Localization Attack by Precoder Feedback Overhearing in 5G Networks and Countermeasures

In fifth-generation (5G) cellular networks, users feed back to the base station index of precoder (from a codebook) be used for downlink transmission. The is strongly related user channel and in turn position within cell. We propose method by which an external attacker determines passively overhearing this unencrypted layer-2 feedback signal. first builds map fed indices Then, victim user, finds its on map. focus type-I single-panel codebook, today only mandatory solution 3GPP standard. analyze attack assess obtained localization accuracy against various parameters. error simplified model describe asymptotic precision. also mitigation our attack, wherein randomly selects among those providing highest rate. Simulations confirm that can achieve high accuracy, significantly reduced when adopted, at cost negligible rate degradation.