5G NR robust tracking and positioning with GNSS assistance

Abstract Global Navigation Satellite Systems (GNSS) is able to achieve centimeter-level accuracy in open-sky areas. However, their performance declines in urban canyons and outdoor shadow areas. Conversely, commercial Fifth Generation Mobile Communications Technology (5G) New Radio (NR) signals, with their wider bandwidth and shorter wavelengths, offer better range accuracy. To enhance positioning accuracy in challenging environments, we developed a deeply integrated method to combine commercial 5G NR signals with the GNSS. This method involves three key steps: Firstly, we use the Secondary Synchronization Signal to aid the Demodulation Reference Signal (SA-DMRS) in the 5G NR synchronization channel, which aims to improve the tracking loop robustness. Secondly, a Phase-Stabilized Kalman Filter (PSKF) is integrated into the Phase-Locked Loop to boost performance under low Carrier-to-Noise Density Ratio conditions. Lastly, the Extended Kalman Filter (EKF) is applied to fuse 5G and GNSS signals for positioning, and the results are fed back to correct the 5G NR tracking loop. Field tests revealed that SA-DMRS boosted range accuracy by 42.3%, PSKF contributed a further 17% improvement, and GNSS-aided improved the range accuracy by about 33.3%. Compared to the GPS (Global Positioning System)-EKF method, our fusion approach enhances horizontal positioning accuracy by approximately 49.8%, and the vertical positioning accuracy is improved by about 53.3%. Additionally, compared to the GPS-only method, the proposed method can still provide positioning services when there are three usable satellites. Compared with the GNSS-only method, the deep coupled method improved the accuracy in the horizontal and vertical by about 51.2% and 24.0%, respectively. These confirm the method’s effectiveness for accurate and reliable positioning in challenging environments.