Beam-Switching-Based Time-of-Arrival Ranging on Commercial 5G NR Signals for Outdoor Positioning

The widespread adoption of 5G wireless communication devices has significantly increased the demand for precise 5G-based positioning services. This study presents a beam-switching time-of-arrival (TOA) ranging technique that leverages commercial 5G new radio (NR) signals and channel state information (CSI) extracted from the physical broadcast channel (PBCH). Initially, theoretical conditions for consistent multi-beam TOA estimation are derived, along with a multi-beam demodulation method designed to meet these conditions. To overcome the challenge of unknown base station (BS) radiation patterns, a signal quality-based beam-switching strategy is developed. Furthermore, a TOA tracking framework is introduced, integrating orthogonal matching pursuit (OMP) for multipath resolution, second-order frequency-locked loop (FLL)-assisted third-order delay-locked loop (DLL) for robust TOA tracking, and total variation regularization for anomaly removal. A software-defined radio (SDR) 5G receiver tailored for commercial beamforming BSs is implemented to validate the proposed system. With clock effects removed, the proposed system yields root-mean-square ranging errors of 3.73m and 4.99m in two distinct complex scenarios, corresponding to an average improvement of 69% in ranging accuracy over single-beam methods.