Digital Signal Vectoring for Crosstalk Mitigation in Multi-Line Transceivers
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Solution Overview
Problem
In large-scale Vectored-DSL systems, obtaining a crosstalk cancellation coefficient matrix requires high computing and storage capabilities, affecting user experience due to the large number of line pairs, and existing solutions do not efficiently mitigate crosstalk between distinct groups of subscriber lines.
Innovation Solution
A multi-line digital transceiver uses digital signal vectoring with block-diagonalization techniques to generate a precoder (postcoder) matrix, effectively mitigating crosstalk between distinct groups of subscriber lines without requiring updates when the set of active subscribers or FDMA/TDMA allocations change, allowing for fast dynamics on a millisecond timescale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crosstalk cancellation coefficient matrix is obtained through channel training in large-scale Vectored-DSL systems, then crosstalk mitigation performance is improved, but computing capability and storage capability requirements increase significantly
Solution Approach 1:
The patent divides the subscriber lines into multiple groups and applies separate precoding matrices for each group. This segmentation approach reduces the overall complexity by breaking down the large-scale crosstalk cancellation problem into smaller, manageable sub-problems, where each group can be processed independently with reduced computing and storage requirements.
Solution Approach 2:
The patent implements partial crosstalk cancellation by focusing on mitigating crosstalk between distinct groups of subscriber lines rather than attempting to cancel all crosstalk effects across the entire system. This partial action approach achieves sufficient performance improvement while avoiding the prohibitive complexity of complete system-wide crosstalk cancellation.
2Reliability
If the precoder matrix is updated when the set of active subscribers or FDMA/TDMA allocations change, then precoding performance is maintained, but system dynamics speed is reduced
Solution Approach 1:
The patent pre-computes and stores multiple precoding matrices corresponding to different group configurations and allocation scenarios. When subscriber sets or allocations change, the system can immediately switch to the pre-computed appropriate matrix without performing time-consuming real-time recomputation, thus maintaining precoding performance while enabling fast dynamics on a millisecond timescale.
3Quantity of substance
If the number of line pairs in a Vectored-DSL system increases, then system capacity is improved, but the requirement for computing and storage capability increases
Solution Approach 1:
The patent segments the large number of line pairs into multiple smaller groups, where each group is handled with its own precoding matrix. This segmentation allows the system to scale to a larger number of line pairs by distributing the computational burden across multiple smaller processing units, thereby increasing system capacity without linearly increasing the computing and storage requirements for each individual processing unit.
Data Source
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AI summary
A multi-line digital transceiver configured to use digital signal vectoring in a manner that causes effects of crosstalk between distinct groups of subscriber lines to be effectively mitigated, without directly attempting to mitigate effects of crosstalk within any one of those distinct groups. In an example embodiment, effects of crosstalk within each of the distinct groups can be mitigated indirectly using an appropriate T/FDMA schedule, according to which, during a given symbol period, a given resource block of any of the distinct groups can carry data corresponding to a single respective subscriber. A precoder (postcoder) matrix for the digital signal vectoring can be generated using block-diagonalization techniques appropriately constrained, e.g., using the groups' definitions, aggregate-transmit-power restrictions, etc. In various embodiments, the disclosed digital signal vectoring can be used on the downlink or on the uplink, or both.