CN105450340A

CN105450340A - LDPC codeword interleaving and mapping method and de-interleaving and de-mapping method

Info

Publication number: CN105450340A
Application number: CN201410438387.9A
Authority: CN
Inventors: 张文军; 尧勇仕; 史毅俊; 徐胤; 徐洪亮; 何大治; 郭序峰; 赵杰; 杨帆
Original assignee: Shanghai National Engineering Research Center of Digital Television Co Ltd
Current assignee: Shanghai National Engineering Research Center of Digital Television Co Ltd
Priority date: 2014-08-29
Filing date: 2014-08-29
Publication date: 2016-03-30

Abstract

An LDPC codeword interleaving and mapping method and a de-interleaving and de-mapping method are disclosed. Included are the steps of dividing an encoded LDPC codeword into a plurality of successive bit sub-blocks according to a predetermined length, and changing the arrangement sequence of the bit sub-blocks in accordance with a corresponding bit exchange pattern to form an LDPC codeword bit-interleaved for the first time; writing the LDPC codeword bit-interleaved for the first time in accordance with a column sequence, and reading out in accordance with a row sequence to obtain an LDPC codeword bit-interleaved for the second time; and carrying out constellation mapping for the LDPC codeword bit-interleaved for the second time according to a constellation map to obtain a symbol stream. The interleaving and mapping method and the de-interleaving and de-mapping method are selected for different LDPC code tables so that the system performance can be better improved.

Description

The intertexture of LDPC code word and mapping method and deinterleaving de-mapping method

Technical field

The present invention relates to digital television techniques field, particularly a kind of intertexture of LDPC code word and mapping method and deinterleaving de-mapping method.

Background technology

In existing broadcast communication standard, LDPC coding, Bit Interleave and constellation mapping are code modulation modes the most common.In different emission systems, LDPC coding, Bit Interleave and constellation mapping all need independent design, and combined debugging, to obtain best channel performance.Therefore, how forming Bit Interleave targetedly for specific LDPC code word and constellation mapping mode, is a technical barrier of this area.

Summary of the invention

The problem that the present invention solves cannot form Bit Interleave targetedly for specific LDPC code word and constellation mapping mode in prior art.

For solving the problem, embodiments provide a kind of intertexture and mapping method of LDPC code word, comprise the steps: by coding after LDPC code word be divided into the multiple sub-blocks of bits of continuous print by predetermined length, and according to sub-blocks of bits described in corresponding bit exchange pattern change put in order formed first time Bit Interleave after LDPC code word; By the LDPC code word column major order write memory space after described first time Bit Interleave and by row order reads the LDPC code word after obtaining second time Bit Interleave in this memory space; Constellation mapping is carried out to obtain symbol stream according to corresponding planisphere to the LDPC code word after described second time Bit Interleave.

The embodiment of the present invention additionally provides a kind of deinterleaving de-mapping method of LDPC code word, comprises the steps: to carry out soft demapping process to obtain bit soft value data to symbol stream soft value data according to corresponding planisphere; Wherein said symbol stream soft value data are the symbol stream that interlace map method that receiving terminal receives LDPC code word described above obtains; Described bit soft value data are sequentially written in memory space by row and column major order reads to obtain first time than the bit soft value data after deinterleave in this memory space; Described first time is divided into the multiple bit soft value data sub-block of continuous print than the bit soft value data after deinterleave by predetermined length, and according to bit soft value data sub-block described in corresponding bit exchange pattern change put in order form second time than the bit soft value data after deinterleave; LDPC decoding process is carried out to obtain decoded bitstream data to described bit soft value data flow.

Compared with prior art, technical solution of the present invention has the following advantages:

Corresponding interlace map and deinterleaving de-mapping method is selected better to be promoted to make systematic function for specific LDPC code table.

Accompanying drawing explanation

Fig. 1 is the schematic flow sheet of the embodiment of the interlace map method of a kind of LDPC code word of the present invention;

Fig. 2 is the schematic flow sheet of the embodiment of the deinterleaving de-mapping method of a kind of LDPC code word of the present invention;

Fig. 3 is the schematic diagram put in order according to sub-blocks of bits described in bit exchange pattern change in the interlace map method of a kind of LDPC code word of the present invention.

Embodiment

Inventor finds in prior art, cannot form Bit Interleave targetedly for specific LDPC code word and constellation mapping mode.

For the problems referred to above, inventor is through research, provide a kind of interlace map method and deinterleaving de-mapping method of LDPC code word, select corresponding interlace map and deinterleaving de-mapping method better to be promoted to make systematic function for different LDPC code tables.

For enabling above-mentioned purpose of the present invention, feature and advantage more become apparent, and are described in detail the specific embodiment of the present invention below in conjunction with accompanying drawing.

