Automatic Uplink Power Control in Satellite Interference Cancellation
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Solution Overview
Problem
Existing satellite communication systems require signal quality reports from remote stations and satellite beacons to maintain a constant signal-to-noise ratio, which is inefficient and unsuitable for point-to-multipoint systems, as they rely on estimating total attenuation rather than specific uplink and downlink attenuations, leading to potential transponder saturation.
Innovation Solution
Implementing automatic uplink power control at the hub station using interference cancellation to estimate and compensate for uplink attenuation without requiring signal quality reports or satellite beacons, by monitoring signal levels and energy per bit to noise power spectral density ratios, allowing for independent power adjustments based on estimated attenuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic uplink power control is implemented using total attenuation estimation from remote station feedback, then signal-to-noise ratio is maintained, but system complexity increases and transponder saturation occurs
Solution Approach 1:
The patent extracts and separates the uplink attenuation estimation from the total attenuation measurement. Instead of using overall attenuation measured at the remote station, the invention directly estimates uplink attenuation at the hub station by analyzing the relationship between uplink signal strength and downlink signal strength, eliminating the need for remote station feedback and complex coordination.
Solution Approach 2:
The patent uses the downlink signal as an intermediary to infer uplink attenuation conditions. By measuring the downlink signal strength at the hub station and comparing it with the transmitted uplink signal strength, the system can estimate uplink attenuation without direct measurement or feedback, using the downlink signal as a mediator to carry information about channel conditions.
2Reliability
If uplink power is boosted to compensate for both uplink and downlink attenuation, then signal reliability improves, but transponder saturation occurs
Solution Approach 1:
The patent segments the attenuation compensation into separate uplink and downlink components. Instead of treating total attenuation as a single value requiring unified compensation, the invention separately estimates uplink attenuation and applies power control only to the uplink transmission, leaving downlink compensation to be handled by adaptive coding and modulation at the receiver.
Solution Approach 2:
The patent applies partial action by compensating only for uplink attenuation rather than total attenuation. The uplink power control adjusts power based on estimated uplink conditions alone, providing sufficient compensation for uplink losses without the excessive power boost that would cause transponder saturation, while relying on other mechanisms for downlink compensation.
3Measurement precision
If satellite beacons are used for uplink attenuation estimation, then power control accuracy improves, but device complexity and cost increase
Solution Approach 1:
The patent enables the hub station to perform self-service attenuation estimation without external assistance from satellite beacons or remote station feedback. The hub station uses its own transmitted uplink signal and the corresponding received downlink signal to estimate uplink attenuation, making the system self-sufficient and eliminating the need for additional beacon infrastructure or complex receiver configurations.
Solution Approach 2:
The patent makes the downlink signal serve multiple functions: it carries information for adaptive coding and modulation while simultaneously serving as a reference for uplink attenuation estimation. This multi-functionality eliminates the need for separate beacon signals, as the regular downlink transmission is reused for dual purposes, reducing system complexity and cost.
Data Source
AI summary
A system and method for performing automatic uplink power control (AUPC), using interference cancellation, to compensate for signal attenuation in a satellite communication system in which uplink path attenuation, forward channel attenuation, or both are estimated at a hub station without requiring signal quality reports from a remote station, and without requiring a satellite beacon. Estimates of uplink path attenuation or forward channel attenuation are used by the hub station to control the output power of a transmitted signal, thereby compensating for the estimated attenuation.