Broadband LEO Constellations for Navigation

Abstract

There has been resurgent interest in building low Earth orbiting (LEO) constellations of satellites on a new scale. Their aim is Internet for the world with plans for potentially thousands of satellites. Here, we explore how these LEO constellations can be utilized for navigation. Closer to Earth, LEO offers stronger signals, strengthening us against jamming and aiding in indoor and urban environments. Proximity is also its weakness, where satellites have a small Earth footprint requiring many to provide global coverage. We show that the strength of the Broadband LEO constellations is their numbers, where they offer threefold improvement in satellite geometry compared to navigation core-constellations today. This allows for relaxation of the signal-in-space user range error, while still matching the position accuracy of GPS. Coupled with the more benign radiation environment in LEO compared to GPS in medium Earth orbit, this enables a navigation payload designed using commercial-off-the-shelf components.

Fault-Free Integrity Analysis of Mega-Constellation-Augmented GNSS

“…However, today's circumstances are di erent. We face a paradigm shift where imminent mega-constellations have the potential to increase the number of operational satellites by at least tenfold [5], and the surge of autonomous systems, partic-ularly ground vehicles, require centimeter-level positioning in GNSS-challenged environments. There is significant potential to improve GNSS navigation performance by using these mega-constellations.…”

“…Another implementation can be found in [4] where LEO satellite signals were used to limit the drift of inertial sensors in GPS-denied areas. More recent work in [5] examined the major components that could allow soon to be deployed mega-constellations to act as navigation satellites if they hosted a dedicated payload.…”

Proposed Orbital Products for Positioning Using Mega-Constellation LEO Satellites

“…Since these LEO satellites are primarily used for communications, to enable positioning, it is proposed that either additional payloads are added to these satellites to provide GNSS-like signals or employ their signals as signals of opportunity for positioning (SOOP) [ 1 ]. Different from the GNSS satellites that are located at the medium Earth orbits (MEOs), the LEO satellites at lower latitudes of about 300 to 1500 km [ 2 ] are able to provide ground users with much stronger signals, which enables positioning in GNSS-challenging areas and makes the signals more resilient against jamming [ 3 ]. A large number of LEO satellites launched or to be launched in the near future by companies such as Iridium, Globalstar, SpaceX, OneWeb, Samsung and Boeing does not only benefit the overall satellite geometry and thus the position dilution of precision (PDOP), the fast-moving LEO satellites and the rapidly changing geometry can also reduce the long convergence time in the precise point positioning (PPP) [ 4 ].…”

Performance Evaluation of Navigation Using LEO Satellite Signals with Periodically Transmitted Satellite Positions

“…LEO satellites are particularly attractive aiding sources for a vehicle's INS in GNSS-challenged environments for several reasons: (i) they are around twenty-times closer to Earth compared to GNSS satellites which reside in medium Earth orbit (MEO), making their received signals between 300 to 2,400 times more powerful than GNSS signals; (ii) thousands of broadband Internet satellites will be launched into LEO by OneWeb, Boeing, SpaceX (Starlink), among others, bringing an abundance of signal sources [25]; and (iii) each broadband provider will deploy satellites into unique orbital constellations transmitting at different frequency bands, making their signals diverse in frequency and direction [26].…”