| 摘要 |
A method of initializing the operation of a remote modem (10) and central office modem (20k) for asymmetric subscriber line modem communications over a twisted pair wire facility (TWP), using discrete multi-tone technology, is disclosed. The initialization process begins with the remote modem (10) issuing an initialization request, in response to which the central office modem (20k) issues an acknowledgment. The remote modem (10) includes a low-cost analog filter (21) for separating upstream communication echoes from downstream data. This analog filter (21) increases the duration of impulse response over the channel, and thus requires time-domain equalization (TEQ) process (31) performed by the remote modem (10) to filter relatively long circular prefixes, so that intersymbol interference is eliminated. Transceiver training processes (62R, 62C) are carried out, through the generation of a pseudo-random sequence of frames by the central office modem (20k), the receipt of which is used by the remote modem (10) to establish its TEQ coefficients and taps in an optimal manner.
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