Recent considerations for reconfigurable intelligent surfaces (RISs) assume
that RISs can convey information by reflection without the need of transmit
radio frequency chains, which, however, is a challenging task. In this paper,
we propose an RIS-enhanced multiple-input single-output system with reflection
pattern modulation, where the RIS can configure its reflection state for
boosting the received signal power via passive beamforming and simultaneously
conveying its own information via reflection. We formulate an optimization
problem to maximize the average received signal power by jointly optimizing the
active beamforming at the access point (AP) and passive beamforming at the RIS
for the case where the RIS's state information is statistically known by the
AP, and propose a high-quality suboptimal solution based on the alternating
optimization technique. We analyze the asymptotic outage probability of the
proposed scheme under Rayleigh fading channels, for which a closed-form
expression is derived. The achievable rate of the proposed scheme is also
investigated for the case where the transmitted symbol is drawn from a finite
constellation. Simulation results validate the effectiveness of the proposed
scheme and reveal the effect of various system parameters on the achievable
rate performance. It is shown that the proposed scheme outperforms the
conventional RIS-assisted system without information transfer in terms of
achievable rate performance.

本文提出了一种基于反射模式调制的 RIS 增强的多输入单输出系统，其中 RIS 可以通过被动波束成形来配置其反射状态以增强接收信号功率并同时通过反射传递自己的信息，并且我们通过优化问题和交替优化技术提出了一种高质量的子优化解决方案，研究了所提出方案的渐近误码概率和可达速率性能，并表明该方案在可达速率性能方面优于传统的无信息传输的 RIS 协助系统。