications are three fundamental technologies that will spearhead the emergence of 5G wireless networks? Their advantages are undeniable. The question is, however, whether these technologies will be sufficient to meet the requirements of future wireless networks that integrate communications, sensing, and computing in a single platform. Wireless networks, in addition, are rapidly evolving towards a software-defined design paradigm, where every part of the network can be configured and controlled via software. In this optimization process, however, the wireless environment itself - the medium or channel - is generally assumed uncontrollable and often an impediment to be reckoned with. For example, signal attenuation limits the network connectivity, multi-path propagation results in fading phenomena, reflections and refractions from objects are a source of uncontrollable interference.

Recently, a new concept called Reconfigurable Intelligent Surfaces (RISs) has emerged wherein every environmental object is coated with man-made intelligent surfaces of configurable electromagnetic materials. These materials contain integrated electronic circuits and software that enable the control of the wireless medium. RISs constitute a new wireless communication research frontier with the goal of realizing metamaterial-coated smart and reconfigurable radio propagation environments through passive and tunable signal transformations. Featured by orders of magnitude lower hardware and energy cost than traditional active antenna-arrays and yet superior performance, RISs are the new driving technology for future wireless networks, especially for enabling them to migrate to higher frequency bands. RISs have the inherent potential of transforming the current wireless network with active nodes solely into a new hybrid network comprising active and passive components co-working in an intelligent way, so as to achieve a sustainable capacity growth with a low and affordable cost and power consumption. Therefore, RISs have the potential to change how wireless networks are currently designed, usher in that hoped-for wireless future, and are regarded as an enabling technology for realizing the emerging concept of metamaterial-assisted smart (programmable) radio environments (SREs). RIS-assisted SREs are a multidisciplinary research endeavor but are not well-understood.

With the above vision, this proposed GdR-ISIS research day is aimed at gathering the latest and most promising research advances on the modeling, analysis, design, and implementation of RIS-empowered wireless networks, and at envisioning new research directions in this emerging field of research.

Programme

Detailed Program (25 May 2021, 14:00-17:30)

*14:00-14:15: Welcome and introduction*

Marco Di Renzo, CNRS & Paris-Saclay University

Merouane Debbah, Huawei France

*14:15-15:00: Invited presentation*

Geoffroy Lerosay (Greenerwave, Paris)

Wavefront shaping in the microwave domain using tunable metasurfaces: From physics to RIS enhanced wireless communications

*15:00-15:45: Contributed presentations*

Matthieu Davy (University of Rennes, France)

Coherent control of waves in chaotic cavities with reconfigurable metasurfaces

Sotiris Droulias (University of Piraeus, Greece)

Reconfigurable intelligent surfaces as a radiating aperture

Philipp del Hougne (University of Rennes, France)

RIS-Based Radio Localization in Rich Scattering Environments: Harnessing Multi-Path with ANN Decoders

*15:45-15:55: Coffee/tea break*

*15:55-16:40: Invited presentation*

Dinh-Thuy Phan-Huy (Orange Labs, Paris)

Electro-Magnetic Field Exposure Aware Radio Design Thanks to Backscattering and Reconfigurable Intelligent Surfaces

*16:40-17:25: Contributed presentations*

Gabriele Gradoni (University of Nottingham, UK)

Engineering Reflective Intelligent Surfaces via Quantum Annealing

Vincenzo Sciancalepore (NEC Laboratories Europe, Germany)

Reconfigurable Intelligent Surfaces Enabling Beamforming for IoT Massive Access

Alessio Zappone (University of Cassino, Italy)

Optimization of Reconfigurable Intelligent Surfaces with Electromagnetic Field Exposure Constraints

*17:25-17:30: Conclusion and farewell*

Marco Di Renzo, CNRS & Paris-Saclay University

Merouane Debbah, Huawei France

Résumés des contributions

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Geoffroy Lerosay (Greenerwave, Paris)

Title: Wavefront shaping in the microwave domain using tunable metasurfaces: From physics to RIS enhanced wireless communications

