A Comparative study on ranging accuracy and interference robustness of LEO-PNT systems in urban and rural scenarios

Abstract

While Global Navigation Satellite Systems (GNSS) have been the primary Positioning, Navigation, and Timing (PNT) solution since their advent, new technologies are being sought to address the limitations of GNSS. For the past few years, the strongest contender to offer global PNT solutions has been the use of Low Earth Orbit (LEO) satellites, not only to overcome the GNSS limitations but also to improve the positioning accuracy and coverage given the proliferation of new, more-demanding applications. The present work aims at shedding light on the LEO theoretically achievable positioning accuracy and interference robustness with respect to GNSS, depending on the choice of the carrier frequency, constellation design, hybridization with GNSS, and available satellite transmission power. The analysis uses a semi-analytical approach with 192,000 Monte Carlo runs, employing an in-house satellite constellation simulator to model 400 users across Europe operating in five representative outdoor scenarios, and for 480 different instances of satellite positions in time. This semi-analytical study provides the necessary insights to derive clear design takeaways depending on the choice of the aforementioned parameters. A moderate Effective Isotropic Radiated Power (EIRP) of 50 dBm is shown to be sufficient for achieving high accuracy outdoors, operating at the C-band in the urban scenarios where GNSS typically struggles. The most cost-effective hybrid LEO plus GNSS solutions come from the combination of 1) ‘CentiSpace-like’ plus BeiDou, and 2) ‘Çelikbilek 1’ plus GPS and Galileo, where LEO satellites drive performance in difficult environments while GNSS provides stability in nominal conditions. The findings suggest using the ‘Çelikbilek 1’ constellation with a 50 dBm EIRP at a 5 GHz carrier frequency or higher as the most effective system design.