Satellite Uplink Scheduling for Link Availability
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Solution Overview
Problem
Current uplink scheduling algorithms for satellite constellations, such as the Galileo system, face challenges in meeting stringent Link Availability (LA) requirements, particularly when the number of satellites exceeds the number of ground station antennas, leading to convergence issues and inability to support complex LA specifications for services like the Commercial Service (CS).
Innovation Solution
A method and apparatus for determining a schedule that selects a subset of satellites for contact with ground station antennas to maximize spatial diversity, ensuring efficient use of ground stations and meeting LA requirements by allocating satellites that maintain current data and support real-time communications, while also considering Navigation Data Refresh Rate and Minimum Contact Duration requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of satellites exceeds the number of ground station antennas, then more satellites can be monitored, but link availability deteriorates due to insufficient antenna resources
Solution Approach 1:
The patent implements dynamic satellite selection and allocation that adapts to changing orbital positions and ground station availability. The system continuously evaluates which satellites are visible and allocates antenna resources dynamically based on current conditions, allowing the constellation to maintain high link availability even when satellite count exceeds antenna count.
Solution Approach 2:
The system changes the parameter of satellite-antenna allocation by implementing flexible many-to-many matching instead of fixed one-to-one pairing. This allows multiple satellites to share antenna resources across different time slots, effectively increasing the capacity of the ground station network to handle larger satellite constellations.
2Productivity
If a subset of satellites is selected for contact, then antenna resources are optimized, but spatial diversity may be reduced
Solution Approach 1:
The patent applies local quality by selecting satellites based on their specific orbital characteristics, visibility windows, and service requirements. Different regions of the satellite constellation are allocated to different ground stations based on local geometric conditions, maximizing spatial diversity while optimizing antenna utilization in each local context.
Solution Approach 2:
The system adds the time dimension to satellite-antenna allocation, allowing satellites to be contacted by different antennas at different times. This temporal dimension enables the system to maintain spatial diversity across the constellation while achieving high antenna utilization efficiency through repeated contacts over the scheduling period.
3Reliability
If complex Link Availability requirements are implemented, then service quality improves, but scheduling algorithm convergence becomes difficult
Solution Approach 1:
The patent segments the complex Link Availability requirements into multiple simpler constraints that can be processed independently. By breaking down the overall LA requirement into individual satellite-antenna contact constraints, the scheduling algorithm can converge more easily while still satisfying the comprehensive service quality requirements.
Solution Approach 2:
The system implements partial satisfaction of Link Availability requirements in each scheduling iteration, progressively approaching full compliance. Rather than requiring complete satisfaction of all complex constraints simultaneously, the algorithm achieves convergence by incrementally improving link availability across the constellation.
Data Source
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AI summary
A method and apparatus are provided for determining a schedule for a contact between a ground segment and a space segment. The ground segment comprises multiple ground stations, each ground station having one or more antennas, such that the overall number of ground station antennas in the ground segment is (Nant), and the space segment comprises a constellation of satellites in orbit, in which the number of satellites is (Nsat). The method comprises selecting a subset of no more than Nant satellites from the Nsat satellites for contact at a given epoch with the ground segment; and allocating each of the selected Nant satellites to the Nant antennas in a one-to-one relationship at the given epoch. The selecting of the subset of no more than Nant satellites from the Nsat satellites comprises determining a subset of the Nant satellites that has maximum spatial diversity.