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

Abstract

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, i.e., the surface reflects the incident signals towards 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 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 the IOS to wireless communications together with relevant research challenges are discussed.

Towards Ubiquitous Positioning by Leveraging Reconfigurable Intelligent Surface

“…• Hybrid Type: This type of RIS enables the dual function of reflection and refraction [32]. In other words, the incident signals will be split into two parts: one part is refracted and the other is reflected, as demonstrated in Fig.…”

Communication Models for Reconfigurable Intelligent Surfaces: From Surface Electromagnetics to Wireless Networks Optimization

“…In Table I and Table II, for completeness, we report two other examples of RISs that are modeled based on the same principle as the RISs considered in [45]. One of the examples reported in Table I considers the RIS introduced in [47], which can simultaneously reflect and refract the incident electromagnetic waves. For this reason, it is characterized by a reflection coefficient and by a transmission coefficient, T m,n , which is defined as the ratio between the refracted electric field and the incident electric field.…”

“…For this reason, it is characterized by a reflection coefficient and by a transmission coefficient, T m,n , which is defined as the ratio between the refracted electric field and the incident electric field. Similar to the RISs in [45], the unit cells of the RIS in [47] can be configured in two different states that are characterized by the pairs (Γ 1 , T 1 ) and (Γ 2 , T 2 ). The other example reported in Table I is the RIS introduced in [48], which operates as a reflecting surface but its unit cells can be configured in four different states.…”

“…The other example reported in Table I is the RIS introduced in [48], which operates as a reflecting surface but its unit cells can be configured in four different states. The RIS in Table II is modeled as a periodic array of unit cells, similar to the RISs in [45], [47] and [48]. Similar to [45] and [48], in addition, it operates only in reflection mode and is characterized by the reflection coefficient Γ m,n .…”

Joint Design for Simultaneously Transmitting And Reflecting (STAR) RIS Assisted NOMA Systems

“…To overcome this limitation, recently, a novel type of RIS, termed simultaneous transmitting and reflecting RISs (STAR-RISs) [5] or intelligent omni-surfaces (IOSs) [6], has been proposed. Different from traditional reflection-only RISs, STAR-RISs can simultaneously transmit and reflect the incident signals, which leads to a full-sapce coverage.…”