Adaptive Crosstalk Cancellation in XDSL Signal Processing
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Solution Overview
Problem
Existing methods for canceling far-end crosstalk in xDSL systems are hindered by the need for a pre-known channel transmission matrix, which is difficult to obtain accurately and is susceptible to environmental changes, limiting their effectiveness in various scenarios.
Innovation Solution
A multi-channel signal processing system with a filter unit at the transmitting end and a feedback unit at the receiving end, using adaptive filter techniques to calculate new filter weight coefficients based on received feedback information, simulates and generates far-end crosstalk signals to pre-cancel noise before transmission, allowing for continuous convergence and effective cancellation of crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pre-known channel transmission matrix is used for crosstalk cancellation, then the calculation can be performed with a fixed filter in the frequency domain, but the matrix is difficult to obtain accurately and is susceptible to environmental changes, reducing reliability
Solution Approach 1:
The patent transforms the static fixed filter approach into a dynamic adaptive filter system. The filter coefficients are continuously updated using feedback from the receiving end through an adaptive algorithm (such as LMS or RLS), allowing the system to automatically adapt to environmental changes and maintain accurate crosstalk cancellation without requiring a pre-known channel matrix.
Solution Approach 2:
The patent introduces a feedback mechanism where the receiving end sends feedback information (such as error signals or channel state information) back to the transmitting end. This feedback is used to continuously update the filter coefficients, enabling the system to self-adjust and maintain optimal performance despite environmental variations, thereby resolving the reliability issue.
2Reliability
If adaptive filtering with feedback is implemented, then accuracy of crosstalk cancellation is improved, but the system complexity increases due to additional feedback unit and coefficient calculation
Solution Approach 1:
The patent combines the filter unit and feedback unit into an integrated adaptive filtering system. The feedback unit and filter unit work together as a unified structure where feedback information is directly processed to update filter coefficients, reducing the need for separate independent components and managing system complexity through functional integration.
3Adaptability or versatility
If filter weight coefficients are continuously updated based on feedback, then the system adapts to environmental changes, but the calculation complexity and processing time increase
Solution Approach 1:
The patent implements periodic updates of filter coefficients based on feedback intervals rather than continuous updates. The adaptive filter recalculates coefficients at specific time intervals or based on trigger conditions (such as significant channel changes), balancing adaptability with computational efficiency and reducing unnecessary processing time.
Data Source
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AI summary
A multiplex signal processing system. The multiplex signal processing system includes a filter unit (310) at sending end and a feedback unit (321) at receiving end, the filter unit (310) includes a signal synthesizing unit (312) and a filter (311), wherein the filter (311) is used for filtering cross-talk resource signal of signal being sent, and according to received feedback information, subsequently continued filtering; the signal synthesizing unit (312) is used for receiving inputted signal being sent and receiving the filter (311) filtered cross-talk resource signal, and synthesizing the signal being sent and the cross-talk resource signal; the feedback unit (321) feeds back the filter (311) according to the received signal being sent. A filter device, a signal processing chip, an external signal processing card and a multiplex signal processing method. The far end cross-talk signal can be adaptively cancelled.