LDPC (Low Density Parity Check) coded modulation hybrid decoding using non-Gray code maps for improved performance
First Claim
1. A decoder implemented to perform hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the decoder comprising:
- a symbol sequence estimate and symbol node update functional block that receives a plurality of symbol metrics corresponding to a symbol of a plurality of symbols of the LDPC-BICM signal and also receives a plurality of initialized LLR (log likelihood ratio) bit edge messages, and wherein;
the plurality of bit edge messages corresponds to a plurality of edges that communicatively couple a plurality of symbol nodes to a plurality of check nodes within an LDPC coded modulation bipartite graph that corresponds to an LDPC code;
the symbol sequence estimate and symbol node update functional block computes a first plurality of possible soft symbol estimates for the symbol;
the symbol sequence estimate and symbol node update functional block updates the plurality of bit edge messages using the plurality of symbol metrics and the plurality of initialized LLR bit edge messages thereby generating a first updated plurality of bit edge messages;
a check node update functional block that updates a plurality of check edge messages using the first updated plurality of bit edge messages thereby generating a first updated plurality of check edge messages, and wherein;
the symbol sequence estimate and symbol node update functional block computes a second plurality of possible soft symbol estimates for the symbol using the first updated plurality of check edge messages;
the symbol sequence estimate and symbol node update functional block updates the first updated plurality of bit edge messages using the received plurality of symbol metrics and the first updated plurality of check edge messages thereby generating a second updated plurality of bit edge messages;
during a last iterative decoding iteration, the symbol sequence estimate and symbol node update functional block makes a best estimate for the symbol of the plurality of symbols of the LDPC-BICM signal using that symbol'"'"'s most recent corresponding plurality of possible soft symbol estimates; and
a hard limiter makes bit estimates based on the best estimate for the symbol such that the bit estimates are hard decisions for each of the individual bits of the symbol.
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Abstract
LDPC (Low Density Parity Check) coded modulation hybrid decoding using non-Gray code maps for improved performance. Check node updating and symbol node updating are successively and alternatively performed on bit edge messages for a predetermined number of decoding iterations or until sufficient degree of precision is achieved. The symbol node updating of the bit edge messages uses symbol metrics corresponding to the symbol being decoded and the bit edge messages most recently updated by check node updating. The check node updating of the bit edge messages uses the bit edge messages most recently updated by symbol node updating. The symbol node updating computes possible soft symbol estimates. LDPC coded modulation hybrid decoding can decode an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal having a symbol mapped using non-Gray code mapping. By using the non-Gray code mapping, a performance improvement is achieved over an only Gray code mapping system.
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Citations
57 Claims
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1. A decoder implemented to perform hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the decoder comprising:
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a symbol sequence estimate and symbol node update functional block that receives a plurality of symbol metrics corresponding to a symbol of a plurality of symbols of the LDPC-BICM signal and also receives a plurality of initialized LLR (log likelihood ratio) bit edge messages, and wherein; the plurality of bit edge messages corresponds to a plurality of edges that communicatively couple a plurality of symbol nodes to a plurality of check nodes within an LDPC coded modulation bipartite graph that corresponds to an LDPC code; the symbol sequence estimate and symbol node update functional block computes a first plurality of possible soft symbol estimates for the symbol; the symbol sequence estimate and symbol node update functional block updates the plurality of bit edge messages using the plurality of symbol metrics and the plurality of initialized LLR bit edge messages thereby generating a first updated plurality of bit edge messages; a check node update functional block that updates a plurality of check edge messages using the first updated plurality of bit edge messages thereby generating a first updated plurality of check edge messages, and wherein; the symbol sequence estimate and symbol node update functional block computes a second plurality of possible soft symbol estimates for the symbol using the first updated plurality of check edge messages; the symbol sequence estimate and symbol node update functional block updates the first updated plurality of bit edge messages using the received plurality of symbol metrics and the first updated plurality of check edge messages thereby generating a second updated plurality of bit edge messages; during a last iterative decoding iteration, the symbol sequence estimate and symbol node update functional block makes a best estimate for the symbol of the plurality of symbols of the LDPC-BICM signal using that symbol'"'"'s most recent corresponding plurality of possible soft symbol estimates; and a hard limiter makes bit estimates based on the best estimate for the symbol such that the bit estimates are hard decisions for each of the individual bits of the symbol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A decoder implemented to perform hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the decoder comprising:
