Analysis of the SINR in LEO-PNT Systems with 5G PRS Multiplexing: Integration of PRS and NTN

The 3rd Generation Partnership Project (3GPP) has integrated a positioning service into the 5G standard since its release 16 and has subsequently introduced support for Non-Terrestrial Networks (NTN). This paper explores the integration of these advancements within a unified framework to create a novel Low Earth Orbit (LEO)-based Positioning, Navigation, and Timing (PNT) service complementary to the existing Global Navigation Satellite System (GNSS). One major challenge in implementing this service is ensuring adequate coverage for users while minimizing interference between the signals from different LEO satellites, as the user requires to receive at least four signals to estimate its position.The Positioning Reference Signal (PRS) is a valuable positioning tool, particularly in scenarios with multiple transmitters. This study focuses on analyzing the interference issues arising when these transmitters are placed onboard LEO satellites. In this satellite context, the coverage area of the beam exceeds that of terrestrial environments, resulting in differential delay. Additionally, multiplexing PRS signals from multiple satellites within the same carrier reduces the Signal-to-Interference-plus-Noise ratio (SINR) owing to the orthogonality loss. To address these challenges, this study proposes a solution based on a Cell Averaging (CA)-Constant False Alarm Rate (CFAR) algorithm. The results of this study show the relationship between the minimum elevation angle of a satellite and the degradation of the SINR owing to other satellites.