Patent ID: 8280036

Claim:
An apparatus comprising: a digital subscriber line (DSL) transmitter configured to transmit a transmitter referred virtual noise for a tone in a subscriber line, wherein the transmitter referred virtual noise is based on a time history of a noise condition in the subscriber line, wherein the transmitter referred virtual noise is obtained by: TXREFVN ⁡ ( i ) = TXPSD ⁡ ( i ) · SNRM min reportedSNR ⁡ ( i ) · SNRM , where TXREFVN(i) is the transmitter referred virtual noise for the DSL tone i, TXPSD(i) is a transmit spectrum power density of the tone in the line, SNRM is a standard operating signal to noise ratio (SNR) margin, reportedSNR(i) is a reported SNR for the point in time and SNRM min is a minimum SNR margin that is less than the standard operating SNR margin.