# US 2021/0242883 A1 · Method and apparatus for fast decoding linear code based on soft decision > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0242883 A1 - Document ID: US20210242883A1 - Status: Published application - Kind: A1 - Application number: 16/651,005 - Filed: 2019-04-19 - Published: 2021-08-05 - Earliest claimed: 2019-03-07 - Assignees: Industry-University Cooperation Foundation Hanyang University - Applicants: Industry-University Cooperation Foundation Hanyang University - Inventors: Chang Ryoul CHOI; Je Chang JEONG - Web page: https://patentgrep.com/patent/US20210242883A1 ## CPC - H03M 13/1111: {Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms} - H03M 13/451: {using a set of candidate code words, e.g. ordered statistics decoding [OSD]} - H03M 13/1108: {Hard decision decoding, e.g. bit flipping, modified or weighted bit flipping} - H03M 13/13: Linear codes - H03M 13/611: {Specific encoding aspects, e.g. encoding by means of decoding} - 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: 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 Disclosed are a method and an apparatus for fast decoding a linear code based on soft decision. The method may comprise sorting received signals in a magnitude order to obtain sorted signals; obtaining hard decision signals by performing hard decision on the sorted signals; obtaining upper signals corresponding to MRBs from the hard decision signals; obtaining a permuted and corrected codeword candidate using the upper signals and an error vector according to a current order; calculating a cost for the current order using a cost function; determining the permuted and corrected codeword candidate as a permuted and corrected codeword according to a result of comparing the calculated cost with a minimum cost; and determining a predefined speeding condition. ## Claims ### Claim 1 A method for fast decoding a linear code based on soft decision, the method comprising: sorting received signals in a magnitude order to obtain sorted signals; obtaining hard decision signals by performing hard decision on the sorted signals; obtaining upper signals corresponding to most reliable bases (MRBs) from the hard decision signals; obtaining a permuted and corrected codeword candidate using the upper signals and an error vector according to a current order; calculating a cost for the current order using a cost function; determining the permuted and corrected codeword candidate as a permuted and corrected codeword according to a result of comparing the calculated cost with a minimum cost; and determining a predefined speeding condition. ### Claim 2 (depends on 1) The method according to claim 1, wherein the obtaining of the permuted and corrected codeword candidate comprises obtaining the permuted and corrected codeword candidate by multiplying the upper signals and the error vector according to the current order with a permuted generator matrix. ### Claim 3 (depends on 1) The method according to claim 1, wherein the cost function is defined as an operation of summing magnitudes of components of the sorted signals, which correspond to positions where the permuted corrected codeword candidate and the hard decision signals have different values. ### Claim 4 (depends on 1) The method according to claim 1, wherein the error vector is defined as a vector having a same length as the MRBs and a hamming weight equal to the current order. ### Claim 5 (depends on 1) The method according to claim 1, wherein the determining of the predefined speeding condition comprises: calculating a speeding threshold by summing components having small magnitudes among components of the sorted signals corresponding to the MRBs; and comparing the calculated speeding threshold with the minimum cost. ### Claim 6 (depends on 5) The method according to claim 5, further comprising, after the comparing, obtaining the permuted and corrected codeword candidate for a next order of the current order in response to determining that the speeding threshold is smaller than the minimum cost as a result of the comparison. ### Claim 7 (depends on 5) The method according to claim 5, wherein the calculating of the speeding threshold comprises calculating the speeding threshold by adding a sum of the components having small magnitudes to a function having a signal-to-noise ratio (SNR), an order, and an error correction code as parameters. ### Claim 8 (depends on 1) The method according to claim 1, further comprising, after the obtaining of the permuted and corrected codeword candidate, comparing a hamming distance between the hard decision signals and the permuted and corrected codeword candidate with a first preconfigured threshold. ### Claim 9 (depends on 8) The method according to claim 8, further comprising, after the comparing the hamming distance with the first preconfigured threshold, in response to determining that the hamming distance is greater than the first preconfigured threshold as a result of the comparison, omitting operations on the error vector and obtaining the permuted and corrected codeword candidate by changing the error vector according to the current order. ### Claim 10 (depends on 1) The method according to claim 1, further comprising, after the obtaining of the permuted and corrected codeword candidate, comparing a hamming distance between the hard decision signals and the permuted and corrected codeword candidate with a second preconfigured threshold; and in response to determining that the hamming distance is less than the second preconfigured threshold, omitting the calculating of the cost, and immediately determining the permuted and corrected codeword candidate as the permuted and corrected codeword. ### Claim 11 An apparatus for decoding a linear code based on soft decision at a high speed, the apparatus comprising: at least one processor; and a memory storing instructions causing the at least one processor to perform at least one step, wherein the at least one step comprises: sorting received signals in a magnitude order to obtain sorted signals; obtaining hard decision signals by performing hard decision on the sorted signals; obtaining upper signals corresponding to most reliable bases (MRBs) from the hard decision signals; obtaining a permuted and corrected codeword candidate using the upper signals and an error vector according to a current order; calculating a cost for the current order using a cost function; determining the permuted and corrected codeword candidate as a permuted and corrected codeword according to a result of comparing the calculated cost with a minimum cost; and determining a predefined speeding condition. ### Claim 12 (depends on 11) The apparatus according to claim 11, wherein the obtaining of the permuted and corrected codeword candidate comprises obtaining the permuted and corrected codeword candidate by multiplying the upper signals and the error vector according to the current order with a permuted generator matrix. ### Claim 13 (depends on 11) The apparatus according to claim 11, wherein the cost function is defined as an operation of summing magnitudes of components of the sorted signals, which correspond to positions where the permuted corrected codeword candidate and the hard decision signals have different values. ### Claim 14 (depends on 11) The apparatus according to claim 11, wherein the error vector is defined as a vector having a same length as the MRBs and a hamming weight equal to the current order. ### Claim 15 (depends on 11) The apparatus according to claim 11, wherein the determining of the predefined speeding condition comprises: calculating a speeding threshold by summing components having small magnitudes among components of the sorted signals corresponding to the MRBs; and comparing the calculated speeding threshold with the minimum cost. ### Claim 16 (depends on 15) The apparatus according to claim 15, further comprising, after the comparing, obtaining the permuted and corrected codeword candidate for a next order of the current order in response to determining that the speeding threshold is smaller than the minimum cost as a result of the comparison. ### Claim 17 (depends on 15) The apparatus according to claim 15, wherein the calculating of the speeding threshold comprises calculating the speeding threshold by adding a sum of the components having small magnitudes to a function having a signal-to-noise ratio (SNR), an order, and an error correction code as parameters. ### Claim 18 (depends on 17) The apparatus according to claim 17, further comprising, after the obtaining of the permuted and corrected codeword candidate, comparing a hamming distance between the hard decision signals and the permuted and corrected codeword candidate with a first preconfigured threshold. ### Claim 19 (depends on 18) The apparatus according to claim 18, further comprising, after the comparing the hamming distance with the first preconfigured threshold, in response to determining that the hamming distance is greater than the first preconfigured threshold as a result of the comparison, omitting operations on the error vector and obtaining the permuted and corrected codeword candidate by changing the error vector according to the current order. ### Claim 20 (depends on 18) The apparatus according to claim 18, further comprising, after the obtaining of the permuted and corrected codeword candidate, comparing a hamming distance between the hard decision signals and the permuted and corrected codeword candidate with a second preconfigured threshold; and in response to determining that the hamming distance is less than the second preconfigured threshold, omitting the calculating of the cost, and immediately determining the permuted and corrected codeword candidate as the permuted and corrected codeword.