Proposed Orbital Products for Positioning Using Mega-Constellation LEO Satellites

Abstract

With thousands of low Earth orbit (LEO) satellites to be launched in the near future, LEO mega-constellations are supposed to significantly change the positioning and navigation service for ground users. The goal of this contribution is to suggest and discuss the feasibility of possible procedures to generate the LEO orbital products at two accuracy levels to facilitate different positioning methods—i.e., Level A orbits with meter-level accuracy as LEO-specific broadcast ephemeris, and Level B orbits with an accuracy of centimeters as polynomial corrections based on Level A orbits. Real data of the LEO satellite GRACE FO-1 are used for analyzing the error budgets. For the Level A products, compared to the orbital user range errors (OUREs) of a few centimeters introduced by the ephemeris fitting, it was found that the orbital prediction errors play the dominant role in the total error budget—i.e., at around 0.1, 0.2 and 1 m for prediction intervals of 1, 2 and 6 h, respectively. For the Level B products, the predicted orbits within a short period of up to 60 s have an OURE of a few centimeters, while the polynomial fitting OUREs can be reduced by a few millimeters when increasing the polynomial degree from one to two.

Deployment of Constellation with Different Inclinations Using the Nodal Precession and Thrust

“…Satellite constellations are satellite systems consisting of multiple satellites with stable geometrical configurations of space orbits and fixed spatial and temporal relationships between the satellites to fulfil specific space missions, which can give greater play to the role of satellites and expand the forms of satellite applications [ 1 ]. It has advantages that are incomparable to those of a single satellite in terms of global coverage, multiplicity, timeliness, and continuity, but at the same time, its construction costs are also incomparable to those of a single satellite, especially at the deployment phase.…”

An improved method for LEO orbit prediction using predicted accelerometer data

“…For precise positioning in the user end, real-time precise orbit and clock products for the LEO satellites are crucial. Typically, there are two common processing models for the LEO orbit determination: the centralized model and the distributed model (Li et al 2019; Wang et al 2020a). The centralized model involves processing data in ground center and uploading the predicted orbits to satellites for broadcast.…”

Visibility of LEO Satellites under Different Ground Network Distributions

“…For applications that need to continuously downlink high-capacity data or highresolution images from LEO satellites to ground stations, this implicitly requires a high-density ground network to guarantee at least the continuous tracking of the satellite signals. Users in remote areas or on the ocean might need to wait for the following downlink when the LEO satellite becomes visible again to the ground network, resulting in a latency of a few hours (Wang & El-Mowafy, 2020). In Yang et al, (2020), LEO satellite clocks were estimated using simulated signals transmitted to ground stations, where the regional network has led to interruptions in the data and results due to the incontinuous data tracking.…”