Method to mitigate effects of ISDN off/on transitions in ADSL
First Claim
1. A method of supporting a digital communication on a plurality of frequency channels, comprising:
- allocating information bits to the frequency channels based on respectively corresponding channel quality indicators that include respective noise margins and Signal-to-Noise Ratio (SNR) values; and
increasing the noise margin corresponding to at least one of a selected group of said frequency channels that are more susceptible to a predetermined type of interference than are the remaining frequency channels;
arithmetically decreasing the at least one SNR value associated with said at least one frequency channel; and
subtracting an excess noise margin SNR value from said at least one SNR value.
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Abstract
The present invention provides for a method and apparatus for allocating data to subchannels used for ADSL transmission over a communication link which supports further system transmissions. An expected interference impact from the further system transmissions is estimated for the ADSL subchannels. Signal-to-noise ratios (SNRs) for the subchannels are determined for bit loading by an estimator (220). In one embodiment, actual noise associated with the communication link is used at initialization to determine a SNR which is subsequently modified by an adjusting unit (205) prior to bit loading responsive to the estimated interference impact. In another embodiment, a virtual noise signal, indicative of the estimated interference impact and generated by a noise signal generator (235), is summed with the actual noise prior to determining a SNR for bit loading. Prior to transmitting, the data is allocated to the subchannels by a bit loader (210) based on respective SNRs modified responsive the estimated interference impact.
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Citations
30 Claims
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1. A method of supporting a digital communication on a plurality of frequency channels, comprising:
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allocating information bits to the frequency channels based on respectively corresponding channel quality indicators that include respective noise margins and Signal-to-Noise Ratio (SNR) values; and increasing the noise margin corresponding to at least one of a selected group of said frequency channels that are more susceptible to a predetermined type of interference than are the remaining frequency channels; arithmetically decreasing the at least one SNR value associated with said at least one frequency channel; and subtracting an excess noise margin SNR value from said at least one SNR value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of supporting a digital communication on a plurality of frequency channels, said method comprising:
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allocating information bits to the frequency channels based on respectively corresponding channel quality indicators that include respective noise margins and Signal-to-Noise Ratio (SNR) values; increasing the noise margin corresponding to at least one of a selected group of said frequency channels that are more susceptible to a predetermined type of interference than are the remaining frequency channels; for said at least one frequency channel, providing first information indicative of a first interference condition that is worse than an actual interference condition on said at least one frequency channels; providing second information indicative of said actual interference condition; adjusting said second information to produce said first information; combining said second information with third information indicative of a virtual noise signal to produce said first information; and producing said channel quality indicator for said at least one frequency channel in response to said first information. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. An apparatus for supporting a digital communication on a plurality of frequency channels, comprising:
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a bit loader for allocating information bits to the frequency channels based on respectively corresponding channel quality indicators that include respective noise margins and Signal-to-Noise (SNR) values; and a channel quality indication unit coupled to said bit loader for providing said channel quality indicators thereto, said channel quality indication unit operable for increasing the noise margin corresponding to at least one of a selected group of said frequency channels that are more susceptible to a predetermined type of interference than are the remaining frequency channels, said channel quality unit further comprising an input for receiving information indicative of an actual interference condition on said at least one frequency channel, and logic coupled to said input for determining an excess noise margin SNR value based on said actual interference information and logic for decreasing the SNR value associated with said at least one frequency channel and for subtracting said excess noise margin SNR value from SNR value. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A digital communication apparatus, comprising:
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a transmitter for performing digital communication on a plurality of frequency channels, including a bit loader for allocating information bits to the frequency channels based on respectively corresponding channel quality indicators that include respective noise margins and Signal-to-Noise (SNR) values; and a channel quality indication unit coupled to said bit loader for providing said channel quality indicators thereto, said channel quality indication unit operable for increasing the noise margin corresponding to at least one of a selected group of said frequency channels that are more susceptible to a predetermined type of interference than are the remaining frequency channels;
said channel quality indication unit comprising;an estimator having a first input for receiving first information indicative of a first interference condition that is worse than an actual interference condition on said at least one frequency channel, said estimator for producing said channel quality indicator for said at least one frequency channel in response to said first information; a second input for receiving second information indicative of said actual interference condition, and logic coupled to said second input and said estimator input for adjusting said second information to produce said first information; and combiner for combining said second information with third information indicative of a virtual noise signal to produce said first information. - View Dependent Claims (30)
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Specification