# US 2021/0242885 A1 · Ldpc decoding method and ldpc decoding apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242885 A1 - Document ID: US20210242885A1 - Status: Published application - Kind: A1 - Application number: 17/159,681 - Filed: 2021-01-27 - Published: 2021-08-05 - Earliest claimed: 2020-02-04 - Assignees: Electronics and Telecommunications Research Institute; Research & Business Foundation Sungkyunkwan University - Applicants: Electronics and Telecommunications Research Institute; Research & Business Foundation SUNGKYUNKWAN UNIVERSITY - Inventors: Sang-Hyo KIM; Gi Yoon PARK; Ok-Sun PARK; Hyunjae LEE; Hyosang JU; Jaesheung SHIN - Web page: https://patentgrep.com/patent/US20210242885A1 ## CPC - H03M 13/1117: {using approximations for check node processing, e.g. an outgoing message is depending on the signs and the minimum over the magnitudes of all incoming messages according to the min-sum rule} - H03M 13/1151: {Algebraically constructed LDPC codes, e.g. LDPC codes derived from Euclidean geometries [EG-LDPC codes] (H03M13/116, H03M13/1174 take precedence)} - H03M 13/09: Error detection only, e.g. using cyclic redundancy check [CRC] codes or single parity bit - H03M 13/1111: {Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms} - H03M 13/1142: {using trapping sets} - H03M 13/1575: {Direct decoding, e.g. by a direct determination of the error locator polynomial from syndromes and subsequent analysis or by matrix operations involving syndromes, e.g. for codes with a small minimum Hamming distance} - H03M 13/3723: {using means or methods for the initialisation of the decoder} - H03M 13/3769: {using symbol combining, e.g. Chase combining of symbols received twice or more} - 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) ## Abstract An LDPC decoding method of a received signal including a plurality of received symbols is provided. A decoding apparatus selects a perturbation space in which perturbation is to be performed based on a code length of the received signal and a maximum number of perturbation rounds indicating a number of perturbation rounds that can be performed, and performs a perturbation round. The decoding apparatus performs perturbation on a corresponding received symbol among the plurality of received symbols in each perturbation round, and decodes the received signal on which the perturbation has been performed. The decoding apparatus determines that decoding is successful when there is a perturbation round in which a decoding result of the received signal satisfies a predetermined condition. ## Claims ### Claim 1 An LDPC decoding method of a received signal including a plurality of received symbols, the LDPC decoding method comprising: selecting a perturbation space in which perturbation is to be performed based on a code length of the received signal and a maximum number of perturbation rounds indicating a number of perturbation rounds that can be performed; performing at least one perturbation round; performing perturbation on a corresponding received symbol among the plurality of received symbols in each perturbation round; decoding the received signal on which the perturbation has been performed; and determining that decoding is successful when there is a perturbation round in which a decoding result of the received signal satisfies a predetermined condition among the at least one perturbation round, wherein the at least one perturbation round comprises a plurality of first perturbation rounds for performing the perturbation on a corresponding one symbol among the plurality of received symbols. ### Claim 2 (depends on 1) The LDPC decoding method of claim 1, wherein the selecting the perturbation space comprises setting a dimension of the perturbation space to be equal to the maximum number of perturbation rounds when the maximum number of perturbation rounds is less than or equal to the code length of the received signal. ### Claim 3 (depends on 1) The LDPC decoding method of claim 1, wherein the selecting the perturbation space comprises setting a dimension of the perturbation space to be equal to the code length of the received signal when the maximum number of perturbation rounds is greater than the code length of the received signal, wherein the at least one perturbation round further comprises at least one second perturbation round for performing the perturbation on corresponding s received symbols among the plurality of received symbols, and wherein s is an integer greater than one. ### Claim 4 (depends on 1) The LDPC decoding method of claim 1, wherein the performing the at least one perturbation round comprises, when the decoding result of the received signal does not satisfy the predetermined condition in one perturbation round, performing a next perturbation round. ### Claim 5 (depends on 1) The LDPC decoding method of claim 1, wherein the performing the at least one perturbation round comprises performing a plurality of perturbation rounds in parallel. ### Claim 6 (depends on 1) The LDPC decoding method of claim 1, wherein the perturbation comprises a process of flipping the corresponding received symbol and multiplying the flipped received symbol with a noise of a predetermined amplitude. ### Claim 7 (depends on 1) The LDPC decoding method of claim 1, further comprising generating a perturbation pattern for a plurality of perturbation rounds corresponding to the maximum number of perturbation rounds, wherein the perturbation pattern indicates an index of the corresponding received symbol in each perturbation round, wherein the plurality of perturbation rounds are prioritized in ascending order of a number of corresponding received symbols, and wherein when the number of corresponding received symbols is same, the plurality of perturbation rounds are prioritized in ascending order of reliability of corresponding received symbols. ### Claim 8 (depends on 1) The LDPC decoding method of claim 1, wherein the decoding the received signal comprises decoding the received signal on which the perturbation has been performed using a belief propagation (BP) decoding scheme. ### Claim 9 (depends on 8) The LDPC decoding method of claim 8, further