CN107888199B - Method and encoder for encoding/decoding input information based on low density parity check - Google Patents

Method and encoder for encoding/decoding input information based on low density parity check Download PDF

Info

Publication number
CN107888199B
CN107888199B CN201711140057.1A CN201711140057A CN107888199B CN 107888199 B CN107888199 B CN 107888199B CN 201711140057 A CN201711140057 A CN 201711140057A CN 107888199 B CN107888199 B CN 107888199B
Authority
CN
China
Prior art keywords
matrix
parity check
ldpc
zero
dual diagonal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201711140057.1A
Other languages
Chinese (zh)
Other versions
CN107888199A (en
Inventor
朴成益
金兴默
许南淏
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electronics and Telecommunications Research Institute ETRI
Original Assignee
Electronics and Telecommunications Research Institute ETRI
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020130055762A external-priority patent/KR101685010B1/en
Application filed by Electronics and Telecommunications Research Institute ETRI filed Critical Electronics and Telecommunications Research Institute ETRI
Publication of CN107888199A publication Critical patent/CN107888199A/en
Application granted granted Critical
Publication of CN107888199B publication Critical patent/CN107888199B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/11—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits using multiple parity bits
    • H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/63—Joint error correction and other techniques
    • H03M13/635—Error control coding in combination with rate matching
    • H03M13/6362—Error control coding in combination with rate matching by puncturing
    • H03M13/6368—Error control coding in combination with rate matching by puncturing using rate compatible puncturing or complementary puncturing
    • H03M13/6393—Rate compatible low-density parity check [LDPC] codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/033—Theoretical methods to calculate these checking codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/11—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits using multiple parity bits
    • H03M13/1102—Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes
    • H03M13/1148—Structural properties of the code parity-check or generator matrix
    • H03M13/118—Parity check matrix structured for simplifying encoding, e.g. by having a triangular or an approximate triangular structure
    • H03M13/1185—Parity check matrix structured for simplifying encoding, e.g. by having a triangular or an approximate triangular structure wherein the parity-check matrix comprises a part with a double-diagonal

Landscapes

  • Physics & Mathematics (AREA)
  • Probability & Statistics with Applications (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Error Detection And Correction (AREA)

Abstract

An LDPC (low density parity check) code for terrestrial cloud broadcasting is provided. A method of encoding input information based on LDPC (low density parity check) includes receiving information and encoding the input information using an LDPC codeword using a parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix of the LDPC code having a higher code rate than a reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value.

