LEO Satellite Constellation GPS Correction Dissemination
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Solution Overview
Problem
The existing GPS system faces accuracy issues due to errors in atomic clock and ephemeris data that increase over time, as the latency in correcting these errors is high due to limitations in telemetry, tracking, and control aspects, leading to inadequate frequency of correction data dissemination to user equipment.
Innovation Solution
A LEO satellite constellation is used to disseminate GPS correction data worldwide by selecting a subset of spot beams for broadcasting, maximizing swath width and controlling message latency, thereby enhancing navigation solution accuracy without compromising the primary duties of the LEO satellites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS correction data is uploaded daily to GPS satellites, then the data can be transmitted to global users, but the errors in GPS data grow proportional to time from upload due to latency in control segment processing
Solution Approach 1:
LEO satellites serve as intermediary nodes between GPS satellites and ground users. They receive GPS correction data from GPS satellites and relay it to users in near-real-time, eliminating the need for daily uploads to GPS satellites and reducing the latency inherent in ground-based control segment processing and retransmission.
Solution Approach 2:
The system introduces a new spatial dimension by placing correction data dissemination in low earth orbit. Instead of relying solely on ground-based control segments that process and retransmit data with latency, LEO satellites provide a direct orbital pathway for rapid global distribution of correction data, fundamentally changing the temporal characteristics of data delivery.
2Productivity
If LEO satellites broadcast GPS correction data using all available spot beams, then correction data can be disseminated worldwide frequently, but the performance of LEO satellites with respect to unrelated broadcast duties is compromised
Solution Approach 1:
The system uses only a subset of available LEO satellite spot beams for GPS correction data broadcast rather than all beams. This partial action approach provides sufficient global coverage through coordinated multiple satellites while preserving the majority of beam resources for primary communication duties, thus maintaining LEO satellite performance reliability.
Solution Approach 2:
The spot beam resources are segmented into distinct functional allocations: a subset dedicated to GPS correction data broadcast and the remaining beams reserved for primary communication duties. This segmentation allows independent optimization of each function without mutual interference, enabling frequent correction data dissemination while maintaining communication reliability.
3Area of stationary object
If the subset of spot beams is not optimized, then GPS correction data can be broadcast simply, but the swath width of the footprint on earth is reduced, requiring more satellites or longer transmission time
Solution Approach 1:
The system pre-calculates and stores optimal spot beam subsets for maximizing swath width coverage before operational deployment. These pre-computed beam configurations account for satellite orbital mechanics and ground coverage requirements, enabling rapid selection of optimal beams during operation without real-time computation complexity.
Solution Approach 2:
The system varies spot beam selection parameters (which specific beams are activated) based on satellite position, orbital phase, and coverage requirements. By dynamically changing beam selection parameters rather than using fixed beam configurations, the system maximizes swath width at different orbital positions while managing complexity through parameterized control algorithms.
Data Source
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AI summary
Methods and systems enhance the accuracy of the global positioning system (GPS) using a low earth orbiting (LEO) satellite constellation. According to embodiments described herein, GPS data is received from GPS satellites at a GPS control segment and is used to create GPS correction data to be utilized by user equipment to correct errors within the GPS data. The GPS correction data is transmitted from the GPS control segment to a LEO ground segment, where it is uplinked to the LEO satellite constellation. To account for bandwidth constraints and minimize any performance degradation of the LEO satellites, the GPS correction data is broadcast to earth on a subset of the total number of available spot beams. The subset of spot beams is selected in part according to satellite angular velocity, bandwidth constraints, and message latency estimates.