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Reconfigurable intelligent surfaces for smart wireless environments: channel estimation, system design and applications in 6G networks

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Abstract

Reconfigurable intelligent surface (RIS), one of the key enablers for the sixth-generation (6G) mobile communication networks, is considered by designers to smartly reconfigure the wireless propagation environment in a controllable and programmable manner. Specifically, an RIS consists of a large number of low-cost and passive reflective elements (REs) without radio frequency chains. The system gain of RIS wireless systems can be achieved by adjusting the phase shifts and amplitudes of the REs so that the desired signals can be added constructively at the receiver. However, an RIS typically has limited signal processing capability and cannot perform active transmitting/receiving in general, which leads to new challenges in the physical layer design of RIS wireless systems. In this paper, we provide an overview of the RIS-aided wireless systems, including the reflection principle, channel estimation, and system design. In particular, two types of emerging RIS systems are considered: RIS-aided wireless communications (RAWC) and RIS-based information transmission (RBIT), where the RIS plays the role of the reflector and the transmitter, respectively. We also envision the potential applications of RIS in 6G networks.

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Acknowledgements

This work was supported in part by National Natural Science Foundation of China (Grant Nos. U1801261, 61631005), in part by National Key R&D Program of China (Grant No. 2018YFB1801105), in part by Macau Science and Technology Development Fund (FDCT), Macau SAR (Grant No. 0009/2020/A1), in part by Key Areas of Research and Development Program of Guangdong Province (Grant No. 2018B010114001), in part by Programme of Introducing Talents of Discipline to Universities (Grant No. B20064), and in part by Fundamental Research Funds for the Central Universities (Grant No. ZYGX2019Z022).

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Authors and Affiliations

  1. Center for Intelligent Networking and Communications, University of Electronic Science and Technology of China, Chengdu, 611731, China

    Ying-Chang Liang, Jie Chen, Ruizhe Long & Zhen-Qing He

  2. School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China

    Xianqi Lin, Chenlu Huang & Shilin Liu

  3. Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, N2L 3G1, Canada

    Xuemin Sherman Shen

  4. Laboratoire des Signaux et Systèmes, Université Paris-Saclay, CNRS, CentraleSupélec, 3 Rue Joliot-Curie, 91192, Gif-sur-Yvette, France

    Marco Di Renzo

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  1. Ying-Chang Liang
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Correspondence to Ying-Chang Liang.

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Liang, YC., Chen, J., Long, R. et al. Reconfigurable intelligent surfaces for smart wireless environments: channel estimation, system design and applications in 6G networks. Sci. China Inf. Sci. 64, 200301 (2021). https://doi.org/10.1007/s11432-020-3261-5

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  • DOI: https://doi.org/10.1007/s11432-020-3261-5

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