CN102412842B - The coded method of a kind of low density parity check code and device - Google Patents

Abstract

The invention provides the coded method of a kind of low density parity check code and device, described method includes: compare female code code check of uniform based matrix support and the size of transmission code rate, according to comparative result, it is determined that the length K ' of input information block bit; The encoder matrix of LDPC code is determined according to uniform based matrix and spreading factor; By the information block bit that the length received is K ', it is determined that information bit to be encoded; Utilize described encoder matrix that information bit to be encoded carries out LDPC coding, and female code code word bits that coding is obtained processes, and obtains code word bits waiting for transmission. The coded method of LDPC code provided by the invention and device, determine basis matrix and spreading factor, carry out input information block length according to the transmission code rate received to determine or encoder matrix process, it is met the code word of aforementioned transmission code check, the basis of best performance achieves the transmutability of code check, reduce hardware design complexity, and less costly.

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 is put to practical use.

An M × N parity check matrix H defines that each code word with N bits satisfies the constraint of M parity check sets, i.e. in the encoded N-bit code word, the code word with M bits, and the information bits with N-M bits_b×z)×(n_b× z), which is a matrix of m_b×n_bEach block matrix is a basic position of z × zFor different powers of the permutation matrix, when the basic permutation matrix is an identity matrix, they are all cyclic shift matrices of the identity matrix, such as right shift, having the following form:

$H=\left[\begin{array}{ccccc}{P}^{h_{00}^b}& P^{h_{01}^b}& P^{h_{02}^b}& ...& P^{h_{0n_{b-1}}^b}\\ P^{h_{10}^b}& P^{h_{11}^b}& P^{h_{12}^b}& ...& P^{h_{1n_{b-1}}^b}\\ ...& ...& ...& ...& ...\\ P^{h_{mb-10}^b}& P^{h_{m_b-11}^b}& P^{h_{m_b-12}^b}& ...& P^{h_{m_b-1n_b-1}^b}\end{array}\right]=P^{H_b}$

by such powersEach 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

The following parameter z, a basis matrix H of 2 × 4 may be used_bAnd the basic permutation matrix is an identity matrix of z × z,

z is 3 and $H_b=\left[\begin{array}{cccc}0& 1& 0& -1\\ 2& 1& 2& 1\end{array}\right]$

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 matrixDifferent code length, pairAnd 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 matricesThe 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_bOrThe elements in (1) represent the powers of the basic permutation matrix, and the basic permutation matrix, namely the unit matrix of z × z, is circularly shifted to the right by one bit, namely the unit matrix is circularly shifted to the right by one column, so that the basic cyclic matrix is circularly shifted by z-1 times at most, if the unit matrix is circularly shifted by z times, the obtained unit matrix is also circularly shifted, and the unit matrix is not circularly shifted_ijIs a basis matrix H_bNon-negative element of row i and column j, P_ijIs a modified basis matrixThe non-negative elements in the ith row and the jth column of the middle row have:

for the modulo (mod) algorithm: ${P_{ij}}^{\′}\≡P_{ij}\mathrm{mod}z\≡P_{ij}mod\frac{N}{n_b};$

for the round (scale + floor) algorithm:

for the round (scale + round) algorithm: ${P_{ij}}^{\′}=Round(P_{ij}\×\frac{z}{z_{max}})=Round(P_{ij}\×\frac{N}{N_{max}})$

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 to getThe operation of the die is carried out,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 non-negative element is:

for the modulo (mod) algorithm: $93\mathrm{mod}\frac{1152}{24}=93\mathrm{mod}48=45;$

for the round (scale + floor) algorithm:

for the round (scale + round) algorithm: $Round(93\×\frac{1152}{2304})=Round\left(46.5\right)=47.$

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_b× z), unified basis matrixIs 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 bit is determined to be (n)_b-m_b) × z, 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_b× 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_b× z of 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_b× z-K' pad bits are rearranged from the 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 useWhen 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 the expansion factor z, utilizing the unit matrix of z × z to expand the corrected basic matrix to obtain the coding matrix of LDPC code, when R is less than 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 × z according to the 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: the information packet bits with length K' are directly used as 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 bits ofThe rearranged mother code codeword bits areThe 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, andrepresenting 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 bitsAs 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) × z, 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_b× 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_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_b× z of 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:

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 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_b× z-K' pad bits are rearranged from the 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 coding matrix doesThe fixed unit is specifically used for correcting the uniform basic matrix, and extending the corrected basic matrix by using the unit matrix of z × z according to the extension factor z to obtain the 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 the expansion factor z, utilizing the unit matrix of z × z to expand the corrected basic matrix to obtain the coding matrix of 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 × z according to the expansion factor z to obtain an encoding 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 areThe rearranged mother code codeword bits areThe 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;

when the comparison result of the comparison unit is R_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 the comparison result of the comparison unit is R_tx＜R_mThen directly decoding the rearranged mother code word bitsAs 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 userAnd an expansion factor z;

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 obtainThe 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_mThen, the length K' of the information packet bit is K_b×z＝(n_b-m_b) × z, when R is_tx＜R_mThen, the generated m is encoded_b× z, are transmitted, so the length K' of the information packet bits can be determined by the parity bit length m_b× z and transmission code rate R_txIs determined, therefore K', m_b× z and R_txCan be expressed by, but is not limited to, the following formula: $\frac{K^{\′}}{K^{\′}+m_b\×z}=R_{tx},$ or $K^{\′}+m_b\×z=func\left(\frac{m_b\×z}{1-R_{tx}}\right),$ OrThus, 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_b× 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 anddetermining an encoding matrix H for an LDPC code_bz；

In this step, first, the correction algorithm and z pairs are usedCorrecting to obtain a corrected basic matrixAccording toAnd z × z are extended to obtain (m)_b×z)×(n_b× z) of a LDPC matrixIn the invention, the device can be used forCoding matrix H as LDPC code_bzOr according to R_txAnd R_mAs a result of the comparison ofIntercepting 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 bits to be transmitted can be determined, and the code word bits to be transmitted are obtained by rearranging, shortening or deleting the mother code words according to the determined length of the code word 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 userAnd a maximum spreading factor z_maxDetermining a spreading factor z according to the required code length, and then executing S305;

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 obtainThe 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_mThen, the length K' of the information packet bit is K_b×z＝(n_b-m_b) × z, when R is_tx＜R_mThen, the generated m is encoded_b× z, are transmitted, so the length K' of the information packet bits can be determined by the parity bit length m_b× z and transmission code rate R_txIs determined, therefore K', m_b× z and R_txCan be expressed by, but is not limited to, the following formula: $\frac{K^{\′}}{K^{\′}+m_b\×z}=R_{tx},$ or $K^{\′}+m_b\×z=func\left(\frac{m_b\×z}{1-R_{tx}}\right),$ OrThus, 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_b× 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.

S305, unifying the basic matrixCorrecting 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 usedCorrecting to obtain a corrected basic matrixAccording toAnd z × z are extended to obtain (m)_b×z)×(n_b× z) of a LDPC matrixAnd 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_b× z, wherein padding bits are added before, after or between the information packet bits, the length of the padding bits being k_b× z-K', and further, for convenience of subsequent processing, filled K_bThe × z-K' bits are preferably all 0 bits, and may be all 1 bits.

S308 to S309, by (m)_b×z)×(n_b× z) of the coding matrix H_bzLDPC coding is carried out on the information bits to be coded to obtainAnd processing the code word bits of the mother code 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_b× z, wherein the first k of the code word bits of the mother code_b× z bits are systematic bits, m_b× z 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 one of upward integer fetching, downward integer fetching, or rounding integer fetching 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_b× z-K' filling bits from rearranged mother code word bit B₀,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 user-defined unified basis matrix for a 4 × 24 LDPC codeAnd a maximum spreading factor z_maxWherein z is_max＝96，As follows:

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

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_b20/24-5/6-0.833, and for the convenience of realization and the code length required in practice, the spreading factor z is 3 × 2⁵＝96。

2. Receiving the current transmission code rate R_txCompare R0.78_txAnd R_mDue to the size of 0.78<0.833, therefore, can pass K' ═ ceil (m)_b×z/(1-R_tx))-m_b× z, K' is 1362, wherein ceil (x) represents an integer for x.

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

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

according toAnd an LDPC matrix obtained by extending the unit matrix of z 96 and z × z to (4 × 96) × (24 × 96)And will matrixCoding matrix H as LDPC code_bz。

4. Receive information packet bit of length K' since 0.78<0.833, i.e. R_tx＜R_mWill have a length of k_b× z-K '558 all 0 bits are padded in front of the information packet bits of length K', resulting in a length K_b× z is 1920 information bits to be encoded.