Abstract: In this talk I will show how, starting from the field of waves in complex media in acoustics and RF, we learned how to control the propagation of light through very scattering media using smart reconfigurable reflectors, namely spatial light modulators. I will explain how this has led us, 8 years ago, to propose to use tunable metasurfaces as smart reflectors to enhance wireless communications. I will show the first results obtained and published in 2014, that proved how a small tunable metasurface placed in an office room can multiply by 10 the energy transmitted between 2 antennas. I will propose a basic application to wireless communications in the context of WIFI, obtained by the company years ago, thus showing the first use of a RIS in a communication system. Then, I will underline what we believe is important to have in mind in terms of wave control versus RIS complexity, notably when it comes to practical applications. I will show a few examples of RIS developed at Greenerwave, from 1GHz to 77GHz, and briefly describe their applications. To finish I will show first examples of RIS aided wireless communications realized in the mmWave range, demonstrating non line of sight mmWave data transmission using low complexity and low consumption tunable metasurfaces. Finally, I will say a few words about my vision of RIS in the future, for both low and high frequencies.

Biography: Geoffroy Lerosey is the co-founder and the inventor of the concepts behind Greenerwave with Mathias Fink. He is on leave from academia to fully support the company?s development and bring his scientific expertise. Geoffroy earned an engineering degree from ESPCI Paris, a Master?s degree in electronics from Universite Pierre et Marie Curie and a PhD in Physics from Université Paris Diderot. He joined University of California at Berkeley for Postdoctoral researches working mainly on metamaterials and plasmonics. Coming back to France, Geoffroy was appointed by French main academic research organization CNRS in 2008 and started a group at Institut Langevin (CNRS & ESPCI Paris). Geoffroy?s researches are in metamaterials and metasurfaces, time reversal and signal processing, subwavelength imaging and focusing techniques, wavefront shaping in optics and RF, photonic and phononic crystals, reverberating and locally resonant media, and span all domains of wave physics from acoustics to optics. Geoffroy has been invited more than 80 times at international conferences, and has given invited seminars in many universities worldwide. He supervised 8 PhD students, 6 postdocs and 20 Master students. His research led 100 scientific articles, 15 patents and 2 startups.

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Matthieu Davy (University of Rennes, France)

Title: Coherent control of waves in chaotic cavities with reconfigurable metasurfaces

Abstract: Wavefront shaping has emerged as powerful tool to control the propagation of diverse wave phenomena in disordered matter for applications including imaging, communication, energy transfer, micromanipulation, and scattering anomalies. By carefully shaping the phase and amplitude profile of a coherent wavefront impinging on a static complex medium, complex scattering effects can to some extent be counteracted (and even harnessed) since they are deterministic. At the same time, various wave-control efforts based on tuning the scattering properties of a complex medium using intelligent surfaces have been proposed. In this talk, I will show that the two approaches can be efficiently combined to unlock new opportunities in wave physics. Firstly, I will demonstrate that we can achieve ?on-demand" coherent perfect absorption (CPA) at an arbitrary frequency by tweaking the scattering properties of a chaotic cavity with programmable metasurfaces. In addition to perfect absorption, the wavefront corresponding to this scattering anomaly provides optimal sensitivity to minute perturbations of the system as a consequence of the divergence of the time-delay. Secondly, I will show that the vexing problem of coherently controlling multiple input channels in wavefront shaping techniques can be overcome by programming the boundary conditions so that the optimal incident wavefront is arbitrarily chosen. Coherent wave control with arbitrary wavefronts will be demonstrated with applications to CPA as well as non-invasive optimal focusing. Our focusing approach leverages the impedance modulation of a port to extract the optimal wavefront from the optimal eigenvector of the generalized Wigner-Smith operator. Our proof-of-principle microwave experiments have immediate technological relevance in secure wireless communication, electronic warfare, precision sensing and wave filtering.

Biography: Matthieu Davy is an assistant professor at the University of Rennes 1. He is conducting his research at IETR, Rennes, France. He is a junior member of 'Institut Universitaire de France' since 2019. His research activities are mainly devoted to the control of wave propagation in disordered media and the enhancement of wave-matter interactions. He investigates both theoretically and experimentally wavefront shaping techniques based on measurements of the scattering matrix. He also leverages tunable metasurfaces to reconfigure and optimize the boundary conditions of an enclosure. He is finally interested in imaging techniques related to the cross-correlation of diffuse electromagnetic fields or taking advantage of compressive devices such as leaky chaotic cavities. His experimental studies are conducted in the microwave range.

