Adaptive turbo peak mitigation for peak-to-average ratio (PAR) reduction using reserved tones

A digital subscriber line (xDSL) system comprising:

• a first mapper configured to map data and a default label indicative of a default set of peak-to-average power ratio (PAR) reduction tones (PRT) tones into to a first symbol;
• a first IFFT configured to convert the first symbol to a first time-domain signal;
• a PAR determination module coupled to the output of the IFFT;
• a PRT determination module coupled to the PAR determination module and configured to select a set of PRT from a predetermined plurality of sets of PRT based on the output of the PAR determination module;
• a first PAR reduction module coupled to the PRT determination module configured to reduce PAR based on the default set of PRT;
• a second mapper coupled to the PRT determination module and configured to map a subset of the data and a label corresponding to a set of PRT selected by the PRT determination module into a second symbol;
• a second IFFT configured to convert the second symbol to a second time-domain signal;
• and
• a second PAR reduction module coupled to the second IFFT configured to reduce PAR based on the set of PRT,
• wherein one or more of the first mapper, first IFFT, PAR determination module, PRT determination module, first PAR reduction module, second mapper, second IFFT and second PAR reduction module are implemented by software executing on a processor.

An xDSL system for transmitting digital data comprising:

• first means for mapping a portion of the data and a default label indicative of a default set of peak-to-average power ratio (PAR) reduction tones (PRT) tones into a symbol, wherein the default label is mapped using PRT signaling tones;
• first IFFT means for generating a time-domain signal from the symbol said time-domain signal having a PAR;
• means for calculating the PAR of said time-domain signal;
• means for selecting a selected set of PRT from a predetermined plurality of sets of PRT based on the PAR, said selected set having a label;
• means for comparing the label of the selected set to the default label;
• first means for processing the time-domain signal using the default set of PRT to reduce PAR, if the label and the default label are identical;
• second means for mapping a subset of the portion of the data and the label of the selected set into a revised symbol, if the label and the default label differ;
• second IFFT means for generating a revised time-domain signal from the revised symbol, if the label of the selected set and the default label differ;
• and
• second means for processing the revised time-domain signal using the selected set of PRT to reduce PAR, if the label of the selected set and the default label differ.