Satellite Uplink Power Control Using PSD for Adjacent-Satellite Interference
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Solution Overview
Problem
Satellite communication systems face challenges in maintaining compliance with Power Spectral Density (PSD) regulations due to dynamic changes in radiation patterns and interference with neighboring satellites, particularly when bandwidth is fixed and power back-off is the only option for non-compliance.
Innovation Solution
A method for uplink power control based on power spectral density, where a terminal's antenna determines maximum allowable modem output power using lookup tables and closed-loop control to ensure compliance with regulatory PSD limits, allowing dynamic adjustment without network intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If power back-off is used to maintain PSD compliance, then interference to neighboring satellites is reduced, but data transmission rates decrease
Solution Approach 1:
The patent implements dynamic power control that adjusts transmit power in real-time based on actual radiation patterns, scan angles, and skew conditions. Instead of static power back-off, the system continuously monitors PSD compliance and dynamically adjusts power levels, allowing maximum throughput when compliant and minimal back-off only when necessary. This resolves the contradiction by making power control adaptive rather than conservative.
Solution Approach 2:
The system employs closed-loop feedback by monitoring actual PSD levels against regulatory masks and using this information to adjust transmit power. The feedback mechanism compares measured radiation patterns with compliance thresholds and automatically adjusts power to maintain compliance while maximizing data rates. This eliminates the need for predetermined conservative back-off levels.
2Reliability
If conservative power limits are applied to ensure PSD compliance, then regulatory compliance is maintained, but unnecessary power reduction occurs reducing efficiency
Solution Approach 1:
The patent transitions from static conservative power limits to dynamic power setting based on real-time antenna radiation patterns, scan angles, and skew conditions. The system calculates actual PSD levels using measured radiation patterns and adjusts power accordingly, ensuring compliance only when necessary rather than applying universal conservative limits. This maintains reliability while eliminating unnecessary power reductions.
Solution Approach 2:
The system changes the parameter used for power control from fixed conservative limits to dynamic PSD calculations based on actual radiation patterns, scan angles, and skew. By using measured radiation pattern data and calculating actual PSD levels, the system adapts power settings to match real compliance requirements rather than predetermined conservative values, improving power efficiency while maintaining regulatory compliance.
3Device complexity
If fixed bandwidth is used in satellite communication, then system simplicity is maintained, but power back-off becomes the only option for PSD non-compliance
Solution Approach 1:
The patent changes the approach to PSD compliance from power-only control to combined bandwidth and power control. The system dynamically adjusts both bandwidth and power levels based on PSD compliance requirements, using measured radiation patterns and scan/skew conditions to determine optimal settings. This adds versatility to PSD compliance while maintaining relative system simplicity through automated control.
4Device complexity
If traditional open-loop power control is used, then system complexity is low, but latency in power adjustments increases
Solution Approach 1:
The patent implements closed-loop feedback control that continuously monitors PSD compliance and immediately adjusts power settings in response to compliance violations. The feedback mechanism uses measured radiation patterns and actual transmit conditions to make real-time power adjustments, eliminating the latency inherent in open-loop systems. This increases control system complexity but dramatically reduces power adjustment latency.
Data Source
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AI summary
A method and apparatus for uplink power control based on power spectral density are disclosed. In one embodiment, the method for use by a terminal in a satellite communication system, the terminal having an antenna, a modem and a controller, the method comprising: determining the scan and skew of the antenna; obtaining, using the controller, a value representing a maximum allowed Power Spectral Density (PSD) for the determined scan and skew; determining, using the controller, a maximum allowable modem power based on the value representing a maximum allowed PSD, where the maximum allowable modem power is that which ensures that transmissions from the terminal do not exceed the maximum allowed PSD if the maximum allowable modem output power is not exceeded by the modem; sending, using the controller, an indication of the allowable modem output power to the modem; and performing one or more transmissions from the terminal based on modem outputs in accordance with the maximum allowable modem output power.