Intelligent Omni-Surfaces for Full-Dimensional Wireless Communications: Principles, Technology, and Implementation

The recent development of metasurfaces has motivated their potential use for improving the performance of wireless communication networks by manipulating the propagation environment through nearly passive sub-wavelength scattering elements arranged on a surface. However, most studies of this technology focus on reflective metasurfaces, that is, the surface reflects the incident signals toward receivers located on the same side of the transmitter, which restricts the coverage to one side of the surface. In this article, we introduce the concept of an intelligent omni-surface (IOS), which is able to serve mobile users on both sides of the surface to achieve full-dimensional communications by jointly engineering its reflective and refractive properties. The working principle of the IOS is introduced, and a novel hybrid beamforming scheme is proposed for IOS-based wireless communications. Moreover, we present a prototype of IOS-based wireless communications and report experimental results. Furthermore, potential applications of IOSs to wireless communications together with relevant research challenges are discussed.