Hybrid Satellite Power Control Reducing Cushion
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Solution Overview
Problem
Satellite communication systems face significant time delays in closed-loop power control, leading to a larger power control cushion and reduced system capacity and quality of service, especially in GEO satellite systems.
Innovation Solution
A power control architecture that combines conventional closed-loop and adaptive open-loop methods, using algorithms in user terminals and gateway stations to recursively calculate returnlink power and provide accurate feedback signals, reducing the power control cushion and enhancing system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed-loop power control is used in satellite communication systems, then power control can be implemented, but the long transmission delay causes large power control cushion and reduced system capacity
Solution Approach 1:
The system performs preliminary power control adjustments using open-loop predictions based on forward link signal quality measurements before the closed-loop feedback arrives. The user terminal estimates return link conditions from forward link measurements and pre-adjusts transmit power to compensate for the anticipated delay, reducing the required power control cushion.
Solution Approach 2:
The invention introduces an intermediary open-loop power control mechanism that uses forward link signal quality as a proxy indicator for return link conditions. This intermediary measurement allows the system to make power control decisions based on more immediate feedback rather than waiting for the delayed return link quality report.
2Reliability
If power control cushion is increased to compensate for long delay, then power control reliability improves, but system capacity decreases
Solution Approach 1:
By performing preliminary power control adjustments using open-loop predictions, the system reduces the time required to achieve reliable power control, thereby reducing the cushion needed and increasing system capacity while maintaining reliability.
Solution Approach 2:
The system dynamically changes the power control cushion parameter based on channel conditions and delay characteristics. Under favorable conditions with accurate open-loop predictions, the cushion can be reduced, increasing capacity. Under adverse conditions, the cushion is increased to maintain reliability.
3Productivity
If open-loop power control is used to reduce delay impact, then system capacity increases, but power control precision decreases
Solution Approach 1:
The system merges open-loop and closed-loop power control methods into a unified hybrid approach. The open-loop component provides timely predictions to reduce delay impact and increase capacity, while the closed-loop component provides precise feedback for accurate power adjustment, combining the advantages of both methods.
Solution Approach 2:
The hybrid system incorporates feedback from both open-loop measurements (forward link signal quality) and closed-loop reports (return link quality). This multi-source feedback mechanism improves overall precision compared to using either method alone, while maintaining the speed benefits of open-loop control.
Data Source
AI summary
Devices and methods are disclosed for reducing power control cushion of a user terminal configured to communicate with a satellite and a gateway station. The present invention provides a power control algorithm implemented in a user terminal that is designed to operate in a satellite communication system. The power control algorithm can recursively calculate a returnlink power to reduce a power control cushion so that an extra link margin is available to the satellite communication system. The present invention also provides a source coding technique that provides an accurate feedback signal for the user terminal. The average metric of input signal frames is coded in a sequence of bits that are carried by contiguous output signal frames.