Ad Astra: Navigation with Megaconstellation LEO Satellites

We are witnessing a space renaissance. Tens of thousands of broadband low Earth orbit (LEO) satellites are expected to be launched by the end of this decade. These planned megaconstellations of LEO satellites along with existing constellations will shower the Earth with a plethora of signals of opportunity, diverse in frequency and direction. These signals could be exploited for positioning, navigation, and timing (PNT) in the inevitable event that global navigation satellite system (GNSS) signals become unavailable (e.g., in deep urban canyons, under dense foliage, during unintentional interference, and intentional jamming) or untrustworthy (e.g., under malicious spoofing attacks).

This talk will overview the challenges associated with exploiting megaconstellation LEO satellites for PNT purposes, namely their unknown signals, poorly known ephemerides, loose synchronization and oscillator instability, and propagation effects. Next, a framework termed STAN: simultaneous tracking and navigation will be introduced to overcome these challenges. We will present an end-to-end approach, spanning theoretical modeling and analysis, specialized cognitive software-defined radio (SDR) design, practical PNT algorithms, and experimental demonstrations of STAN on the ground and aerial vehicles, navigating with multi-constellation LEO satellite signals (Starlink, OneWeb, Orbcomm, Iridium, and NOAA) to an unprecedented level of accuracy. Insights into future research directions and engineering implementation challenges will be provided as concluding remarks.