CN102412842A

CN102412842A - Method and device for encoding low-density parity check code

Info

Publication number: CN102412842A
Application number: CN2010102933236A
Authority: CN
Inventors: 龚贤卫; 袁志锋; 徐俊; 李长兴
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2010-09-25
Filing date: 2010-09-25
Publication date: 2012-04-11
Anticipated expiration: 2030-09-25
Also published as: WO2012037749A1; CN102412842B

Abstract

The invention provides a method and device for encoding a low-density parity check code. The method comprises the following steps of: comparing a mother code rate and a transmission code rate which are supported by a uniform basic matrix; determining the length K'of an input information grouping bit according to a comparison result; determining an encoding matrix of the low-density parity check (LDPC) code according to the uniform basic matrix and an expansion factor; determining an information bit to be encoded according to the received information grouping bit with the length of K'; and performing LDPC encoding on the information bit to be encoded by using the encoding matrix, and processing a mother code word bit obtained through encoding to acquire a code word bit to be transmitted. By the method and device for encoding the LDPC code, the basic matrix and the expansion factor are determined; the input information grouping length is determined or the encoding matrix is processed according to the received transmission code rate, so the code word which is in accordance with the transmission code rate can be acquired; on the basis of the optimal performance, the changeability of the code rate is realized; furthermore, the hardware design complexity is reduced and the cost is lower.

Description

Coding method and device for low-density parity check code

Technical Field

The present invention relates to the field of digital communications, and in particular, to a method and an apparatus for encoding a low density parity check code.

Background

At present, digital communication systems are commonly used communication systems. As shown in fig. 1, the digital communication system is composed of a transmitting end, a channel and a receiving end, wherein the transmitting end generally includes a source, a source encoder, a channel encoder and a modulator (or a writing unit); the receiving end generally includes a demodulator (or a readout unit), a channel decoder, a source decoder, and a sink; a channel (or a storage medium) exists between a transmitting end and a receiving end, a noise source exists in the channel in the digital communication system, and a channel coding link (including channel coding and decoding, modulation and demodulation, and the like) is the most critical technology of the whole digital communication physical layer, which determines the effectiveness and reliability of the underlying transmission of the digital communication system.

The channel encoder is used for resisting various noises and interferences in the transmission process, and ensuring the reliability of information transmission by artificially adding redundant information to ensure that a system has the capability of automatically correcting errors. Low Density Parity Check (LDPC) codes are linear block codes that can be defined by a very sparse Parity Check matrix or bipartite graph, and Low-complexity encoding and decoding can be implemented by using the sparsity of the Check matrix thereof, so that the LDPC code is put to practical use.

An M × N parity check matrix H defines that each codeword with N bits satisfies the constraint of M parity check sets, i.e., N-bit codewords with M bits of check bits and N-M bits of information bits are encoded. Let the parity check matrix H of the LDPC code be (m)_b×z)×(n_b×z) Is a matrix of m_b×n_bEach block matrix is different powers of a basic permutation matrix of z × z, and when the basic permutation matrix is an identity matrix, the basic permutation matrix is a cyclic shift matrix of the identity matrix, and if the basic permutation matrix is a right shift matrix, the block matrix has the following form:

by such powers

Each block matrix can be uniquely identified and the unit matrix can be represented by 0 in power and the zero matrix by-1 in power. Thus, if each block matrix of H is replaced by its power, one m is obtained_b×n_bPower matrix of (H)_b. Herein is defined as H_bIs the basis matrix of H, H being called H_bThe spreading matrix of (2). In the actual encoding, z is the code length/the number of columns of the basic matrix N/N_bReferred to as spreading factor. For example, a matrix

A2 x 4 basis matrix H can be used with the following parameters z_bAnd the basic permutation matrix is an identity matrix of z x z,

z is 3 and

H_{b} = [\begin{matrix} 0 & 1 & 0 & - 1 \\ 2 & 1 & 2 & 1 \end{matrix}]

therefore, it can also be said that the encoder of the LDPC code is composed of the basic matrix H_bAnd the expansion factor z and the basic permutation matrix are generated uniquely.

If a basic matrix is adopted by the LDPC for each different spreading factor, a codec of the LDPC code needs to store one basic matrix for each different code length, and when the code length is various, a plurality of basic matrices need to be stored, and the storage and other problems need to be considered. Therefore, when the variable code length needs to be realized, the LDPC codes with various code lengths in a certain range of the same code rate use the same form of basic matrix, and the matrix is called as a uniform basic matrix

Different code length, pair

And correcting and expanding to obtain a parity check matrix H, so that the generated codec can be suitable for occasions with variable code length.

Wherein the modification is to use spreading factors of different code lengths to pair the basic matrix H_bOr unifying the basis matrices

The non-negative value in (1) is corrected so that the corrected element value is smaller than the spreading factor value at the code length.

This is because H_bOr

The element in (1) represents the power of the basic permutation matrix, and the basic permutation matrix, namely the unit matrix of z × z, is equivalent to the unit matrix circularly shifts right by one bit every cycle, namely the unit matrix circularly shifts right by one column, so that the basic cyclic matrix is circularly shifted by z-1 times at most; if the loop is cycled z times, the resulting identity matrix is again the identity matrix, which is equal to no cyclic shift. There are many kinds of correction algorithms, for example, a modulo (mod), a round (scale + floor), a round (scale + round), etc. can be used, and P is set_ijIs a basis matrix H_bNon-negative element, P 'of row i and column j of'_ijFor the modified basis matrix

The non-negative elements in the ith row and the jth column of the middle row have:

for the modulo (mod) algorithm:

<math> <mrow> <msubsup> <mi>P</mi> <mi>ij</mi> <mo>′</mo> </msubsup> <mo>&equiv;</mo> <msub> <mi>P</mi> <mi>ij</mi> </msub> <mi>mod</mi> <mi>z</mi> <mo>&equiv;</mo> <msub> <mi>P</mi> <mi>ij</mi> </msub> <mi>mod</mi> <mfrac> <mi>N</mi> <msub> <mi>n</mi> <mi>b</mi> </msub> </mfrac> <mo>;</mo> </mrow> </math>

for the round (scale + floor) algorithm:

for the round (scale + round) algorithm:

<math> <mrow> <msubsup> <mi>P</mi> <mi>ij</mi> <mo>′</mo> </msubsup> <mo>=</mo> <mi>Round</mi> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>ij</mi> </msub> <mo>×</mo> <mfrac> <mi>z</mi> <msub> <mi>z</mi> <mi>max</mi> </msub> </mfrac> <mo>)</mo> </mrow> <mo>=</mo> <mi>Round</mi> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>ij</mi> </msub> <mo>×</mo> <mfrac> <mi>N</mi> <msub> <mi>N</mi> <mi>max</mi> </msub> </mfrac> <mo>)</mo> </mrow> </mrow> </math>

wherein z is the spreading factor corresponding to the current code length, i.e. the number of rows or columns of the block matrix, z_maxFor the maximum supported code length N_maxThe corresponding spreading factor. mod is the operation of the modulus taking,

for the rounding operation, Round is the rounding operation.