Description

Method and encoder for encoding/decoding input information based on low density parity check
The application is a divisional application of an invention patent application with the application date of 2013, 8 and 29, and the application number of 201310383264.5, and the invention name of the invention is 'low-density parity check code for ground cloud broadcasting'.
Cross Reference to Related Applications
The present application claims priority from korean patent application No. 10-2013-0055762, filed on 5, 16, 2013, the contents of which are incorporated herein by reference in their entirety.
Technical Field
Embodiments of the present invention are directed to an LDPC (low density parity check) code for a terrestrial cloud broadcasting signal to correct an error occurring on a radio channel in a terrestrial cloud broadcasting system operating in a single frequency network.
Background
Current terrestrial TV broadcasts cause co-channel interference amounting to three times the service coverage and thus cannot reuse the same frequency in areas within three times the service coverage. Thus, a region in which frequencies cannot be reused is called white space (white space). The appearance of white space drastically deteriorates spectral efficiency. This situation leads to a need for transmission techniques that facilitate frequency reuse and white space removal, which focuses on robustness of reception, as well as an increase in transmission capacity, in order to enhance spectral efficiency.
Terrestrial Cloud Broadcasting techniques have recently been proposed in the literature entitled "A New Transmission-Reuse Friendly Digital Broadcasting Transmission System", published IEEE Transactions on Broadcasting, vol.58, No.3on IEEE Transactions on Broadcasting, vol.58, No.3, which provide easy Reuse, prevent white space from occurring, and allow easy setup and operation of single frequency networks.
The use of such terrestrial cloud broadcasting technology enables broadcasters to transmit broadcast contents, which are identical nationwide or different in each local area, through a single broadcast channel. However, in order to achieve such an object, a receiver should be able to receive one or more terrestrial cloud broadcast signals in a region in which signals transmitted from different transmitters overlap (i.e., an overlapping region), and should be able to distinguish the received terrestrial cloud broadcast signals from each other and demodulate the distinguished signals.
In other words, one or more cloud broadcast signals should be demodulated in a situation where the same channel interference exists and timing and frequency synchronization is not guaranteed for each transmission signal.
For this reason, the terrestrial cloud broadcasting system needs to operate in an environment in which noise power is greater than power of a broadcast signal, that is, a negative SNR (signal-to-noise ratio) environment. Therefore, there is a need for an error correction code that operates even in such a negative SNR environment for terrestrial cloud broadcasting.
Disclosure of Invention
An object of the present invention is to provide an LDPC encoder and an LDPC encoding method for encoding input information based on LDPC (low density parity check).
It is another object of the present invention to provide an LDPC (low density parity check) code that operates even in a negative SNR (signal-to-noise ratio) environment for terrestrial cloud broadcasting.
It is another object of the present invention to provide an LDPC code having better performance and lower complexity than existing LDPC codes.
According to an aspect of the present invention, a method of encoding input information based on LDPC (low density parity check) includes: receiving information; and encoding the input information using the LDPC codeword using a parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix of the LDPC code having a higher code rate than a reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value.
In an embodiment, the parity check matrix may include a zero matrix, an identity matrix (identity matrix), and a dual diagonal matrix.
In another embodiment, the encoded LDPC codeword may include a systematic portion corresponding to input information, a first parity portion corresponding to a dual diagonal matrix, and a second parity portion corresponding to an identity matrix.
In another embodiment, the encoding step may comprise: calculating the first parity part using the first parity check matrix and the input information; and calculating the second parity part using the second parity check matrix based on the input information and the calculated first parity part.
In another embodiment, the cell matrices of the dual diagonal matrix may constitute dual diagonals and be identity matrices, while the remaining cell matrices of the dual diagonal matrix may be zero matrices.
In another embodiment, the cell matrix constituting the dual diagonal matrix of the dual diagonal may be continuous with the cell matrix constituting the diagonal of the identity matrix.
In another embodiment, the method may further include, prior to the encoding step, determining a code rate of the LDPC code and determining the size of the dual diagonal matrix according to the determined code rate.
In another embodiment, the parity check matrix may include a zero matrix and a cyclic permutation matrix.
According to another aspect of the present invention, an LDPC encoder includes: an input unit for receiving information; and an encoding unit for encoding the input information using the LDPC codeword using a parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix of the LDPC code having a higher code rate than a reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value.
