Downstream only suspend-type Q-Mode

摘要

A method of providing downstream suspend type Q-mode for ADSL between a central office (CO) modem and consumer premise equipment (CPE) modem is presented. Q-mode allows for transmitter power savings while at the same time minimizes the generation of time-varying crosstalk. During the initialization stage the CO transmits a pair of messages wherein the first message informs the CPE of a power cutback level and the second message indicates a signal point for each subchannel from which is formed the Q-mode signal Q. The CO sends the CPE the maximum and minimum number of frames for exit and the CPE chooses a number of frames within those limits. The system enters the Q-mode by the CO sending a Q-mode enter signal. The system exits the Q-mode by the CO sending an exit signal. During Q-mode, all high modem layers are frozen, and upon exit are restarted.