Reduced symbol rate handshake signaling in ADSL systems

In an asynchronous digital subscriber line (ADSL) system comprising a central office High Speed ADSL Terminating Unit (HSTU-C) in bidirectional discrete multitone (DMT) communication with a remote High Speed ADSL Terminating Unit (HSTU-R), a method for improving handshake detection robustness comprising:

• transmitting handshake signaling via a first subset of carrier sets of a DMT transmission bandwidth between the HSTU-C and HSTU-R at a first symbol rate;
• determining a presence of near end cross talk (NEXT) in a second subset of carrier sets of the DMT transmission bandwidth;
• and
• transmitting the at least one handshake symbol via the second subset of carrier sets at a second symbol rate so that at least one sub-symbol of the at least one handshake symbol transmitted over the second subset of carrier sets is substantially unaffected by near end cross talk.

An asynchronous digital subscriber line (ADSL) system comprising:

• a central office High Speed ADSL Terminating Unit (HSTU-C);
• and
• a remote High Speed ADSL Terminating Unit (HSTU-R) in bi-directional discrete multitone (DMT) communication with the HSTU-C;
• wherein the HSTU-C is adapted to:
• transmit handshake signaling to the HSTU-R via a first subset of carrier sets at a first symbol rate;
• and
• transmit handshake signaling to the HSTU-R via a second subset of carrier sets at a second symbol rate, the second rate being less than the first rate.