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

This article presents a multibit reconfigurable intelligent surface (RIS) with a high phase resolution, capable of beam-steering in the azimuthal plane at sub-6 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 (LoS) and nonline-of-sight (NLoS) conditions, communication via a junction between long corridors, and a multifloor scenario with propagation via windows. This work explores the potential for RIS deployment to mitigate NLoS effects in indoor wireless communications. In a single transmitter (Tx), single receiver (Rx) NLoS link, received power improvement of as much as 40 dB is shown to be achievable by suitable placement of an RIS, with an instantaneous bandwidth of at least 100 MHz possible over a 3-4.5 GHz range. In addition, the effects of phase resolution on the optimal power reception for the multibit RIS have been experimentally verified, with a 2.65 dB improvement compared with a 1 bit case.