Patent ID: 7352805

Claim:
A method for performing adaptive xDSL communications comprising: determining line conditions of a communications channel connecting a transmitter and a receiver, wherein determining line conditions of a communications channel comprises sending a line probing signal from the transmitter to the receiver and estimating a line loop length based on the line probing signal, wherein estimating the line loop length comprises solving the expression Al=−10 Log 10 (Pr/Pt), where Al is the loop attenuation, Pr is the received power estimated at the receiver and Pt is the transmit power, and the Al is indexed against a pre-populated table correlating loop attenuation and loop length; estimating a maximum number of usable sub-carrier based on the determined line conditions, wherein the maximum number of usable sub-carrier is indicative of a maximum usable bandwidth spanning from a lowest frequency usable sub-carrier to a maximum frequency usable sub-carrier; determining a FFT size based at least on part on the maximum number of usable sub-carriers; based at least in part of the determined FFT size, selecting a receiver sampling frequency; determining, based at least in part on the line conditions, whether or not to utilize a time-domain equalizer (TEQ), and if so determining the length of the TEQ, and the size of cyclic extension to use; and communicating from the receiver to the transmitter the size of the FFT, the sampling frequency and, if used, the size of the cyclic extension.