For example, for LDPC code with code length 1152 bits, let its basic matrix H_bIs 93, the maximum supported code length is 2304, the size of the basic matrix is 12 × 24, and the result of correcting the basic matrix is:

for the modulo (mod) algorithm:

93 \mod \frac{1152}{24} = 93 \mod 48 = 45;

for the round (scale + floor) algorithm:

for the round (scale + round) algorithm:

<math> <mrow> <mi>Round</mi> <mrow> <mo>(</mo> <mn>93</mn> <mo>×</mo> <mfrac> <mn>1152</mn> <mn>2304</mn> </mfrac> <mo>)</mo> </mrow> <mo>=</mo> <mi>Round</mi> <mrow> <mo>(</mo> <mn>46.5</mn> <mo>)</mo> </mrow> <mo>=</mo> <mn>47</mn> <mo>.</mo> </mrow> </math>

the LDPC code with variable code length of specific code rate can completely use one coder/decoder because of having the same form of basic matrix, wherein the same form of basic matrix can also be called as uniform basic matrix

Assume that the parity check matrix H of an LDPC code has a size of (m)_b×z)×(n_bXz), unified basis matrix

Is m in size_b×n_bThen the LDPC code supports the mother code rate R_m＝(n_b-m_b)/n_b(ii) a If the length of the input information packet is K ', the code word bit to be transmitted with the length of N' is obtained after a series of processing, and the code word is called as the transmission code rate R_tx＝K′/N′。

In ieee802.16e, the code rates supported by LDPC codes are 1/2, 2/3, 3/4, and 5/6, and in the encoding scheme of the existing LDPC code, LDPC encoding matrices H with different mother code rates are usually adopted to ensure that the LDPC code has a certain degree of flexible code rate and performance, and at this time, four basic matrices H appear_bA plurality of LDPC codecs are required on hardware, so that the implementation cost of the hardware is greatly increased; or, a coder/decoder capable of adapting to various mother code rates is used to realize coding and decoding with different code rates, but the hardware design is very complex, and the cost of hardware implementation is also greatly increased.

Disclosure of Invention

In view of the above, the main objective of the present invention is to provide a method and an apparatus for encoding an LDPC code, which implement encoding of an LDPC code with an arbitrary variable code rate.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

a method of encoding a low density parity check, LDPC, code, the method comprising the steps of:

comparing the mother code rate supported by the unified basic matrix with the transmission code rate, and determining the length K' of the input information grouping bit according to the comparison result;

determining an encoding matrix of the LDPC code according to the unified basic matrix and the expansion factor;

determining information bits to be coded by received information packet bits with the length of K';

and performing LDPC coding on the information bits to be coded by using the coding matrix, and processing the code word bits of the mother code obtained by coding to obtain the code word bits to be transmitted.

The method further comprises the following steps: and setting a uniform basic matrix and an expansion factor of the LDPC code.

Before comparing the mother code rate supported by the uniform basic matrix with the transmission code rate, the method further comprises: receiving a current transmission code rate;

determining the length K' of the input information packet bit as follows according to the comparison result:

when R is_tx≥R_mWhen the length K' of the information packet is determined to be (n)_b-m_b) Xz; when R is_tx＜R_mWhen the length of the information packet bit is determined to be K ═ func (m)_b×z×R_tx/(1-R_tx) Or K ═ func (m)_b×z/(1-R_tx))-m_bX z, or K ═ func (func (m)_b×z/(1-R_tx))×R_tx)；

Wherein R is_txFor transmission of code rate, R_mIs the code rate of the mother code, m_b、n_bRespectively, the number of rows and columns of the unified basic matrix, z is a spreading factor, func (x) is one of integer up, integer down, or integer round off for x.

And determining the coding matrix of the LDPC code according to the unified basic matrix and the expansion factor as follows:

and correcting the unified basic matrix, and expanding the corrected basic matrix by using a unit matrix of z multiplied by z according to an expansion factor z to obtain an encoding matrix of the LDPC code.

The received information packet bit with the length of K' determines that the information bit to be coded is as follows:

when R is_tx≥R_mWhen the coding is carried out, the received information grouping bit with the length of K' is directly used as the information bit to be coded; when R is_tx＜R_mThen, padding bits are added to the information packet bits of length K' to form a length K_bXz information bits to be encoded.

The processing of the mother code codeword bits obtained by encoding is as follows:

rearranging the code words of the mother code obtained by encoding, wherein the code words of the mother code before rearrangement have the bit of A₀，A₁，…，A_nb×z-1The rearranged mother code word bit is B₀，B₁，…，B_nb×z-1The rearrangement formula is:

wherein k is_b＝n_b-m_bPV represents a codeword rearrangement vector whose set of elements is n_b-m_b，n_b-m_b+1，n_b-m_b+2，…，n_b-1}, PV (x) denotes an element in the PV vector with index x, x being a non-negative integer;

when R is_tx≥R_mThen, the rearranged mother code word bit B is processed₀，B₁，…，B_nb×z-1Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted;

when R is_tx＜R_mWhen k is to be added_bxz-K' padding bits from rearranged mother code codeword bits B₀，B₁…，B_nb×z-1The systematic bits are deleted, and the rest code word bits of the mother code are used as code word bits to be transmitted.

The determining of the encoding matrix of the LDPC code is as follows:

correcting the unified basic matrix, and expanding the corrected basic matrix by using a unit matrix of z multiplied by z according to an expansion factor z to obtain an expansion matrix of the LDPC code;

when R is_tx≥R_mThen, taking the extended matrix as the coding matrix of the LDPC code; when R is_tx＜R_mWhile, truncating func (m) to the right of the spreading matrix_b×z/(1-R_tx) Column), using the intercepted matrix as the coding matrix of the LDPC code; or,

when in use

When the number of the base matrixes is a positive integer, correcting the unified base matrix to obtain a corrected base matrix;

when R is_tx≥R_mThen, according to an expansion factor z, expanding the corrected basic matrix by using a unit matrix of z multiplied by z to obtain an encoding matrix of the LDPC code; when R is_tx＜R_mThen, k 'to the right of the corrected base matrix is intercepted'_b+m_bAnd expanding the matrix obtained by intercepting by using a unit matrix of z multiplied by z according to the expansion factor z to obtain the coding matrix of the LDPC code.

The received information packet bit with the length of K' determines that the information bit to be coded is as follows: the information packet bits with length K' are directly used as information bits to be encoded.

rearranging the code words of the mother code obtained by encoding, wherein the code words of the mother code before rearrangement have the bits of

The rearranged mother code codeword bits are

The rearrangement formula is:

wherein,

PV represents a codeword rearrangement vector whose elements are grouped into

PV (x) represents an element with index x in the PV vector, wherein x is a non-negative integer, and

representing the upward integer of x;

when R is_tx≥R_mThen, the rearranged mother code word bits are rearrangedTaking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted;

when R is_tx＜R_mThen directly decoding the rearranged mother code word bits

As the codeword bits to be transmitted.

An apparatus for encoding an LDPC code, comprising an encoding unit, the apparatus further comprising: the device comprises a comparison unit, a grouping bit determination unit, a coding matrix determination unit, an information bit determination unit and a code word processing unit; wherein,

the comparison unit is used for comparing the mother code rate supported by the unified basic matrix with the transmission code rate;

a packet bit determination unit for determining the length K' of the input information packet bits according to the comparison result of the comparison unit;

the encoding matrix determining unit is used for determining an encoding matrix of the LDPC code according to the unified basic matrix and the expansion factor;

an information bit determining unit, configured to receive an information packet bit with a length of K', determine an information bit to be encoded, and transmit the information bit to an encoding unit;

and the code word processing unit is used for processing the mother code word obtained by LDPC coding of the coding unit to obtain the code word bit to be transmitted.

The device further comprises: and the setting unit is used for setting the uniform basic matrix and the expansion factor of the LDPC code.

The apparatus further comprises an input unit for receiving a current transmission code rate;

the grouping bit determining unit is specifically used for determining when the comparison result of the comparing unit is R_tx≥R_mWhen the length K' of the information packet bit is determined to be (n)_b-m_b) Xz; when the comparison result of the comparison unit is R_tx＜R_mWhen the length of the information packet bit is determined to be K ═ func (m)_b×z×R_tx/(1-R_tx) Or K ═ func (m)_b×z/(1-R_tx))-m_bX z, or K ═ func (func (m)_b×z/(1-R_tx))×R_tx) (ii) a Wherein R is_txFor transmission of code rate, R_mIs the code rate of the mother code, m_b、n_bRespectively, the number of rows and columns of the unified basic matrix, z is a spreading factor, func (x) is one of integer up, integer down, or integer round off for x.

