Design and Evaluation of Reconfigurable Intelligent Surfaces in Real-World Environment

Reconfigurable intelligent surfaces (RISs) have promising coverage and data-rate gains for wireless communication systems in 5G and beyond. Prior work has mainly focused on analyzing the performance of these surfaces using simulations or lab-level prototypes. To draw accurate insights about the actual performance of these systems, this paper develops an RIS proof-of-concept prototype and extensively evaluates its potential gains in the field under realistic wireless communication settings. In particular, a 160-element RIS, operating at a 5.8 GHz band, is designed, fabricated, and accurately measured in the anechoic chamber. This surface is then integrated into a wireless communication system and the beamforming gains, pathloss, and coverage improvements are evaluated in realistic outdoor communication scenarios. When both the transmitter and receiver employ directional antennas, the developed RIS achieves 15-20 dB gain in the signal-to-noise ratio (SNR) in a range of ±60° beamforming angles. In terms of coverage, and considering a far-field experiment with a blockage between a basestation and a grid of mobile users and with an average signal path of 35 m, the RIS provides an average SNR improvement of 6 dB (max 8 dB) within an area > 75 m2. Thanks to the scalable RIS design, these SNR gains can be directly increased with larger RIS areas. For example, a single 1,600-element RIS with the same design is expected to provide 26 dB SNR gain for a similar deployment (theoretical estimation). These results draw useful insights into the design and performance of RIS systems and provide an important proof for their potential gains in real-world far-field wireless communication environments.