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Sotiris Droulias (University of Piraeus, Greece)

Title: Reconfigurable intelligent surfaces as a radiating aperture

Abstract: The primary goal of a Reconfigurable Intelligent Surface (RIS) is to redirect an incident wave to any desired angle. To achieve this, the RIS is made of periodically repeated subwavelength scatterers (unit cells) with tunable properties. Each unit cell imposes locally a certain phase change on the incident wave and the total redirected wave is then synthesized as a linear superposition of the individual contributions from all unit cells. Here, instead of treating the RIS locally, i.e. in terms of the individual scatterers, we treat the RIS globally, i.e. as a continuous radiating source of finite extent that is being driven by the incident wave; the role of the RIS is to impose the necessary phase gradient on the incident wave, and the unit cells essentially discretize, i.e. spatially sample, the interaction. Under this approach we provide insight to the effect of the finite RIS size and we derive concise expressions, which are crucial for the optimization of the RIS-assisted link.

Biography: Sotiris Droulias is currently a research associate at the department of Digital Systems, ICT School, University of Piraeus (UPRC). He has a Diploma in Electrical and Computer Engineering and a PhD in Nonlinear Photonics, both received from the National Technical University of Athens, Greece. Before joining the UPRC group in January 2021 he was a member of the Photonic- Phononic- and Meta- materials group at FORTH, Greece. His research interests include metamaterials, photonic crystals, metasurfaces, nanolasers, plasmonics.

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Philipp del Hougne (University of Rennes, France)

Title: RIS-Based Radio Localization in Rich Scattering Environments: Harnessing Multi-Path with ANN Decoders

Abstract: Rich scattering scenarios (e.g., indoor environments in buildings, vessels, metro stations, airplanes) challenge conventional ray-tracing-based radio localization techniques such as those using a wave?s time or angle of arrival. Instead of fighting the multi-path-induced complexity, here we show that it can be leveraged as a virtue. Based on recent physics-driven experimental investigations in chaotic microwave cavities, we explore how complex wave propagation encodes localization information in multiplexed measurements and what signal processing tools are capable of decoding it. We focus in particular on multiplexing with configurational degrees of freedom offered by a series of random RIS configurations; these schemes operate with single-port single-frequency (and possibly intensity-only) measurements. Via a comparison of various digital decoding techniques (virtual time reversal, matrix inversion, neural network, ...) we identify deep learning as noise-robust reliable decoder, arguing that simple fully-connected layers are better suited than convolutional architectures. Moreover, we demonstrate experimentally that the achievable localization resolution can be orders of magnitude below the wavelength. Finally, we discuss opportunities for optimizing the RIS configurations through a "learned sensing? paradigm such that the physical multiplexing process during wave propagation pre-selects information relevant to the localization task.

Biography: Philipp del Hougne is a tenured CNRS researcher affiliated with IETR (Univ Rennes), France. He graduated in physics from Imperial College London, UK, and was awarded a doctorate in physics by Université Sorbonne Paris Cité, France. During his Ph.D. studies, he was with the Institut Langevin in Paris, and also a visiting scholar with the Center for Metamaterials and Integrated Plasmonics, Duke University. He subsequently held postdoctoral positions in Nice, France, Rennes, France, and Lausanne, Switzerland. His research interests lie in molding the flow of information through tailored wave-matter interactions, in particular metamaterial-programmable complex media, for applications in wireless communication, intelligent imaging and sensing, and analog computing.

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Dinh-Thuy Phan-Huy (Orange Labs, Paris)

Title: Electro-Magnetic Field Exposure Aware Radio Design Thanks to Backscattering and Reconfigurable Intelligent Surfaces

Abstract: Each new generation of mobile network (3G, 4G, 5G) has been improved with respect to the previous generation, in terms of spectral efficiency, capacity and energy efficiency, to support the continuous growth of the Internet traffic. However, each generation adds up its own cost in terms of spectrum and energy consumption to the costs of all previously deployed ones. In particular, it adds up its own contribution to the overall Electro-Magnetic Field (EMF) exposure. Even though each new deployed generation meets the EMF thresholds fixed by countries regulations, obtaining the acceptance of the general public still can be a challenge. 6G, currently still at Research stage, has the opportunity to be the first generation to take into account EMF exposure in its design, from the start. We believe it is now the time to start exploring disruptive approaches for transmitting more with zero added EMF exposure. In this talk, we explore two promising new types of devices that do not generate any additional wave: Ambient Backscatters and Reconfigurable Intelligent Surfaces. Whereas ambient backscatters send messages by backscattering ambient waves from on-going communications, Reconfigurable Intelligent Surfaces improve the link budget of on-going communications by performing reflected beamforming. We will provide first insights on use cases, performance evaluation studies and experiments.

