Patent ID: 7423984

Claim:
A digital subscriber line transmission method for transmitting downstream data from a device on an office side to a device on a subscriber side and upstream data from the device on the subscriber side to the device on the office side over a single line by switching between these data transmissions in time-division fashion, dividing data of one symbol, modulating carrier waves having different frequencies by each item of divided data and frequency-multiplexing the modulated signals, and transmitting the frequency-multiplexed signals a few symbols at a time, said method comprising the steps of: generating a training symbol sequence, which comprises a plurality of successive symbols, in bursts on a training-symbol transmitting side at time of training carried out prior to data communication; adding some data that is contained within the training symbol sequence onto the beginning and the end of this symbol sequence as redundancy data; and transmitting the training symbol sequence onto which some of the data has been added to a training-symbol receiving side, wherein, at the time of training, a length of a training symbol sequence after the redundancy data has been added thereon is set in such a manner that the training symbol sequence will not be influenced by near-end crosstalk from a neighboring line.