The coding matrix determining unit is specifically configured to modify the uniform basic matrix, and extend the modified basic matrix by using a zxz identity matrix according to an extension factor z to obtain a coding matrix of the LDPC code.

The information bit determination unit is specifically configured to determine when the comparison result of the comparison unit is R_tx≥R_mThen, the received information packet bit with length of K' is alignedReceiving as information bits to be encoded; when the comparison result of the comparison unit is R_tx＜R_mThen, padding bits are added to the information packet bits of length K' to form a length K_bXz information bits to be encoded.

The code word processing unit is specifically configured to rearrange the mother code word obtained by encoding by the encoding unit, where the mother code word bit before rearrangement is a₀，A₁，…，A_nb×z-1The rearranged mother code word bit is B₀，B₁，…，B_nb×z-1The rearrangement formula is:

when the comparison result of the comparison unit is R_tx≥R_mThen, the rearranged mother code word bit B is processed₀，B₁，…，B_nb×z-1Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted;

when the comparison result of the comparison unit is R_tx＜R_mWhen k is to be added_bxz-K' padding bits from rearranged mother code codeword bits B₀，B₁，…，B_nb×z-1The systematic bits are deleted, and the rest code word bits of the mother code are used as code word bits to be transmitted.

The encoding matrix determining unit is specifically used for correcting the uniform basic matrix, and according to an expansion factor z, expanding the corrected basic matrix by using a unit matrix of z multiplied by z to obtain an expansion matrix of the LDPC code; when comparing the ratio of the unitsThe result is R_tx≥R_mThen, taking the extended matrix as the coding matrix of the LDPC code; when the comparison result of the comparison unit is R_tx＜R_mWhile, truncating func (m) to the right of the spreading matrix_b×z/(1-R_tx) Column), using the intercepted matrix as the coding matrix of the LDPC code; or at

When the number of the base matrixes is a positive integer, correcting the unified base matrix to obtain a corrected base matrix; when the comparison result of the comparison unit is R_tx≥R_mThen, according to an expansion factor z, expanding the corrected basic matrix by using a unit matrix of z multiplied by z to obtain an encoding matrix of the LDPC code; when the comparison result of the comparison unit is R_tx＜R_mThen, k 'to the right of the corrected base matrix is intercepted'_b+m_bAnd expanding the matrix obtained by intercepting by using a unit matrix of z multiplied by z according to the expansion factor z to obtain the coding matrix of the LDPC code.

The information bit determining unit is specifically configured to directly use the received information packet bits with length K' as information bits to be encoded.

The code word processing unit is specifically configured to rearrange the mother code word obtained by the encoding unit, where the mother code word bits before rearrangement are

The rearranged mother code codeword bits are

The rearrangement formula is:

wherein,

PV represents a codeword rearrangement vector, its element setIs composed of

PV (x) represents an element with an index of x in a PV vector, wherein x is a non-negative integer;

when the comparison result of the comparison unit is R_tx≥R_mThen, the rearranged mother code word bits are rearranged

Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted;

when the comparison result of the comparison unit is R_tx＜R_mThen directly decoding the rearranged mother code word bits

As the codeword bits to be transmitted.

The coding method and the device of the LDPC code provided by the invention determine a basic matrix and an expansion factor, determine the length of the input information packet or process the coding matrix according to the received transmission code rate to obtain the code word meeting the transmission code rate, realize the variability of the code rate on the basis of optimal performance, reduce the complexity of hardware design for realizing different code rates and have lower realization cost.

Drawings

Fig. 1 is a block diagram of a digital communication system;

FIG. 2 is a schematic diagram of an implementation flow of a coding method of an LDPC code provided in the present invention;

FIG. 3 is a flowchart illustrating a first embodiment of a method for encoding an LDPC code according to the present invention;

FIG. 4 is a flowchart illustrating a second embodiment of an LDPC encoding method according to the present invention;

fig. 5 is a block diagram of an LDPC code encoding apparatus according to the present invention.

Detailed Description

The basic idea of the invention is as follows: comparing the mother code rate supported by the unified basic matrix with the transmission code rate, and determining the length K' of the input information grouping bit according to the comparison result; determining an encoding matrix of the LDPC code according to the unified basic matrix and the expansion factor; determining information bits to be coded by received information packet bits with the length of K'; and performing LDPC coding on the information bits to be coded by using the coding matrix, and processing the code word bits of the mother code obtained by coding to obtain the code word bits to be transmitted.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings by way of examples.

Fig. 2 shows a flow of an encoding method of an LDPC code provided by the present invention, as shown in fig. 2, the method includes the following steps:

s201, receiving a uniform basic matrix of LDPC code with fixed size determined by user

And an expansion factor z;

in this step, the user can determine a size m according to actual requirements_b×n_bUnified basis matrix of

And a maximum spreading factor z_maxWherein m is_b、n_b、z_maxIs a positive integer, let k_b＝n_b-m_bThen obtain

The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_b(ii) a And determines the spreading factor z according to the code length of the digital communication system in transmission, and generally, for the convenience of hardware implementation, the spreading factor z is a power of 2 or a positive integer multiple of the power of 2.

S202, receiving the current transmission code rate R_txComparison of R_txAnd R_mDetermining the length K' of the input information packet bits according to the comparison result;

in this step, when R is_tx≥R_mWhen the length K' of the information packet is K_b×z＝(n_b-m_b) Xz; when R is_tx＜R_mThen, the generated m is encoded_bThe xz parity bits are transmitted, so that the information packet length K' can be determined by the parity bit length m_bXz and transmission code rate R_txIs determined, therefore K', m_bXz and R_txCan be expressed by, but is not limited to, the following formula:

or

Or

Thus, K' may be represented by, but is not limited to, the following formula: k ═ func (m)_b×z×R_tx/(1-R_tx) Or K ═ func (m)_b×z/(1-R_tx))-m_bX z, or K ═ func (func (m)_b×z/(1-R_tx))×R_tx) (ii) a Where func (x) may represent one of integer up, integer down, or integer round off for x.

S203, according to the expanding factor z and

determining an encoding matrix H for an LDPC code_bz；

In this step, first, the correction algorithm and z pairs are used

Correcting to obtain a corrected basic matrix

According to

And z and zxz are extended to obtain (m)_b×z)×(n_bXz) LDPC matrices

In the invention, the device can be used for

Coding matrix H as LDPC code_bzOr according to R_txAnd R_mAs a result of the comparison of

Intercepting to obtain an encoding matrix H of the LDPC code_bz。

S204, determining information bits to be coded by the received information packet bits with the length of K';

in particular, according to the coding matrix H_bzSize and R of_txAnd R_mAnd processing the information packet bits to obtain the information bits to be coded.

S205, encoding the matrix H_bzAnd carrying out LDPC coding on the information bits to be coded to obtain mother code word bits, and processing the mother code word bits to obtain the code word bits to be transmitted.

In particular, according to the transmission code rate R_txThe length of the code word bit to be transmitted can be determined, and the code word of the mother code is rearranged, shortened or punctured according to the determined length of the code word bit to be transmittedTo the codeword bits to be transmitted.

Fig. 3 shows a flow of implementing a first embodiment of the LDPC code encoding method provided in the present invention, and as shown in fig. 3, the method includes the following steps:

S301-S302, receiving a uniform basic matrix of LDPC code with fixed size determined by user

And a maximum spreading factor z_maxDetermining a spreading factor z according to the required code length, and then executing S305;

The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_b(ii) a And determines the spreading factor z according to the code length required by the digital communication system in transmission, and generally, for hardware implementation, the spreading factor z is a power of 2 or a positive integer multiple of the power of 2.

