Bit Swap established on EOC for VDSL

After the VDSL (Very High-bit-rate Digital Subscriber Line) system enters into fast mode, not all the tones have the same margin. In order to cope with the crosstalk noise, Bit Swap is utilized to swap the tone pairs: the one has a high margin while the other one has a relatively low margin. Although the Bit Swap has been proposed before, there is no Bit Swap established on EOC(Embedded Operational Channel) and the scheme proposes coarse and fine SNR margin tuning algorithm. The paper presents the architecture and process of Bit Swap based on EOC and also implements the algorithm to adjust the margin for tones calculated to be swapped. After thoroughly tested, the test results show that the proposed scheme functions well. Compared with the scheme without Bit Swap, it greatly improves the performance against crosstalk noise and can reduce the RS errors to zero.