System and method for profile selection during fast retrain of a wideband modem

A digital subscriber line transmission unit using the discrete multi-tone communication standard configured to adaptively select and apply a system profile during a fast retrain comprising:

• an analog front end, said analog front end operative to receive a multicarrier input signal and transmit a multicarrier output signal for communication to a remote digital subscriber line transmission unit through the public switched telephone network;
• a memory device operative to store a transition probability matrix and a multiplicity of system profiles;
• and
• a digital signal processor, said digital signal processor operative to perform a full system initialization, store the resulting system profile in the memory device following successful system initializations, and update the transition probability matrix, said digital signal processor responsive to a request to perform a fast retrain of the transmission unit, wherein the fast retrain consists of identifying a current system profile, selecting a previously stored system profile with the highest probability of successfully configuring the transmission unit given the current system profile, applying the selected system profile and updating the transition probability matrix;
• wherein the digital signal processor generates, identifies, and stores a current system profile by averaging a received pseudo-noise symbol.

A method for adaptively selecting and applying a system profile during a fast retrain of a digital subscriber line transmission unit using the discrete multi-tone communications standard comprising:

• storing system profiles following successful system initializations;
• generating, identifying, and storing a current system profile;
• recording the number of times a previously stored system profile is successfully selected to replace the current profile to create a transition probability matrix;
• generating and storing a temporary system profile;
• comparing and selecting the previously stored system profile with the highest probability of resulting in a successful fast retrain;
• applying the selected previously stored system profile to the system;
• and
• adjusting the transition probability matrix;
• wherein the step of generating, identifying, and storing a current system profile is accomplished by an average received pseudo-noise symbol.