DSL Joining Line Crosstalk Estimation via Sparse Pilot Transmission
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Solution Overview
Problem
The initialization time in DSL communication systems is prolonged due to the need for extensive pilot signal transmission across multiple active lines, which increases with the number of lines, affecting data rates and capacity due to crosstalk interference.
Innovation Solution
The method involves determining a crosstalk coupling vector for a joining line by transmitting pilot signals across a reduced number of disturber lines, using compressive sensing and orthogonal matching pursuit algorithms to estimate crosstalk, thereby reducing the number of time instances required for initialization and applying precoder coefficients to mitigate crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pilot signals are transmitted across all active lines to determine crosstalk coefficients, then measurement precision is improved, but loss of time increases due to the large number of time instances required
Solution Approach 1:
The patent segments the set of all active lines into two groups: disturber lines (which cause significant crosstalk) and non-disturber lines. By focusing pilot signal transmission only on disturber lines, the system divides the measurement task into manageable segments, reducing the total number of pilot transmissions required while still achieving sufficient crosstalk coefficient accuracy for initialization.
Solution Approach 2:
The patent applies partial action by transmitting pilot signals on only a subset of lines (specifically, only disturber lines) rather than all active lines. This partial measurement approach is sufficient to determine the crosstalk coefficients needed for the joining line's initialization, thereby reducing the number of time instances required without completely sacrificing measurement precision.
2Productivity
If the number of active communication lines increases, then system capacity is improved, but device complexity increases due to the quadratic growth in pilot signal transmissions
Solution Approach 1:
The patent segments the active lines into disturber and non-disturber categories, allowing the initialization process to focus only on the relevant subset. This segmentation prevents the complexity from growing quadratically with the total number of lines, as the number of pilot transmissions depends only on the number of disturber lines, which remains relatively small even as system capacity increases.
Solution Approach 2:
The patent applies local quality by treating different lines differently based on their crosstalk characteristics. Instead of applying the same measurement procedure uniformly to all lines, the system identifies and focuses resources on disturber lines that have significant impact, thereby reducing overall system complexity while maintaining effectiveness.
3Reliability
If pilot signals are transmitted on more lines, then reliability of crosstalk determination is improved, but use of energy increases due to extended transmission duration
Solution Approach 1:
The patent uses partial action by transmitting pilot signals only on disturber lines rather than all active lines. This partial transmission is sufficient to reliably determine crosstalk coefficients for the joining line, as non-disturber lines contribute negligibly to crosstalk. Consequently, energy consumption is reduced proportionally to the reduction in transmission time.
Solution Approach 2:
The patent extracts and isolates the disturber lines from the complete set of active lines. By identifying and separating only those lines that significantly contribute to crosstalk, the system performs measurements only where necessary, thereby maintaining reliability of crosstalk determination while minimizing energy consumption during the initialization process.
Data Source
AI summary
At least one example embodiment discloses a method of determining crosstalk for a joining line in a communication system having a plurality of current active lines. The method includes obtaining a number of disturber lines among the plurality of current active lines, the number of disturber lines being less than a number of the plurality of current active lines, obtaining a pilot matrix, a first dimension of the pilot matrix being based on the number of disturber lines, the pilot matrix representing a sequence of pilots to be transmitted across the plurality of current active lines and the joining line, the first dimension being a number of time instances, the number of time instances being less than the number of the plurality of active lines and determining a crosstalk coupling vector for the joining line based on the pilot matrix.