| 摘要 |
A method and system for escaping from a fast retrain sequence in an ADSL system, particularly in a splitterless ADSL system. In one aspect of the invention, in order to minimize the impact of needing to complete nearly all of a fast retrain sequence, particularly when the sequence is unnecessary, the invention allows a responding transceiver unit to reply to a fast retrain request from an initiating transceiver unit with an "initialization" response. This response, not part of any standard ADSL fast retrain protocol, aborts a fast retrain sequence, and permits initialization to commence without the delay caused by waiting for completion of the fast retrain sequence. In another aspect of the invention, a fast retrain sequence is allowed to proceed up to a certain point, and then truncated by sending a command between a responding transceiver unit and an initiating transceiver unit. In particular, whenever initialization and power cut-back are both required (a typical case in ADSL systems), a fast retrain sequence is initiated, acknowledged, and executed until the end of the power cut-back section of the conventional fast retrain sequence, at which time a digital message is exchanged between the initiating transceiver unit and responding transceiver unit indicating the desire to escape from the fast retrain sequence prematurely. Thus, the fast retrain sequence can be truncated to improve performance while still maintaining the benefits of the conventional power cut-back function.
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