摘要
The demanding objectives for the future sixth generation(6G)of wireless communication networks have spurred recent research efforts on novel materials and radio-frequency front-end architectures for wireless connectivity,as well as revolutionary communication and computing paradigms.Among the pioneering candidate technologies for 6G belong the reconfigurable intelligent surfaces(RISs),which are artificial planar structures with integrated electronic circuits that can be programmed to manipulate the incoming electromagnetic field in a wide variety of functionalities.Incorporating RISs in wireless networks have been recently advocated as a revolutionary means to transform any wireless signal propagation environment to a dynamically programmable one,intended for various networking objectives,such as coverage extension and capacity boosting,spatiotemporal focusing with benefits in energy efficiency and secrecy,and low electromagnetic field exposure.Motivated by the recent increasing interests in the field of RISs and the consequent pioneering concept of the RIS-enabled smart wireless environments,in this paper,we overview and taxonomize the latest advances in RIS hardware architectures as well as the most recent developments in the modeling of RIS unit elements and RIS-empowered wireless signal propagation.We also present a thorough overview of the channel estimation approaches for RIS-empowered communications systems,which constitute a prerequisite step for the optimized incorporation of RISs in future wireless networks.Finally,we discuss the relevance of the RIS technology in the latest wireless communication standards,and highlight the current and future standardization activities for the RIS technology and the consequent RIS-empowered wireless networking approaches.
基金
supported by the EU H2020 Industrial Leadership Project(No.101017011)
the Scientific and Technological Research Council of Turkey(TUBITAK)(No.120E401).
作者简介
To whom correspondence should be addressed:Ruiqi Liu received the BS and MS degrees(with honors)in electronic engineering from Tsinghua University in 2016 and 2019,respectively.He is now a master researcher in the Wireless Research Institute of ZTE Corporation,responsible for long-term research as well as standardization.His research interests include reconfigurable intelligent surfaces,wireless positioning,quantum communication,and visible light communication.He is the author or co-author of one book and one book chapter.He has authored and submitted more than 500 technical documents to 3GPP TSG RAN4,where he served as the co-rapporteur of the work item(WI)on NR RRM enhancement and the feature lead of multiple features.He currently serves as the vice chair of ISG RIS in the ETSI.He actively participates in organizing committees,technical sessions,workshops,symposia,and industrial panels in IEEE conferences as the chair,organizer,moderator,or panelist.He serves as the editor of ITU Journal of Future and Evolving Technologies(ITU J-FET)and the associate editor of IET Quantum Communication.He is the standardization officer for IEEE ComSoc ETI on reconfigurable intelligent surfaces(ETI-RIS)and the standards liaison officer for IEEE ComSoc Signal Processing and Computing for Communications Technical Committee(SPCC-TC).E-mail:jian.mengnan@zte.com.cn;Yuanwei Liu received the BS and MS degrees from Beijing University of Posts and Telecommunications in 2011 and 2014,respectively,and the PhD degree in electrical engineering from Queen Mary University of London,UK,in 2016.He was with the Department of Informatics,King’s College London,from 2016 to 2017,where he was a postdoctoral researcher.He has been a senior lecturer(associate professor)with the School of Electronic Engineering and Computer Science,Queen Mary University of London,since 2021.His research interests include non-orthogonal multiple access,5G/6G networks,machine learning,and stochastic geometry.He is a Web of Science Highly Cited Researcher 2021.He is currently a senior editor of IEEE Communications Letters,an editor of the IEEE Transactions on Wireless Communications and the IEEE Transactions on Communications.He serves as the leading guest editor for IEEE JSAC special issue on next generation multiple access,a guest editor for IEEE JSTSP special issue on signal processing advances for non-orthogonal multiple access in next generation wireless networks.He has served as a TPC member for many IEEE conferences,such as GLOBECOM and ICC.He received IEEE ComSoc Outstanding Young Researcher Award for EMEA in 2020.He received the 2020 Early Achievement Award of the IEEE ComSoc Signal Processing and Computing for Communications(SPCC)Technical Committee.He received 2021 Early Achievement Award of IEEE Communication Theory Technical Committee(CTTC).He received the Exemplary Reviewer Certificate of IEEE Wireless Communications Letters in 2015,IEEE Transactions on Communications in 2016 and 2017,and IEEE Transactions on Wireless Communications in 2017 and 2018.He has served as the publicity co-chair for VTC 2019-Fall.He is the leading contributor for“Best Readings for Non-Orthogonal Multiple Access(NOMA)”and the primary contributor for“Best Readings for Reconfigurable Intelligent Surfaces(RIS)”.He serves as the chair of Special Interest Group(SIG)in SPCC Technical Committee on the topic of signal processing techniques for next generation multiple access(NGMA),the vice-chair of SIG Wireless Communications Technical Committee(WTC)on the topic of Reconfigurable Intelligent Surfaces for Smart Radio Environments(RISE),and the tutorials and invited presentations officer for Reconfigurable Intelligent Surfaces Emerging Technology Initiative..E-mail:yuanwei.liu@qmul.ac.uk;Chau Yuen received the BEng and PhD degrees from Nanyang Technological University(NTU),Singapore,in 2000 and 2004,respectively.He was a postdoctoral researcher with Lucent