S303 to S304, receiving the current transmission code rate R_txComparison of R_txAnd R_mDetermining the length K' of the input information packet bits according to the comparison result;

in this step, when R is_tx≥R_mWhen the length K' of the information packet is K_b×z＝(n_b-m_b) Xz; when R is_tx＜R_mThen, the generated m is encoded_bXz parity bits are transmitted, and thus the information packet is transmittedThe length K' may be determined by the check bit length m_bXz and transmission code rate R_txIs determined, therefore K', m_bXz and R_txCan be expressed by, but is not limited to, the following formula:

or

Or

S305, unifying the basic matrix

Correcting to obtain the coding matrix H of the LDPC code by using z expansion_bzThen, S308 is executed;

in this step, first, the correction algorithm and z pairs are used

Correcting to obtain a corrected basic matrix

According to

And z and zxz are extended to obtain (m)_b×z)×(n_bXz) LDPC matrices

And will matrixCoding matrix H as LDPC code_bz。

S306-S307, determining information bits to be coded by the received information packet bits with the length of K';

specifically, when R is_tx≥R_mWhen the coding is carried out, the received information grouping bit with the length of K' is directly used as the information bit to be coded; when R is_tx＜R_mThen, padding bits are added to the information packet bits of length K' to form a length K_bXz information bits to be coded, wherein the method for adding the padding bits can be in a mode of front of, behind or alternating with the information packet bits, and the length of the padding bits is k_bxz-K', and additionally, for ease of subsequent processing, filled K_bThe xz-K' bits are preferably all 0 bits, and may be all 1 bits.

S308 to S309, by (m)_b×z)×(n_bXz) encoding matrix H_bzAnd carrying out LDPC coding on the information bits to be coded to obtain mother code word bits, and processing the mother code word bits to obtain the code word bits to be transmitted.

In particular by encoding the matrix H_bzThe bit length of the mother code word is N ═ N by the LDPC coding_bXz, where the first k of the mother code codeword bits_bXz bits are systematic bits, m_bXz bits are parity bits.

In order to improve the reliability of codeword transmission, the obtained mother code codeword bits may be first subjected to codeword rearrangement, assuming that the mother code codeword bits before rearrangement are a₀，A₁，…，A_nb×z-1The code word bits of the mother code after the code word rearrangement are B₀，B₁，…，B_nb×z-1Then the codeword rearrangement is represented by the following formula:

wherein PV represents a codeword rearrangement vector, PV includes m_bA different element, whose set of elements is { n }_b-m_b，n_b-m_b+1，n_b-m_b+2，…，n_b-1} and each element is different from the others, PV (x) denotes the element in the PV vector with index x, where x is a non-negative integer.

When R is_tx≥R_mThen, the puncturing operation is carried out, namely the rearranged mother code word bit B is obtained₀，B₁，…，B_nb×z-1Taking func (K'/R) from small to large according to the index_tx) And bits as codeword bits to be transmitted, where func (x) may represent a kind of integer fetching up, integer fetching down, or integer fetching by rounding up for x, and specifically, an appropriate operation may be selected for func (x) according to an actual application.

When R is_tx＜R_mThen, a shortening operation is performed to add k in S304_bMother code word bit B obtained by rearranging xz-K' filling bits₀，B₁，，B_nb×z-1The systematic bits are deleted (for the deletion operation, the padding bits are preferably all 0 or all 1 bits in S304), and the remaining bits of the mother code codeword are used as the bits of the codeword to be transmitted.

The first embodiment of the LDPC code encoding method is specifically described below with reference to examples:

the first embodiment is as follows:

1. receiving a unified basis matrix for a 4 x 24 LDPC code determined by a userAnd a maximum spreading factor z_maxWherein z is_max＝96，

As follows:

\begin{matrix} 1 & 25 & 55 & - 1 & 47 & 4 & - 1 & 91 & 84 & 8 & 86 & 52 & 82 & 33 & 5 & 0 & 36 & 20 & 4 & 77 & 80 & 0 & - 1 & - 1 \\ - 1 & 6 & - 1 & 36 & 40 & 47 & 12 & 79 & 47 & - 1 & 41 & 21 & 12 & 71 & 14 & 72 & 0 & 44 & 49 & 0 & 0 & 0 & 0 & - 1 \\ 51 & 81 & 83 & 4 & 67 & - 1 & 21 & - 1 & 31 & 24 & 91 & 61 & 81 & 9 & 86 & 78 & 60 & 88 & 67 & 15 & - 1 & - 1 & 0 & 0 \\ 68 & - 1 & 50 & 15 & - 1 & 36 & 13 & 10 & 11 & 20 & 53 & 90 & 29 & 92 & 57 & 30 & 84 & 92 & 11 & 66 & 80 & - 1 & - 1 & 0 \end{matrix}

can yield m_b＝4，n_b＝24，k_b＝n_b-m_b＝24-4＝20，

The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_bWhen 20/24 is 5/6 is 0.833, the spreading factor z is 3 × 2 for easy realization and practical code length⁵＝96。

2. Receiving the current transmission code rate R_txCompare R0.78_txAnd R_mSince 0.78 < 0.833, the size of (c) can be increased by K' ═ ceil (m)_b×z/(1-R_tx))-m_bX z, K' is 1362, wherein ceil (x) denotes an integer up to x.

3. Correcting the unified basic matrix by a round-robin (scale + floor) algorithm and a spreading factor zObtaining a modified basis matrix

As follows:

\begin{matrix} 1 & 25 & 55 & - 1 & 47 & 4 & - 1 & 91 & 84 & 8 & 86 & 52 & 82 & 33 & 5 & 0 & 36 & 20 & 4 & 77 & 80 & 0 & - 1 & - 1 \\ - 1 & 6 & - 1 & 36 & 40 & 47 & 12 & 79 & 47 & - 1 & 41 & 21 & 12 & 71 & 14 & 72 & 0 & 44 & 49 & 0 & 0 & 0 & 0 & - 1 \\ 51 & 81 & 83 & 4 & 67 & - 1 & 21 & - 1 & 31 & 24 & 91 & 61 & 81 & 9 & 86 & 78 & 60 & 88 & 67 & 15 & - 1 & - 1 & 0 & 0 \\ 68 & - 1 & 50 & 15 & - 1 & 36 & 13 & 10 & 11 & 20 & 53 & 90 & 29 & 92 & 57 & 30 & 84 & 92 & 11 & 66 & 80 & - 1 & - 1 & 0 \end{matrix}

according to

An LDPC matrix of (4 × 96) × (24 × 96) obtained by extending a unit matrix of z 96 and z × z

And will matrix

Coding matrix H as LDPC code_bz。

4. The information packet bit with the length of K' is received, and R is the length of the information packet bit since 0.78 < 0.833_tx＜R_mWill have a length of k_bX z-K '558 all 0 bits are padded in front of the information packet bits of length K', resulting in a length K_bInformation bits to be encoded of 1920 × z.

5. Mixing (4X 96) X (24X 96) H_bzFor length of k_bLDPC coding is carried out on the information bits to be coded with the length of 1920 being multiplied by z, and the length of N is obtained_b2304, where the first 1920 bits are systematic bits and the last 384 bits are parity bits.

The code word rearrangement is carried out on the code word bits of the mother code, and the code word bits of the mother code before rearrangement are assumed to be A₀，A₁，，A₂₃₀₃The code word bit of the mother code after the code word rearrangement is B₀，B₁，…，B₂₃₀₃The codeword rearrangement is represented by the following formula:

where PV denotes a codeword rearrangement vector, and PV ═ {20, 21, 22, 23 }. And because 0.78 < 0.833, namely R_tx＜R_mThe 558 all 0 bits filled in the front of the information packet bit in 4 are rearranged to obtain the mother code word bit B₀，B₁，…，B₂₃₀₃The rest code word bits B of the mother code are deleted from the systematic bits in the code₅₅₈，B₅₅₉，...，B₂₃₀₃As the codeword bits to be transmitted.

