User Equivalent Range Error and Positioning Accuracy Analysis for ToA-Based Techniques Using PRS and SSB in 5G/6G NTN

The integration of Non-Terrestrial Network (NTN) within the Fifth Generation (5G) and Sixth Generation (6G) ecosystem offers new opportunities for global Positioning, Navigation, and Timing (PNT) services, particularly in environments where Global Navigation Satellite System (GNSS) signals are obstructed or degraded. This work investigates the positioning performance of Time of Arrival (ToA)-based techniques using both Positioning Reference Signal (PRS) and Synchronization Signal Block (SSB) signals in 5G NTN scenarios. A comprehensive User Equivalent Range Error (UERE) model is developed, incorporating satellite, receiver, and propagation-related error sources across FR1 and FR2 frequency bands. The influence of satellite geometry is assessed through a Geometrical Dilution of Precision (GDOP) analysis, while a minimum satellite visibility evaluation quantifies the likelihood of observing at least four satellites above various elevation masks for representative LEO constellations at 600 km and 1200 km altitudes. Monte Carlo simulations quantify the impact of UERE on positioning accuracy, revealing that the 95th-percentile horizontal errors range from approximately 8 m to 26 m, depending on signal type, frequency band, and orbital altitude. The results demonstrate that ToA-based positioning using PRS can surpass typical urban GNSS-level accuracy, highlighting its potential in GNSS-challenged environments. In comparison, SSB-based positioning remains a viable alternative, offering reduced complexity at the cost of moderate accuracy trade-offs. The study offers a unified framework for understanding positioning accuracy in 5G/6G NTN, bridging UERE modeling, satellite visibility, and signal design considerations, and supporting the ongoing development of reliable global PNT services.