According to another aspect of the present invention, a method of decoding an LDPC (low density parity check) code by an LDPC decoder includes: receiving an LDPC codeword encoded by a parity check matrix, and decoding the received LDPC codeword using the parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix of an LDPC code having a higher code rate than a reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value.
According to another aspect of the present invention, an LDPC decoder comprises: a receiving unit for receiving an LDPC (Low Density parity check) codeword encoded by a parity check matrix; and a decoding unit for decoding the received LDPC codeword using the parity check matrix, wherein the parity check matrix may have a structure obtained by combining a first parity check matrix of the LDPC code having a higher code rate than the reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value.
In the terrestrial cloud broadcasting system, LDPC (low density parity check) operation even in a negative SNR (signal to noise ratio) environment can be provided.
This code provides better performance and lower complexity than the LDPC codes used in DVB-T2 (digital video broadcasting-terrestrial version 2) and DVB-S2 (digital video broadcasting-satellite-second generation) systems.
Drawings
Embodiments of the invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings, wherein:
fig. 1 is a diagram illustrating a PCM (parity check matrix) structure of a QC-LDPC (quasi-cyclic low density parity check) code used in a DVB (digital video broadcasting) system;
FIG. 2 is a flowchart illustrating a method of encoding input information using an LDPC code operating in a negative SNR (signal to noise ratio) environment according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating a PCM structure of an LDPC code according to an embodiment of the present invention;
fig. 4 is a diagram illustrating a PCM structure of a QC-LDPC code for terrestrial cloud broadcasting, in which the length of a codeword is 8192;
FIG. 5 is an expanded view of the PCM structure shown in FIG. 4;
fig. 6 is a diagram illustrating a PCM structure of a QC-LDPC code for terrestrial cloud broadcasting, in which the length of a codeword is 16384;
fig. 7 is a diagram illustrating a PCM structure of a QC-LDPC code for terrestrial cloud broadcasting, in which the length of a codeword is 32768;
fig. 8 is a diagram illustrating a PCM structure of a QC-LDPC code for terrestrial cloud broadcasting, in which the length of a codeword is 65536;
FIG. 9 illustrates an example of a PCM structure of an LDPC code according to a code rate according to an embodiment of the present invention;
FIG. 10 is a graph illustrating performance of an LDPC code according to an embodiment of the present invention;
FIG. 11 is a flowchart illustrating a method of decoding an LDPC codeword according to an embodiment of the present invention; and
FIG. 12 is a block diagram illustrating an LDPC encoder and an LDPC decoder according to an embodiment of the present invention.
Detailed Description
Embodiments of the present invention will be described in detail with reference to the accompanying drawings to be studied by those skilled in the art. However, the present invention may be implemented in various ways, and is not limited thereto. The drawings have omitted the matters irrelevant to the present invention, and like components have been assigned like reference numerals throughout the specification.
As used herein, when an element "comprises" or "comprises" another element, unless stated otherwise, the element may further comprise or include the other element without excluding the other element. Also, as used herein, the term "unit" or "portion" means a basis for processing at least one function or operation, which may be implemented in hardware or software or in a combination of software and hardware.
Fig. 1 is a diagram illustrating a PCM (parity check matrix) structure of a QC-LDPC (quasi-cyclic low density parity check) code used in a DVB (digital video broadcasting) system.
In general, an LDPC code is known as an error correction code that is closest to the shannon limit in an AWGN (additive white gaussian noise) channel and a bit wave (Turbo) code provides better performance of asymptotic (asymptotheca) while enabling parallel decoding.
Such LDPC codes are defined by randomly generated low density PCM (parity check matrix). However, the randomly generated LDPC code requires a large amount of memory to store the PCM and requires a long time to access the memory.
To solve such a problem of the memory, a QC-LDPC (quasi-cyclic LDPC) code has been proposed, and the QC-LDPC code composed of a zero matrix or CPM (cyclic permutation matrix) is defined by pcm (h) shown in equation 1:
[ equation 1]
Figure BDA0001471297700000051
Here, P is CPM having a size L × L, and is defined as in equation 2:
[ equation 2]
Figure BDA0001471297700000053
Furthermore, PiBy shifting i (0 ≦ i) to the right<L) times obtained matrix, identity matrix
Figure BDA0001471297700000052
Has a dimension L × L, P∞Is a zero matrix with size L x L. Thus, in the case of a QC-LDPC code, only component i may be stored in order to store PiAnd thus the memory required to store the PCM is reduced to 1/L.
As an example, the QC-LDPC code used in the DVB system shown in fig. 1 is composed of an I matrix and a P matrix. The I matrix is a matrix having a size (N-K). times.K, and the P matrix is a bi-diagonal matrix having a size (N-K). times.N-K. Here, N is the length of the codeword, and K is the length of the input information.
