Multi-Functional Reconfigurable Intelligent Surface: System Modeling and Performance Optimization

Abstract

In this paper, we propose and study a multi-functional reconfigurable intelligent surface (MF-RIS) architecture. In contrast to conventional single-functional RIS (SF-RIS) that only reflects signals, the proposed MF-RIS simultaneously supports multiple functions with one surface, including reflection, refraction, amplification, and energy harvesting of wireless signals. As such, the proposed MF-RIS is capable of significantly enhancing RIS signal coverage by amplifying the signal reflected/refracted by the RIS with the energy harvested. We present the signal model of the proposed MF-RIS, and formulate an optimization problem to maximize the sum-rate of multiple users in an MF-RIS-aided non-orthogonal multiple access network. We jointly optimize the transmit beamforming, power allocations as well as the operating modes and parameters for different elements of the MF-RIS and its deployment location, via an efficient iterative algorithm. Simulation results are provided which show significant performance gains of the MF-RIS over SF-RISs with only some of its functions available. Moreover, we demonstrate that there exists a fundamental trade-off between sum-rate maximization and harvested energy maximization. In contrast to SF-RISs which can be deployed near either the transmitter or receiver, the proposed MF-RIS should be deployed closer to the transmitter for maximizing its communication throughput with more energy harvested.

arXiv commentThis paper has been accepted by IEEE Transactions on Wireless Communications

References in corpus (7)

• Active RIS vs. Passive RIS: Which Will Prevail in 6G?
• STAR: Simultaneous Transmission And Reflection for 360° Coverage by Intelligent Surfaces
• Joint Design for Simultaneously Transmitting And Reflecting (STAR) RIS Assisted NOMA Systems
• Joint Deployment and Multiple Access Design for Intelligent Reflecting Surface Assisted Networks
• Safeguarding NOMA Networks via Reconfigurable Dual-Functional Surface under Imperfect CSI
• Intelligent Omni-Surfaces for Full-Dimensional Wireless Communications: Principle, Technology, and Implementation
• Compact User-Specific Reconfigurable Intelligent Surfaces for Uplink Transmission

Cited by in corpus (4)

• Hybrid RIS-Assisted MIMO Dual-Function Radar-Communication System
• Multi-Functional RIS-Enabled in SAGIN for IoT: A Hybrid Deep Reinforcement Learning Approach with Compressed Twin-Models
• Federated Deep Reinforcement Learning for Energy Efficient Multi-Functional RIS-Assisted Low-Earth Orbit Networks
• Codebook-Based Self-Sustainable RIS: Optimal Splitting Schemes and Power Allocation