5G Vehicle Positioning in Tunnels with Single Anchor TDOA Exploiting Multipath Reflectors

We investigate the problem of vehicle positioning inside a tunnel, addressed by exploiting 5G cellular uplink signals received by a single anchor station, e.g., a base station (BS) or road-side unit (RSU). Leveraging the multipath component (MPC) characterization introduced in 3GPP Release 17, which labels each signal arrival as line-of-sight (LOS) or non-line-ofsight (NLOS), we exploit the MPC identification of received signal echoes to enhance vehicle positioning. Assuming the availability of high-definition maps of the environment, we embed their knowledge with MPC data to dynamically identify signal reflectors and convert the environment into a network of auxiliary anchors for positioning. The proposed framework leverages single-anchor time difference of arrival (SA-TDOA) alongside angle of arrival (AOA) measurements. In contrast to standard TDOA approaches, the SA-TDOA measurement does not require synchronization between the mobile terminal and the anchor, nor the synchronization among the anchors, thus favoring its adoption in real-world deployments. A joint tracking of the vehicle and reflectors is performed by means of an extended Kalman filter. Simulation results demonstrate the augmentation capability of the proposed method, which exhibits high accuracy and robustness in both LOS and NLOS scenarios.