Beyond 5G non terrestrial networks for direct-to-device joint communication and positioning services provision: Part I—system scenarios and architectures

Global Navigation Satellite System (GNSS) vulnerability to jamming and spoofing necessitates resilient Positioning Navigation Timing (PNT) alternatives. While Fifth Generation (5G) offers terrestrial positioning, its coverage limitations motivate the development of ubiquitous complements. A dedicated Low Earth Orbiting-Positioning Navigation Timing (LEO-PNT) layer, providing rapid orbital geometry and enhanced link budgets, offers a robust solution to augment or replace legacy GNSS. Simultaneously, Direct to Device (D2D) satellite connectivity via 3rd Generation Partnership Project (3GPP) Non Terrestrial Network (NTN) is extending Terrestrial Network (TN) coverage. A critical open question is whether these communication-centric Low Earth Orbit (LEO) systems can provide robust positioning services. Integration challenges include high satellite mobility, extreme Doppler shifts, and the conflict between multi-satellite visibility for positioning versus minimized beam overlap for communication capacity. This paper investigates using Mobile Satellite Services (MSS) spectrum and 3GPP NTN for integrated positioning and communication services. Based on realistic use cases, we propose and characterize three candidate LEO NTN architectures. In a companion paper1, these architectures are analyzed in depth, evaluating fundamental trade-offs between positioning accuracy, system availability, and communication throughput.