Intelligent Reflecting Surface based Passive Information Transmission: A Symbol-Level Precoding Approach

TL;DR

This paper introduces IRS-based passive information transmission systems utilizing symbol-level precoding, enabling passive reflection and simultaneous information delivery to multiple receivers with optimized power and QoS.

Contribution

It proposes two novel IRS passive transmission schemes and develops algorithms for power minimization and QoS balancing, advancing IRS passive transmission research.

Findings

Feasibility of IRS-based passive information transmission demonstrated.

Proposed algorithms outperform benchmark schemes.

Effective simultaneous primary and secondary information delivery achieved.

Abstract

Intelligent reflecting surfaces (IRS) have been proposed as a revolutionary technology owing to its capability of adaptively reconfiguring the propagation environment in a cost-effective and hardware-efficient fashion. While the application of IRS as a passive reflector to enhance the performance of wireless communications has been widely investigated in the literature, using IRS as a passive transmitter recently is emerging as a new concept and attracting steadily growing interest. In this paper, we propose two novel IRS-based passive information transmission systems using advanced symbol-level precoding. One is a standalone passive information transmission system, where the IRS operates as a passive transmitter serving multiple receivers by adjusting its elements to reflect unmodulated carrier signals. The other is a joint passive reflection and information transmission system, where the IRS not only enhances transmissions for multiple primary information receivers (PIRs) by passive reflection, but also simultaneously delivers additional information to a secondary information receiver (SIR) by embedding its information into the primary signals at the symbol level. Two typical optimization problems, i.e., power minimization and quality-of-service (QoS) balancing, are investigated for the proposed IRS-based passive information transmission systems. Simulation results demonstrate the feasibility of IRS-based passive information transmission and the effectiveness of our proposed algorithms, as compared to other benchmark schemes.