Comparison of MEO, LEO, and Terrestrial IoT Configurations in Terms of GDOP and Achievable Positioning Accuracies

Complementary solutions to the Medium EarthOrbit (MEO) Global Navigation Satellite Systems (GNSS) aremore and more in demand to be able to achieve seamless positioning worldwide, in outdoor as well as in indoor scenarios,and to cope with increased interference threats in GNSS bands.Two of such complementary systems can rely on the emergingLow Earth Orbit (LEO) constellations and on the terrestriallong-range Internet of Things (IoT) systems, both under rapiddevelopments nowadays. Standalone positioning solutions basedon such systems complementary to GNSS can be beneficial insituations where GNSS signal is highly affected by interferences,such as jammers and spoofers, while hybrid GNSS and nonGNSS solutions making use of LEO and terrestrial IoT signalsas signals of opportunity can improve the achievable positioningaccuracy in a wide variety of scenarios. Comparative researchof performance bounds achievable through MEO, LEO, and terrestrial IoT signals are still hard to find in the current literature.It is the goal of this paper to introduce a unified framework tocompare these three system types, based on geometry matricesand error modeling, and to present a performance analysis interms of Geometric Dilution of Precision (GDOP) and positioningaccuracy bounds.