# US 10,374,632 B2 · Low density parity check coded modulation for optical communications > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,632 B2 - Document ID: US10374632B2 - Status: Granted - Kind: B2 - Application number: 15/729,110 - Filed: 2017-10-10 - Published: 2018-04-12 - Granted: 2019-08-06 - Earliest claimed: 2016-10-10 - Assignees: NEC Corporation - Applicants: NEC Laboratories America, Inc.; NEC Corporation - Inventors: Shaoliang Zhang; Fatih Yaman; Ting Wang; Yoshihisa Inada - Web page: https://patentgrep.com/patent/US10374632B2 ## CPC - H03M 13/116: {Quasi-cyclic LDPC [QC-LDPC] codes, i.e. the parity-check matrix being composed of permutation or circulant sub-matrices} - H03M 13/1171: {Parity-check or generator matrices with non-binary elements, e.g. for non-binary LDPC codes} - H03M 13/2906: {using block codes (H03M13/2957 takes precedence)} - H03M 13/2957: {Turbo codes and decoding} - H03M 13/616: {Matrix operations, especially for generator matrices or check matrices, e.g. column or row permutations} - H04B 10/27: Arrangements for networking - H04B 10/516: Details of coding or modulation - H04B 10/616: {Details of the electronic signal processing in coherent optical receivers} - H04L 1/0041: {Arrangements at the transmitter end} - H04L 1/0045: {Arrangements at the receiver end} - H04L 1/005: {Iterative decoding, including iteration between signal detection and decoding operation} - H04L 1/0058: {Block-coded modulation} - H04L 1/0065: {Serial concatenated codes} - H03M 13/2792: {Interleaver wherein interleaving is performed jointly with another technique such as puncturing, multiplexing or routing} - H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C) - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems and methods for data transport in optical communications systems, including a transmitter for encoding a received information sequence by constructing an outer and inner quasi cyclic-low-density parity check (QC-LDPC) code. The encoding includes dividing the received information sequence into a plurality of messages of equal length, encoding each of the messages into a codeword to generate a plurality of outer codewords, cascading the plurality of outer codewords to generate a bit sequence, and executing inner encoding to encode each of the plurality of outer codewords into codewords in QC-LDPC inner code. A receiver decodes a received data stream based on the QC-LDPC inner code using two-phase decoding including iteratively performing at least one of inner/outer and outer/inner decoding until a threshold condition is reached. ## Claims ### Claim 1 A method for data transport in optical communications systems, comprising: generating concatenated code with a particular target code rate by encoding a received information sequence by constructing an outer and inner quasi cyclic-low-density parity check (QC-LDPC) code, the encoding comprising: dividing the received information sequence into a plurality of messages of equal length; encoding each of the messages into a codeword to generate a plurality of outer codewords; cascading the plurality of outer codewords to generate a bit sequence; and executing inner encoding to encode each of the plurality of outer codewords into codewords in QC-LDPC inner code, the dividing the received information sequence, encoding each of the messages into the codeword, cascading the plurality of outer codewords, and the executing the inner encoding being iteratively executed to continually improve the code rate until the target code rate is achieved; and decoding a received data stream based on the QC-LDPC inner code using two-phase decoding, the decoding comprising iteratively performing at least one of inner/outer and outer/inner decoding until a threshold condition is reached. ### Claim 2 (depends on 1) The method as recited in claim 1, wherein the encoding further comprises: generating a parity check matrix for a projective geometry (PG) outer code; generating a base matrix for QC-LDPC inner code over a Galois Field (GF) to satisfy a row-column (RC) constraint; and forming a parity check matrix for the QC-LDPC inner code by dispersing each entry in the base matrix using a circulant permutation matrix. ### Claim 3 (depends on 1) The method as recited in claim 1, wherein the decoding further comprises iteratively switching between inner and outer decoding until a target error performance has been reached. ### Claim 4 (depends on 1) The method as recited in claim 1, wherein the inner/outer decoding further comprises: setting a maximum number of inner decoding iterations, and checking a syndrome of a decoded word based on a parity check matric of the inner code at the end of each inner decoding iteration; setting a maximum number of outer decoding iterations, and decoding all failed words outputted by an inner decoder; and iteratively performing inner/outer decoding until the entire decoding is successful or a preset maximum number of overall inner/outer decoding iterations is reached. ### Claim 5 (depends on 4) The method as recited in claim 4, wherein the outer/inner decoding is performed by executing the steps of the inner/outer decoding in reverse order. ### Claim 6 (depends on 1) The method as recited in claim 1, wherein the QC-LDPC code is of length 8000 bits and rate 0.7 with a bit error rate (BER) of 10−15 with a net coding gain (NCG) of greater than 12 dB. ### Claim 7 A system for data transport in optical communications systems, comprising: a transmitter, including a processor, the processor being configured for: generating concatenated code with a particular target code rate by encoding a received information sequence by constructing an outer and inner quasi cyclic-low-density parity check (QC-LDPC) code, the encoding comprising: dividing the received information sequence into a plurality of messages of equal length; encoding each of the messages into a codeword