Global Navigation Satellite Systems (GNSSs) are the most widespread technology for Position Navigation and Timing (PNT). They have been traditionally deployed exploiting Medium Earth Orbit (MEO) or Geosynchronous Orbit (GSO) satellites. To meet future demands and overcome MEO and GSO limitations, GNSSs based on Low Earth Orbit (LEO) constellations have been investigated as a radical system change. Although characterized by a higher Doppler effect, a PNT service supplied by LEO satellites can provide received signals that are about 30 dB stronger. Moreover, broadband LEO constellations and the forthcoming mega-constellations can be exploited to deliver a piggybacked PNT service. With this cost-effective solution, a PNT service might be subject to substantial bandwidth limitations. A narrowband implementation of the so-called meta-signal approach in GNSS receivers, namely Virtual Wideband (VWB), can tolerate harsh Doppler conditions while reducing the processed bandwidth. It is thus suited to a secondary PNT service delivered by LEO satellites. The aim of this work is to show the applicability of the VWB architecture to signals provided by a piggybacked PNT service, hosted on a mega-constellation. Through this case study we demonstrate the capability of this implementation to bear high Doppler conditions while empowering the potential of LEO PNT.

Global Navigation Satellite Systems (GNSSs) are by far the most widespread technology for Position Navigation and Timing (PNT). They have been traditionally deployed exploiting Medium Earth Orbit (MEO) or Geostationary Earth Orbit (GEO) satellite constellations. To meet future demands and overcome MEO and GEO limitations, GNSSs based on Low Earth Orbit (LEO) constellations have been investigated as a radical system change. Although characterized by a higher Doppler effect, a PNT service supplied by means of LEO satellites can provide received signals that are about 30 dB stronger. Moreover, existing LEO constellations and the forthcoming mega-constellations, which are designed for broadband internet coverage, can be exploited to provide a piggybacked PNT service. With this cost-effective solution, a secondary PNT service might be subject to an economical use of resources, which may result in substantial bandwidth limitations. At the same time, the introduction of meta-signals in the GNSS literature has brought a new receiver signal processing strategy, particularly effective in terms of available bandwidth exploitation. It allows to increase the positioning accuracy exploiting a wideband processing approach, which might be challenging under severe Doppler conditions. A narrowband implementation of the meta-signal concept, namely Virtual Wideband (VWB) can tolerate harsh Doppler conditions while also reducing the processed bandwidth. It is thus more effective when addressing a secondary PNT service, where a limited frequency occupation might be an essential requirement. The aim of this work is to show the applicability of a VWB receiver architecture on signals provided by a piggybacked PNT service, hosted on a broadband LEO constellation. We demonstrate the capability of this implementation to bear high Doppler conditions while empowering the potential of LEO PNT.

Advancements in communication, manufacturing, and launch technologies have significantly accelerated the development of low-Earth orbit (LEO) satellite communication constellations. Simultaneously, the rapid expansion of LEO satellite platforms presents new opportunities for navigation enhancements and substantial benefits for Internet of Things (IoT) applications. This survey highlights the latest advancements in the integrated communication and navigation (ICAN) technologies, emphasizing key research issues. Specifically, we discuss the motivation and feasibility of integrating communication and navigation on LEO satellite platforms, analyzing various LEO-based navigation paradigms while assessing their respective advantages and limitations. We further explore the mutual promotion of navigation and communication under the ICAN paradigm and discuss waveform design, analyzing the characteristics of different waveform design approaches. Finally, we highlight the unique challenges and identify open research topics within the ICAN framework for future exploration.