comprising: calculating a number of sign mismatches of variable nodes (nSMV); and when the number of sign mismatches in a first received symbol among the plurality of received symbols is greater than the number of sign mismatches in a second received symbol among the plurality of received symbols, determining that reliability of the first received symbol is lower than reliability of the second received symbol. ### Claim 10 (depends on 1) The LDPC decoding method of claim 1, wherein the decoding the received signal comprises: calculating a log likelihood ratio of the received signal on which the perturbation has been performed; and decoding the received signal on which the perturbation has not been performed based on the log likelihood ratio. ### Claim 11 (depends on 10) The LDPC decoding method of claim 10, wherein the predetermined condition comprises a condition in which an LDPC syndrome check according to the decoding result and a CRC check of a codeword according to the decoding result are passed. ### Claim 12 (depends on 10) The LDPC decoding method of claim 10, wherein the predetermined condition comprises a condition in which an LDPC syndrome check according to the decoding result and a maximum likelihood check according to the decoding result are passed. ### Claim 13 An LDPC decoding apparatus of a received signal including a plurality of received symbols, the LDPC decoding apparatus comprising: a memory that stores one or more instructions; and a processor that by executing the one or more instructions: selects a perturbation space in which perturbation is to be performed based on a code length of the received signal and a maximum number of perturbation rounds indicating a number of perturbation rounds that can be performed; performs perturbation on a corresponding received symbol among the plurality of received symbols in each perturbation round; decodes the received signal on which the perturbation has been performed in each perturbation round; when a decoding result of the received signal satisfies a predetermined condition in each perturbation round, determines that decoding is successful; and when the decoding result of the received signal fails to satisfy the predetermined condition in each perturbation round, proceeds to a next perturbation round among the plurality of perturbation rounds, wherein the plurality of perturbation rounds comprise a plurality of first perturbation rounds for performing the perturbation on a corresponding one symbol among the plurality of received symbols. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the plurality of perturbation rounds proceed in an ascending order of a number of corresponding received symbols, and wherein when the number of the corresponding received symbols is same, the plurality of perturbation rounds proceed in an ascending order of reliability of the corresponding received symbols. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein the processor sets a dimension of the perturbation space to be equal to the maximum number of perturbation rounds when the maximum number of perturbation rounds is less than or equal to the code length of the received signal. ### Claim 16 (depends on 13) The apparatus of claim 13, wherein the processor sets a dimension of the perturbation space to be equal to the code length of the received signal when the maximum number of perturbation rounds is greater than the code length of the received signal, wherein the plurality of perturbation rounds further comprise at least one second perturbation round proceeds after the plurality of first perturbation rounds, wherein the at least one second perturbation round performs the perturbation on corresponding s received symbols among the plurality of received symbols, and wherein s is an integer greater than one. ### Claim 17 An LDPC decoding apparatus of a received signal including a plurality of received symbols, the LDPC decoding apparatus comprising: a memory that stores one or more instructions; and a processor that by executing the one or more instructions: sets the plurality of received symbols as a perturbation space; performs a plurality of perturbation rounds in parallel; performs perturbation on a corresponding received symbol among the plurality of received symbols in each perturbation round; decodes the received signal on which the perturbation has been performed in each perturbation round; and when there is a perturbation round in which a decoding result of the received signal satisfies a predetermined condition among the plurality of perturbation rounds, determines that decoding is successful, wherein the plurality of perturbation rounds comprise a plurality of first perturbation rounds for performing the perturbation on a corresponding one symbol among the plurality of received symbols. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the plurality of perturbation rounds are assigned in an ascending order of a number of corresponding received symbols, wherein when the number of the corresponding received symbols is same, the plurality of perturbation rounds are assigned in an ascending order of reliability of the corresponding received symbols, and wherein the processor determines whether the decoding is successful in an assigned order of the plurality of perturbation rounds. ### Claim 19 (depends on 17) The apparatus of claim 17, wherein the processor sets a dimension of the perturbation space to be equal to a maximum number of perturbation rounds when the maximum number of perturbation rounds is less than or equal to a code length of the received signal. ### Claim 20 (depends on 17) The apparatus of claim 17, wherein the processor sets a dimension of the perturbation space to be equal to a code length of the received signal when a maximum number of perturbation rounds is greater than the code length of the received signal, wherein the plurality of perturbation rounds further comprise at least one second perturbation round, wherein the at least one second perturbation round performs the perturbation on corresponding s received symbols among the plurality of received symbols, and wherein s is an integer greater than one.