to generate a plurality of outer codewords; cascading the plurality of outer codewords to generate a bit sequence; and executing inner encoding to encode each of the plurality of outer codewords into codewords in QC-LDPC inner code, the dividing the received information sequence, encoding each of the messages into the codeword, cascading the plurality of outer codewords, and the executing the inner encoding being iteratively executed to continually improve the code rate until the target code rate is achieved; and transmitting a data stream in accordance with the QC-LDPC inner code over a transmission medium. ### Claim 8 (depends on 7) The system as recited in claim 7, further comprising a receiver configured to decode a received data stream based on the QC-LDPC inner code using two-phase decoding, the decoding comprising iteratively performing at least one of inner/outer and outer/inner decoding until a threshold condition is reached. ### Claim 9 (depends on 7) The system as recited in claim 7, wherein the encoding further comprises: generating a parity check matrix for a projective geometry (PG) outer code; generating a base matrix for QC-LDPC inner code over a Galois Field (GF) to satisfy a row-column (RC) constraint; and forming a parity check matrix for the QC-LDPC inner code by dispersing each entry in the base matrix using a circulant permutation matrix. ### Claim 10 (depends on 8) The system as recited in claim 8, wherein the receiver is further configured to iteratively switch between inner and outer decoding until a target error performance has been reached. ### Claim 11 (depends on 8) The system as recited in claim 8, wherein the inner/outer decoding comprises: setting a maximum number of inner decoding iterations, and checking a syndrome of a decoded word based on a parity check matric of the inner code at the end of each inner decoding iteration; setting a maximum number of outer decoding iterations, and decoding all failed words outputted by an inner decoder; and iteratively performing inner/outer decoding until the entire decoding is successful or a preset maximum number of overall inner/outer decoding iterations is reached. ### Claim 12 (depends on 8) The system as recited in claim 8, wherein the outer/inner decoding is performed by executing the steps of inner/outer decoding in reverse order. ### Claim 13 (depends on 7) The system as recited in claim 7, wherein the QC-LDPC code is of length 8000 bits and rate 0.7 with a bit error rate (BER) of 10−15 with a net coding gain (NCG) of greater than 12 dB. ### Claim 14 A system for data transport in optical communications systems, comprising: a receiver, including a processor, the processor being configured to: decode a received data stream based on a QC-LDPC inner code using two-phase decoding, the received data stream including generated concatenated code with a particular target code rate, the decoding comprising iteratively performing at least one of inner/outer and outer/inner decoding until a threshold condition is reached, the inner/outer decoding further comprising: setting a maximum number of inner decoding iterations, and checking a syndrome of a decoded word based on a parity check matric of the inner code at the end of each inner decoding iteration; setting a maximum number of outer decoding iterations, and decoding all failed words outputted by an inner decoder; and iteratively performing the inner/outer decoding until the entire decoding is successful or a preset maximum number of overall inner/outer decoding iterations is reached. ### Claim 15 (depends on 14) The system as recited in claim 14, further comprising: a transmitter, including a hardware processor, the processor being configured for: generating the concatenated code with a particular target code rate by encoding a received information sequence by constructing an outer and inner quasi cyclic-low-density parity check (QC-LDPC) code, the encoding comprising: dividing the received information sequence into a plurality of messages of equal length; encoding each of the messages into a codeword to generate a plurality of outer codewords; cascading the plurality of outer codewords to generate a bit sequence; and executing inner encoding to encode each of the plurality of outer codewords into codewords in QC-LDPC inner code, the dividing the received information sequence, encoding each of the messages into the codeword, cascading the plurality of outer codewords, and the executing the inner encoding being iteratively executed to continually improve the code rate until the target code rate is achieved; and transmitting a data stream in accordance with the QC-LDPC inner code over a transmission medium. ### Claim 16 (depends on 15) The system as recited in claim 15, wherein the encoding further comprises: generating a parity check matrix for a projective geometry (PG) outer code; generating a base matrix for QC-LDPC inner code over a Galois Field (GF) to satisfy a row-column (RC) constraint; and forming a parity check matrix for the QC-LDPC inner code by dispersing each entry in the base matrix using a circulant permutation matrix. ### Claim 17 (depends on 14) The system as recited in claim 14, wherein the receiver is further configured to iteratively switch between inner and outer decoding until a target error performance has been reached. ### Claim 18 (depends on 14) The system as recited in claim 14, wherein the outer/inner decoding is performed by executing the steps of inner/outer decoding in reverse order. ### Claim 19 (depends on 14) The system as recited in claim 14, wherein the QC-LDPC code is of length 8000 bits and rate 0.7 with a bit error rate (BER) of 10−15 with a net coding gain (NCG) of greater than 12 dB. ### Claim 20 (depends on 15) The system as recited in claim 15, wherein the cascading further comprises cascading output sequences of outer code to satisfy a coding rate of the inner code.