ZTE Communications ›› 2022, Vol. 20 ›› Issue (1): 14-20.doi: 10.12142/ZTECOM.202201003

• Special Topic • Previous Articles    

Some Observations and Thoughts about Reconfigurable Intelligent Surface Application for 5G Evolution and 6G

HOU Xiaolin1(), LI Xiang1, WANG Xin1, CHEN Lan1, SUYAMA Satoshi2   

  1. 1.DOCOMO Beijing Communications Laboratories Co. , Ltd. , Beijing 100190, China
    2.NTT DOCOMO, INC. , Tokyo 239-8536, Japan
  • Received:2021-12-14 Online:2022-03-25 Published:2022-04-06
  • About author:HOU Xiaolin (hou@docomolabs-beijing.com.cn) received the B.S. degree in telecommunication engineering and the Ph.D. degree in communication and information system from Beijing University of Posts and Telecommunications, China in 2000 and 2005, respectively. Now he is the director of wireless technology department of DOCOMO Beijing Laboratories. He has a strong academic and industrial background and has been actively contributing to 4G and 5G research, standardization, and trials. He is now focusing on the research and standardization towards 5G evolution and 6G, including massive MIMO, mmWave, RIS, flexible duplex, NOMA, waveform, and the applications of artificial intelligence in physical layer design.|LI Xiang received the B.S. degree in communication engineering from Wuhan University, China, the M.S. degree in electrical engineering, and the Ph.D. degree in communications engineering from the University of Rostock, Germany in 2005, 2012, and 2018, respectively. In 2019, he joined DOCOMO Beijing Laboratories as an advanced researcher in wireless technology department. His research interests include multi-antenna systems, interference management, wireless relaying, and cooperative communications. He is currently focusing on the physical layer technologies towards 6G, including Mega MIMO, RIS, and Terahertz communications.|WANG Xin received the B.S. degree in electronics engineering and the Ph.D. degree in signal and information processing from Beihang University, China in 2001 and 2008, respectively. He is now a senior researcher in wireless technology department of DOCOMO Beijing Laboratories. His current research interests include Mega-MIMO (ultra-massive MIMO) technologies on high frequency bands, reconfigurable intelligent surfaces, deep learning for physical layer design, and Terahertz communications.|CHEN Lan received the M.E. and Ph.D. degrees from the Department of Communications and Computer Engineering of Kyoto University, Japan. She joined the NTT DOCOMO in 1999. Since then, she has been involved in research on LTE and LTE-Advanced and 3GPP RAN standardization. From 2013 to 2016, she was involved in the development for the enhancement of commercial radio NW. Since July 2016, she has been leading DOCOMO Beijing Laboratories on the research and standardization on 5G, evolution and beyond, and deep-learning based AI innovation. She received the Best Paper Awards in ICT2002 and ChinaCom2012, and Encouragement Award and Accomplishment Award in field of ICT from ITU Association of Japan in 2014 and 2018, respectively.|SUYAMA Satoshi received the B.S. degree in electrical and electronic engineering, the M.S. degree in information processing, and the Dr. Eng. degree in communications and integrated systems, all from Tokyo Institute of Technology, Japan, in 1999, 2001, and 2010, respectively. From 2001 to 2013, he was an assistant professor in the Department of Communications and Integrated Systems, the Tokyo Institute of Technology, Japan. He has been engaged in research on OFDM mobile communications systems and applications of the adaptive signal processing, including turbo equalization, interference cancellation and channel estimation. Since April 2013, he has joined NTT DOCOMO, Inc. and has been involved in research and development of 5G mobile communications system. He is currently the manager of 6G Laboratories in NTT DOCOMO. He received the Best Paper Prize from the European Wireless Technology Conference (EuWiT) in 2009, Best Paper Award from International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) in 2016, and the Paper Award from IEICE in 2012.


Reconfigurable intelligent surface (RIS) is one of the hottest research topics for 5G evolution and 6G. It is expected that RIS can improve the system capacity and coverage with low cost and power consumption. This paper first discusses typical applications of RIS for 5G evolution and 6G, including RIS-aided smart channels and RIS-aided mega multiple-input multiple-output (MIMO). Then, several observations from RIS trials and system-level simulations are presented, especially those on the deployment strategy and the potential performance gain of RIS for coverage enhancement. The near-field effect and a two-step dynamic RIS beamforming method are also discussed. Finally, we summarize the challenges and opportunities of the RIS technology for 5G evolution and 6G, including hardware design, system and channel modeling, algorithm design and optimization, and standardization. We also suggest a step-by-step commercialization strategy as a conclusion.

Key words: 5G evolution, 6G, beamforming, coverage, RIS