arXiv:2610.20923v1 Announce Type: new Abstract: This paper considers uplink channel state information (CSI)-based sensing as an opportunistic approach to enabling sensing in cellular networks, with minimum required modifications to the infrastructure. A practical sensing signal processing procedure is presented, combining 5G positioning function with multi-antenna array processing for passive target localization. The approach is validated through simulation and practical experiments with a software-defined radio-based setup, utilizing open-source software frameworks and commercially available hardware components. Results demonstrate feasibility of the uplink CSI-based sensing for detection, localization and tracking of moving targets over local areas.