Fig. 2 is a flowchart illustrating a method of encoding input information using an LDPC code operating in a negative SNR (signal-to-noise ratio) environment according to an embodiment of the present invention, and fig. 3 is a diagram illustrating a PCM structure of the LDPC code according to an embodiment of the present invention.
Referring first to fig. 2, if information to be encoded is typed (210) and a code rate is determined (220), an LDPC encoder according to the present invention determines the size of a double diagonal matrix variably included in a parity check matrix according to the determined code rate (230), in this case, although the code rate is determined after the information to be encoded is typed in fig. 2, if necessary, the code rate may be previously determined before the information is input or may be determined when the information is input.
Thereafter, the LDPC encoder shown in fig. 3 may encode input information using the LDPC codeword using the determined parity check matrix. Here, the parity check matrix may have a structure in which a first parity check matrix (PCM [ A B ]) for an LDPC code having a higher code rate than a reference value (e.g., 0.5) and a second parity check matrix (PCM [ C D ]) for an LDPC code having a lower code rate than the reference value are combined with each other.
As an example, referring to fig. 3, the parity check matrix according to the present invention may include a double diagonal matrix B, an identity matrix D, and a zero matrix. Here, in the dual diagonal matrix B, the cell matrix constituting the dual diagonal line may be an identity matrix, and the remaining cell matrices may be zero matrices. The cell matrix of the dual diagonal lines constituting the dual diagonal matrix B may be continuous with the cell matrix of the diagonal lines constituting the identity matrix D.
In fig. 3, N is the length of a codeword, K is the length of information, and g is a value that varies depending on the code rate. The matrix a and the matrix C have sizes g × K and (N-K-g) × (K + g), respectively, and may be composed of a cyclic permutation matrix and a zero matrix having a size L × L. Furthermore, matrix Z is a zero matrix with a size g × (N-K-g), while matrix B is a double diagonal matrix with a size g × g. Matrix B may be expressed as in equation 3:
[ equation 3]
Figure BDA0001471297700000061
Which is a cell matrix and is an identity matrix having a size L x L.
The LDPC codeword encoded by the parity check matrix shown in fig. 3 may include a systematic part of (N-K) × K corresponding to input information, a first parity part corresponding to the dual diagonal matrix B, and a second parity part corresponding to the identity matrix D.
The LDPC encoder according to the present invention may calculate a first parity part using the input information and a first parity check matrix (PCM [ AB ]), and may calculate a second parity part using a second parity check matrix (PCM [ C D ]) based on the input information and the calculated first parity part.
In particular, the LDPC encoder according to the present invention may encode input information using the following equation 4:
[ equation 4]
HcT＝0
Here, H is a parity check matrix, and c is an LDPC codeword.
Meanwhile, equation 4 may be separated as shown in equation 5:
[ equation 5]
Figure BDA0001471297700000071
Figure BDA0001471297700000072
Where s is the system part, P1Is the first parity portion, and P2Is the second parity portion.
Since B is a double diagonal matrix, it is used to calculate the first parity part P1The encoding process of (2) may be performed by a block type accumulator. Furthermore, since D is an identity matrix, the second parity partP2Can pass through
Figure BDA0001471297700000073
But simply calculated. Thus, the LDPC encoder according to the present invention has an efficient linear time coding algorithm and thus reduces its complexity.
By way of example, N, K and g for an LDPC code with code rate 0.25 with codeword lengths 8192, 16384, 32768, and 65536, respectively, are given in table 1.
[ Table 1]
N K g
8192 2048 160
16384 4096 320
32768 8192 640
65536 16384 1280
An exemplary method for expressing the PCM of the QC-LDPC code designed in table 1 will now be described.
Assume that a QC-LDPC code having a code rate of 4/, N-28, and K-16, and consisting of 4 × 4CPM has a PCM as shown in equation 6:
[ equation 6]
Figure BDA0001471297700000082
The PCM may be represented as follows.
73-matrix size (column # -7 and row # -3)
2311111-column weight distribution
Column 0 weight 2, column 1 weight 3,
column 2 weight is 1, column 3 weight is 1,
column 4 weight is 1, column 5 weight is 1,
the column 6 weight is 1.
334-line weight distribution
Line 0 is weighted by 3, line 1 is weighted by 3,
row 2 has a weight of 4.
-the position of the non-zero matrix of each line
014 non-zero matrix position of row 0, row weight 3
135 non-zero matrix position of row 1, row weight 3
0126 non-zero matrix position of row 2, row weight 4
Exponent value of the non-zero matrix of each line
Exponent value of non-zero matrix of row 0 of 230
Exponent value of non-zero matrix of row 1 of 120
2300 exponent value of non-zero matrix of row 2
The PCM of the QC-LDPC code having a code rate of 0.25, which operates in a negative SNR environment of the terrestrial cloud broadcasting system according to the present invention, can be expressed in such a manner as to result in the following embodiments:
[ example 1]
Figure BDA0001471297700000091
Figure BDA0001471297700000101
Figure BDA0001471297700000111
Figure BDA0001471297700000121
Figure BDA0001471297700000131
Figure BDA0001471297700000141
Figure BDA0001471297700000151
Figure BDA0001471297700000161
