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Method and arrangement in a DSL vectoring system

A technology of vector and channel coefficients, which is applied in the field of DLE processing of disorderly departure events in DSL vectorization systems, and can solve problems such as large crosstalk

Active Publication Date: 2017-05-24
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, when using higher frequencies for communication (such as in G.fast), the crosstalk between lines is greater, so all parts of the channel coefficient matrix are affected to a greater degree, even though changes in some parts may still is dominant

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  • Method and arrangement in a DSL vectoring system
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  • Method and arrangement in a DSL vectoring system

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Embodiment Construction

[0016] In short, a solution is provided for enabling a fast update of the precoder after a sudden impedance change at the end of the line. A fast channel estimation method is provided to quickly track channel changes and update the precoder accordingly. The fast channel estimation or tracking method utilizes a new model for estimating the channel and is applicable to all frequencies used for DSL communication, also to higher frequencies around 30 MHz and beyond.

[0017] The solutions described herein relate specifically to emerging broadband communication systems over multi-pair copper cables, such as the recently drafted standard ITU-T G.fast [1]. In general, a distinction is made between sudden impedance changes caused by lines inside the quantized group (hereinafter called out-of-order outgoing lines) and changes caused by lines outside the quantized group (hereinafter called outside line termination changes). The present invention focuses on the former, ie out-of-order o...

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Abstract

Vector Control Entity and method therein for Disorderly Leaving Events, DLEs, causing Sudden Termination Change in a DSL system. The method comprises, when a DLE occurs on a line m in a vectored group of DSL lines, and the transmission on line m is, at least partly, continued: obtaining at least one error sample from CPEs connected to other lines in the vectored group of DSL lines, and calculating an estimate of the channel coefficients, H', changed due to the DLE. The estimate is calculated based on the at least one error sample, and thus a channel estimate is provided. The method further comprises modifying a downstream precoder, based on the channel estimate, such that retraining of the other lines in the vectored group due to the DLE is avoided. The estimate of the channel coefficients is calculated based on the model H'=H+C<lambda>H.

Description

technical field [0001] The present invention relates to methods and arrangements in a Digital Subscriber Line (DSL) system, in particular to the handling of disorderly leave events (DLE) in DSL vectored systems. Background technique [0002] Vectoring technology eliminates FEXT (Far End Cross Talk) between DSL lines and thus maximizes DSL system performance. Vectoring technology enables the provision of 100 Mbps per subscriber using DSL lines eg between the end of the fiber optic network and the customer premises equipment CPE. [0003] ITU-T, the Telecommunication Standardization Sector of the International Telecommunication Union, has been standardizing the vectorization standard G.993.5[1], and the first proposal for G.993.5 was approved on April 22, 2010. The elimination of FEXT is performed at the DSLAM (Digital Subscriber Line Access Multiplexer) side. The downstream FEXT is pre-cancelled by the precoder in the DSLAM, while the upstream FEXT is canceled by the upstre...

Claims

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Application Information

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IPC IPC(8): H04B3/32H04M11/06
CPCH04M11/062H04B3/32
Inventor E·L·d·梅代罗斯P-E·埃里克森黄叶子吕晨光T·梅吉萨彻
Owner TELEFON AB LM ERICSSON (PUBL)