A Universal Framework of Superimposed RIS-Phase Modulation for MISO Communication

TL;DR

This paper introduces a universal superimposed RIS-phase modulation scheme that enhances MISO communication by transmitting extra information through RIS phase offsets, with theoretical analysis and numerical validation.

Contribution

It proposes a novel superimposed RIS-phase modulation framework, providing theoretical analysis and demonstrating improved communication performance over existing methods.

Findings

Achieves reliable communication of more bits than existing schemes.

Diversity order is 0.5 for all parameter settings.

Doubling RIS elements or antennas is equivalent to a 3 dB power increase.

Abstract

To fully exploit the additional dimension brought by reconfigurable intelligent surface (RIS), it is recently suggested by information theory that modulating information upon RIS phases is able to send extra information with increased communication rate. In this paper, we propose a novel superimposed RIS-phase modulation (SRPM) scheme to transfer extra messages by superimposing information-bearing phase offsets to conventionally optimized RIS phases. The proposed SRPM is interpreted as a universal framework for RIS phase modulation. Theoretical union bound of the average bit error rate (ABER) of the proposed SRPM is also derived with the maximum likelihood (ML) detection. The diversity order is characterized as 0.5 for all parameter settings, which is useful for determining the optimal choice of the phase modulation parameters. Furthermore, we discover that doubling the number of either RIS reflecting elements or the transmit antennas is equivalent to a 3 dB increment in the transmit power for SRPM. Numerical results demonstrate the effectiveness of SRPM and reveal that it achieves reliable communication of more bits than existing schemes.