Figure BDA0001471297700000171
[ example 2]
Figure BDA0001471297700000172
Figure BDA0001471297700000181
Figure BDA0001471297700000191
Figure BDA0001471297700000201
Figure BDA0001471297700000211
Figure BDA0001471297700000221
Figure BDA0001471297700000231
Figure BDA0001471297700000241
Figure BDA0001471297700000251
Figure BDA0001471297700000261
Figure BDA0001471297700000271
Figure BDA0001471297700000281
Figure BDA0001471297700000291
Figure BDA0001471297700000301
Figure BDA0001471297700000311
Figure BDA0001471297700000321
Figure BDA0001471297700000331
[ example 3]
Figure BDA0001471297700000332
Figure BDA0001471297700000341
Figure BDA0001471297700000351
Figure BDA0001471297700000361
Figure BDA0001471297700000371
Figure BDA0001471297700000381
Figure BDA0001471297700000391
Figure BDA0001471297700000401
Figure BDA0001471297700000411
Figure BDA0001471297700000421
Figure BDA0001471297700000431
Figure BDA0001471297700000441
Figure BDA0001471297700000451
Figure BDA0001471297700000461
Figure BDA0001471297700000471
Figure BDA0001471297700000481
Figure BDA0001471297700000491
Figure BDA0001471297700000501
Figure BDA0001471297700000511
Figure BDA0001471297700000521
Figure BDA0001471297700000531
Figure BDA0001471297700000541
Figure BDA0001471297700000551
Figure BDA0001471297700000561
Figure BDA0001471297700000571
Figure BDA0001471297700000581
Figure BDA0001471297700000591
Figure BDA0001471297700000601
Figure BDA0001471297700000611
Figure BDA0001471297700000621
Figure BDA0001471297700000631
Figure BDA0001471297700000641
Figure BDA0001471297700000651
[ example 4]
Figure BDA0001471297700000652
Figure BDA0001471297700000661
Figure BDA0001471297700000671
Figure BDA0001471297700000681
Figure BDA0001471297700000691
Figure BDA0001471297700000701
Figure BDA0001471297700000711
Figure BDA0001471297700000721
Figure BDA0001471297700000731
Figure BDA0001471297700000741
Figure BDA0001471297700000751
Figure BDA0001471297700000761
Figure BDA0001471297700000771
Figure BDA0001471297700000781
Figure BDA0001471297700000791
Figure BDA0001471297700000801
Figure BDA0001471297700000811
Figure BDA0001471297700000821
Figure BDA0001471297700000831
Figure BDA0001471297700000841
Figure BDA0001471297700000851
Figure BDA0001471297700000861
Figure BDA0001471297700000871
Figure BDA0001471297700000881
Figure BDA0001471297700000891
Figure BDA0001471297700000901
Figure BDA0001471297700000911
Figure BDA0001471297700000921
Figure BDA0001471297700000931
Figure BDA0001471297700000941
Figure BDA0001471297700000951
Figure BDA0001471297700000961
Figure BDA0001471297700000971
Figure BDA0001471297700000981
Figure BDA0001471297700000991
Figure BDA0001471297700001001
Figure BDA0001471297700001011
Figure BDA0001471297700001021
Figure BDA0001471297700001031
Figure BDA0001471297700001041
Figure BDA0001471297700001051
Figure BDA0001471297700001061
Figure BDA0001471297700001071
Figure BDA0001471297700001081
Figure BDA0001471297700001091
Figure BDA0001471297700001101
Figure BDA0001471297700001111
Figure BDA0001471297700001121
Figure BDA0001471297700001131
Figure BDA0001471297700001141
Figure BDA0001471297700001151
Figure BDA0001471297700001161
Figure BDA0001471297700001171
Figure BDA0001471297700001181
Figure BDA0001471297700001191
Figure BDA0001471297700001201
Figure BDA0001471297700001211
Figure BDA0001471297700001221
Figure BDA0001471297700001231
Figure BDA0001471297700001241
Figure BDA0001471297700001251
Figure BDA0001471297700001261
Figure BDA0001471297700001271
Figure BDA0001471297700001281
Fig. 4 to 8 illustrate examples of a PCM structure of an LDPC code according to an embodiment of the present invention.
As an example, fig. 4 illustrates a PCM structure of a QC-LDPC code for terrestrial cloud broadcasting, in which the length of a codeword is 8192, and fig. 5 is an expanded view of the PCM structure shown in fig. 4.
Meanwhile, fig. 6 illustrates a PCM structure of the QC-LDPC code for terrestrial cloud broadcasting, in which the length of the codeword is 16384, fig. 7 illustrates a PCM structure of the QC-LDPC code for terrestrial cloud broadcasting, in which the length of the codeword is 32768, and fig. 8 illustrates a PCM structure of the QC-LDPC code for terrestrial cloud broadcasting, in which the length of the codeword is 65536.
Fig. 9 illustrates an example of a PCM structure of an LDPC code according to a code rate according to an embodiment of the present invention.
The PCM of the LDPC code according to the present invention includes a plurality of single parity check codes, and thus, it can be shortened for each different code rate, as shown in fig. 9. For example, LDPC codes with code rates 1/2 and 1/3 can be easily generated by truncating the PCM by 50 and 83.3%. This means that only a part of the entire codeword can be decoded in a high SNR region by the LDPC code according to the present invention. Therefore, the LDPC decoder can save power consumption and reduce latency.
Fig. 10 is a graph illustrating performance of an LDPC code according to an embodiment of the present invention.
As an example, in fig. 10, the performance of the QC-LDPC code having a code rate of 0.25 is shown compared to the SNR. For the purpose of calculation experiments, an LLR (log likelihood ratio) -based sum-product algorithm that performs QPSK (quadrature phase shift keying) modulation and 50-time repetition decoding has been assumed.
Meanwhile, fig. 10 also illustrates an LDPC code used in the DVB-T2/S2 system having a code rate of 0.25 and a codeword length of 64800 to show excellent performance of the LDPC code redesigned according to the present invention. In addition, table 2 below shows that BER (bit error probability) is 2 × 10-6At a performance gap stemming from the shannon limit of LDPC codes designed for terrestrial cloud broadcasting, and table 3 shows the complexity of LDPC codes proportional to the number of 1 s in PCM.
