Resumen
Descripción general del contenido del recurso.
High accuracy positioning has become a key capability for fifth generation (5G) mobile networks and their future generations; however, the achievable performance is still severely limited by network time synchronization, particularly for positioning schemes based on the time difference of arrival (TDOA) principle. This investigation examines the impact of inter next-generation NodeB (gNB) timing uncertainty on 5G New Radio (NR) positioning in a 3rd Generation Partnership Project (3GPP) compliant Urban Macro (UMa) environment, and quantifies the performance improvements that are possible through deployment of a Precision Time Network (PTN) overlay as compared to typical Global Navigation Satellite System (GNSS) based synchronization techniques. A downlink NR positioning reference signal (NR-PRS) derived TDOA measurement and positioning model is employed in this work, in which gNB to gNB clock offsets are explicitly represented in the observation equations, enabling a clear separation of the contributions of radio measurement noise, geometry, and network time errors in the total localization error budget. The synchronization model is calibrated using representative residual timing regimes motivated by measurement-based data from an operated PTN infrastructure and by commonly assumed GNSS timing performance, corresponding to PTN-grade and GNSS-grade synchronization levels, respectively. Rather than treating these cases only as fixed deterministic offsets, the analysis models them as effective residual timing regimes with different uncertainty levels. Extensive Monte Carlo simulations are then performed in a two-dimensional UMa scenario using NR-PRS waveforms and a standard nonlinear least-squares solver for user equipment (UE) position estimation. In addition to the baseline timing comparison, a realistic propagation case is also considered through an effective measurement-level model that captures excess delay and increased timing uncertainty under non-line-of-sight (NLOS) conditions. The resulting error distributions for ideal timing, GNSS-grade timing, and PTN-grade timing show that PTN-grade synchronization leads to significant reductions in both median and upper-tail positioning errors when compared with GNSS-grade operation, while remaining substantially closer to the ideal timing reference under identical radio and geometry assumptions. In the baseline timing comparison, PTN-grade synchronization reduces the median and 90th-percentile positioning errors by about 29.8% and 29.7%, respectively, relative to GNSS-grade timing. Under realistic propagation, the overall error level increases for all synchronization modes, but PTN-grade timing still provides improvements of approximately 10.9% in median error and 11.7% at the 90th percentile relative to GNSS-grade timing. These results indicate that PTN based operator controlled timing overlays offer a practical and effective way to fully realize the potential of NR positioning in forthcoming 5G and beyond networks, and they are also expected to be a key enabler for high accuracy positioning and sensing in future 6G systems.
