Decoding circuit, decoding method and computer program
Provided is a decoding circuit used for coherent digital signal processing, including: a distributor that distributes a decoding metric obtained by demodulating transmission data transmitted from a transmission device to each of a plurality of lanes on the basis of information on noise generated in a communication channel and a received signal; a first likelihood calculation circuit that is provided in one of the plurality of lanes and calculates a first logarithmic likelihood ratio using the decoding metric distributed by the distributor; a decoding unit that performs error correction decoding using the first logarithmic likelihood ratio and acquires an error-corrected code word; one or more second likelihood calculation circuits that are provided in a lane different from the lane in which the first likelihood calculation circuit is provided among the plurality of lanes, calculate a second logarithmic likelihood ratio on the basis of the decoding metric distributed by the distributor and the acquired code word, and perform hard decision; a combining unit that combines an output of the decoding unit and an output of the one or more second likelihood calculation circuits; and an outer code decoding unit that decodes an outer code.
1 . A decoding circuit used for coherent digital signal processing, the decoding circuit comprising:
a distributor configured to distribute a decoding metric obtained by demodulating transmission data transmitted from a transmission device to each of a plurality of lanes on the basis of information on noise generated in a communication channel and a received signal;
a first likelihood calculation circuit that is provided in one of the plurality of lanes and calculates a first logarithmic likelihood ratio using a decoding metric distributed by the distributor;
a decoder configured to perform error correction decoding using the first logarithmic likelihood ratio and acquires an error-corrected code word;
one or more second likelihood calculation circuits that are provided in a lane different from the lane in which the first likelihood calculation circuit is provided among the plurality of lanes, calculate a second logarithmic likelihood ratio on the basis of the decoding metric distributed by the distributor and the error-corrected code word acquired by the decoder, and perform hard decision;
a combiner configured to combine an output of the decoder and an output of the one or more second likelihood calculation circuits.
2 . The decoding circuit according to claim 1 ,
wherein the first logarithmic likelihood ratio is λj(1), and
the first likelihood calculation circuit calculates the first logarithmic likelihood ratio based on following Expression (1),
[
Math
.
1
]
λ
j
(
1
)
=
l
j
(
1
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l
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2
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l
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1
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in Expression (1), I on the right side represents logarithmic likelihood, and the operator O⋅ (⋅ is located at the center of O) represents an operator of a function that outputs one real number from two real numbers.
3 . The decoding circuit according to claim 1 ,
wherein the second logarithmic likelihood ratio is λj(i) (i is an integer of 1 or more), and
the one or more second likelihood calculation circuits calculate the second logarithmic likelihood ratio based on following Expression (2),
[
Math
.
2
]
λ
j
(
i
)
=
l
j
(
i
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+
(
-
1
)
z
j
(
1
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(
l
j
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1
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l
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(
2
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⊙
…
⊙
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i
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1
)
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i
+
1
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2
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in Expression (2), I on the right side represents logarithmic likelihood, and the operator O⋅ (⋅ is located at the center of O) represents an operator of a function that outputs one real number from two real numbers.
4 . A decoding method used for coherent digital signal processing, the decoding method comprising:
distributing, by a distributor, a decoding metric obtained by demodulating transmission data transmitted from a transmission device to each of a plurality of lanes on the basis of information on noise generated in a communication channel and a received signal;
calculating, by a first likelihood calculation circuit that is provided in one of the plurality of lanes, a first logarithmic likelihood ratio using the distributed decoding metric;
performing, by a decoder, error correction decoding using the first logarithmic likelihood ratio and acquiring an error-corrected code word;
calculating, by one or more second likelihood calculation circuits that are provided in a lane different from the lane in which the first likelihood calculation circuit is provided among the plurality of lanes, one or more second logarithmic likelihood ratios on the basis of the decoding metric distributed by the distributor and the acquired error-corrected code word, and performing hard decision;
combining, by a combiner, an output of the decoder and an output of the one or more second likelihood calculation circuit.
5 . A non-transitory storage medium that stores a program for making a computer perform processes, the processes comprising:
distributing a decoding metric obtained by demodulating transmission data transmitted from a transmission device to each of a plurality of lanes on the basis of information on noise generated in a communication channel and a received signal;
calculating a first logarithmic likelihood ratio using the distributed decoding metric;
performing error correction decoding using the first logarithmic likelihood ratio and acquiring an error-corrected code word;
calculating one or more second logarithmic likelihood ratios on the basis of the distributed decoding metric and the acquired error-corrected code word, and performing hard decision;
combining the acquired error-corrected code word with the calculated one or more second logarithmic likelihood ratios.