Example two:

1. receiving a unified basis matrix for a 4 x 24 LDPC code determined by a user

And a maximum spreading factor z_maxWherein z is_max＝96，

As follows:

\begin{matrix} 1 & 25 & 55 & - 1 & 47 & 4 & - 1 & 91 & 84 & 8 & 86 & 52 & 82 & 33 & 5 & 0 & 36 & 20 & 4 & 77 & 80 & 0 & - 1 & - 1 \\ - 1 & 6 & - 1 & 36 & 40 & 47 & 12 & 79 & 47 & - 1 & 41 & 21 & 12 & 71 & 14 & 72 & 0 & 44 & 49 & 0 & 0 & 0 & 0 & - 1 \\ 51 & 81 & 83 & 4 & 67 & - 1 & 21 & - 1 & 31 & 24 & 91 & 61 & 81 & 9 & 86 & 78 & 60 & 88 & 67 & 15 & - 1 & - 1 & 0 & 0 \\ 68 & - 1 & 50 & 15 & - 1 & 36 & 13 & 10 & 11 & 20 & 53 & 90 & 29 & 92 & 57 & 30 & 84 & 92 & 11 & 66 & 80 & - 1 & - 1 & 0 \end{matrix}

m can be obtained_b＝4，n_b＝24，k_b＝n_b-m_b＝24-4＝20，The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_b20/24-5/6-0.833, and for convenience of implementation, the spreading factor z is determined to be 2⁶＝64。

2. Receiving the current transmission code rate R_txCompare R to 0.875_txAnd R_mSince 0.875 > 0.833, the packet length K' is K_b×z＝1280。

3. Correcting the unified basic matrix by a round-robin (scale + floor) algorithm and a spreading factor z

Obtaining a modified basis matrix

As follows:

\begin{matrix} 0 & 16 & 36 & - 1 & 31 & 2 & - 1 & 60 & 56 & 5 & 57 & 34 & 54 & 22 & 3 & 0 & 24 & 13 & 2 & 51 & 53 & 0 & - 1 & - 1 \\ - 1 & 4 & - 1 & 34 & 26 & 31 & 8 & 52 & 31 & - 1 & 27 & 14 & 8 & 47 & 9 & 48 & 0 & 29 & 32 & 0 & 0 & 0 & 0 & - 1 \\ 34 & 54 & 55 & 2 & 44 & - 1 & 14 & - 1 & 20 & 16 & 60 & 40 & 54 & 6 & 57 & 52 & 40 & 58 & 44 & 10 & - 1 & - 1 & 0 & 0 \\ 45 & - 1 & 33 & 10 & - 1 & 24 & 8 & 6 & 7 & 13 & 35 & 60 & 19 & 61 & 38 & 20 & 56 & 61 & 7 & 44 & 53 & - 1 & - 1 & 0 \end{matrix}

according toAn LDPC matrix of (4 × 64) × (24 × 64) obtained by extending a unit matrix of z ═ 64 and z × z

And will matrix

Coding matrix H as LDPC code_bz。

4. Receiving the information packet bit with the length of K '═ 1280, and since 0.875 is greater than 0.833, the length of K' ═ K is_bThe 1280 information packet bits are directly used as information bits to be encoded.

5. Mixing (4X 64) × (24X 64) H_bzFor length K ═ K_bCarrying out LDPC coding on the information bits to be coded with the length of 1280 multiplied by z to obtain the length of N_bX z 1536 mother code codeword bits, where the first 1280 bits are systematic bits and the last 256 bits are parity bits.

Performing code word repetition on code word bits of mother codeRow, assume the mother code codeword bits before rearrangement to be A₀，A₁，…，A₁₅₃₅The code word bits of the mother code after the code word rearrangement are B₀，B₁，…，B₁₅₃₅Then the codeword rearrangement is represented by the following formula:

where PV denotes a codeword rearrangement vector, and PV ═ {20, 21, 22, 23 }. Since 0.875 is more than 0.833, the compound belongs to R_tx≥R_mThe rearranged mother code word bit B₀，B₁，…，B₁₅₃₅Taking floor (K'/R) from small to large according to the index_tx) 1462 bits, i.e. B₀，B₁，…，B₁₄₆₁As the codeword bit to be transmitted, wherein floor (x) denotes taking an integer number down for x.

Fig. 4 shows a flow of implementing a second embodiment of the LDPC code encoding method provided in the present invention, and as shown in fig. 4, the method includes the following steps:

s401 to S402, receiving a uniform basic matrix of LDPC code with fixed size determined by user

And a maximum spreading factor z_maxDetermining an expansion factor z according to the required code length;

in this step, the user can determine a size m according to actual requirements_b×n_bUnified basis matrix ofAnd a maximum spreading factor z_maxWherein m is_b、n_b、z_maxIs a positive integer, let k_b＝n_b-m_bThen obtain

S403, receiving the current transmission code rate R_txThen, S404 and S405 are respectively executed.

S404, comparing R_txAnd R_mDetermines the length K' of the input information packet bits according to the comparison result, and then performs S406;

or

Or

S405, for the unified basic matrix

Correcting to determine the encoding matrix H of LDPC code_bzThen, S407 is executed;

in this step, first, the correction algorithm and z pairs are used

Correcting to obtain a corrected basic matrix

According to

And z and zxz are extended to obtain (m)_b×z)×(n_bXz) LDPC spreading matrix

When R is_tx≥R_mThen the matrix will be expanded

Coding matrix H as LDPC code_bz(ii) a When R is_tx＜R_mBy intercepting

Right func (m)_b×z/(1-R_tx) Column to obtain a size of (m)_b×z)×func(m_b×z/(1-R_tx) H) of a coding matrix_bz. And also

Thus, the coding matrix H of the LDPC code at this time_bzHas a size of (m)_b×z)×(K′+m_b×z)。

In addition, when

When it is a positive integer, the step is to unify the basic matrix

Is corrected to obtainAfter that, it can also be based on R_txAnd R_mTo the corrected basis matrix

After processing, using expansion factor z to expand to obtain coding matrix H of LDPC code_bz。

Specifically, when R is_tx≥R_mThen, to the corrected basic matrixExpanding to obtain a coding matrix H_bzObtaining a coding matrix H in particular according to the above method_bzThe process is the same and is not described again;

when R is_tx＜R_mBy interceptingK 'on the right'_b+m_bColumn, obtained with a size of m_b×(k′_b+m_b) Of (2) matrix

According to

And a spreading factor z, spread to obtain (m)_b×z)×((k′_b+m_b) Xz) of LDPC codes_bz. In S403, when R is_tx＜R_mWhen the temperature of the water is higher than the set temperature,

and alsoIs a positive integer and, therefore,

namely, it is

Therefore, the coding matrix H of the LDPC code is obtained at this time_bzIs also (m)_b×z)×(K′+m_b×z)。

S406, receiving information grouping bits with the length of K', and directly taking the information grouping bits as information bits to be coded;

s407 to S408, by encoding matrix H_bzAnd carrying out LDPC coding on the information bits to be coded to obtain mother code word bits, and processing the mother code word bits to obtain the code word bits to be transmitted.

Specifically, when R is_tx≥R_mWhen the passage size is (m)_b×z)×(n_bXz) of LDPC codes_bzLDPC coding is carried out on information bits to be coded, and the length of the obtained mother code codeword bit is N ═ K' + m_b×z＝n_bXz, where the first K' bits of the mother code codeword bits are systematic bits and the last m bits are systematic bits_bXz bits are check bits, wherein the length of the information bits to be encoded is K ═ K_b×z＝(n_b-m_b)×z。

In order to improve the reliability of code word transmission, firstly, code word rearrangement is carried out on the obtained code word bits of the mother code, and the code word bits of the mother code before rearrangement are assumed to be

The code word rearranged mother code has the code word bits ofThe codeword rearrangement is represented by the following formulaRepresents:

wherein,

PV represents a codeword rearrangement vector, PV includes m_bA different element, the set of elements being

And each element is different from the others, PV (x) denotes an element with an index x in the PV vector, where x is a non-negative integer.

