LEO GNSS Spectrum Underlay for Rapid Carrier-Phase Positioning
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Solution Overview
Problem
Existing GNSS technologies face challenges in achieving global, rapid, and affordable centimeter-level positioning with integrity, particularly due to spectrum limitations and the need for expensive infrastructure, and current methods like RTK and PPP do not provide timely integrity warnings.
Innovation Solution
A GNSS carrier phase-based positioning system utilizing LEO and MEO satellite constellations, which estimates carrier phase biases through two processing steps to enable rapid, high-integrity, centimeter-level accuracy by leveraging LEO satellite signals broadcast at a lower power flux density, allowing access to limited spectrum for enhanced positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RTK positioning uses a dense network of ground reference stations to achieve centimeter-level accuracy, then positioning precision is improved, but infrastructure cost and complexity increase
Solution Approach 1:
The patent introduces LEO satellites as intermediary relay stations between MEO GNSS satellites and ground receivers. These LEO satellites carry precise clock and ephemeris data from MEO satellites down to the ground, enabling centimeter-level positioning without requiring dense ground reference station networks. The LEO constellation acts as a mobile intermediary that bridges the gap between space-based signal sources and ground-based measurement points.
2Area of stationary object
If PPP provides nearly global centimeter-level positioning service, then geographic coverage is improved, but convergence time increases to 10-15 minutes
Solution Approach 1:
The patent pre-loads precise ephemeris and clock correction data onto LEO satellites during their passes over ground reference stations. This preliminary action allows the LEO satellites to carry up-to-date precise orbital and timing information to regions that may not have direct access to ground stations, enabling rapid convergence of PPP solutions globally without the 10-15 minute delay.
3Measurement precision
If LEO satellites broadcast at higher power flux density to improve signal strength, then positioning accuracy is improved, but spectrum regulatory compliance deteriorates
Solution Approach 1:
The patent implements different power flux density levels for different LEO satellite functions: higher power for positioning-related carrier phase signals and lower power for other communications. This local quality differentiation allows the system to optimize positioning accuracy in specific spectrum bands while complying with regulatory limits in other bands, effectively separating the quality requirements for different signal types.
4Stability of the object's composition
If GNSS spectrum bands are tightly regulated to protect existing services, then service stability is improved, but access for new high-performance applications deteriorates
Solution Approach 1:
The patent transitions from traditional two-dimensional spectrum allocation (frequency and time) to a three-dimensional approach by adding the spatial dimension through LEO satellite orbits. By utilizing the orbital dimension, the system can provide high-performance positioning services in underused spectral regions at different altitudes and locations, effectively expanding spectrum access without interfering with existing ground-based GNSS services.
Data Source
AI summary
A global, rapid acquisition, centimeter-level accuracy, high-integrity, space-based positioning service for autonomous ground vehicles, unmanned aerial vehicles (UAS), air taxis, all-weather aircraft precision landing, precision agriculture, and offshore machine control is presented. Low Earth orbit (LEO) constellations of satellites are a means to enhance medium Earth orbit (MEO) global satellite navigation systems (GNSS). An efficient spectrum broadcast “underlay” that enables users to access LEO carrier phase signals and their broad applications. User equipment employs coherent feed forward of the MEO GNSS ambiguous solution to recover the LEO carrier phase broadcast via robust coherent signal processing gain. Subsequently, the LEO carrier phase residuals enable rapid resolution of the unknown carrier phase biases to yield rapid acquisition of high-performance user positioning.