5. H of (4 × 96) × (24 × 96)_bzFor length of k_b× z 1920, the length of N N is obtained by LDPC coding_b× z is 2304, 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 bits of the mother code after the code word rearrangement are B₀,B₁,…,B₂₃₀₃Then the codeword rearrangement is represented by the following formula:

where PV denotes a codeword rearrangement vector, and PV ═ {20,21,22,23 }. And due to 0.78<0.833, i.e. 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 user-defined unified basis matrix for a 4 × 24 LDPC codeAnd a maximum spreading factor z_maxWherein z is_max＝96，As follows:

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

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_mDue to the size of 0.875>0.833, so the packet length K' K_b×z＝1280。

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

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

according toAnd an LDPC matrix in which a unit matrix of z 64 and z × z is extended to obtain (4 × 64) × (24 × 64)And will matrixCoding matrix H as LDPC code_bz。

4. Information packet bits of length K1280 are received since 0.875>0.833 changing the length K' ═ K_b× z 1280 information packet bits are directly used as information bits to be encoded.

5. H of (4 × 64) × (24 × 64)_bzFor length K ═ K_b× z 1280, and performing LDPC encoding to obtain length N N_b× z is 1536 mother code word bits, wherein the first 1280 bits are systematic bits and the last 256 bits are check 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,…,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 }. And due to 0.875>0.833 of R_tx≥R_mWill be rearranged to obtainBit B of mother code word₀,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 userAnd 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 obtainThe 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.

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

S404, comparing R_txAnd R_mIs determined according to the comparison resultInputting the length K' of the information packet bits and then performing S406;

in this step, when R is_tx≥R_mThen, the length K' of the information packet bit is K_b×z＝(n_b-m_b) × z, when R is_tx＜R_mThen, the generated m is encoded_b× z, are transmitted, so the length of the information packet K' can be determined by the length of the parity bits m_b× z and transmission code rate R_txIs determined, therefore K', m_b× z and R_txCan be expressed by, but is not limited to, the following formula: $\frac{K^{\&prime;}}{K^{\&prime;}+m_b\&times;z}=R_{tx},$ or $K^{\&prime;}+m_b\&times;z=func\left(\frac{m_b\&times;z}{1-R_{tx}}\right),$ OrThus, 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_b× 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.

S405, for the unified basic matrixCorrecting to determine the encoding matrix H of LDPC code_bzThen, S407 is executed;

in this step, first, the correction algorithm and z pairs are usedCorrecting to obtain a corrected basic matrixAccording toAnd z × z are extended to obtain (m)_b×z)×(n_b× z) of LDPC (Low Density parity check) matrix

When R is_tx≥R_mThen the matrix will be expandedCoding matrix H as LDPC code_bz(ii) a When R is_tx＜R_mBy interceptingRight 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 alsoThus, the coding matrix H of the LDPC code at this time_bzHas a size of (m)_b×z)×(K'+m_b×z)。

In addition, whenWhen it is a positive integer, the step is to unify the basic matrixIs corrected to obtainAfter that, it can also be based on R_txAnd R_mTo the corrected basis matrixAfter 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) matrixAccording toAnd a spreading factor z, spread to obtain (m)_b×z)×((k′_b+m_b) × z) 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, $k_b^{\&prime;}+m_b=\frac{m_b}{1-R_{tx}},$ namely, it is $(k_b^{\&prime;}+m_b)\&times;z=func\left(\frac{m_b\&times;z}{1-R_{tx}}\right)=K^{\&prime;}+m_b\&times;z,$ 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_b× z) 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_b× z, wherein the first K' bits of the code word bits of the mother code are systematic bits and the last m bits are systematic bits_b× z bits are check bits, wherein the length of the information bit to be coded 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 beThe code word rearranged mother code has the code word bits ofThe codeword rearrangement is represented by the following formula:

wherein,PV represents a codeword rearrangement vector, PV includes m_bA different element, the set of elements beingAnd 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 outTaking 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 obtainedAs 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 user-defined unified basis matrix for a 6 × 24 LDPC codeAnd a maximum spreading factor z_maxWherein z is_max＝96，As follows:

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

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 for easy realization and achievementThe code length of the code which is actually required is determined, and the spreading factor z is 3 × 2⁵＝96。

2. Receiving the current transmission code rate R_txCompare R0.9_txAnd R_mDue to the size of 0.9>0.75, so the information packet length K' K_b×z＝1728。

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

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

according toAnd an LDPC matrix obtained by extending the unit matrix of z 96 and z × z to (6 × 96) × (24 × 96)Yet another 0.9>0.75, then the matrix will beCoding 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_b× z 1728 information packet bits directly as information bits to be encoded.

