Distributed Privacy-Preserving Fusion for Multi-UAV Target Localization via Free-Noise Masking

Multi-UAV target localization relies on cooperative fusion of local, perception-derived geometric measurements over an edge network. While distributed fusion improves scalability and robustness compared with a centralized architecture, the iterative message exchanges may leak sensitive information to external eavesdroppers or honest-but-curious peers. This paper proposes a privacy-preserving distributed fusion method for multi-UAV localization via free-noise masking. The key idea is a double-injection mechanism. Specifically, each UAV masks its transmitted iterate with a locally generated bounded noise vector, while injecting the same noise into its local update so that the perturbations cancel exactly in the network-average dynamics under doubly stochastic mixing. As a result, the proposed PPDO-FN scheme preserves the practical convergence and weighted least squares localization accuracy of non-private distributed gradient descent, without requiring heavy cryptography or a trusted server. We further introduce reconstruction-based privacy metrics under transcript attacks and quantify the privacy–accuracy tradeoff. Simulation results demonstrate (i) near-identical accuracy and consensus behavior to the non-private baseline, (ii) monotonic privacy improvement with increasing masking strength, and (iii) the necessity of double-injection canceling compared with a naive single-injection baseline. Finally, we provide an end-to-end case study to connect the image-level detection to the geometric localization and then to privacy-preserving distributed fusion, illustrating engineering viability for our proposed approach.