Existing and future GNSS receivers must be able to operate reliably when multiple LEO PNT signals are present, with the opportunity for LEO PNT to become interoperable with GNSS MEO in the same way multi-constellation receivers use signals ....

Exploiting GNSS signals and services has been one a major technical development of the last few decades, enabling a large variety of applications to use position, navigation and timing (PNT) information. Starting with GPS and followed by other global and regional GNSS, a multiplicity of signals is now available to worldwide users in the available spectrum allocations concentrated in the L-band. RadioFrequency Compatibility (RFC)—a concept formally defined many years ago by the International Committee on GNSS (ICG) of the United Nations Office for Outer Space Affairs (UNOOSA)—has been a cornerstone for the coexistence of GNSS signals in any chipset or receiver. These systems can be exploited at user level to provide unprecedented position accuracy and availability, and in some cases even benefit from interoperable signals to achieve superior performance compared to what any single system can do on its own. Implementing RFC among the GNSS is mostly left to the various system providers, which act upon provisions of the Radio Regulations, established under the International Telecommunication Union (ITU), such as Resolutions 609 and 610. Providers use well-established methodologies to assess compatibility, shaped over many years, that consider the specific characteristics of GNSS systems. These methodologies have been defined considering emissions from Medium Earth Orbit (MEO) and Geostationary Orbit (GEO) satellites, assuming typical power levels on ground within a certain range. More recently, novel concepts have been developed to provide PNT signals from satellites in Low Earth Orbit (LEO), generally referred to as LEO PNT. These concepts include exploitation of frequency diversity by transmitting navigation signals in alternative frequency bands such as UHF, the Radio Determination Satellite Systems (RDSS) S-band, or Radio-Navigation Satellite Systems (RNSS) C-band. Most of these new systems also incorporate L-band signals to aid legacy user service adoption. Some LEO PNT initiatives have chosen signals in the L-band at received power levels comparable to classic GNSS, while others are considering significantly higher levels. This, combined with the fact the world economy now relies heavily on GNSS, makes it crucial to assess the RFC of LEO PNT signals with the billions of terminals that have been designed to process signals transmitted from MEO and GEO satellites. Additionally, it is essential to verify the applicability of well-established methodologies to this new category of signals and systems, with different orbital characteristics and potentially significant variations in power levels at the user terminal input. This article investigates the topic of Radio Frequency (RF) compatibility among LEO PNT and classic GNSS, focusing on the impact at user level and ways to ensure existing and future GNSS receivers will be able to operate reliably in the presence of multiple signals transmitted by LEO PNT systems. To ensure compatibility with existing GNSS, LEO PNT signals shall not cause harmful interference that degrades GNSS receiver performance, which is typically measured by the effective C/N0 level. We pay specific attention to RFC in L-band RNSS allocations, which is already densely populated by many regional and global PNT systems.

PAONNI Matteo;  PICCOLO Andrea;  CUCCHI Luca;  MENZIONE Francesco;  PICCHI Ottavio;  WALLNER Stefan;  ANGHILERI Marco;  VAZQUEZ ALOCÉN César;  GIORDANO Pietro;  JULIEN Olivier; 

2026-05-18

Autonomous Media

JRC146174

https://insidegnss.com/,    https://publications.jrc.ec.europa.eu/repository/handle/JRC146174,