Reconfigurable Intelligent Surface Empowered Optimization for Spectrum Sharing: Scenarios and Methods

Abstract

The reconfigurable intelligent surface (RIS) has the capability to reconstruct the radio environment of wireless channels, which can alleviate the interference in the spectrum-sharing system (SSS). In this article, the current research directions of the RIS-aided SSS and the proposed methods of the joint optimization about passive beamforming of the RIS and the active beamforming of the access points are summarized and analyzed to obtain good insight into this technique. The RIS can improve the spectral efficiency (SE) and energy efficiency (EE) even in complicated scenarios, such as the SSS coexisting with multiple primary networks (PNs) or several secondary networks (SNs). The simulation results indicate that the deployment of the RIS and the varying number of reflecting elements on the RIS have significant impact on the gain of the RIS brought in the SSS. Although the RIS-aided SSS has some challenges including the discretization of reflecting coefficients on the RIS, it still has huge potentials to be utilized in diverse fields such as vehicular or unmanned aerial vehicles (UAVs) communications.