Reflection (computer programming)

Engineering

MIMO

Modulation (music)

Quadrature amplitude modulation

Telecommunications

Computer science

Acoustics

Physics

Bit error rate

Electronic engineering

Transmission (telecommunications)

Programming language

Channel (broadcasting)

Wireless

IEEE Journal on Selected Areas in Communications

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.

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