Multi-layer PNT Solutions for Harsh User Conditions

The provision of positioning, navigation and timing (PNT) services in harsh user conditions is still a challenging problem. Indeed, the joint exploitation of multiple systems, technologies and techniques is expected to be required to achieve an accurate, resilient, and ubiquitous PNT solution in different and changing user environments, extending from open-sky to deep-urban and indoors. The focus of this paper is to present critical aspects pertaining to the multi-layer PNT system-of-systems’ approach, in which GNSS systems in MEO are exploited together with LEO satellites, 5G networks, and collaborative user solutions, among others. Some of the approaches that can support the provision of instantaneous high-accuracy solutions are discussed, namely the exploitation of meta-signals or wide-band signals in hybrid-PNT solutions, and the use of super-pilot signals for the provision of both fast-acquisition and high-accuracy code observables. Additionally, some of the tools being developed at ESA's ESTEC site for the demonstration of multi-layer PNT solutions are presented.