[ Table 2]
Length (N) Shannon limit [ SNR, dB] Difference from limit [ dB ]]
8192 -3.804 1.29
16384 -3.804 0.99
32768 -3.804 0.79
65536 -3.804 0.6
DVB(64800) -3.804 1.29
[ Table 3]
Length (N) Number of one in PCM
8192 36,352
16384 72,736
32768 145,504
65536 291,040
DVB(64800) 194,399
Referring to fig. 10 and tables 2 and 3, in the LDPC code redesigned according to the present invention, the LDPC code having a codeword length of 65536 performs about 0.69dB better than the LDPC code of the DVB-T2/S2 system having a codeword length of 64800 but has a complexity of about 50% higher. However, the LDPC codes with codeword lengths 16384 and 32768 perform about 0.3dB and about 0.5dB respectively better than the LDPC codes of DVB-T2/S2 system with codeword length 64800 but with a complexity about 63% and about 25% lower respectively. In addition, the LDPC codes redesigned according to the present invention (when their codeword lengths are 8192, 16384, 32768, and 65536) have a BER of 2 × 10-6Is spaced from the shannon limit by about 1.29dB, about 0.99dB, about 0.79dB and about 0.6 dB.
Fig. 11 is a flowchart illustrating a method of decoding an LDPC codeword according to an embodiment of the present invention.
Referring to fig. 11, the LDPC decoder according to the present invention, when receiving an LDPC codeword (1110), decodes the received LDPC codeword using a parity check matrix obtained by combining a first parity check matrix of the LDPC code having a higher code rate than a reference value (e.g., 0.5) and a second parity check matrix of the LDPC code having a lower code rate than the reference value (1120). At this time, as shown in fig. 3, the parity check matrix may include a zero matrix Z, an identity matrix D, and a dual diagonal matrix B. In the dual diagonal matrix B, the cell matrix constituting the dual diagonal is an identity matrix, and the remaining cell matrices may be zero matrices. The cell matrix of the dual diagonal lines constituting the diagonal matrix B may be continuous with the cell matrix of the diagonal lines constituting the identity matrix D.
FIG. 12 is a block diagram illustrating an LDPC encoder and an LDPC decoder according to an embodiment of the present invention.
Referring to fig. 12, as an example, an LDPC encoder 1210 according to the present invention may include an input unit 1212, a determination unit 1214, and an encoding unit 1216. LDPC decoder 1220 may include a receiving unit 1222 and a decoding unit 1224.
The input unit 1212 receives information to be encoded.
The determination unit 1214 determines a code rate of the LDPC code, and determines the size of the double diagonal matrix depending on the determined code rate.
The encoding unit 1216 encodes the information input through the input unit 1212 with the LDPC codeword by using the parity check matrix having the code rate determined by the determination unit 1214. Here, the parity check matrix may include a zero matrix and a cyclic permutation matrix.
Meanwhile, as an example, the parity check matrix may have a structure in which a first parity check matrix of the LDPC code having a higher code rate than the reference value and a second parity check matrix of the LDPC code having a lower code rate than the reference value are combined. Here, the reference value may be, for example, 0.5. It may include a zero matrix, an identity matrix, and a dual diagonal matrix. In particular, the parity check matrix may have the structure shown in fig. 3, and in such a case, the first parity check matrix may include a double diagonal matrix B, and the second parity check matrix may include an identity matrix D. In the dual diagonal matrix B, the cell matrix constituting the dual diagonal line may be an identity matrix, and the remaining cell matrices may be zero matrices. The cell matrix constituting the dual diagonal line may be continuous with the cell matrix constituting the diagonal line of the identity matrix D.
As an example, the encoding unit 1216 may encode the input information with the LDPC codeword by calculating a first parity part using the information input through the input unit 1212 and a first parity check matrix, and by calculating a second parity part using a second parity check matrix based on the input information and the calculated first parity part.
The LDPC codeword encoded by the encoding unit 1216 may include a systematic part corresponding to information input through the input unit 1212, a first parity part corresponding to a dual diagonal matrix, and a second parity part corresponding to an identity matrix.
Meanwhile, the receiving unit 1222 of the decoder 1220 receives the LDPC codeword encoded by the parity check matrix. The LDPC codeword received by the receiving unit 1222 may include a systematic part, a first parity part, and a second parity part.
As shown in fig. 3, the decoding unit 1224 decodes the LDPC codeword received by the receiving unit 1222 using the parity check matrix shown in fig. 3.
Although the exemplary embodiments of the present invention have been described, the present invention is not limited thereto, and various modifications or variations may be made thereto without departing from the scope of the invention. The embodiments described herein are not provided to limit but to describe the present invention, and the present invention is not limited thereto. The scope of the invention should be construed in the appended claims, and the spirit of the invention within the equivalents should be construed to be included in the scope of the invention.

