DSL Modem Crosstalk Compensation via Vectoring
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Solution Overview
Problem
Communication systems, particularly Digital Subscriber Line (DSL) systems, face challenges in reducing noise caused by fluctuating crosstalk due to frequent transitions between full power and low power modes, which disrupt signal decoding and increase power consumption.
Innovation Solution
Implementing vectoring techniques and monitoring crosstalk coupling characteristics to pre-code transmitted signals and process received signals, adjusting operating modes to compensate for fluctuating crosstalk effects, and using probe signals to determine crosstalk coefficients between lines, thereby minimizing non-stationary crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If modems frequently transition between full power and low power modes to conserve energy, then power consumption is reduced, but fluctuating crosstalk noise increases and disrupts signal decoding
Solution Approach 1:
The system performs preliminary detection of crosstalk coupling characteristics when a modem transitions to low power mode, and proactively notifies affected modems before the actual transition occurs. This allows victim modems to pre-adjust their signal processing parameters, compensating for the incoming crosstalk disturbance and maintaining signal decoding accuracy throughout the power mode transition.
Solution Approach 2:
The system implements a feedback mechanism where the transmitting modem detects its own crosstalk coupling characteristics to other lines and communicates this information back to the victim modems. The victim modems use this feedback information to adjust their receiving parameters dynamically, creating a closed-loop system that maintains communication quality despite power mode transitions.
2Object-affected harmful factors
If vectoring techniques are implemented to reduce fluctuating crosstalk, then signal quality improves, but system complexity increases
Solution Approach 1:
The patent extracts and measures only the specific crosstalk coupling characteristics between lines using probe signals, rather than implementing full-blown vectoring that requires complex multi-line coordination and real-time signal processing. This selective extraction approach reduces the computational burden and system complexity while still providing the necessary information for effective crosstalk compensation.
Solution Approach 2:
The system introduces probe signals as an intermediary mechanism to indirectly measure crosstalk coupling characteristics without requiring direct complex interactions between all lines. These probe signals serve as mediators that carry information about the coupling characteristics, enabling simplified calculation and compensation compared to full vectoring approaches.
3Measurement precision
If probe signals are used to determine crosstalk coefficients, then measurement precision improves, but loss of time increases due to additional signaling
Solution Approach 1:
The system performs crosstalk measurements using probe signals in advance, during connection establishment or during periods when data traffic is low. By completing the measurements beforehand, the system has the crosstalk coupling characteristics ready when power mode transitions occur, eliminating the need for time-consuming measurements during critical transition periods and minimizing impact on application processes.
Data Source
AI summary
A system that incorporates teachings of the present disclosure may include, for example, a controller to: determine crosstalk coupling characteristics between a plurality of lines of a Digital Subscriber Line (DSL) system connected to a plurality of modems based on a transition between a full power mode and one or more other modes, and provide the determined crosstalk coupling characteristics to one or more of the plurality of modems for performance of at least one of pre-coding a transmitted signal and processing a received signal along a line of the plurality of lines, where the pre-coding and processing is performed based at least in part on the determined crosstalk coupling characteristics, and where the pre-coding of the transmitted signal and the processing of the received signal reduce effects of fluctuating crosstalk. Other embodiments are disclosed.