This work proposes RIS-enabled channel signature modulation (RIS-CSM), a lightweight index modulation scheme for reconfigurable intelligent surfaces (RIS). An N-element RIS is partitioned into disjoint groups, each employing predetermined binary reflection patterns to generate distinct channel signatures at an $n_R$-antenna receiver, without RIS-side beamforming. Information is embedded in the indices of these signatures, enabling simple channel estimation and scalable spectral efficiency. A closed-form upper bound on error probability and capacity analysis are derived, revealing diversity order $n_R$ and coding gain proportional to N. Simulation results under Rayleigh fading validate the theoretical analysis. Moreover, simulations indicate that spatial correlation among RIS elements can improve system performance at low spectral efficiency.

翻译：本文提出了一种基于可重构智能表面（RIS）的轻量级索引调制方案——RIS使能的信道特征调制（RIS-CSM）。该方案将包含N个单元的RIS划分为互不相交的组，每组采用预设的二进制反射模式，在配备$n_R$根天线的接收端生成独特的信道特征，而无需RIS端进行波束成形。信息通过嵌入这些特征的索引进行传输，实现了简化的信道估计和可扩展的频谱效率。本文推导了误码概率的闭形式上界并进行了容量分析，揭示了分集阶数为$n_R$，且编码增益与N成正比。瑞利衰落信道下的仿真结果验证了理论分析。此外，仿真表明，在低频谱效率场景下，RIS单元间的空间相关性有助于提升系统性能。