High-Resolution Programmable Scattering for Wireless Coverage Enhancement: An Indoor Field Trial Campaign

Abstract: This paper presents a multi-bit reconfigurable intelligent surface (RIS) with a high phase resolution, capable of beam-steering in the azimuthal plane at sub-6 Gigahertz (GHz). Field trials in realistic indoor deployments have been carried out, with coverage enhancement performance ascertained for three common wireless communication scenarios. Namely, serving users in an open lobby with mixed line of sight and non-line of sight conditions, communication via a junction between long corridors, and a multi-floor scenario with propagation via windows. This work explores the potential for reconfigurable intelligent surface (RIS) deployment to mitigate non-line of sight effects in indoor wireless communications. In a single transmitter, single receiver non-line of sight link, received power improvement of as much as 40 dB is shown to be achievable by suitable placement of a RIS, with an instantaneous bandwidth of at least 100 MHz possible over a 3 to 4.5 GHz range. In addition, the effects of phase resolution on the optimal power reception for the multi-bit RIS have been experimentally verified, with a 2.65 dB improvement compared to a 1-bit case.