Reconfigurable Intelligence Surface with Potential Tunable Meta-Devices for 6G: Design and System-Level Evaluation

Reconfigurable intelligent surface (RIS) technology has emerged as a promising solution to address high-frequency band issues, including low penetration power and increasing shadowing regions, by artificially reconfiguring radio propagation. Previous research on RIS has pre-dominantly relied on metasurfaces based on specific diode-driven devices, and the practical challenges associated with this design have yet to be resolved. This article proposes potential RIS designs through meta-devices, including liquid crystal, 2D material, active metamaterial, and uniquely investigates an electrowetting-based beam tuning methodology. Taking into account the imperfect tuning capabilities of each device, we examine and reflect the relationship between the phase tuning range of RIS and the additional angular variation of the reflected wave. In addition, this article evaluates the RIS performance on a large scale via system-level simulation using 3D ray tracing, reflecting a realistic urban environment. We propose an evaluation methodology that integrates ray tracing with RIS's reflection characteristics and describes RIS-based beamforming throughput performance across various scenarios. Through the empirical evaluation of RIS incorporating meta-device characteristics, this work offers practical intuitions for RIS design contributing to its feasibility and efficiency for B5G/6G standardization and commercialization.