发表机构
Ulsan National Institute of Science and Technology (UNIST); The University of Manchester; University College London（蔚山科学技术院; 曼彻斯特大学; 伦敦大学学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对OFDM-ISAC系统，提出基于星座成形的感知隐私增强框架，通过分析测距MSE差距，设计Eve感知与不可知方案，实验验证了隐私与通信的权衡。
AI 中文摘要
将感知功能集成到通信网络中引入了新的隐私风险，因为被动窃听者（Eve）可能利用ISAC数据信号作为机会信号，对目标进行未经授权的感知。在本文中，我们为OFDM-ISAC系统开发了一种增强感知隐私的几何星座成形（GCS）框架。关键观察是，依赖于星座的测距性能是接收者特定的。对于Eve处的匹配滤波，测距均方误差（MSE）由星座峰度（kurt）决定，而合法接收者（Alice）处的逆滤波则由逆二阶矩（ism）决定。基于闭式MSE表达式，我们将感知隐私定义为Eve与Alice之间的测距MSE差距，并刻画其与这两个矩的依赖关系。分析表明，符号功率分布的正偏度是正固有矩差距（即kurt-ism）的必要条件。我们进一步推导了固有矩差距的精确基于偏度的分解以及一个典型的两环表征，为增强隐私的星座几何提供了分析指导。然后，我们提出了Eve感知和Eve不可知的GCS设计，通过最小欧氏距离（MED）平衡感知隐私和通信可靠性，其中Eve不可知设计仅依赖于固有矩差距。数值结果展示了可扩展的隐私-通信权衡，而空中实验表明，所提出的星座成形显著增加了Eve与Alice之间的测距误差差距，仅以较小的通信吞吐量损失为代价。
英文摘要
The integration of sensing into communication networks introduces a new privacy risk, as a passive eavesdropper (Eve) may exploit ISAC data signals as signals of opportunity to perform unauthorized sensing of targets. In this paper, we develop a sensing-privacy-enhancing geometric constellation shaping (GCS) framework for OFDM-ISAC systems. The key observation is that constellation-dependent ranging performance is receiver-specific. For matched filtering at Eve, the ranging MSE is governed by the constellation kurtosis $\kurt$, whereas reciprocal filtering at the legitimate receiver (Alice) is governed by the inverse second-order moment $\ism$. Based on closed-form MSE expressions, we define sensing privacy as the ranging MSE gap between Eve and Alice and characterize its dependence on these two moments. The analysis shows that positive skewness of the symbol-power distribution is necessary for a positive intrinsic moment gap, namely $\kurt-\ism$. We further derive an exact skewness-based decomposition of the intrinsic moment gap and a canonical two-ring characterization, providing analytical guidelines for privacy-enhancing constellation geometries. We then formulate Eve-aware and Eve-agnostic GCS designs that balance sensing privacy and communication reliability through the minimum Euclidean distance (MED), with the Eve-agnostic design depending only on the intrinsic moment gap. Numerical results demonstrate scalable privacy--communication trade-offs, while over-the-air experiments show that the proposed constellation shaping substantially increases the ranging error gap between Eve and Alice with only a small communication throughput loss.
Comments13 pages, 11 figures
