The Potential of LEO-PNT Mega-Constellations for Ionospheric 3-D Imaging: A Simulation Study

The rapid increase of the number of low Earth orbit (LEO) satellites brings up the possibility of LEO satellite missions transmitting dedicated signals for positioning, navigation, and timing (PNT). Although great attention has been paid in recent years to understand the benefits of LEO satellites for PNT, dense LEO constellations will also provide unique measurements of the Earth's upper atmosphere. The benefits of the highly dense LEO-PNT systems are explored in this work to analyze the potential gains of using total electron content (TEC) measurements derived from LEO-PNT systems for 3-D ionospheric imaging. As a result, we have found obvious improvement in the ionospheric imaging system by including LEO satellites to the system geometry. Furthermore, our investigation has discovered that accurate electron density representations can be obtained even when no horizontal viewing angles are included in the imaging system, which is a unique point to imaging systems. In addition, we propose a method to derive accurate 3-D electron density representation based on ranging measurements from intersatellite links. The method provides accurate electron density estimations with no evident bias, but it still depends on the accuracy of background representations. The results indicate that improvements of over 80% can be achieved for both vertical and horizontal distributions of the ionosphere in comparison to the background.