Claims (11)

1. A method for encoding input information based on low density parity check, LDPC, the method comprising:
receiving information; and
the input information is encoded into an LDPC codeword using a parity check matrix,
wherein the parity check matrix includes:
the first matrix a is a matrix of a,
a double diagonal matrix B having the same number of rows and columns as the number of rows of the first matrix A,
a zero matrix Z having the same number of rows as the number of columns of the dual diagonal matrix B,
a second matrix C having the same number of rows as the number of columns of the zero matrix Z, and
an identity matrix D having the same number of rows and columns as the number of columns of the zero matrix Z, wherein the first matrix A is adjacent to the dual diagonal matrix B in the parity check matrix, the first matrix A and the dual diagonal matrix B are adjacent to the second matrix C in the parity check matrix,
wherein the identity matrix D is adjacent to the second matrix C and the zero matrix Z,
wherein the non-zero elements of the dual diagonal matrix B are all the same,
wherein the encoded LDPC codeword includes a systematic part corresponding to input information, a first parity part corresponding to the dual diagonal matrix B, and a second parity part corresponding to the identity matrix D.
2. The method of claim 1, wherein the step of encoding the input information into the LDPC codeword comprises:
calculating the first parity part using the first matrix a and the dual diagonal matrix B and the input information; and
based on the input information and the calculated first parity part, the second parity part is calculated using the second matrix C and the identity matrix D.
3. The method of claim 1, wherein the cells of the dual diagonal matrix B form dual diagonals corresponding to non-zero cells, and the remaining cells of the dual diagonal matrix B are all zero.
4. The method of claim 3, wherein one diagonal line of the dual diagonal lines is continuous with a diagonal line of the identity matrix D.
5. The method of claim 1, further comprising, prior to the step of encoding the input information into the LDPC codeword,
determining the code rate of the LDPC code; and
and determining the size of the dual diagonal matrix B according to the determined code rate.
6. A low density parity check, LDPC, encoder comprising:
an input unit for receiving input information; and
an encoding unit for encoding the input information into an LDPC codeword using a parity check matrix,
wherein the parity check matrix includes:
the first matrix a is a matrix of a,
a double diagonal matrix B having the same number of rows and columns as the number of rows of the first matrix A,
a zero matrix Z having the same number of rows as the number of columns of the dual diagonal matrix B,
a second matrix C having the same number of rows as the number of columns of the zero matrix Z, and
an identity matrix D having the same number of rows and columns as the number of columns of the zero matrix Z, wherein the first matrix A is adjacent to the dual diagonal matrix B in the parity check matrix, the first matrix A and the dual diagonal matrix B are adjacent to the second matrix C in the parity check matrix,
wherein the identity matrix D is adjacent to the second matrix C and the zero matrix Z,
wherein the non-zero elements of the dual diagonal matrix B are all the same,
wherein the encoded LDPC codeword includes a systematic part corresponding to input information, a first parity part corresponding to the dual diagonal matrix B, and a second parity part corresponding to the identity matrix D.
7. The LDPC encoder according to claim 6, wherein the encoding unit calculates the first parity part by using the first matrix a and the dual diagonal matrix B and the input information; and encodes the input information by calculating the second parity part using the second matrix C and the identity matrix D based on the input information and the calculated first parity part.
8. The LDPC encoder according to claim 6, wherein the cells of the dual diagonal matrix B constitute dual diagonal lines corresponding to non-zero cells, and the remaining cells of the dual diagonal matrix B are all zero.
9. The LDPC encoder according to claim 6, wherein one diagonal line of the dual diagonal lines is continuous with a diagonal line of the identity matrix D.
10. The LDPC encoder of claim 6, further comprising a determining unit for determining a code rate of the LDPC code; and determining the size of the dual diagonal matrix B according to the determined code rate.
11. A method of decoding an LDPC code by a low density parity check, LDPC, decoder, the method comprising:
receiving a signal corresponding to the LDPC codeword encoded by the parity check matrix; and
decoding a received signal corresponding to the LDPC codeword using the parity check matrix,
wherein the parity check matrix includes:
the first matrix a is a matrix of a,
a double diagonal matrix B having the same number of rows and columns as the number of rows of the first matrix A,
a zero matrix Z having the same number of rows as the number of columns of the dual diagonal matrix B,
a second matrix C having the same number of rows as the number of columns of the zero matrix Z, and
an identity matrix D having the same number of rows and columns as the number of columns of the zero matrix Z, wherein the first matrix A is adjacent to the dual diagonal matrix B in the parity check matrix, the first matrix A and the dual diagonal matrix B are adjacent to the second matrix C in the parity check matrix,
wherein the identity matrix D is adjacent to the second matrix C and the zero matrix Z,
wherein the non-zero elements of the dual diagonal matrix B are all the same,
wherein the encoded LDPC codeword includes a systematic part corresponding to input information, a first parity part corresponding to the dual diagonal matrix B, and a second parity part corresponding to the identity matrix D.
CN201711140057.1A 2013-05-16 2013-08-29 Method and encoder for encoding/decoding input information based on low density parity check Active CN107888199B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
KR1020130055762A KR101685010B1 (en) 2012-06-01 2013-05-16 Low density parity check code for terrestrial cloud trasmission
KR10-2013-0055762 2013-05-16
CN201310383264.5A CN104168029B (en) 2013-05-16 2013-08-29 Low density parity check code for the broadcast of ground cloud

