This paper studies location privacy in uplink MIMO systems, where a user equipment seeks to spoof the angular signature observed by a single base station performing localization. We propose a blind analog precoder design that manipulates the perceived angle-of-arrival and angle-of-departure configuration without requiring channel-gain knowledge. The method enforces consistency between the received signal and a desired spoofed angular subspace, and is solved using an alternating optimization algorithm under practical amplitude constraints. Simulations in a multipath scenario show that the proposed approach achieves near-perfect angular spoofing and clearly outperforms pilot-only blind spoofing, which exhibits an error floor. The results also show a trade-off between spoofing accuracy and communication rate, depending on the chosen virtual geometry.
@article{arxiv.2605.00535,
title = {From Pilot to Precoding Design: Blind Angular Spoofing For Location Privacy in MIMO Systems},
author = {Priyanka Maity and Lorenzo Italiano and Alireza Pourafzal and Gonzalo Seco-Granados and Hui Chen and Monica Nicoli and Henk Wymeersch},
journal= {arXiv preprint arXiv:2605.00535},
year = {2026}
}