5G Positioning Reference Signal impact assessment in Non-Terrestrial Networks communication service

Alejandro Gonzalez-Garrido, Ottavio M. Picchi, Francesco Menzione

5G New Radio (NR) Non-Terrestrial Networks (NTNs) extend cellular connectivity through Low Earth Orbit (LEO) and Medium Earth Orbit (MEO) satellite constellations while enabling the reuse of downlink NR Positioning Reference Signals (PRS) to provide Positioning, Navigation, and Timing (PNT) services alongside broadband communications. However, the large inter-satellite differential propagation delays inherent to NTN geometry may cause PRS transmissions from non-serving satellites to overlap with the serving-satellite data stream. This paper analyzes this coexistence by deriving a statistical model for the slant-range distribution over the visible spherical cap and extending it to dual-shell constellations through a mixture formulation, yielding a closed-form cumulative distribution function (CDF) of the differential delay. The model is validated using a 10-day orbit simulation representative of a dual-shell European NTN constellation. Detection limits of non-serving satellite PRS under interference from the serving-satellite data stream are characterized in terms of the effective carrier-to-noise density ratio. The impact of periodic PRS transmissions on the uncoded bit error rate (BER) is also evaluated for standardized NR Frequency Range 1 (FR1) and Frequency Range 2 (FR2) configurations. Monte Carlo simulations show that the probability of simultaneous multi-PRS overlap remains below a few percent, depending on PRS duration and repetition period, while PRS detection remains feasible despite data interference. When the PRS is received about 25 dB below the data signal, its impact on uncoded BER is negligible over a wide range of repetition periods, whereas BER degradation increases with PRS duty cycle. These results demonstrate that NR-PRS-based PNT can coexist with broadband downlink in NTN under appropriate PRS periodicity design.