多用户VDSL2系统远端串扰抵消算法

随着宽带接入网速率提升，VDSL2技术成为最后一公里的主流接入方式。用户数量急剧增加使传输线路之间串扰成为制约VDSL2系统性能的重要因素，线路之间串扰分为近端串扰（NEXT）和远端串扰（FEXT），VDSL2系统采用正交频分复用调制技术，近端串扰可以通过滤波器滤除，远端串扰却无法消除。主要研究VDSL2系统远端串扰噪声消除的方法，提出远端串扰噪声如何进行评估和计算，推导出远端串扰噪声计算公式，通过公式可以计算出每条线路受到其他线路串扰噪声的大小，然后发送信号时通过串扰噪声预抵消运算，接收到的信号就能成功消除串扰噪声的影响，提高了接收信号的SNR值，进而提升了VDSL2传输速率。

Far-end crosstalk cancellation algorithm in multi-user VDSL2 system

As broadband access network speed advances,VDSL2 technology has become the mainstream method of the last mile access.The dramatic increase in the number of user transmission makes the signal crosstalk an important factor between the transmissions lines, which restricts VDSL2 system performance. The crosstalk between the lines is divided into a near end crosstalk (NEXT) and a far end crosstalk (FEXT).VDSL2 system uses DMT carrier modulation technique, and near end crosstalk can be filtered out by the filter, but far end crosstalk cannot be eliminated. This paper mainly studies a method of far end crosstalk noise cancellation in VDSL2 system, proposes how far end crosstalk noise is evaluated and calculated, and derives the far end crosstalk offset formula.And it calculates the influence of crosstalk noise from other lines on each line.The receiver’s signal can eliminate the influence of crosstalk noise by the crosstalk noise pre elimination algorithm at the transmitter.Therefore,SNR values of the receiver's signal and VDSL2 transmission rate are improved.