Patent ID: 8085835

Claim:
A cable modem, comprising: a receiver configured to receive a subsequent ranging response generated by a cable modem termination system, the subsequent ranging response generated after the cable modem termination system generates a first ranging response, and the subsequent ranging response comprising a plurality of ranging parameters including an upstream communications parameter, a timing adjust parameter, a power level adjust parameter, a carrier frequency offset parameter, and a plurality of equalization parameters, the equalization parameters including a number of ranging response equalizer coefficients; a pre-equalizer configured to: determine a delay offset based, at least in part, on a location of a main tap and a specified main tap location, wherein the specified main tap location is included in the subsequent ranging response; subsequent to the determination of the delay offset, convolve current pre-equalizer coefficients with the ranging response equalizer coefficients to generate new pre-equalizer coefficients for the main tap and a number of non-main taps, wherein each one of the taps has a real part and an imaginary part, and wherein the pre-equalizer is further configured to adjust the imaginary part of the main tap to zero; identify each non-main tap having a determined magnitude squared value below a specified threshold and to set the new pre-equalizer coefficients for the real part and the imaginary part of each identified non-main tap to zero; and generate scaled coefficients using the new pre-equalizer coefficients for the main tap and non-main taps; and a gain stage configured to adjust a transmit power of the cable modem in response to an equalizer coefficient gain change value, the equalizer coefficient gain change value being determined, at least in part, from a ratio of a current equalizer coefficient gain value and a new equalizer coefficient gain value.