Is LEO-Based Positioning with Mega-Constellations the Answer for Future Equal Access Localization?

Capital expenditures and indoor challenges are two of the main obstacles towards equal-access positioning services worldwide. Global Navigation Satellite Systems (GNSS) are not well functioning indoors and in some outdoor challenging scenarios, such dense forest canopies, or hilly terrains rich in vegetation, due, for example, to multipaths and low carrier-to-noise ratios. Terrestrial solutions can be nowadays used to complement GNSS, but they are typically costly to deploy with high coverage and do not offer equal access, for example in some low-revenue countries, in regions forbidding wireless 5G access due to health concerns, or in areas hard to reach with terrestrial infrastructure, such as deep jungle, desert areas with sandy dunes, or deep valleys/deep canyons. As many Low Earth Orbit (LEO) mega-constellations are emerging and their satellites are significantly closer to Earth than GNSS satellites, solutions based on LEO could complement GNSS. LEO-based communications are expected to be widespread in the next decade, and they will offer a global and-easy-to-access infrastructure, with the main costs to the end user coming from the receiver equipment. It is our assumption that future wireless receivers will support the integration of terrestrial and satellite infrastructure, and thus, the LEO-based positioning tasks could be mainly implemented as software adds-on on existing future receivers. Nevertheless, a closer proximity to Earth does not automatically mean stronger received signals or acceptable positioning accuracy, especially when the carrier frequencies of the new LEO signals are higher than those in GNSS. In here, we present a feasibility study of LEO-based equal-access localization, by looking at the current opportunities, benefits, and challenges of LEO mega-constellations used as signals of opportunities (SoO). We show that there is an unharnessed-yet potential of future LEO mega-constellations for equal-access localization, although several chal-lenges are still to be overcome.