Distortion compensating device
AssigneeFujitsu Limited
InventorTakayuki Ozaki
Life of this patent
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Abstract
A distortion compensating device provided in a receiver for compensating distortion which is added to a signal in a transmission path. The signal is generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram. The device includes a signal-point-position averaging circuit for producing an average signal point for each of a plurality of distributions of received signal points in the signal space diagram. A discrimination circuit in the device discriminates the average signal point closest to a received signal point from other average signal points in the signal space diagram.
Claims21
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, the signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- signal-point-position averaging means for producing an average signal point for each of a plurality of distributions of received signal points in said signal space diagram;
- and
- discrimination means for discriminating the average signal point closest to a received signal point from other average signal points in said signal space diagram.
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- signal-point-position averaging means for producing an average signal point for each of a plurality of distributions of received signal points in said signal space diagram;
- and
- discrimination means for defining threshold lines in a checkered pattern between said average signal points in said signal space diagram, and for discriminating a received signal point by said threshold lines.
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- signal-point-position averaging means for producing an average signal point for each of a plurality of distributions of received signal points in said signal space diagram;
- and
- discrimination means for shifting a received signal point by a distance based on a difference between said specified signal point and a corresponding average signal point in an opposite direction of that from the specified signal point and the corresponding average signal point, and for discriminating a shifted received signal point by threshold lines defined by the specified signal points.
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- error-signal generation means for generating an error signal indicating a relationship between a corrected received signal point and a corresponding specified signal point in the signal space diagram;
- average-error-signal calculating means for producing an average error signal by accumulating a latest error signal from the error-signal generation means for each received signal supply;
- correction means for producing the corrected received signal by subtracting said average error signal from a received signal;
- and
- discrimination means for discriminating the corrected received signal from the correction means.
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- distortion-compensated signal calculating means for producing a distortion-compensated signal S which is calculated by an equation:
- S=V−α1V−α2V2−α3V3 . . . ,
- where V is a received signal, and αn is a given factor.
A distortion compensating device provided in a receiver for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, said device comprising:
- discrimination means for discriminating a received signal according to threshold lines partitioning the signal space diagram into discrimination areas, the threshold lines being defined so that the discrimination areas on an outer side of the signal space diagram can be wider than the discrimination areas on an inner side of the signal space diagram.
A distortion compensating device provided in a transmitter for compensating distortion added to a signal in a transmission path, said signal being generated in a multi-level modulator of a transmitter in which a digital signal is mapped to one of a plurality of specified signal points in a signal space diagram, aid device comprising:
- variable mapping means for changing a mapping pattern of the specified signal points according to a level of a received signal in a receiver.
Dependencies are inferred from the claim text.