Vectoring for Low Power Modes in DSL Systems
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Solution Overview
Problem
High-speed data transmission over telephone lines faces cross-talk issues between copper wires, particularly when using low power modes with few symbols transmitted, which complicates signal interference mitigation.
Innovation Solution
The method involves determining and using precoder and postcoder matrices to manage cross-talk between high and low power lines, ensuring that the transmission and reception processes do not mitigate the cross-talk effects in a way that compromises signal quality, particularly by setting specific scaling matrices to maintain desired thresholds and power levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low power modes are used where no or only few symbols are sent over some lines, then power consumption is reduced, but cross-talk mitigation complexity increases
Solution Approach 1:
The system segments lines into high power lines and low power lines, applying different transmission strategies to each segment. Low power lines transmit no or few symbols while high power lines maintain normal transmission, allowing selective power management without requiring complex cross-talk mitigation for all lines
Solution Approach 2:
Instead of applying full cross-talk mitigation processing to all lines, the system applies precoding selectively - the precoder matrix is determined and applied regardless of whether low power lines are transmitting symbols, but the mitigation is optimized to handle the partial transmission scenario where only high power lines are active
2Reliability
If precoding is applied to mitigate cross-talk between all lines, then signal quality is improved, but the cross-talk effect from high power lines to low power lines is not properly addressed in low power modes
Solution Approach 1:
The precoder matrix is designed with local quality optimization - it is determined and applied specifically to address the cross-talk scenario where high power lines transmit symbols and low power lines do not. The matrix structure accounts for the asymmetric transmission pattern, providing targeted cross-talk mitigation for the high-to-low power line direction without requiring full bidirectional mitigation
Solution Approach 2:
The system changes the transmission parameters dynamically - the precoder matrix determination and application is performed based on the transmission mode (whether low power lines are sending symbols or not). This parameter adaptation allows the same precoding framework to handle both full-power and low-power modes effectively
Data Source
AI summary
In one embodiment, the method includes determining (S410), at an access node (100), a precoder matrix for precoding transmission from the access node to a plurality of downstream devices (200) over a plurality of lines. The plurality of lines include high power lines and low power lines. The high power lines are in active communication and transmit more symbols per frame than the low power lines. The method further includes precoding (S420) a signal vector using the precoder matrix regardless of the symbols the signal vector is sending over the low power lines. Here, the determining determines the precoder matrix such that the precoding does not mitigate the cross-talk effect the high power lines have on the low power lines. The method also includes transmitting (S430) over the plurality of lines based on the precoded signal vector.