Quadrature amplitude modulation communication system with transparent error correction
First Claim
1. A multi-level QAM (quadrature amplitude modulation) communication system having signal processing path and utilizing an n bits ("n" being an integer) QAM signal having 2n signal points, comprising:
- differential encoder/decoder means, located along said signal processing path, for differentially encoding/decoding n pieces of an input digital signal series to resolve phase ambiguity contained in a differentially encoded input signal series;
error correction means including a Reed-Solomon encoder and a Reed-Solomon decoder, provided inside said differential encoder/decoder means along said signal processing path for said input digital signal series, for error-control-encoding/decoding n pieces of said differentially encoded input signal series by utilizing at least one of said digital signal series to correct errors by employment of Reed-Solomon codes; and
QAM modulator/demodulator means, located along said signal processing path, for QAM-modulating/demodulating n pieces of error-control-encoded signals series so as to produce 2n QAM signals.
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Abstract
In a multi-level QAM communication system, Reed-Solomon encoders and Reed-Solomon decoders are employed for error correction purposes. The phase ambiguity of the received signal is eliminated with differential coding. The multi-level QAM communication system utilizing n bits ("n" being an integer) QAM signal having 2n signal points, comprises: a quadrature differential encoder/decoder unit for differentially encoding/decoding n pieces of input digital signal series to produce n pieces of differentially coded signal series; an error correction unit including a Reed-Solomon encoder and a Reed-Solomon decoder, provided inside the quadrature differential encoder/decoder unit along a signal processing path of the input digital signal series, for error-correcting the n pieces of differentially-coded signal series by utilizing at least one of the digital signal series with employment of a Reed-Solomon code; and, a QAM modulator/demodulator unit for QAM-modulating/demodulating n pieces of error-corrected signal series so as to produce 2n QAM signals.
202 Citations
16 Claims
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1. A multi-level QAM (quadrature amplitude modulation) communication system having signal processing path and utilizing an n bits ("n" being an integer) QAM signal having 2n signal points, comprising:
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differential encoder/decoder means, located along said signal processing path, for differentially encoding/decoding n pieces of an input digital signal series to resolve phase ambiguity contained in a differentially encoded input signal series; error correction means including a Reed-Solomon encoder and a Reed-Solomon decoder, provided inside said differential encoder/decoder means along said signal processing path for said input digital signal series, for error-control-encoding/decoding n pieces of said differentially encoded input signal series by utilizing at least one of said digital signal series to correct errors by employment of Reed-Solomon codes; and QAM modulator/demodulator means, located along said signal processing path, for QAM-modulating/demodulating n pieces of error-control-encoded signals series so as to produce 2n QAM signals. - View Dependent Claims (2, 3, 4, 5)
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6. A multi-level QAM (quadrature amplitude modulation) communication system having a signal processing path and for producing an n bits ("n" being an integer) QAM signal having 2n signal points from n pieces of an input digital signal series, comprising:
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differential encoder/decoder means, located along said signal processing path, for differentially encoding/decoding at least two pieces of said input digital signal series for determining a quadrant of a phase plane for a signal point mapping among said n pieces of said input digital signal series so as to produce at least two pieces of differentially-encoded signal series; first error correction means, provided inside said differential encoder-decoder means and located along said signal processing path for said input digital signal series, for error correction so as to produce at least two pieces of first error-control-encoded signal series; second error correction means, located along said signal processing path, provided directly to receive remaining pieces of said input digital signal series so as to produce a second error-control-encoded signal series; and
,QAM modulator/demodulator means, located along said signal processing path, for QAM-modulating/demodulating both said first error-control-encoded signal series and second error-control-encoded signal series so as to output said n bits QAM signal, whereby phase ambiguity contained in said differentially-encoded signal series is solved. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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14. A multi-level QAM (quadrature amplitude modulation) communication system having signal processing path and for producing 2n pieces of n-bit ("n" being an integer) QAM signal points from n pieces of an input signal series comprising:
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encoder/decoder means, located along said signal processing path utilizing a Reed-Solomon code of a Galois field GF (21), for error-correction-encoding/decoding h pieces of an input signal series ("h" being a positive integer smaller than or equal to "n" and "1" being larger than or equal to "h"); and QAM-modulating/demodulating mans positioned inside said encoder/decoder means along said signal processing path for said n pieces of input signal series, for QAM-modulating/demodulating said n pieces of input signal series containing h pieces of Reed-Solomon encoded input signal series so as to resolve phase ambiguity contained in said h pieces of Reed-Solomon encoded input signal series. - View Dependent Claims (15, 16)
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Specification