Multi-carrier transmission systems
First Claim
1. A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol, said system including digital receiver and transmitter units, said receiver unit including a symbol detection unit, characterized in that said system is adapted to determine a parameter for each single carrier, said parameter being indicative of a deviation of a received signal from a corresponding constellation point;
- to compare the parameter with an upper and lower limit; and
, if the parameter is outside said limits, to change the constellation used to modulate the carrier to a neighboring constellation.
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Accused Products
Abstract
A multi-carrier transmission system such as a DMT based VDSL system. The system uses orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol. This estimate includes digital receiver and transmitter units with the receiver unit including a symbol detection unit. This system is adapted to determine a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point. It compares the parameter with an upper lower limit and if the parameter is outside the limits, changes the constellation used to modulate the carrier to a neighboring constellation. The symbol detection unit may be used to determine a parameter such as the ratio d2/σ2, where d is the shortest distance between neighboring constellations, σ is a standard deviation and σ2 is the variance of the deviations of the input and output signal values of the symbol detection unit.
67 Citations
34 Claims
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1. A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol, said system including digital receiver and transmitter units, said receiver unit including a symbol detection unit, characterized in that said system is adapted to determine a parameter for each single carrier, said parameter being indicative of a deviation of a received signal from a corresponding constellation point;
- to compare the parameter with an upper and lower limit; and
, if the parameter is outside said limits, to change the constellation used to modulate the carrier to a neighboring constellation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- to compare the parameter with an upper and lower limit; and
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12. In a multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol, said system including digital receiver and transmitter units, said receiver unit including a symbol detection unit, a method for determining a constellation (bit-loading) for each single carrier, characterized by the steps of determining a parameter for each single carrier, said parameter being indicative of a deviation of a received signal from a corresponding constellation point;
- comparing the parameter with an upper and lower limit; and
, if the parameter is outside said limits, changing the constellation for the carrier to a neighboring constellation. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
- comparing the parameter with an upper and lower limit; and
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24. A multi-carrier transmission system using orthogonal carriers with high order QAM constellations for the transmission of multiple bits per carrier and symbol, the system comprising:
digital receiver and transmitter units for determining a parameter for each single carrier with the parameter being indicative of a deviation of a received signal from a corresponding constellation point, for comparing the parameter with an upper and lower limit, and for changing the constellation used to modulate the carrier to a neighboring constellation if the parameter is outside the limits. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
Specification