Biography: Dinh-Thuy Phan Huy received the degree in engineering from Supelec, in 2001, and the Ph.D. degree in electronics and telecommunications from the National Institute of Applied Sciences of Rennes, France, in 2015. In 2001, she joined France Telecom R&D (now Orange Labs Networks), Châtillon, France. She led the national French collaborative research projects TRIMARAN (2011-2014) and SpatialModulation (2016-2019). She participated to the following 5G PPP projects: METIS, Fantastic 5G, mmMAGIC and 5GCAR. She holds more than 40 patents and has published more than 20 papers. She is the recipient of several awards in France: Prix Impact Economique des Rencontres du Numérique 2016 from the French National Research Agency, Grand Prix de l?Electronique du General Ferrié 2018 from the French Society of Electricity, Electronics and Information and Communication Technologies and the Prix Irène Joliot Curie 2018, category Femme-Recherche-Entreprise, from the French Ministry of Education and Research. Her research interests include wireless communications and beamforming, time reversal, spatial modulation, backscattering and intelligent reconfigurable surfaces. She is involved in Hexa-X, which is EU Flagship project on 6G, and in RISE-6G EU project on reconfigurable intelligent surfaces for 6G.

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Gabriele Gradoni (University of Nottingham, UK)

Title: Engineering Reflective Intelligent Surfaces via Quantum Annealing

Abstract: The Reconfigurable Intelligent Surface (RIS) is a planar structure engineered to have properties that enable dynamical electromagnetic wave control. Researchers have devoted substantial efforts to devise RIS optimization methods that achieve specific scattering profiles. A key question arises on how complex is to select the phase configuration that produces a RIS scattered field matching the prescribed scattering profile. In practice, the enormous parameter space provided by the array of RIS meta-atoms needs to be explored quickly within their available degrees of freedom. This is of paramount importance where a solution to the optimization problem is not available in closed form and thus constitutes a deeply intensive computational task. It is proposed to find the optimal phase configuration by a physics-based approach inspired from quantum physics. Both radar cross section and impedance formalism are used to calculate the RIS scattered wave energy, which configures as an Ising Hamiltonian: A common mathematical abstraction employed in statistical mechanics to describe the spin state of arrays of quantum particles. An analogy can be made between the binary meta-atom state and the particle spin degree of freedom to design the reflection phase mask of the RIS. The global solution of the problem, i.e., the values of the local reflection phases across the RIS, is obtained by computing the ground state of the effective Ising Hamiltonian via quantum annealing. Future research directions concern the extension to multi-level (beyond binary) RIS optimization and the inclusion of meta-atom coupling fluctuations driven by multipath fading.

Biography: Gabriele Gradoni received the Ph.D. degree in electromagnetics from the Universita' Politecnica delle Marche, Ancona, Italy, in 2010. He was a Visiting Researcher with the Time, Quantum, and Electromagnetics Team, National Physical Laboratory, Teddington, U.K., and a Research Associate with the Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, USA. He is Associate Professor of Mathematical Sciences and Electromagnetics Engineering with the University of Nottingham, U.K. His research activity is in probabilistic and asymptotic methods for propagation in complex wave systems, electromagnetic wave chaos, and MIMO wireless systems. He is a member of the IEEE, the American Physical Society, and the Italian Electromagnetics Society. He received the URSI Commission B Young Scientist Award in 2010 and 2016, the Gaetano Latmiral Prize in 2015, and the 2020 Honorable Mention Transaction Paper of IEEE Transactions on Electromagnetic Compatibility. Since 2014, he has been the URSI Commission E Early Career Representative. Since 2020, he is a Royal Society Industry Fellow at the Maxwell Centre, Cavendish Laboratory, University of Cambridge, U.K., and an Adjunct Associate Professor at the University of Illinois, Urbana Champaign.

