T9 – Intelligent Surfaces for 6G and Beyond: From Stacked Intelligent Metasurfaces and Beyond-Diagonal RIS to ISAC and Advanced Wave Engineering

Co-presenter: Marco Di Renzo, CNRS-CentraleSupélec, France & King’s College London, UK
Co-presenter: Bruno Clerckx, Imperial College London (UK)
Co-presenter: Aryan Kaushik, OUF Innovative, UK, RakFort , Ireland, and IIITD, India
Co-presenter: Doohwan Lee, NTT, Inc., Japan

Abstract: For 6G and beyond wireless systems, intelligent surface technologies are emerging as key enablers for transforming wireless environments and enabling new communication paradigms. In particular, advanced architecture such as stacked intelligent metasurfaces and beyond-diagonal reconfigurable intelligent surfaces (BD-RIS) are attracting significant attention due to their ability to provide enhanced flexibility and control over electromagnetic wave propagation. Building on these architectural innovations, this tutorial also covers their key application domains, including Integrated Sensing and Communications (ISAC) and advanced wave engineering techniques for high-capacity transmission and interference management.

This tutorial first introduces these architectural innovations, focusing on stacked intelligent metasurfaces that enable multi-layer wave manipulation and BD-RIS that generalize conventional reconfigurable surfaces through inter-element coupling and non-diagonal scattering responses. These architectures offer new degrees of freedom for jointly controlling amplitude, phase, and coupling of electromagnetic waves, enabling more powerful and flexible signal processing directly in the propagation domain. Building upon these foundations, the tutorial then explores key application domains enabled by these technologies. In particular, it discusses ISAC, where intelligent surfaces support the seamless integration of sensing and communication functionalities. It also presents advanced wave engineering techniques for high-capacity transmission, interference mitigation, and robust operation in complex wireless environments.

By covering the evolution from advanced surface architectures to their practical applications, this tutorial provides a comprehensive understanding of how intelligent surfaces will shape 6G and beyond wireless systems.

Co-presenter’s Bios:

Marco Di Renzo:

Prof. Marco Di Renzo (Fellow, IEEE) received the Laurea (cum laude) and Ph.D. degrees in electrical engineering from the University of L’Aquila, Italy, in 2003 and 2007, respectively, and the Habilitation à Diriger des Recherches (Doctor of Science) degree from University Paris-Sud (currently Paris-Saclay University), France, in 2013. Currently, he is a CNRS Research Director (Professor) and the Head of the Intelligent Physical Communications group in the Laboratory of Signals and Systems (L2S) at Paris-Saclay University – CNRS and CentraleSupelec, Paris, France. Also, he is an elected member of the L2S Board Council and a member of the L2S Management Committee, and is a Member of the Admission and Evaluation Committee of the Ph.D. School on Information and Communication Technologies, Paris-Saclay University. He is a Founding Member and the Academic Vice Chair of the Industry Specification Group (ISG) on Reconfigurable Intelligent Surfaces (RIS) within the European Telecommunications Standards Institute (ETSI), where he served as the Rapporteur for the work item on communication models, channel models, and evaluation methodologies. He is a Fellow of the IEEE, IET, EURASIP, and AAIA; an Academician of AIIA; an Ordinary Member of the European Academy of Sciences and Arts, an Ordinary Member of the Academia Europaea; an Ambassador of the European Association on Antennas and Propagation; and a Highly Cited Researcher. Also, he holds the 2023 France-Nokia Chair of Excellence in ICT at University of Oulu (Finland), he holds the Tan Chin Tuan Exchange Fellowship in Engineering at Nanyang Technological University (Singapore), and he was a Fulbright Fellow at City University of New York (USA), a Nokia Foundation Visiting Professor at Aalto University, Finland; and a Royal Academy of Engineering Distinguished Visiting Fellow at Queen’s University Belfast, U.K. His recent research awards include the 2021 EURASIP Best Paper Award, the 2022 IEEE COMSOC Outstanding Paper Award, the 2022 Michel Monpetit Prize conferred by the French Academy of Sciences, the 2023 EURASIP Best Paper Award, the 2023 IEEE ICC Best Paper Award, the 2023 IEEE COMSOC Fred W. Ellersick Prize, the 2023 IEEE COMSOC Heinrich Hertz Award, the 2023 IEEE VTS James Evans Avant Garde Award, the 2023 IEEE COMSOC Technical Recognition Award from the Signal Processing and Computing for Communications Technical Committee, the 2024 IEEE COMSOC Fred W. Ellersick Prize, the 2024 Best Tutorial Paper Award, and the 2024 IEEE COMSOC Marconi Prize Paper Award in Wireless Communications. He served as the Editor-in-Chief of IEEE Communications Letters during the period 2019-2023, and he is now serving on the Advisory Board. He is currently serving as a Voting Member of the Fellow Evaluation Standing Committee and as the Director of Journals of the IEEE Communications Society.

