Digital subscriber line transmission method, apparatus and system
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Accused Products
Abstract
When training carried out prior to data communication is performed in digital subscriber line transmission (xDSL), the side which transmits training symbols adds some data that is contained in a training symbol sequence onto at least one of the beginning and end of this symbol sequence and then transmits the training symbol sequence. The receiving side removes the data that has been added onto the training symbol sequence and executes training processing. The length of the training symbol sequence and of a transmit symbol sequence at time of normal communication is set in such a manner that the symbol sequence will not fall within an interval in which effects of near-end crosstalk from a neighboring line are received. Further, at the time of training prior to data communication, timing information, which specifies an interval in which effects of crosstalk from a neighboring line are received, is inserted into a training symbol sequence and the training symbol sequence is transmitted from a device on the office side to a device on the subscriber side.
16 Citations
11 Claims
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1-3. -3. (canceled)
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4. A digital subscriber line transmission method for transmitting downstream data from a device on an office side to a device on a subscriber side and upstream data from the device on the subscriber side to the device on the office side over a single line by switching between these data transmissions in time-division fashion, dividing data of one symbol, modulating carrier waves having different frequencies by each item of divided data and frequency-multiplexing the modulated signals, and transmitting the frequency-multiplexed signals in bursts a few symbols at a time, said method comprising the steps of:
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generating a pilot-tone signal with which synchronously processing is executed;
making the length of an interval in which a signal is not being transmitted between contiguous transmit burst symbol sequences a whole-number multiple of the cycle of the pilot-tone signal; and
assuring continuity of sample data in contiguous transmit burst symbol sequences by executing processing in sync with the pilot-tone signal. - View Dependent Claims (5)
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6-8. -8. (canceled)
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9. A digital subscriber line transmission apparatus for transmitting downstream data from a device on an office side to a device on a subscriber side and upstream data from the device on the subscriber side to the device on the office side over a single line by switching between these data transmissions in time-division fashion, dividing data of one symbol, modulating carrier waves having different frequencies by each item of divided data and frequency-multiplexing the modulated signals, and transmitting the frequency-multiplexed signals in bursts a few symbols at a time, said apparatus comprising:
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a pilot-tone signal generator for generating a pilot-tone signal with which synchronously processing is executed;
means for making the length of an interval in which a signal is not being transmitted between contiguous transmit burst symbol sequences a whole-number multiple of the cycle of the pilot-tone signal; and
means for executing processing in sync with the pilot-tone signal and assuring continuity of sample data in contiguous transmit burst symbol sequences. - View Dependent Claims (10)
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11-23. -23. (canceled)
Specification