Fractional bit rate encoding in a discrete multi-tone communication system
AssigneeParadyne Corporation
InventorWilliam L. Betts
Life of this patent
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Abstract
Fractional bit rate encoding in a discrete multi-tone (DMT) communication environment allows the transmission of fractional bit rates, thus maximizing the use of signal-to-noise ratio (SNR) available on each of the DMT carriers, or tones, while maintaining a constant power density over the entire frequency spectrum.
Claims29
A digital subscriber line (DSL) transceiver, comprising:
- a fractional encoder, comprising a modulus converter, configured to encode a group of data bits into a plurality of words, each word encoding a non-integer number of data bits, each word associated with one of a plurality of tones;
- a constellation encoder configured to encode each word into a signal space constellation, each constellation associated with one of the plurality of tones, wherein the plurality of constellations and associated tones form a symbol;
- and
- a discrete multi-tone (DMT) transmitter configured to transmit the constellation on its associated tone in the symbol,
- wherein the modulus converter operates by switching between the plurality of tones.
A digital subscriber line (DSL) transceiver, comprising:
- a fractional encoder, comprising a shell mapper, configured to encode a group of data bits into a plurality of words, each word encoding a non-integer number of data bits, each word associated with one of a plurality of tones;
- a constellation encoder configured to encode each word into a signal space constellation, each constellation associated with one of the plurality of tones, wherein the plurality of constellations and associated tones form a symbol;
- and
- a discrete multi-tone (DMT) transmitter configured to transmit the constellation on its associated tone in the symbol,
- wherein the shell mapper lowers an overall peak factor of a combination of the constellations in the symbol.
A digital subscriber line (DSL) transceiver, comprising:
- a fractional encoder configured to encode a group of data bits into a plurality of words, each word encoding a non-integer number of data bits, each word associated with one of a plurality of tones;
- a constellation encoder configured to encode each word into a signal space constellation, each constellation associated with one of the plurality of tones, wherein the plurality of constellations and associated tones form a symbol;
- and
- a discrete multi-tone (DMT) transmitter configured to transmit the constellation on its associated tone in the symbol,
- wherein the DMT transmitter is further configured to transmit all tones in the plurality at the same power and at a specified PSD with no ripple.
A digital subscriber line (DSL) transceiver, comprising:
- means for fractionally encoding each of the plurality of tones with a non-integer number of bits, wherein the total number of bits over the plurality of tones is an integer;
- means for constellation encoding each tone with a modulation symbol;
- and
- means for modulating each tone,
- wherein the encoding means includes shell mapping means and the shell mapping means lowers an overall peak factor of a combination of signal space constellations associated with the symbol.
A method for encoding fractional bit rates using discrete multi-tone (DMT) modulation, the method comprising the steps of:
- fractionally encoding a group of words to produce a group of constellation signal points, each signal point selected from a plurality of constellations, each constellation associated with one of a plurality of tones, where a size M, M is an integer and >1 of each of the constellations is selected to match an SNR of the associated tone;
- and
- modulating each signal point with the associated tone.
Dependencies are inferred from the claim text.