In embodiments of the present invention, transmitter terminal is: first the bit stream after message sink coding, Bose-Chaudhuri-Hocquenghem Code is input to the coding that LDPC encoder carries out the LDPC code word of specific code check code length, input bit interleaver afterwards, interleaving treatment is carried out according to certain specific Bit Interleave patterning method, subsequently the data after Bit Interleave process are carried out the QPSK constellation mapping of corresponding code check, modulate afterwards, launch, experience channel.Receiver end is: the data after channel are carried out demodulation, and the data input De-mapping module then after demodulation, carries out QPSK demapping.Afterwards the bit soft value information that De-mapping module exports is input to de-interleaving block and carries out deinterleaving, output to ldpc decoder afterwards, the decoding based on specific LDPC code word is carried out to it, output bit flow of finally decoding.

As shown in Figure 1 be the schematic flow sheet of the embodiment of the interlace map method of a kind of LDPC code word of the present invention.With reference to figure 1, the interlace map method of LDPC code word comprises the steps:

Step S11: by coding after LDPC code word be divided into the multiple sub-blocks of bits of continuous print by predetermined length, and according to sub-blocks of bits described in corresponding bit exchange pattern change put in order formed second time Bit Interleave after LDPC code word;

Step S12: by the LDPC code word column major order write memory space after described first time Bit Interleave and by row order reads the LDPC code word after obtaining second time Bit Interleave in this memory space;

Step S13: constellation mapping is carried out to obtain symbol stream according to corresponding planisphere to the LDPC code word after described second time Bit Interleave.

In described step S13, the LDPC code word after described coding is divided into the multiple sub-blocks of bits of continuous print by predetermined length, wherein said predetermined length is 320.Further, according to sub-blocks of bits described in corresponding bit exchange pattern change put in order formed first time Bit Interleave after LDPC code word.Its detailed process is detailed as shown in Figure 3, in figure 3, and (m ₀, m ₁..., m _n/320-1) be the bit exchange pattern of 320 length bits sub-blocks.

Particularly, the code length of the LDPC code word in LDPC code table is 19200, and corresponding bit exchange pattern is: 14,342,439,758,255,156,431,829,313,314,753,242,492,827,443,643,710,384,111 126335248505459452635231782502220305721461553514019916

It should be noted that, in the present embodiment, each numerical value in described bit exchange pattern refers to the position without sub-blocks of bits described before bit exchange.Such as, the 3rd numerical value 24 implication in above-mentioned bit exchange pattern refers to and original after bit exchange, nowadays becomes the 3rd sub-blocks of bits without the 25th sub-blocks of bits before bit exchange.

Corresponding planisphere is:

In described step S12, such as, be the LDPC code word (the LDPC code word after first time Bit Interleave) of 19200 bits for code length, by its column major order write memory space and by row order reads in this memory space, wherein every row 9600 bit, totally 2 row.

Afterwards to the bitstream data (b after above-mentioned Bit Interleave ₀, b ₁..., b _n-1), according to QPSK planisphere, the decimal number corresponding to every two binary bit sequence is mapped to some constellation point, obtains symbol stream (the corresponding constellation point of each complex symbol).Such as, two corresponding decimal numbers of bit ' 01 ' of input are 1, then correspond to the constellation point of the 0.707106781186548-0.707106781186548i in QPSK planisphere, this constellation point being shown as on real number axis and axis of imaginaries, real number axis 0.707106781186548, axis of imaginaries 0.707106781186548.Then utilize symbol stream to carry out generation OFDM symbol at modulation module, finally launch.

In the present embodiment, described LDPC code word be to message sink coding after bit stream obtain after specific LDPC coding, wherein said specific LDPC coding can adopt prior art to realize.

Particularly, the code word of this LDPC is with L × L (L is generally 320) for sub-block size, and code table is as follows:

Table 1 code check 1/4N _ldpc=19200, L × L=320 × 320, M=14400

Before elaboration coding method, first to doing description below to the mother matrix of definite form:

Mother matrix has the capable n row of m, each digital p of the i-th row jth row _ijthe all row representing unit matrix circulate to the right and offset p _ijthe submatrix produced, the size of submatrix is 320 × 320.Such as, in table 1 p ₀₀=201, this digitized representation matrix of 320 × 320, this matrix to be produced by 201 elements of circulation skew to the right by row by the unit matrix of 320 × 320; Such as p _ijwhen=0, represent the unit matrix of 320 × 320; When the i-th row jth row do not have numeral, this place represents the full 0 matrix of 320 × 320; When the i-th row jth shows multiple numeral, represent the XOR that this place is the cyclic shift of multiple unit matrix, such as, in table 1 time, representing this matrix is by arranging matrix that 290 elements of circulation skew to the right obtain with the unit matrix by 320 × 320 by the matrix arranging matrix that 309 elements of circulation skew to the right obtain and obtain by element XOR by the unit matrix of 320 × 320.

