Navigation with Multi-Constellation LEO Satellite Signals of Opportunity: Starlink, OneWeb, Orbcomm, and Iridium.

This paper summarizes current state-of-the-art navigation results with multi-constellation low Earth orbit (LEO) satellite signals of opportunity. Experimental results with four LEO satellite constellations are presented: Starlink, OneWeb, Orbcomm, and Iridium. Two receiver designs are presented: (R1) a cognitive opportunistic navigation approach, which utilizes minimal, publicly available prior knowledge about the LEO satellite signal structure and (R2) a blind approach, which assumes no prior knowledge of the signals. Stationary positioning and mobile ground vehicle navigation results are presented. For the ground vehicle, results with two frameworks are presented: (N1) a LEO-aided inertial navigation system (INS) simultaneous tracking and navigation (STAN) and (N2) a LEO-aided differential STAN. The results reveal the tremendous promise of exploiting multi-constellation LEO satellite signals of opportunity for navigation. For positioning: (i) with R1, starting with an initial estimate about 179 km away, by exploiting signals from 6 Starlink, 1 Orbcomm, and 4 Iridium, a final two-dimensional (2-D) position error of 6.5 m was achieved and (ii) with R2, starting with an initial estimate about 3,600 km away, by exploiting signals from 4 Starlink, 2 OneWeb, 1 Orbcomm, and 1 Iridium, a final 2-D position error of 5.1 m was achieved. For navigation, a ground vehicle was equipped with an industrial-grade inertial measurement unit (IMU) and an altimeter. (i) With R1 and N1, the vehicle traversed 4.15 km in 150 seconds (GNSS signals were only available for the first 2.33 km). By exploiting signals from 3 Starlink, 2 Orbcomm, and 1 Iridium, the 3-D position root mean squared error (RMSE) and final 3-D error were 18.4 m and 27.1 m, respectively. The GNSS-aided INS position RMSE and final 3-D error were 118.5 m and 472.7 m, respectively. (ii) With R2 and N2, the vehicle traversed 1.03 km in 110 seconds (GNSS signals were only available for the first 0.11 km). By exploiting signals from 4 Starlink, 1 OneWeb, 2 Orbcomm, and 1 Iridium, the 3-D position RMSE and final 3-D error were 9.5 m and 4.4 m, respectively. The GNSS-aided INS position RMSE and final 3-D error were 205 m and 525 m, respectively.