Wideband OFDMA Power Equalization for CATV Upstream
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Solution Overview
Problem
Existing CATV systems face challenges in equalizing transmit power levels across wide OFDMA channels due to varying power levels within the 96 MHz channel, which can lead to signal interference and reduced bandwidth at higher frequencies.
Innovation Solution
A method to calculate power adjustments using calibration measurements across the upstream spectrum, employing a polynomial function to determine appropriate transmit power levels for each frequency within the OFDMA channel, ensuring equalization at the receiver input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional single power level measurement per channel is used, then device complexity is reduced, but manufacturing precision of power equalization deteriorates due to wide 96 MHz OFDMA channel variations
Solution Approach 1:
The patent segments the wide 96 MHz OFDMA channel into multiple frequency subsets (e.g., low, mid, high frequency ranges), and performs separate power measurements on each subset. This segmentation allows the system to capture power variations across the wide bandwidth while managing measurement complexity through structured subdivision of the frequency spectrum.
Solution Approach 2:
The patent applies local quality by performing power measurements at multiple specific frequency points within different subsets of the OFDMA channel, rather than using a single averaged measurement. This localized measurement approach ensures that power variations at different frequency regions are accurately captured and compensated, improving overall power equalization precision.
2Reliability
If power levels are not equalized across frequency, then device complexity is reduced, but signal interference increases due to varying power levels within the channel
Solution Approach 1:
The patent changes the power parameter dynamically across different frequency subsets by calculating separate power adjustment values for each frequency range. The system adjusts the transmit power level based on measured power variations in low, mid, and high frequency subsets, ensuring consistent received power levels across the entire 96 MHz OFDMA channel and reducing signal interference.
3Productivity
If wide 96 MHz channels are used, then bandwidth efficiency is improved, but power equalization becomes difficult due to frequency-dependent power variations
Solution Approach 1:
The patent segments the wide 96 MHz channel into multiple frequency subsets for separate power measurement and adjustment. This segmentation enables the system to maintain wide bandwidth utilization while achieving precise power equalization across each subset, resolving the conflict between bandwidth efficiency and power level consistency.
Solution Approach 2:
The patent applies local quality measurements at multiple frequency points within the wide channel and applies frequency-specific power adjustments. This approach maintains the benefits of wide 96 MHz channel bandwidth while ensuring consistent power levels across different frequency regions, enabling both high productivity and precise power equalization.
Data Source
AI summary
Devices, systems, and methods for determining adjustments used by an upstream transmitters to set the transmit power of at least one upstream OFDMA channel, where the adjustments are made using calibration values to determine constants in continuous expression of power as a function of frequency, and thereafter using the function to determine the adjustment.