Mother matrix extension is line number by rule is as described above M=320 × m, and columns is the matrix of N=320 × n, this matrix is exactly the check matrix H of LDPC code word, wherein M refers to the check row of check matrix, and N refers to the row of check equations, also represents the length of code word.

The process of coding is exactly first produce the long information bit sequence I=[i of N-M ₁i ₂i ₃i _n-M], the process of a remaining M check bit is then tried to achieve by the check matrix of LDPC code word.Finally obtain code word C=[i ₁i ₂i ₃i _n-Mp ₁p ₂p _m], this code word meets C × H ^t=0.

It should be noted that:

Last code word C=[i ₁i ₂i ₃i _n-Mp ₁p ₂p _m] in check bit part be in fact exactly utilize C × H ^t=0 this relation is tried to achieve; The order verifying column information row in H matrix is the check column that strictly correspond in mother matrix, information column, and usually to follow previous section be information column, and aft section is the structure of check column.So front N-M check bit in C correspond to front N-M information column in H, M the check bit below in C correspond to last M check column in H.

The embodiment of the present invention additionally provides a kind of deinterleaving de-mapping method of LDPC code word.As shown in Figure 2 be the schematic flow sheet of the embodiment of the deinterleaving de-mapping method of a kind of LDPC code word of the present invention.With reference to figure 2, the deinterleaving de-mapping method of LDPC code word comprises the steps:

Step S21: soft demapping process is carried out to obtain bit soft value data according to corresponding planisphere to symbol stream soft value data; Wherein said symbol stream soft value data are the symbol stream that interlace map method that receiving terminal receives LDPC code word as claimed in claim 1 obtains;

Step S22: described bit soft value data are sequentially written in memory space by row and column major order reads to obtain first time than the bit soft value data after deinterleave in this memory space, corresponding by arranging the columns write with step S12 by the columns of row;

Step S23: described first time is divided into the multiple bit soft value data sub-block of continuous print than the bit soft value data after deinterleave by predetermined length, and according to bit soft value data sub-block described in corresponding bit exchange pattern change put in order form second time than the bit soft value data after deinterleave;

Step S24: LDPC decoding process is carried out to obtain decoded bitstream data to described bit soft value data flow.

By the coding of above-mentioned LDPC, intertexture and modulation system, the thresholding of system under rayleigh fading channel can be made to reach-2.02, effectively can increase coverage rate.

Although the present invention with preferred embodiment openly as above; but it is not for limiting the present invention; any those skilled in the art without departing from the spirit and scope of the present invention; the Method and Technology content of above-mentioned announcement can be utilized to make possible variation and amendment to technical solution of the present invention; therefore; every content not departing from technical solution of the present invention; the any simple modification done above embodiment according to technical spirit of the present invention, equivalent variations and modification, all belong to the protection range of technical solution of the present invention.

Claims

1. an interlace map method for LDPC code word, is characterized in that, comprise the steps:

By coding after LDPC code word be divided into the multiple sub-blocks of bits of continuous print by predetermined length, and according to sub-blocks of bits described in corresponding bit exchange pattern change put in order formed second time Bit Interleave after LDPC code word;

By the LDPC code word column major order write memory space after described first time Bit Interleave and by row order reads in this memory space, obtains the LDPC code word after second time Bit Interleave;

Constellation mapping is carried out to obtain symbol stream according to corresponding planisphere to the LDPC code word after described second time Bit Interleave; Wherein, described bit exchange pattern and described planisphere are corresponding with specifying the LDPC code table of code check.

2. the interlace map method of LDPC code word as claimed in claim 1, it is characterized in that, described predetermined length is 320 bits.

3. the interlace map method of LDPC code word as claimed in claim 1, is characterized in that, in described LDPC code table, the code length of LDPC code word is 19200 bits, code check is 1/4;

Code table is:

Corresponding bit exchange pattern is: 14,342,439,758,255,156,431,829,313,314,753,242,492,827,443,643,710,384,111 126335248505459452635231782502220305721461553514019916

Corresponding planisphere is:

4. the interlace map method of LDPC code word as claimed in claim 1, it is characterized in that, the number of described column major order is 2 row.

5. a deinterleaving de-mapping method for LDPC code word, is characterized in that, comprise the steps:

Soft demapping process is carried out to obtain bit soft value data according to corresponding planisphere to symbol stream soft value data; Wherein said symbol stream soft value data are the symbol stream that interlace map method that receiving terminal receives LDPC code word as claimed in claim 1 obtains;

Described bit soft value data are sequentially written in memory space by row and column major order reads to obtain first time than the bit soft value data after deinterleave in this memory space;

Described first time is divided into the multiple bit soft value data sub-block of continuous print than the bit soft value data after deinterleave by predetermined length, and according to bit soft value data sub-block described in corresponding bit exchange pattern change put in order form second time than the bit soft value data after deinterleave;

LDPC decoding process is carried out to obtain decoded bitstream data to described bit soft value data flow.