Technologies Bell Labs at Murray Hill in 2005.From 2006 to 2010,he was with the Institute for Infocomm Research(I2R),Singapore.Since 2010,he has been with the Singapore University of Technology and Design.He received the IEEE Marconi Prize Paper Award in Wireless Communications and EURASIP Best Paper Award for Journal on Wireless Communications and Networking on 2021,IEEE Asia Pacific Outstanding Young Researcher Award on 2012,and IEEE VTS Singapore Chapter Outstanding Service Award on 2019.He serves as an editor for IEEE Transactions on Communications and IEEE Transactions on Vehicular Technology,awarded as the top editor during 2009−2015.He also served as the guest editor for several special issues,including IEEE Journal on Selected Areas in Communications,IEEE Wireless Communications Magazine,IEEE Communications Magazine,IEEE Vehicular Technology Magazine,IEEE Transactions on Cognitive Communications and Networking,and Elsevier Applied Energy.He is currently an IEEE fellow and distinguished lecturer of IEEE Vehicular Technology Society.E-mail:yuenchau@sutd.edu.sg;George C.Alexandropoulos received the engineering diploma,MASc,and PhD degrees in computer engineering and informatics from University of Patras,Greece in 2003,2005,and 2010,respectively.He has held research positions at various Greek universities and research institutes,as well as at the Mathematical and Algorithmic Sciences Lab,Paris Research Center,Huawei Technologies France,and he is currently an assistant professor with the Department of Informatics and Telecommunications,National and Kapodistrian University of Athens(NKUA),Greece.His research interests span the general areas of algorithmic design and performance analysis for wireless networks with emphasis on multi-antenna transceiver hardware architectures,active and passive reconfigurable metasurfaces,millimeter wave communications,as well as distributed machine learning algorithms.He currently serves as an editor for IEEE Transactions on Wireless Communications,IEEE Communications Letters,IEEE Wireless Communications Letters,ELSEVIER Computer Networks,Frontiers in Communications and Networks,and the ITU Journal on Future and Evolving Technologies,as well as a guest editor for various IEEE journals.He is a senior member of the IEEE Communications,Signal Processing,and Information Theory Societies as well as a professional engineer of the Technical Chamber of Greece.He has participated and/or technically managed more than 10 European Union(EU)research and innovation projects,as well as several Greek and international research projects.He is currently NKUA’s principal investigator for the EU H2020 RISE-6G research and innovation project dealing with RIS-empowered smart wireless environments.He has received the best PhD thesis award in 2010,the IEEE Communications Society Best Young Professional in Industry Award in 2018,the EURASIP Best Paper Award of the Journal on Wireless Communications and Networking in 2021,the IEEE Marconi Prize Paper Award in Wireless Communications in 2021,and the Best Paper Award from the IEEE GLOBECOM in 2021.More information is available at www.alexandropoulos.info.E-mail:alexandg@di.uoa.gr;Ertugrul Basar received the BS degree from Istanbul University,Turkey,in 2007,and the MS and PhD degrees from Istanbul Technical University,Turkey,in 2009 and 2013,respectively.He is currently an associate professor with the Department of Electrical and Electronics Engineering,KoçUniversity,Istanbul,Turkey and the director of Communications Research and Innovation Laboratory(CoreLab).His primary research interests include MIMO systems,index modulation,intelligent surfaces,waveform design,visible light communications,and signal processing for communications.He currently serves as a senior editor of IEEE Communications Letters and the editor of IEEE Transactions on Communications and Frontiers in Communications and Networks.He is a senior member of IEEE and the academic chair of IEEE ComSoc Emerging Technologies Initiative on Reconfigurable Intelligent Surfaces.He is the author/co-author of around 160 journal and conference publications and 8 patents(granted/applied),which received around 8000 citations.The most recent recognition of his research includes the IEEE Communications Society Best Young Researcher Award for the Europe,Middle East,and Africa Region in 2020.E-mail:ebasar@ku.edu.tr;Chongwen Huang received the BSc degree from Nankai University,Binhai College,in 2010 and the MSc degree from University of Electronic Science and Technology of China(UESTC,Chengdu)in 2013.He joined the Institute of Electronics,Chinese Academy of Sciences(IECAS,Beijing)as a research engineer in 2013.He received the PhD degree from Singapore University of Technology and Design(SUTD,Singapore)and CentraleSupélec University(Paris,France),in 2019.From 2019 to 2020,he was a postdoctoral researcher in SUTD.Since Sep.2020,he joined into Zhejiang University as a tenure-track young professor.He is the recipient of IEEE Marconi Prize Paper Award in Wireless Communications,and IEEE ComSoc Asia-Pacific Outstanding Young Researcher Award in 2021.He was also a recipient of Singapore Government PhD scholarship,and PHC Merlion PhD Grant 2016−2019 for studying in CentraleSupélec,France.He has served as an editor of IEEE Communications Letter,Elsevier Signal Processing,EURASIP Journal on Wireless Communications and Networking,and Physical Communication since 2021.In addition,He also has served the chair of some wireless communications flagship conference,including session chair of 2021 IEEE WCNC,2021 IEEE VTC-Fall,and symposium chair of IEEE WCSP 2021,etc.His main research interests are focused on holographic MIMO surface/reconfigurable intelligent surface,B5G/6G wireless communication,mmWave/THz communications,deep learning technologies for wireless communications,etc.E-mail:chongwenhuang@zju.edu.cn。