When R is_tx≥R_mThen, the puncturing operation is carried out, namely the code word bits of the mother code obtained after rearrangement are carried out

Taking func (K'/R) from small to large according to the index_tx) Bits as code word bits to be transmitted, i.e.Are the codeword bits to be transmitted. Wherein func (x) may represent one of upward integer fetching, downward integer fetching and integer rounding for x, and an appropriate operation may be selected for func (x) according to the actual application.

When R is_tx＜R_mThen, since the encoding matrix H is obtained in S403_bzThe interception operation is performed in the process, so that the code word bits of the mother code obtained after rearrangement can be obtained

As the codeword bits to be transmitted.

The second embodiment of the LDPC code encoding method is specifically described below with reference to examples:

example three:

1. receiving a unified basis matrix for a user-defined 6 x 24 LDPC codeAnd a maximum spreading factor z_maxWherein z is_max＝96，

As follows:

\begin{matrix} 6 & 38 & 3 & 93 & - 1 & - 1 & - 1 & 30 & 70 & - 1 & 86 & - 1 & 37 & 30 & 4 & 11 & - 1 & 46 & 48 & 0 & - 1 & - 1 & - 1 & - 1 \\ 62 & 94 & 19 & 84 & - 1 & 92 & 78 & - 1 & 15 & - 1 & - 1 & 92 & - 1 & 45 & 24 & 32 & 30 & - 1 & - 1 & 0 & 0 & - 1 & - 1 & - 1 \\ 71 & - 1 & 55 & - 1 & 12 & 66 & 45 & 79 & - 1 & 78 & - 1 & - 1 & 10 & - 1 & 22 & 55 & 70 & 82 & - 1 & - 1 & 0 & 0 & - 1 & - 1 \\ 38 & 61 & - 1 & 66 & 9 & 73 & 47 & 64 & - 1 & 39 & 61 & 43 & - 1 & - 1 & - 1 & - 1 & 95 & 32 & 0 & - 1 & - 1 & 0 & 0 & - 1 \\ - 1 & - 1 & - 1 & - 1 & 32 & 52 & 55 & 80 & 95 & 22 & 6 & 51 & 24 & 90 & 44 & 20 & - 1 & - 1 & - 1 & - 1 & - 1 & - 1 & 0 & 0 \\ - 1 & 63 & 31 & 88 & 20 & - 1 & - 1 & - 1 & 6 & 40 & 56 & 16 & 71 & 53 & - 1 & - 1 & 27 & 26 & 48 & - 1 & - 1 & - 1 & - 1 & 0 \end{matrix}

can yield m_b＝6，n_b＝24，k_b＝n_b-m_b＝24-6＝18，

The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_b18/24-3/4-0.75, and for the convenience of realization and the code length of the code required in practice, the spreading factor z is determined to be 3 × 2⁵＝96。

2. Receiving the current transmission code rate R_txCompare R0.9_txAnd R_mSince 0.9 > 0.75, the packet length K' K ═ K_b×z＝1728。

3. By rounding (scale + floor) algorithm andspreading factor z corrects unified basis matrix

Obtaining a modified basis matrix

As follows:

\begin{matrix} 6 & 38 & 3 & 93 & - 1 & - 1 & - 1 & 30 & 70 & - 1 & 86 & - 1 & 37 & 30 & 4 & 11 & - 1 & 46 & 48 & 0 & - 1 & - 1 & - 1 & - 1 \\ 62 & 94 & 19 & 84 & - 1 & 92 & 78 & - 1 & 15 & - 1 & - 1 & 92 & - 1 & 45 & 24 & 32 & 30 & - 1 & - 1 & 0 & 0 & - 1 & - 1 & - 1 \\ 71 & - 1 & 55 & - 1 & 12 & 66 & 45 & 79 & - 1 & 78 & - 1 & - 1 & 10 & - 1 & 22 & 55 & 70 & 82 & - 1 & - 1 & 0 & 0 & - 1 & - 1 \\ 38 & 61 & - 1 & 66 & 9 & 73 & 47 & 64 & - 1 & 39 & 61 & 43 & - 1 & - 1 & - 1 & - 1 & 95 & 32 & 0 & - 1 & - 1 & 0 & 0 & - 1 \\ - 1 & - 1 & - 1 & - 1 & 32 & 52 & 55 & 80 & 95 & 22 & 6 & 51 & 24 & 90 & 44 & 20 & - 1 & - 1 & - 1 & - 1 & - 1 & - 1 & 0 & 0 \\ - 1 & 63 & 31 & 88 & 20 & - 1 & - 1 & - 1 & 6 & 40 & 56 & 16 & 71 & 53 & - 1 & - 1 & 27 & 26 & 48 & - 1 & - 1 & - 1 & - 1 & 0 \end{matrix}

according toAn LDPC matrix of (6 × 96) × (24 × 96) obtained by extending a unit matrix of z 96 and z × z

And 0.9 > 0.75, then the matrix is dividedCoding matrix H as LDPC code_bz。

4. Receiving information packet bits of length K1728 and converting the information packet bits of length K to K_bThe 1728 information packet bits are directly used as information bits to be encoded.

5. Mixing (6X 96) X (24X 96) H_bzFor length K ═ K_b1728, and performing LDPC coding to obtain the final productTo a length of N ═ K' + m_b×z＝n_b2304, where the first 1728 bits are systematic bits and the last 576 bits are parity bits.

The code word rearrangement is carried out on the code word bits of the mother code, and the code word bits of the mother code before rearrangement are assumed to be A₀，A₁，…，A₂₃₀₃The code word bits of the mother code after the code word rearrangement are B₀，B₁，…，B₂₃₀₃Then the codeword rearrangement is represented by the following formula:

wherein,PV denotes a codeword rearrangement vector, and PV ═ 18, 19, 20, 21, 22, 23 }. Since 0.9 is more than 0.75, the compound belongs to R_tx≥R_mThe rearranged mother code word bit B₀，B₁，…，B₂₃₀₃Taking ceil (K'/R) from small to large according to the index_tx) 1920 bits, i.e. B₀，B₁，…，B₁₉₁₉As the codeword bits to be transmitted, ceil (x) indicates that x is taken as an integer.

Example four:

1. receiving a unified basis matrix for a user-defined 6 x 24 LDPC code

And a maximum spreading factor z_maxWherein z is_max＝96，

As follows:

\begin{matrix} 6 & 38 & 3 & 93 & - 1 & - 1 & - 1 & 30 & 70 & - 1 & 86 & - 1 & 37 & 30 & 4 & 11 & - 1 & 46 & 48 & 0 & - 1 & - 1 & - 1 & - 1 \\ 62 & 94 & 19 & 84 & - 1 & 92 & 78 & - 1 & 15 & - 1 & - 1 & 92 & - 1 & 45 & 24 & 32 & 30 & - 1 & - 1 & 0 & 0 & - 1 & - 1 & - 1 \\ 71 & - 1 & 55 & - 1 & 12 & 66 & 45 & 79 & - 1 & 78 & - 1 & - 1 & 10 & - 1 & 22 & 55 & 70 & 82 & - 1 & - 1 & 0 & 0 & - 1 & - 1 \\ 38 & 61 & - 1 & 66 & 9 & 73 & 47 & 64 & - 1 & 39 & 61 & 43 & - 1 & - 1 & - 1 & - 1 & 95 & 32 & 0 & - 1 & - 1 & 0 & 0 & - 1 \\ - 1 & - 1 & - 1 & - 1 & 32 & 52 & 55 & 80 & 95 & 22 & 6 & 51 & 24 & 90 & 44 & 20 & - 1 & - 1 & - 1 & - 1 & - 1 & - 1 & 0 & 0 \\ - 1 & 63 & 31 & 88 & 20 & - 1 & - 1 & - 1 & 6 & 40 & 56 & 16 & 71 & 53 & - 1 & - 1 & 27 & 26 & 48 & - 1 & - 1 & - 1 & - 1 & 0 \end{matrix}

can yield m_b＝6，n_b＝24，k_b＝n_b-m_b＝24-6＝18，

The supported mother code rate is R_m＝(n_b-m_b)/n_b＝k_b/n_b18/24-3/4-0.75, and for easy realization and practical code length, 2-2 expansion factor is determined⁶＝64。

2. Receiving the current transmission code rate R_txR is 0.6, compare_txAnd R_mSince 0.6 < 0.75, the size of (c) can be increased by K' ═ ceil (m)_b×z/(1-R_tx))-m_bX z, and K' is 576, wherein ceil (x) represents an integer up to x.

