One of the key enablers of future wireless communications is constituted by massive multiple-input multiple-output (MIMO) systems, which can improve the spectral efficiency by orders of magnitude. In existing massive MIMO systems, however, conventional phased arrays are used for beamforming. This method results in excessive power consumption and high hardware costs. Recently, reconfigurable intelligent surface (RIS) has been considered as one of the revolutionary technologies to enable energy-efficient and smart wireless communications, which is a two-dimensional structure with a large number of passive elements. In this paper, we develop a new type of high-gain yet low-cost RIS that bears 256 elements. The proposed RIS combines the functions of phase shift and radiation together on an electromagnetic surface, where positive intrinsic-negative (PIN) diodes are used to realize 2-bit phase shifting for beamforming. This radical design forms the basis for the world's first wireless communication prototype using RIS having 256 two-bit elements. The prototype consists of modular hardware and flexible software that encompass the following: the hosts for parameter setting and data exchange, the universal software radio peripherals (USRPs) for baseband and radio frequency (RF) signal processing, as well as the RIS for signal transmission and reception. Our performance evaluation confirms the feasibility and efficiency of RISs in wireless communications. We show that, at 2.3 GHz, the proposed RIS can achieve a 21.7 dBi antenna gain. At the millimeter wave (mmWave) frequency, that is, 28.5 GHz, it attains a 19.1 dBi antenna gain. Furthermore, it has been shown that the RIS-based wireless communication prototype developed is capable of significantly reducing the power consumption.
Bibliographical noteFunding Information:
Corresponding author: Shenheng Xu (email@example.com) This work was supported in part by the National Natural Science Foundation of China for Outstanding Young Scholars under Grant 61722109, in part by the National Natural Science Foundation of China under Grant 61571270, in part by the Royal Academy of Engineering under the U.K.–China Industry Academia Partnership Programme Scheme under Grant U.K.-CIAPP\49, in part by the National Key Research and Development Program of China under Grant 2018YFB1801500, in part by the IITP by the Korean Government (MSIP) under Grant 2019-0-00685 and Grant 2016-11-1719, in part by the European Commission through the H2020 ARIADNE Project under Grant 871464, in part by the Engineering and Physical Sciences Research Council Projects under Grant EP/Noo4558/1, Grant EP/PO34284/1, and Grant COALESCE, in part by the Royal Society’s Global Challenges Research Fund Grant, and in part by the European Research Council’s Advanced Fellow Grant QuantCom.
All Science Journal Classification (ASJC) codes
- Computer Science(all)
- Materials Science(all)