Power Spectrum Density Optimization for DSL Crosstalk
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Solution Overview
Problem
Crosstalk interference limits the performance of DSL systems such as ADSL2, VDSL2, and G.fast, as existing methods for reducing crosstalk do not effectively stabilize transmit power and optimize power spectrum density (PSD) across initialization and showtime phases.
Innovation Solution
A system and method that utilize detection tones to estimate crosstalk-free feedback data, allowing for the optimization of PSD by adjusting power levels across tones, maintaining a consistent or similar PSD from initialization to showtime phases, thereby stabilizing data throughput and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If crosstalk precoding is used to cancel FEXT between subscriber lines, then crosstalk interference is reduced, but transmit power stability and PSD optimization across initialization and showtime phases deteriorates
Solution Approach 1:
The system performs preliminary PSD optimization during the initialization phase by detecting background noise on quiet tones and calculating optimized PSD values before transitioning to showtime phase. This preliminary action ensures that when crosstalk precoding is activated in showtime, the transmit power levels are already optimized and stable, preventing power fluctuations.
Solution Approach 2:
The system uses feedback from background noise detection on quiet tones to continuously optimize PSD. The receiver detects background noise during quiet tones, feeds back this information to the transmitter, which then adjusts transmit power levels accordingly. This closed-loop feedback mechanism maintains transmit power stability even when crosstalk precoding is active.
2Object-affected harmful factors
If existing crosstalk reduction methods are used, then some crosstalk cancellation is achieved, but PSD optimization and data rate capacity deteriorate
Solution Approach 1:
The system optimizes PSD by changing the power level parameter for each tone based on detected background noise characteristics. By adjusting the power spectral density distribution across different tones according to actual channel conditions, the system achieves both effective crosstalk cancellation and maximized data rate capacity, resolving the contradiction between the two objectives.
3Productivity
If transmit power is increased to improve signal quality, then data rate capacity improves, but power consumption increases
Solution Approach 1:
Instead of uniformly increasing transmit power across all tones, the system applies local quality optimization by adjusting power levels individually for each tone based on its specific background noise characteristics and channel conditions. This allows the system to achieve necessary data rate capacity only where needed, minimizing overall power consumption while maintaining productivity.
Data Source
AI summary
A method comprising allocating one or more detection tones of a sync symbol for crosstalk-free feedback data estimation, wherein the one or more detection tones are a quiet signal; transmitting the one or more detection tones to a computing device, receiving the crosstalk-free feedback data from the computing device, wherein the crosstalk-free feedback data comprises data associated with a background noise detected during the detection tones; determining an optimized PSD based at least in part on the crosstalk-free feedback data; and adjusting a transmission PSD of a plurality of tones based at least in part on the optimized PSD.