Obtaining a modified basis matrix

As follows:

\begin{matrix} 4 & 25 & 2 & 62 & - 1 & - 1 & - 1 & 20 & 46 & - 1 & 57 & - 1 & 24 & 25 & 2 & 7 & - 1 & 30 & 32 & 0 & - 1 & - 1 & - 1 & - 1 \\ 41 & 62 & 12 & 56 & - 1 & 61 & 52 & - 1 & 10 & - 1 & - 1 & 61 & - 1 & 30 & 16 & 21 & 20 & - 1 & - 1 & 0 & 0 & - 1 & - 1 & - 1 \\ 47 & - 1 & 36 & - 1 & 8 & 44 & 30 & 52 & - 1 & 52 & - 1 & - 1 & 6 & - 1 & 14 & 36 & 46 & 54 & - 1 & - 1 & 0 & 0 & - 1 & - 1 \\ 25 & 40 & - 1 & 44 & 6 & 48 & 31 & 42 & - 1 & 26 & 40 & 28 & - 1 & - 1 & - 1 & - 1 & 63 & 21 & 0 & - 1 & - 1 & 0 & 0 & - 1 \\ - 1 & - 1 & - 1 & - 1 & 21 & 34 & 36 & 53 & 63 & 14 & 4 & 34 & 16 & 60 & 29 & 13 & - 1 & - 1 & - 1 & - 1 & - 1 & - 1 & 0 & 0 \\ - 1 & 42 & 20 & 58 & 13 & - 1 & - 1 & - 1 & 4 & 26 & 37 & 10 & 47 & 35 & - 1 & - 1 & 18 & 17 & 32 & - 1 & - 1 & - 1 & - 1 & 0 \end{matrix}

according to

An LDPC matrix of (6 × 64) × (24 × 64) obtained by extending a unit matrix of z ═ 64 and z × zAnd since 0.6 < 0.75, therefore intercept

Ceil (m) on the right_b×z/(1-R_tx) 960 columns, resulting in a coding matrix H of size (6 × 64) × 960_bz。

In addition, the step can also be processed as follows: obtaining a modified basis matrix

And because 0.6 is less than 0.75,

intercepting

K 'on the right'_b+m_bColumn 15 with 9+6, resulting in a matrix size of 6 × (9+6)

According to

And z ═LDPC coding matrix H of (6 × 64) × (15 × 64) obtained by extending unit matrix of 64 and z × z_bz。

4. Information packet bits of length K 'are received and the information packet bits of length K' 576 are directed as the information bits to be encoded.

5. Mixing (6X 64) × (15X 64) H_bzLDPC coding is carried out on the information bits to be coded with the length of K '═ 576, and the length of N' + m is obtained_b×z＝n_bX z is 960 bits of the mother code codeword, where the first 576 bits are systematic bits and the last 384 bits are parity bits.

The code word rearrangement is carried out on the code word bits of the mother code, and the code word bits of the mother code before rearrangement are assumed to be A₀，A₁，…，A₉₅₉The code word bits of the mother code after the code word rearrangement are B₀，B₁，…，B₉₅₉Then the codeword rearrangement is represented by the following formula:

wherein,PV denotes a codeword rearrangement vector, and PV is {9, 10, 11, 12, 13, 14 }. And because 0.6 is less than 0.75, namely R_tx＜R_mSince 3 is obtaining the encoding matrix H_bzThe interception operation is performed in the process, so that the code bit B of the mother code obtained after rearrangement can be obtained₀，B₁，…，B₉₅₉As the codeword bits to be transmitted.

Fig. 5 shows a structure of an encoding apparatus of an LDPC code provided by the present invention, as shown in fig. 5, the apparatus includes: an encoding unit 10, a comparing unit 20, a grouping bit determining unit 30, an encoding matrix determining unit 40, an information bit determining unit 50, and a code word processing unit 60; the comparing unit 20 is configured to compare the mother code rate supported by the uniform basic matrix with the transmission code rate; the grouping bit determining unit 30 is used for determining the length K' of the input information grouping bit according to the comparison result of the comparing unit; the encoding matrix determining unit 40 is configured to determine an encoding matrix of the LDPC code according to the uniform basis matrix and the spreading factor; the information bit determining unit 50 is configured to receive an input information bit, obtain an information packet bit with a length K' according to the information packet bit length determined by the packet bit determining unit 30, determine an information bit to be encoded, and transmit the information bit to the encoding unit 10; the codeword processing unit 60 is configured to process a mother code codeword obtained by performing LDPC encoding on the encoding unit 10 to obtain a codeword bit to be transmitted.

Further, the apparatus further includes a setting unit 70 for setting a uniform basis matrix and a spreading factor of the LDPC code.

Further, the apparatus further comprises an input unit 80, configured to receive a current transmission code rate; the grouping bit determining unit 30 is specifically configured to determine when the comparison result of the comparing unit 20 is R_tx≥R_mWhen the length K' of the information packet bit is determined to be (n)_b-m_b) Xz; when the comparison result of the comparison unit 20 is R_tx＜R_mWhen the length of the information packet bit is determined to be K ═ func (m)_b×z×R_tx/(1-R_tx) Or K ═ func (m)_b×z/(1-R_tx))-m_bX z, or K ═ func (func (m)_b×z/(1-R_tx))×R_tx) (ii) a Wherein R is_txFor transmission of code rate, R_mIs the code rate of the mother code, m_b、n_bRespectively, the number of rows and columns of the unified basic matrix, z is a spreading factor, func (x) is one of integer up, integer down, or integer round off for x.

Further, the coding matrix determining unit 40 is specifically configured to modify the uniform basic matrix, and extend the modified basic matrix by using a zxz identity matrix according to an extension factor z to obtain a coding matrix of the LDPC code.

Accordingly, the number of the first and second electrodes,the information bit determination unit 50 is specifically used when the comparison result of the comparison unit 20 is R_tx≥R_mWhen the coding is carried out, the received information grouping bit with the length of K' is directly used as the information bit to be coded; when the comparison result of the comparison unit 20 is R_tx＜R_mThen, padding bits are added to the information packet bits of length K' to form a length K_bXz, where the padding bits are all 0 bits or all 1 bits.

Accordingly, the code word processing unit 60 is specifically configured to rearrange the mother code word encoded by the encoding unit 10, where the mother code word bits before rearrangement are a₀，A₁，…，A_nb×z-1The rearranged mother code word bit is B₀，B₁，…，B_nb×z-1The rearrangement formula is:

wherein k is_b＝n_b-m_bPV represents a codeword rearrangement vector whose set of elements is n_b-m_b，n_b-m_b+1，n_b-m_b+2，…，n_b-1}, PV (x) denotes an element in the PV vector with index x, x being a non-negative integer; when the comparison result of the comparison unit 20 is R_tx≥R_mThen, the rearranged mother code word bit B is processed₀，B₁，…，B_nb×z-1Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted; when the comparison result of the comparison unit 20 is R_tx＜R_mWhen k is to be added_bxz-K' padding bits from rearranged mother code codeword bits B₀，B₁，…，B_nb×z-1The systematic bits are deleted, and the rest code word bits of the mother code are used as code word bits to be transmitted.