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a symbol sequence estimate and symbol node update functional block; and a check node update functional block that is communicatively coupled to the symbol sequence estimate and symbol node update functional block, and wherein; the symbol sequence estimate and symbol node update functional block and the check node update functional block cooperatively perform iterative decoding processing of a symbol of a plurality of symbols of the LDPC-BICM signal by successively and alternatively updating a plurality of bit edge messages and a plurality of check edge messages; the plurality of bit edge messages and the plurality of check edge messages, respectively, correspond to a plurality of edges that communicatively couple a plurality of symbol nodes to a plurality of check nodes within an LDPC coded modulation bipartite graph that corresponds to an LDPC code; the symbol sequence estimate and symbol node update functional block performs updating of the plurality of bit edge messages using a plurality of symbol metrics and a plurality of check edge messages most recently updated by the check node update functional block; the plurality of symbol metrics corresponds to the symbol of the plurality of symbols of the LDPC-BICM signal; and the check node update functional block performs updating of the plurality of check edge messages using a plurality of bit edge messages most recently updated by the symbol sequence estimate and symbol node update functional block. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A decoding method that performs hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the method comprising:
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receiving I, Q (In-phase, Quadrature) values corresponding to a symbol of a plurality of symbols of the LDPC-BICM signal; computing a plurality of symbol metrics corresponding to the symbol; initializing a plurality of initialized LLR (log likelihood ratio) bit edge messages during an initial decoding iteration; performing iterative decoding processing that includes performing symbol node updating and performing check node updating to update a plurality of bit edge messages and a plurality of check edge messages, respectively; wherein the symbol node updating includes; computing a plurality of possible soft symbol estimates for the symbol during each decoding iteration; updating the plurality of bit edge messages using the plurality of symbol metrics corresponding to the symbol and a plurality of check edge messages most recently updated during check node updating; wherein the check node updating includes; updating the plurality of check edge messages using a plurality of bit edge messages most recently updated during symbol node updating; during a last iterative decoding iteration, making a best estimate for the symbol using that symbol'"'"'s most recent corresponding plurality of possible soft symbol estimates; and making bit estimates based on the best estimate for the symbol such that the bit estimates are hard decisions for each of the individual bits of the symbol. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A decoder implemented to perform hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the decoder comprising:
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a symbol sequence estimate and symbol node update functional block; and a check node update functional block that is communicatively coupled to the symbol sequence estimate and symbol node update functional block, and wherein; the symbol sequence estimate and symbol node update functional block and the check node update functional block cooperatively perform iterative decoding processing of a symbol of a plurality of symbols of the LDPC-BICM signal by successively and alternatively updating a plurality of bit edge messages and a plurality of check edge messages; the plurality of bit edge messages and the plurality of check edge messages, respectively, correspond to a plurality of edges that communicatively couple a plurality of symbol nodes to a plurality of check nodes within an LDPC coded modulation bipartite graph that corresponds to an LDPC code; the symbol sequence estimate and symbol node update functional block performs updating of the plurality of bit edge messages using a plurality of symbol metrics and a plurality of check edge messages most recently updated by the check node update functional block; the plurality of symbol metrics correspond to the symbol of the plurality of symbols of the LDPC-BICM signal; the check node update functional block performs updating of the plurality of check edge messages using a plurality of bit edge messages most recently updated by the symbol sequence estimate and symbol node update functional block; the LDPC-BICM signal is a variable modulation signal; a first symbol of the plurality of symbols is mapped according to a first modulation that includes an 8 PSK (8 Phase Shift Key) shaped constellation whose constellation points are mapped according to a corresponding Gray code mapping; and a second symbol of the plurality of symbols is mapped according to a second modulation that includes the 8 PSK shaped constellation whose constellation points are mapped according to a corresponding non-Gray code mapping. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A decoder implemented to perform hybrid decoding of an LDPC-BICM (Low Density Parity Check-Bit Interleaved Coded Modulation) signal that includes at least one symbol that is mapped using a non-Gray code mapping, the decoder comprising:
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a symbol sequence estimate and symbol node update functional block; and a check node update functional block that is communicatively coupled to the symbol sequence estimate and symbol node update functional block, and wherein; the symbol sequence estimate and symbol node update functional block and the check node update functional block cooperatively perform iterative decoding processing of a symbol of a plurality of symbols of the LDPC-BICM signal by successively and alternatively updating a plurality of bit edge messages and a plurality of check edge messages to assist in making an estimate of the symbol. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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Specification