  The prospects of using a Reconfigurable Intelligent Surface (RIS) to aid
wireless communication systems have recently received much attention from
academia and industry. Most papers make theoretical studies based on elementary
models, while the prototyping of RIS-aided wireless communication and
real-world field trials are scarce. In this paper, we describe a new RIS
prototype consisting of 1100 controllable elements working at 5.8 GHz band. We
propose an efficient algorithm for configuring the RIS over the air by
exploiting the geometrical array properties and a practical receiver-RIS
feedback link. In our indoor test, where the transmitter and receiver are
separated by a 30 cm thick concrete wall, our RIS prototype provides a 26 dB
power gain compared to the baseline case where the RIS is replaced by a copper
plate. A 27 dB power gain was observed in the short-distance outdoor
measurement. We also carried out long-distance measurements and successfully
transmitted a 32 Mbps data stream over 500 m. A 1080p video was live-streamed
and it only played smoothly when the RIS was utilized. The power consumption of
the RIS is around 1 W. Our paper is vivid proof that the RIS is a very
promising technology for future wireless communications.