Bruno Clerckx:

Prof. Bruno Clerckx is Professor of Wireless Communications and Signal Processing, the Head of the Communications and Signal Processing Group, and the Head of the Wireless Communications and Signal Processing Lab, within the Electrical and Electronic Engineering Department, Imperial College London, London, U.K. He spent many years in industry with Silicon Austria Labs (SAL), Austria, where he was the Chief Technology Officer (CTO) responsible for all research areas of Austria’s top research center for electronic based systems, and with Samsung Electronics, South Korea, where he actively contributed to 4G (3GPP LTE/LTE-A and IEEE 802.16m) standardization. He also was a Professor at Korea University and a visiting Professor at Seoul National University, South Korea, and held various long or short-term visiting research appointments at Stanford University, EURECOM, National University of Singapore, The University of Hong Kong, Princeton University, The University of Edinburgh, The University of New South Wales, and Tsinghua University. He has authored two books on “MIMO Wireless Communications” and “MIMO Wireless Networks”, 300 peer reviewed international research papers, and 150 standards contributions, and is the inventor of 80 issued or pending patents among which several have been adopted in the specifications of 4G (and still in use in 5G) standards and are used by billions of devices worldwide. His research spans the general area of wireless communications and signal processing for wireless networks. He has been a Technical Program Committee (TPC) member, a symposium chair, or a TPC chair of many symposia on communication theory, signal processing for communications and wireless communications for several leading international IEEE conferences. He was an Elected Member of the IEEE Signal Processing Society SPCOM (Signal Processing for Communications and Networking) Technical Committee. He served as an Editor for the IEEE TRANSACTIONS ON COMMUNICATIONS, the IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, and the IEEE TRANSACTIONS ON SIGNAL PROCESSING. He has also been a (lead) guest editor for special issues of the EURASIP Journal on Wireless Communications and Networking, IEEE ACCESS, the IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS and the IEEE JOURNAL OF SELECTED TOPICS IN SIGNAL PROCESSING, and the PROCEEDINGS OF THE IEEE. He was an Editor for the 3GPP LTE-Advanced Standard Technical Report on CoMP. He is the founding chair of IEEE special interest groups on Rate Splitting Multiple Access (RSMA) and Beyond Diagonal Reconfigurable Intelligent Surface (BD-RIS), both being promising technologies for 6G and beyond. He received the prestigious Blondel Medal 2021 from France for exceptional work contributing to the progress of Science and Electrical and Electronic Industries, the 2021 Adolphe Wetrems Prize in mathematical and physical sciences from Royal Academy of Belgium, multiple awards from Samsung, IEEE best student paper award, and the EURASIP (European Association for Signal Processing) best paper award 2022. He is a Fellow of the IEEE and the IET, and an IEEE Communications Society Distinguished Lecturer 2021-2023.

Aryan Kaushik:

Dr. Aryan Kaushik is Chief Executive Officer (CEO) at OUF Innovative (UK), Chief Innovation Officer (CIO) at RakFort (Ireland), and Adjunct Professor at IIIT Delhi (India). He previously served as Associate Professor at Manchester Metropolitan University (2024–25), and as Assistant Professor (Senior Grade) at the University of Sussex (2021–24), where he also held roles including Recruitment and Admissions Tutor and Academic Advisor. Prior to that, he was a Research Fellow at University College London (2020–21). He completed his PhD in Communications Engineering at
the University of Edinburgh (2019) and MSc in Telecommunications at HKUST (2015). He has also held multiple visiting academic and research appointments across leading institutions in Europe and Asia. He has been recognized among the world’s top 2% scientists (Stanford/Elsevier, 2025). He has contributed to international research funding and evaluation activities, including roles as reviewer and panel member for major agencies, and has served as external assessor and PhD examiner at several universities worldwide. Dr. Kaushik holds leadership roles within the IEEE Communications Society, including chairing initiatives on emerging technologies and AI-driven integration of terrestrial and non-terrestrial networks, and contributing to global 6G standardization efforts such as IEEE standards and the one6G association. His work brings together academia, industry, and standardization communities in next-generation communications. His research interests include signal processing for 5G/6G wireless communications, integrated sensing and communications, intelligent and holographic surfaces, non-terrestrial networks (including satellite and UAV communications), millimeter-wave massive MIMO, energy-efficient systems, and AI/ML-driven wireless technologies. He has been involved as principal investigator and research lead in multiple funded projects spanning sustainable 6G, integrated sensing systems, and autonomous UAVs, including major UK funded collaborative programs. He has received multiple exemplary editor awards across several IEEE journals and serves as editor for a range of leading IEEE and IET publications. He has also authored and edited several books on next-generation wireless communications and served as guest editor for numerous special issues in prominent journals, contributing to the advancement of emerging communication technologies. Dr. Kaushik has delivered over 130 keynote, invited, and tutorial talks at major international conferences and academic/industry events worldwide. He has been actively involved in organizing, chairing, and contributing to leading IEEE conferences, including roles in technical program committees, workshops, and symposia across flagship venues.

Doohwan Lee:

Dr. Doohwan Lee is a Senior Distinguished Researcher at NTT Network Innovation Laboratories. From 2012 to 2014, he was a full-time lecturer at the University of Tokyo. From 2016 to 2018, he was a part-time lecturer at Kanagawa University. He received the Best Paper Award and Best Technical Exhibition Award from the IEICE Software Radio in 2011, the IEICE Communications Society Excellent Paper Award in 2012, the IEICE SRW Young Researcher’s Award in 2016, the Best Technical Exhibition Award from SmartCom 2014, the Best Paper Award from SmartCom 2016, the Best Paper Award and Special Technical Award in Smart Radio from IEICE Smart Radio in 2017, the Distinguished Contributions Award from the IEICE Communications Society in 2021, the ComEX Best Letter Award in 2023, and the Radio Achievement Award from the Ministry of Internal Affairs and Communications in Japan in 2024. He has served as general co-chair of many workshops held at the IEEE ICC, GLOBECOM, PIMRC, and VTC. He was a co-chair of the Membership Development Committee (MDC) of the IEEE ComSoC APB in 2022 and 2023. He is a IEEE Communications Society Distinguished Lecturer 2026-2027.