Patent ID: 7035400

Claim:
A communications system that comprises: a subscriber modem; a central office modem; and a communications channel coupled between the subscriber modem and the central office modem and configured to transport uplink signals from the subscriber modem to the central office modem, and further configured to transport downlink signals from the central office modem to the subscriber modem, wherein at frequencies below a selected frequency M E2F , the power spectral density of the transmitted uplink signals is proportional to the power spectral density of the transmitted downlink signals by a positive scale factor, and wherein at frequencies above M E2F , the power spectral density of the uplink signals are limited to one or more uplink frequency bands and the downlink signals are limited to one or more downlink frequency bands that are disjoint from the uplink frequency bands, and wherein the total bandwidth of the uplink frequency bands is proportional to the total bandwidth of the downlink frequency bands by the same positive scale factor.