Explicit channel state information (CSI) feedback in IEEE~802.11 conveys \emph{transmit beamforming directions} by reporting quantized Givens rotation and phase angles that parametrize the right-singular subspace of the channel matrix. Because these angles encode fine-grained spatial signatures of the propagation environment, recent work have shown that plaintext CSI feedback can inadvertently reveal user activity, identity, and location to passive eavesdroppers. In this work, we introduce a standards-compatible \emph{differentially private (DP) quantization mechanism} that replaces deterministic angular quantization with an $\varepsilon$-DP stochastic quantizer applied directly to the Givens parameters of the transmit beamforming matrix. The mechanism preserves the 802.11 feedback structure, admits closed-form sensitivity bounds for the angular representation, and enables principled privacy calibration. Numerical simulations demonstrate strong privacy guarantees with minimal degradation in beamforming performance.

翻译：IEEE 802.11中的显式信道状态信息反馈通过报告量化吉文斯旋转角和相位角，将信道矩阵的右奇异子空间参数化，从而传输发射波束赋形方向。由于这些角度编码了传播环境的细粒度空间特征，近期研究表明，明文CSI反馈可能无意中向被动窃听者泄露用户活动、身份和位置信息。本文提出一种标准兼容的差分隐私量化机制，用直接应用于发射波束赋形矩阵吉文斯参数的ε-差分隐私随机量化器替代确定性角度量化。该机制保留了802.11反馈结构，给出了角度表示的闭式灵敏度边界，并支持原则性隐私校准。数值仿真表明，该机制在波束赋形性能损失极小的前提下实现了强隐私保障。