DPBO Parameter Determination for DSL Crosstalk Reduction
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Solution Overview
Problem
Existing access network technologies, such as ADSL, face challenges in coexisting with newer high-bandwidth technologies like VDSL over shared twisted pair cables due to signal crosstalk, which is exacerbated by varying cable loss across different frequencies and lengths, leading to impaired service quality.
Innovation Solution
The method involves determining a set of downstream power back-off (DPBO) parameter values using a pseudo-inverse of a frequency matrix and cable loss data, allowing for accurate characterization of cable loss and reduction of crosstalk by adjusting the transmit power of VDSL signals to match the power level of ADSL signals, thereby ensuring effective coexistence of both technologies over the same wire binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If VDSL signals are transmitted over shared twisted pair cables with ADSL signals, then high-bandwidth services can be provided, but signal crosstalk occurs due to varying cable loss across different frequencies and lengths
Solution Approach 1:
The patent applies parameter changes by adjusting the transmit power spectral density of VDSL signals across different frequency bands. By modifying the power parameters dynamically based on cable loss characteristics at each frequency, the system optimizes signal transmission while minimizing crosstalk interference with ADSL signals sharing the same medium.
Solution Approach 2:
The patent implements local quality by applying frequency-specific power back-off adjustments rather than uniform power reduction across all frequencies. Each frequency component receives tailored power management based on its specific cable loss characteristics, enabling precise control of crosstalk while maintaining overall service quality.
2Reliability
If cable loss is not accurately characterized, then service quality deteriorates due to impaired signal transmission, but accurate characterization requires complex measurements across multiple frequencies and cable lengths
Solution Approach 1:
The patent uses copying by creating a mathematical model (frequency matrix representing cable loss characteristics) that replicates the complex cable behavior without requiring physical measurements for every scenario. This model can be derived from limited measurements and then reused to predict and correct cable loss effects across various conditions.
Solution Approach 2:
The patent applies parameter changes by transforming the complex cable loss characterization problem into a set of manageable parameters (frequency-dependent loss values stored in a matrix). These parameters can be efficiently computed and stored, enabling accurate cable modeling without the complexity of continuous physical measurements.
3Ease of operation
If uniform power transmission is used for VDSL signals, then transmission simplicity is maintained, but crosstalk with ADSL signals increases due to frequency-dependent cable loss variations
Solution Approach 1:
The patent applies parameter changes by implementing frequency-dependent power back-off for VDSL signals. Instead of uniform power transmission, the system dynamically adjusts power levels at different frequencies based on cable loss characteristics, effectively reducing crosstalk while maintaining operational feasibility through automated parameter adjustment.
Solution Approach 2:
The patent uses feedback by utilizing cable loss measurements and frequency matrix data to automatically determine appropriate power back-off parameters for VDSL transmission. This closed-loop approach ensures that power adjustment decisions are based on actual cable characteristics, reducing crosstalk while maintaining transmission simplicity through automated control.
Data Source
AI summary
Methods, systems, and apparatus for determining values of downstream power back-off parameters are disclosed. In one aspect, a method includes receiving cable loss data of a cable configured to deliver a digital subscriber line (DSL) signal; identifying a cable model that characterizes a cable loss value at a frequency over a length of the cable; and determining a set of downstream power back-off (DPBO) parameter values of the cable model based on a product of a pseudo-inverse of a frequency matrix including a plurality of different frequencies and a vector of the cable loss data that includes a plurality of cable loss values with respect to the plurality of different frequencies of the pseudo-inverse of the frequency matrix.