DSL Noise Cancellation via Sync Symbol Extraction
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Solution Overview
Problem
Existing DSL technologies face significant performance degradation due to noise interference, particularly from residual DSL data signal energy in noise reference signals and non-optimal frequency band focus in conventional cancellation techniques, leading to data rate loss and inefficient noise cancellation.
Innovation Solution
The use of techniques that acquire and store noise-free synchronization symbols to clean up noise reference signals, create simulated data transmission silence, and employ frequency band agile cancellation to avoid detrimental frequency bands, allowing for effective noise cancellation and optimized frequency band focus, thereby enhancing DSL data transmission performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise cancellation techniques using line-derived noise reference signals are employed, then noise reduction is achieved, but data signal cancellation occurs due to residual DSL data signal energy in the noise reference signal
Solution Approach 1:
The patent extracts and removes the residual DSL data signal energy from the noise reference signal before using it for noise cancellation. This is achieved by processing the noise reference signal to separate and eliminate the correlated data signal components, leaving only the pure noise components for cancellation. This resolves the contradiction by removing the harmful data signal portion while preserving the useful noise reduction capability.
Solution Approach 2:
The patent applies different processing treatments to different frequency bands or signal components within the noise reference signal. By identifying and selectively processing only the portions containing residual data signal energy while leaving other portions intact, the system achieves local optimization that eliminates data cancellation in affected bands while maintaining noise cancellation effectiveness in other bands.
2Object-affected harmful factors
If broadband energy-reducing cancellation algorithms are used, then overall noise energy is reduced, but frequency band optimization is lost resulting in poor DSL transmission performance improvement
Solution Approach 1:
The patent transitions from uniform broadband noise reduction to frequency-selective noise cancellation by applying different cancellation strategies to different frequency bands. Each frequency band is analyzed and processed individually based on its noise characteristics and importance to DSL performance, allowing optimization of cancellation focus in bands that yield the greatest performance enhancement while avoiding bands where cancellation would be detrimental.
Solution Approach 2:
The patent dynamically adjusts cancellation parameters such as filter coefficients, cancellation depth, and frequency weighting based on the specific noise conditions and DSL signal characteristics in each frequency band. This parameter optimization allows the system to achieve better DSL performance by adapting the cancellation behavior to match the actual transmission requirements and noise profile of each frequency region.
Data Source
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AI summary
A method and apparatus in a noise cancellation system that receives a noise reference signal via a noise reference signal input port, and performs at least one of procedures a and b set forth below for reducing noise in a DSL data signal transmitted on a DSL transmission line to which the noise cancellation system is coupled: a.i.) creating a noise free representation of a DSL synchronization symbol repeatedly occurring in the transmitted DSL data signal, and a.ii.) reducing the noise in the transmitted DSL data signal based on the noise free representation of the DSL synchronization symbol and the received noise reference signal, and b.i.) analyzing at least one of the received noise reference signal and the transmitted DSL data signal to identify one or more frequency bands in which to de-emphasize noise cancellation in the transmitted DSL data signal, and b.ii.) causing the noise cancellation system to de-emphasize noise cancellation in the identified one or more frequency bands of the transmitted DSL data signal, responsive to the analysis.