US Patent 7496144 Allocating data between tones in a VDSL system

A new protocol is proposed for transmission of data through lines such as telephone lines. The tones of a signal are associated into groups 10, 11, and tone ordering, gain selection, and/or bit swapping within the processing system are done within the members of a group 10, 11. This idea is applicable both to tone ordering etc., following the training stage, and also to the dynamic configuration changes subsequently, for example, bit swapping. The computational cost of coding and decoding the data is reduced (compared to treating all the tones of a given direction equivalently), and the invention makes it possible to significantly reduce the memory requirements of the encoder and decoder.