MIMO Transmission through Reconfigurable Intelligent Surface: System Design, Analysis, and Implementation

TL;DR

This paper introduces a novel RIS architecture capable of amplitude and phase modulation to enhance MIMO-QAM wireless transmission, supported by hardware analysis and real-time prototype implementation.

Contribution

It presents a new RIS design that enables amplitude and phase control, improving MIMO-QAM transmission beyond phase-only modulation, with practical hardware considerations and real-world testing.

Findings

Successful real-time RIS-based MIMO-QAM transmission demonstrated

Hardware constraints analyzed and incorporated into system design

Prototype validates the effectiveness of the proposed RIS architecture

Abstract

Reconfigurable intelligent surface (RIS) is a new paradigm that has great potential to achieve cost-effective, energy-efficient information modulation for wireless transmission, by the ability to change the reflection coefficients of the unit cells of a programmable metasurface. Nevertheless, the electromagnetic responses of the RISs are usually only phase-adjustable, which considerably limits the achievable rate of RIS-based transmitters. In this paper, we propose an RIS architecture to achieve amplitude-and-phase-varying modulation, which facilitates the design of multiple-input multiple-output (MIMO) quadrature amplitude modulation (QAM) transmission. The hardware constraints of the RIS and their impacts on the system design are discussed and analyzed. Furthermore, the proposed approach is evaluated using our prototype which implements the RIS-based MIMO-QAM transmission over the air in real time.