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Vincenzo Sciancalepore (NEC Laboratories Europe, Germany)

Title: Reconfigurable Intelligent Surfaces Enabling Beamforming for IoT Massive Access

Abstract: Massive access for Internet-of-Things (IoT) in beyond 5G networks represents a daunting challenge for conventional bandwidth-limited technologies. Millimeter-wave technologies (mmWave) - which provide large chunks of bandwidth at the cost of more complex wireless processors in harsher radio environments - is a promising alternative to accommodate massive IoT but its cost and power requirements are an obstacle for wide adoption in practice. In this context, meta-materials arise as a key innovation enabler to address this challenge by Re-configurable Intelligent Surfaces (RISs). In this talk we take on the challenge and study a beyond 5G scenario consisting of a multi-antenna base station (BS) serving a large set of single-antenna user equipment (UEs) with the aid of RISs to cope with non-line-of-sight paths. Specifically, we build a mathematical framework to jointly optimize the precoding strategy of the BS and the RIS parameters in order to minimize the system sum mean squared error (SMSE). This novel approach reveals convenient properties used to design two algorithms, RISMA and Lo-RISMA, which are able to either find simple and efficient solutions to our problem (the former) or accommodate practical constraints with low-resolution RISs (the latter). Numerical results show that our algorithms outperform conventional benchmarks that do not employ RIS (even with low-resolution metasurfaces) with gains that span from 20% to 120% in sum rate performance.

Biography: Vincenzo Sciancalepore (Senior Member, IEEE) received the M.Sc. degree in telecommunications engineering and telematics engineering in 2011 and 2012, respectively, and the double Ph.D. degrees in 2015. He is currently a Senior 5G Researcher with NEC Laboratories Europe GmbH, Heidelberg, focusing his activity on network virtualization and network slicing challenges. He is involved in the IEEE Emerging Technologies Committee leading the initiatives on SDN and NFV. He was a recipient of the National Award for the Best Ph.D. Thesis in the area of communication technologies (wireless and networking) issued by GTTI in 2015. He is the Industry Chair of the IEEE COMSOC Emerging Technology Initiative on Reconfigurable Intelligent Surfaces and the Technical Manager of the H2020 project RISE-6G on Reconfigurable Intelligent Surfaces.

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Alessio Zappone (University of Cassino, Italy)

Title: Optimization of Reconfigurable Intelligent Surfaces with Electromagnetic Field Exposure Constraints

Abstract: his talk addresses the problem of maximizing the achievable rate in a reconfigurable intelligent surface (RIS)- assisted communication link, by enforcing conventional maximum power constraints and additional constraints on the maximum exposure to electromagnetic radiations of the end-users. The RIS phase shift matrix, the transmit beamforming filter, and the linear receive filter are jointly optimized, and the resulting optimization framework is introduced. The optimality of the developed solutions is discussed and it is shown that the use of a RIS enables to fulfill exposure constraints, while at the same time allowing to achieve data rates comparable with scenarios in which no exposure constraint is enforced

Biography: Prof. Alessio Zappone obtained his Ph.D. degree in electrical engineering in 2011 from the University of Cassino and Southern Lazio, Cassino, Italy. He has been with the Technische Universitat Dresden, Germany, from 2012 to 2016, and with the LANEAS group of CentraleSupelec as an experienced Marie Curie Fellow from 2017 to 2019. Alessio is an IEEE Senior Member, serves as senior area editor for the IEEE SIGNAL PROCESSING LETTERS and has served as guest editor for the IEEE JOURNAL ON SELECTED AREAS ON COMMUNICATIONS (Special Issues on Energy-Efficient Techniques for 5G Wireless Communication Systems and on Wireless Networks Empowered by RIS). He chairs the special interest group REFLECTIONS on RIS, activated within the SPCE-TC, he is a vice-chair of the ETI on RIS of the IEEE and Communication Society.

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Date : 2021-05-25

Lieu : Online


Thèmes scientifiques :
D - Télécommunications : compression, protection, transmission

Inscriptions closes à cette réunion.

(c) GdR 720 ISIS - CNRS - 2011-2022.