Using Multi-Constellation Low Earth Orbit Satellites for Positioning, Navigation & Timing Data

Tuesday - May 23 2023, 10:45 UTC - 1 year ago

Researchers have developed an algorithm that uses LEO satellites signals to locate any point on Earth with unprecedented accuracy. The study was presented at the IEEE/ION Position Location and Navigation Symposium (PLANS) 2023 conference in Monterey, California, and won the Best Student Paper Award. This study proposes utilizing signals from LEO satellites as an alternative to GNSS positioning, navigation and timing needs, as they reside about 20 times closer to Earth compared to GNSS satellites.

Researchers have developed an algorithm that can "eavesdrop" on any signal from a satellite and use it to locate any point on Earth, much like GPS. The study represents the first time an algorithm was able to exploit signals broadcast by multi-constellation low Earth orbit satellite (LEO) satellites, namely Starlink, OneWeb, Orbcomm and Iridium. Researchers found that by listening to the signals of eight LEO satellites for about 10 minutes, their algorithm could achieve unprecedented accuracy in locating a stationary receiver on the ground and was able to converge on it with an error of only about 5.8 meters.

The research, led by Zak Kassas, a professor of electrical and computer engineering at The Ohio State University and director of the Department of Transportation Center for Automated Vehicles Research with Multimodal AssurEd Navigation (CARMEN), was presented last week at the IEEE/ION Position Location and Navigation Symposium (PLANS) 2023 conference in Monterey, California. Along with Ohio State Ph.D. students Sharbel Kozhaya and Haitham Kanj, the paper, which demonstrated the first ever exploitation of unknown OneWeb LEO satellite signals, won the conference's Best Student Paper award.

The researchers did not need assistance from the satellite operators to use the signals, and they emphasized that they had no access to the actual data being sent through the satellites - only to publicly available information related to the satellites' downlink transmission frequency and a rough estimate of the satellites' location.

From transportation to communication systems to the power grid and emergency services, nearly every aspect of modern society relies on positioning, navigation and timing data from global navigation satellite systems (GNSS), or GPS, that orbit the Earth. Despite this, because GPS system signals are weak and susceptible to interference, they can often become unreliable in certain places such as indoor environments or in deep urban canyons. In addition, GNSS signals are spoofable, which poses serious security risks in safety-critical applications, such as aviation.

In the long term, such complications could lead to a number of navigational and cybersecurity issues, especially as virtually all of our current systems rely heavily on GPS, Kassas said. Technologies on the rise, such as autonomous vehicles, he noted, are beginning to amplify the limitations of our current GNSS systems. "It's becoming more pressing to find civilian and military alternatives to GPS, whether as a backup or in the case when GPS isn't there whatsoever," said Kassas.

This study builds on previous research by Kassas' lab that solely used six SpaceX satellite signals to pinpoint a location within 10 meters of accuracy, which was recently reduced to 6.5 meters. "The Starlink study scratched the surface of what is possible," said Kassas.

His work suggests utilizing signals from LEO satellites as an alternative for humans' positioning, navigation and timing needs, as they reside about 20 times closer to Earth compared to GNSS satellites, which reside in medium Earth orbit - a little more than 20,000 kilometers above the planet.