LEO-PNT for Augmenting Europe's Space-based PNT Capabilities

With GNSS as flagship, space-based PNT enables the single largest downstream space sector, worth about (sic)150 billion annually and growing at the rate of 10 per cent per year [29]. The associated infrastructures (e.g. Galileo, GPS) are evolving and introducing new capabilities to meet more demanding needs, in a context of hybrid and system-of-systems PNT solutions. Meanwhile, PNT solutions which exploit signals from LEO (what is being called LEO-PNT) are emerging as a major trend of evolution for space-based PNT, backed by the benefits of multi-layer architectures and new industrial and business models in the Space sector (the so-called New Space). Many initiatives are now being taken worldwide, driven either by institutional or commercial stakes. Europe is taking part to the evolution of this landscape, supported by solid industrial grounds in New Space capabilities and PNT technologies, as well as by institutional initiatives. For instance, the proposal for a regulation of the European Union to establish IRIS2 ("Infrastructure for Resilience, Interconnection & Security by Satellites") refers to LEO-PNT as potential non-communication mission. In this context, this paper provides an overview of the current initiatives, and in particular, objectives, opportunities, trade-offs and possible solutions for LEO-PNT in the context of evolutions of European space-based infrastructures. The scope comprises an overview of the global LEO-PNT landscape, and in particular of the European one, for both purpose-built LEO-PNT and more opportunistic approaches such as the integration of PNT capabilities in existing or future satcom signals (e.g. 5G NTN). Possible use cases leveraging LEO-PNT are presented together with the associated design drivers and technologies, trade-offs and some examples of working points illustrating the differentiators of LEO-PNT in augmenting and complementing European GNSS capabilities. Technological enablers on the payload side as well as on the user side are addressed and discussed, based on ongoing studies and proof-of-concept developments, as well as incoming opportunities, such as the LEO-PNT In-Orbit Demonstrator under preparation.