Low peak-to-average ratio quiescent mode architecture and signal design method for DMT modems

摘要

A physical layer is presented which maps an all zero bit stream to a DMT symbol with low PAR. This allows the AFE to save power while the physical layer of the modem operates identically for both Showtime and Idle data. A minimum amount of changes relative to the existing DMT transmitter architecture are required, most notably the removal of a scrambler from the physical layer and the addition of an XOR mapping (17) and symbol inverter (25). A method is presented for designing the XOR mapping which takes into account upsampling and filtering in the AFE.