With the increasing threat posed by modulation classification to wireless security, this paper proposes a secure communication framework based on modulation order confusion (MOC), which intentionally disguises the original modulation as a higher- or lower-order one to mislead eavesdroppers. For single-antenna systems, two schemes are developed: symbol random mapping and symbol time diversity, enabling modulation order confusion with customized receivers. For multi-antenna systems, receiver-transparent MOC schemes are proposed, including series-expansion-based and constellation-path-based signal designs, and are further extended to RIS-assisted systems with joint beamformer and RIS reflection design. Numerical results show that the proposed schemes effectively defeat both deep-learning-based and expert-knowledge-based modulation classifiers without degrading communication performance.

翻译：随着调制分类对无线安全的威胁日益加剧，本文提出了一种基于调制阶数混淆的安全通信框架，该框架通过将原始调制信号有意伪装成更高或更低阶的调制方式，以误导窃听者。针对单天线系统，本文设计了两种方案：符号随机映射与符号时间分集，使其能够与定制化接收机协同实现调制阶数混淆。针对多天线系统，本文提出了接收机透明的调制阶数混淆方案，包括基于级数展开和基于星座路径的信号设计，并进一步扩展至智能反射面辅助系统，实现了波束成形器与反射单元设计的联合优化。数值结果表明，所提方案能有效对抗基于深度学习和基于专家知识的调制分类器，且不降低通信性能。