5. H of (6 × 96) × (24 × 96)_bzFor length K ═ K_b× z 1728, and obtaining length N K + m_b×z＝n_b× z is 2304, wherein 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 }. And due to 0.9>0.75, belonging 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 user-defined unified basis matrix for a 6 × 24 LDPC codeAnd a maximum spreading factor z_maxWherein z is_max＝96，As follows:

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

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_mDue to the size of 0.6<0.75, so K' ceil (m) may be passed_b×z/(1-R_tx))-m_b× z, K' is 576, wherein ceil (x) denotes an integer upward of x.

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

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

according toAnd an LDPC matrix in which a unit matrix of z 64 and z × z is extended to obtain (6 × 64) × (24 × 64)And due to 0.6<0.75, therefore cutCeil (m) on the right_b×z/(1-R_tx) Column 960, 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 matrixAnd due to 0.6<0.75，InterceptingK 'on the right'_b+m_bColumn 15 with 9+6, resulting in a matrix size of 6 × (9+6)According toAn LDPC coding matrix H obtained by extending the unit matrix of z 64 and z × z to (6 × 64) × (15 × 64)_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. H of (6 × 64) × (15 × 64)_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_b× 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.

Coding the code word bits of the mother codeWord rearrangement, assuming the mother code codeword bits before rearrangement 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 due to 0.6<0.75, i.e. 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) × z, 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_b× 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 information bit determination unit 50 is specifically configured to determine 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_b× z, wherein 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-1Rearranged mother code codeword bitsIs 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_b× z-K' pad bits are rearranged from the 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 encoding matrix determining unit 40 is specifically configured to modify the uniform basic matrix, and extend the modified basic matrix by using the identity matrix of z × z according to the extension factor z to obtain the extension matrix of the LDPC code, where the comparison result of the comparing 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 the expansion factor z, the corrected basic matrix is expanded by using the unit matrix of z × zObtaining a coding 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 × z according to the expansion factor z to obtain an encoding 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 areThe rearranged mother code codeword bits areThe 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; when the comparison result of the comparison unit 20 is R_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 the comparison result of the comparison unit 20 isR_tx＜R_mThen directly decoding the rearranged mother code word bitsAs 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 (18)

1. 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 uniform basic matrix with the transmission code rate, and determining the length K' of the input information grouping bit according to the comparison result: when R is_tx≥R_mWhen the length K' of the information packet bit is determined to be (n)_b-m_b) × z, 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_b× 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 an expansion factor, func (x) is one of integer fetching up, integer fetching down or integer fetching round for x;

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.

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: and receiving the 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:

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.

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

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_b× z information bits to be coded k_b＝n_b-m_b。

6. The method of claim 5, 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 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_b× z-K' pad bits are rearranged from the 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:

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 useWhen 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 the expansion factor z, utilizing the unit matrix of z × z to expand the corrected basic matrix to obtain the coding matrix of LDPC code, when R is less than 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 × z according to the expansion factor z to obtain an encoding matrix of the LDPC code.

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 areThe 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, andrepresenting 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 bitsAs 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,

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; wherein the grouping bit determining unit is specifically configured to determine 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) × z, 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_b× 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 an expansion factor, func (x) is one of integer fetching up, integer fetching down or integer fetching round for x;

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.

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_b× z information bits to be coded k_b＝n_b-m_b。

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,…,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 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 junction of the comparison unitThe fruit is R_tx<R_mWhen k is to be added_b× z-K' pad bits are rearranged from the 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.

16. The apparatus of 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 unit matrix of z × z according to an extension factor z to obtain an extension matrix of the LDPC code, and when the comparison result of the comparing 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 the expansion factor z, utilizing the unit matrix of z × z to expand the corrected basic matrix to obtain the coding matrix of 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 × z according to the expansion factor z to obtain an encoding 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. According to the rightThe apparatus of claim 17, wherein the code word processing unit is specifically configured to rearrange the mother code word obtained by the encoding unit, and bits of the mother code word before rearrangement areThe rearranged mother code codeword bits areThe 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;

when the comparison result of the comparison unit is R_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 the comparison result of the comparison unit is R_tx<R_mThen directly decoding the rearranged mother code word bitsAs the codeword bits to be transmitted.