A TDOA-Assisted Direct Position Determination for Efficient Geolocalization Using LEO Satellites

This paper presents an initial effort for the trusted geolocation of Internet of Things (IoT) devices based on the booming low-earth-orbit (LEO) satellites. As the high signal-to-noise ratio (SNR) reception cannot always be guaranteed at LEO satellites, the recently developed direct position determination (DPD) approach is adopted. For such passive localization systems, the efficient DPD execution is challenging due to the vast coverage area of LEO satellites. In order to reduce the computational complexity, we propose a method to narrow the search area using the time difference of arrival (TDOA) measurements and error variances. In this way, the size of the searching area is determined by both geometrical constraints and qualities of received signals, and signals with a higher SNR are more effective in positioning as their search areas are usually smaller. The superior accuracy performance of the proposed method is also verified through the comparison with conventional two-step methods. Mento Carlo simulations show that the proposed approach provides a robust and trusted localization service, and the positioning error is less than 10 kilometers when the SNR is lower than -15dB.