Adaptive Allocation For Variable Bandwidth Multicarrier Communication
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Abstract
Data is distributed among the channels of an asynchronous data subscriber loop (ADSL) communications system in accordance with an adaptive algorithm which from time to time measures the signal to noise ratio of the various channels and finds a margin for each channel dependent on achievement (where possible) of a given bit error rate and a desired data transmission rate. The margin distribution is achieved by augmenting the constellation signal to noise ratio to enhance computational efficiency and allow redetermination of bit allocation tables during transmission as necessary. Pairs of bit allocation tables are maintained at the transmitter and receiver and one table of each pair at the transmitter and receiver is updated while the other pair is in use for controlling communication.
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Citations
8 Claims
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1-6. -6. (canceled)
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7. A transmitter in a multicarrier modulation system, comprising:
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means for specifying a first allocation of bits to subchannels used during current communication with a receiver; and
means for specifying a different allocation of bits to subchannels, wherein the transmitter stores the means for specifying a different allocation of bits to subchannels for use during subsequent communication with the receiver.
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8. A receiver in a multicarrier modulation system, comprising:
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means for specifying a first allocation of bits to subchannels used during current communication with a transmitter over a communication channel; and
means for specifying a different allocation of bits to subchannels, wherein the receiver stores the means for specifying a different allocation of bits to subchannels for use during subsequent communication with the transmitter.
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Specification