Further, the coding matrix determining unit 40 is specifically configured to modify the uniform basic matrix, and according to the expansion factor z, expand the modified basic matrix by using a zxz identity matrix to obtain an LDAn extended matrix of PC codes; when the comparison result of the comparison unit 20 is R_tx≥R_mThen, taking the extended matrix as the coding matrix of the LDPC code; when the comparison result of the comparison unit is R_tx＜R_mWhile, truncating func (m) to the right of the spreading matrix_b×z/(1-R_tx) Column), using the intercepted matrix as the coding matrix of the LDPC code; or atWhen the number of the base matrixes is a positive integer, correcting the unified base matrix to obtain a corrected base matrix; when the comparison result of the comparison unit 20 is R_tx≥R_mThen, according to an expansion factor z, expanding the corrected basic matrix by using a unit matrix of z multiplied by z to obtain an encoding matrix of the LDPC code; when the comparison result of the comparison unit 20 is R_tx＜R_mThen, k 'to the right of the corrected base matrix is intercepted'_b+m_bAnd expanding the matrix obtained by intercepting by using a unit matrix of z multiplied by z according to the expansion factor z to obtain the coding matrix of the LDPC code.

Accordingly, the information bit determination unit 50 is specifically configured to directly take the received information packet bits with length K' as information bits to be encoded.

Accordingly, the code word processing unit 60 is specifically configured to rearrange the mother code word obtained by the encoding unit 10, where the mother code word bits before rearrangement are

The rearranged mother code codeword bits are

The rearrangement formula is:

wherein,

PV represents a codeword rearrangement vector whose elements are grouped into

PV (x) represents an element with an index of x in a PV vector, wherein x is a non-negative integer; when the comparison result of the comparison unit 20 is R_tx≥R_mThen, the rearranged mother code word bits are rearranged

Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted; when the comparison result of the comparison unit 20 is R_tx＜R_mThen directly decoding the rearranged mother code word bits

As the codeword bits to be transmitted.

It should be noted that encoding and decoding are corresponding to each other, so that the encoding method and the decoding device of the LDPC code provided by the present invention also have corresponding inverse operations, and are not described herein again.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.

Claims

1. A method of encoding a low density parity check, LDPC, code, the method comprising the steps of:

2. The method of claim 1, further comprising: and setting a uniform basic matrix and an expansion factor of the LDPC code.

3. The method of claim 1 or 2, wherein comparing the mother code rate supported by the uniform basis matrix with the transmission code rate further comprises: receiving a current transmission code rate;

4. The method according to claim 1 or 2, wherein the determining the coding matrix of the LDPC code according to the unified base matrix and the spreading factor is:

5. The method of claim 4, wherein the information bits to be encoded are determined from the received information packet bits of length K':

6. The method of claim 5, wherein the processing of the encoded mother code codeword bits is:

when R is_tx＜R_mWhen k is to be added_bxz-K' padding bits from rearranged mother code codeword bits B₀，B₁，…，B_nb×z-1The systematic bits are deleted, and the rest code word bits of the mother code are used as code word bits to be transmitted.

7. The method of claim 3, wherein determining the coding matrix of the LDPC code is:

when in use

8. The method of claim 7, wherein the information bits to be encoded are determined from the received information packet bits of length K': the information packet bits with length K' are directly used as information bits to be encoded.

9. The method of claim 8, wherein the processing of the encoded mother code codeword bits is:

rearranging the code words of the mother code obtained by encoding, wherein the code words of the mother code before rearrangement have the bits ofThe rearranged mother code codeword bits are

The rearrangement formula is:

wherein,

PV represents a codeword rearrangement vector whose elements are grouped intoPV (x) represents an element with index x in the PV vector, wherein x is a non-negative integer, and

representing the upward integer of x;

when R is_tx≥R_mThen, the rearranged mother code word bits are rearranged

Taking func (K'/R) from small to large according to the index_tx) Bits as codeword bits to be transmitted; when R is_tx＜R_mThen directly decoding the rearranged mother code word bits

As the codeword bits to be transmitted.

10. An apparatus for encoding an LDPC code, comprising an encoding unit, the apparatus further comprising: the device comprises a comparison unit, a grouping bit determination unit, a coding matrix determination unit, an information bit determination unit and a code word processing unit; wherein,

11. The apparatus of claim 10, further comprising: and the setting unit is used for setting the uniform basic matrix and the expansion factor of the LDPC code.

12. The apparatus of claim 10 or 11, further comprising an input unit for receiving a current transmission code rate;

13. The apparatus according to claim 10 or 11, wherein the coding matrix determining unit is specifically configured to modify the uniform base matrix, and extend the modified base matrix by using a zxz identity matrix according to an extension factor z to obtain a coding matrix of the LDPC code.

14. The apparatus according to claim 13, wherein the information bit determining unit is specifically configured to determine when the comparison result of the comparing unit is R_tx≥R_mWhen the coding is carried out, the received information grouping bit with the length of K' is directly used as the information bit to be coded; when the comparison result of the comparison unit is R_tx＜R_mThen, padding bits are added to the information packet bits of length K' to form a length K_bXz information bits to be encoded.

15. The apparatus according to claim 14, wherein the codeword processing unit is specifically configured to rearrange the mother code codeword encoded by the encoding unit, and bits of the mother code codeword before rearrangement are a₀，A₁，…，A_nb×z-1The rearranged mother code word bit is B₀，B₁，…，n_b×z-1The rearrangement formula is:

when the comparison result of the comparison unit is R_tx≥R_mThen, the rearranged mother code word bit B is processed₀，B₁，…，B_nb×z-1Sequentially taking fun from small to large according to indexesc(K′/R_tx) Bits as codeword bits to be transmitted;

16. The apparatus according to claim 12, wherein the coding matrix determining unit is specifically configured to modify the uniform base matrix, and extend the modified base matrix by using a zxz identity matrix according to an extension factor z to obtain an extension matrix of the LDPC code; when the comparison result of the comparison unit is R_tx≥R_mThen, taking the extended matrix as the coding matrix of the LDPC code; when the comparison result of the comparison unit is R_tx＜R_mWhile, truncating func (m) to the right of the spreading matrix_b×z/(1-R_tx) Column), using the intercepted matrix as the coding matrix of the LDPC code; or atWhen the number of the base matrixes is a positive integer, correcting the unified base matrix to obtain a corrected base matrix; when the comparison result of the comparison unit is R_tx≥R_mThen, according to an expansion factor z, expanding the corrected basic matrix by using a unit matrix of z multiplied by z to obtain an encoding matrix of the LDPC code; when the comparison result of the comparison unit is R_tx＜R_mThen, k 'to the right of the corrected base matrix is intercepted'_b+m_bAnd expanding the matrix obtained by intercepting by using a unit matrix of z multiplied by z according to the expansion factor z to obtain the coding matrix of the LDPC code.

17. The apparatus according to claim 16, wherein the information bit determining unit is specifically configured to use the received information packet bits with length K' directly as information bits to be encoded.

18. The apparatus according to claim 17, wherein the codeword processing unit is specifically configured to rearrange the mother code codeword obtained by the encoding unit, and bits of the mother code codeword before rearrangement areThe rearranged mother code codeword bits are

The rearrangement formula is:

wherein,

PV represents a codeword rearrangement vector whose elements are grouped intoPV (x) represents an element with an index of x in a PV vector, wherein x is a non-negative integer;

As the codeword bits to be transmitted.