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
CN201310383264.5A Division CN104168029B (en) 2013-05-16 2013-08-29 Low density parity check code for the broadcast of ground cloud

Publications (2)

Publication Number Publication Date
CN107888199A CN107888199A (en) 2018-04-06
CN107888199B true CN107888199B (en) 2021-11-09

Family

ID=51845028

Family Applications (2)

Application Number Title Priority Date Filing Date
CN201310383264.5A Active CN104168029B (en) 2013-05-16 2013-08-29 Low density parity check code for the broadcast of ground cloud
CN201711140057.1A Active CN107888199B (en) 2013-05-16 2013-08-29 Method and encoder for encoding/decoding input information based on low density parity check

Family Applications Before (1)

Application Number Title Priority Date Filing Date
CN201310383264.5A Active CN104168029B (en) 2013-05-16 2013-08-29 Low density parity check code for the broadcast of ground cloud

Country Status (2)

Country Link
CN (2) CN104168029B (en)
DE (1) DE102013109351B4 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018143743A1 (en) 2017-02-06 2018-08-09 엘지전자 주식회사 Ldpc code transmission method using row-orthogonal structure, and device therefor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101047391A (en) * 2006-04-27 2007-10-03 华为技术有限公司 Low density parity check coding method, device and parity check matrix generating method
CN101047392A (en) * 2007-03-23 2007-10-03 北京航空航天大学 Decoder device of multi-code LDPC code and decoding method
CN101150551A (en) * 2006-09-18 2008-03-26 国家广播电影电视总局广播科学研究院 Interweaving scheme of QPSK/8PSK system for low-density checksum coding

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7752520B2 (en) * 2004-11-24 2010-07-06 Intel Corporation Apparatus and method capable of a unified quasi-cyclic low-density parity-check structure for variable code rates and sizes
US7802171B2 (en) * 2006-02-08 2010-09-21 Interdigital Technology Corporation Wireless communication method and system for bit interleaved coded modulation and iterative decoding
KR101119111B1 (en) * 2006-05-04 2012-03-16 엘지전자 주식회사 Method of data reretransmission using Low Density Parity Check Code
KR101154995B1 (en) * 2006-07-14 2012-06-15 엘지전자 주식회사 Method for performing a Low Density Parity Check encoding
KR100834650B1 (en) * 2006-09-04 2008-06-02 삼성전자주식회사 Apparatus and method for transmitting/receiving signal in a communication system
BRPI0806757A2 (en) * 2007-01-24 2011-09-13 Qualcomm Inc ldpc encoding and decoding of variable size packages
KR101286014B1 (en) 2011-11-21 2013-07-18 광주과학기술원 Direct CH arylation by using palladium-based catalyst

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101047391A (en) * 2006-04-27 2007-10-03 华为技术有限公司 Low density parity check coding method, device and parity check matrix generating method
CN101150551A (en) * 2006-09-18 2008-03-26 国家广播电影电视总局广播科学研究院 Interweaving scheme of QPSK/8PSK system for low-density checksum coding
CN101047392A (en) * 2007-03-23 2007-10-03 北京航空航天大学 Decoder device of multi-code LDPC code and decoding method

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
On Construction of Rate-Compatible Low-Density Parity-Check Codes;M.R.Yazdani等;《IEEE communications Letters》;20040331(第3期);430-434 *

Also Published As

Publication number Publication date
DE102013109351A1 (en) 2014-11-20
DE102013109351B4 (en) 2017-09-21
CN107888199A (en) 2018-04-06
CN104168029B (en) 2017-12-22
CN104168029A (en) 2014-11-26

Similar Documents

Publication Publication Date Title
KR101952161B1 (en) Low density parity check code for terrestrial cloud trasmission
CA2959619C (en) Low density parity check encoder having length of 16200 and code rate of 3/15, and low density parity check encoding method using the same
CA2864642A1 (en) Low density parity check encoder, and low density parity check encoding method using the same
CA2960669C (en) Low density parity check encoder having length of 64800 and code rate of 5/15, and low density parity check encoding method using the same
KR102506682B1 (en) Low density parity check decoder with 64800 length and 4/15 rate, and method using the same
CA2963911A1 (en) Low density parity check encoder having length of 16200 and code rate of 2/15, and low density parity check encoding method using the same
KR102506681B1 (en) Low density parity check decoder with 64800 length and 7/15 rate, and method using the same
CN107888199B (en) Method and encoder for encoding/decoding input information based on low density parity check
KR102500053B1 (en) Low density parity check decoder with 16200 length and 2/15 rate, and method using the same
KR102513139B1 (en) Low density parity check decoder with 16200 length and 4/15 rate, and method using the same
KR102506686B1 (en) Low density parity check decoder with 64800 length and 2/15 rate, and method using the same
KR102500084B1 (en) Low density parity check decoder with 16200 length and 5/15 rate, and method using the same
KR102506685B1 (en) Low density parity check decoder with 64800 length and 5/15 rate, and method using the same
KR102043663B1 (en) Ldpc(low density parity check) - rs(reed solomon) 2-dimensional code for terrestrial cloud broadcasting
KR20150049775A (en) Adaptive decoding method of ldpc(low density parity check) - rs(reed solomon) 2-dimensional code and apparatus using thereof
KR20160020991A (en) Low density parity check encoder with 16200 length and 3/15 rate, and method using the same

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant