New Generation of PNT User Terminals Exploiting Hybridization with LEO Constellations

This paper will provide the main outcomes of the first phase of the HybPNT project aiming at assessing the PNT capabilities of different LEO-PNT initiatives (dedicated, fused and opportunistic LEO-PNT) either considered standalone or properly combined (i.e. hybridized), using possible commonalities. To support those assessments, a detailed literature survey covering the Iridium, Globalstar, Starlink, Xona, Trustpoint constellations, and finally up-coming 5G NTN systems defined in the 3GPP standardization, will provide the required configurations for system volume simulations (SVSs). The study also benefits of the adaptation of and Endto-End simulator which has been enhanced to model specificities of LEO-COM. Extensive SVS campaigns allow to assess key performance indicator (KPI) focusing on the accuracy, robustness and resilience of the single point positioning (SPP) solution. The paper points out several limits intrinsic to the communication systems starting with the reduced observability, but also the noncontinuous transmission of positioning signal patterns (PSP) exploited for time-of-arrival (ToA) and frequency-of-arrival (FoA) estimation. Mitigations are proposed either at UT or at system levels, such as the optimization of the signal layer but also of the orchestration for the positioning reference signal (PRS) transmission, applicable for 5G non-terrestrial networks (5G NTN) systems. The paper shows that the hybridization allows to go beyond the limits of each individual system, but requires a suitable design of the hybrid PNT terminal, especially for PNT services taking place in the higher frequency regions (Ku-/Ka-Band).