CN107786210B

CN107786210B - Middle and high code rate LDPC code word structure and coding method for multi-point cooperative communication system

Info

Publication number: CN107786210B
Application number: CN201610786198.XA
Authority: CN
Inventors: 张文军; 张根宁; 何大治; 徐胤; 管云峰; 王延峰
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2016-08-30
Filing date: 2016-08-30
Publication date: 2021-03-09
Anticipated expiration: 2036-08-30
Also published as: CN107786210A

Abstract

The invention provides a medium-high code rate LDPC code word structure and a coding method for a multi-point cooperative communication system, wherein a code word with the lowest code rate is called a mother code and is an LDPC code word of a QC-IRA structure with the code length of N and information bits of K, and the code is carried out according to a coding code table and a coding method to obtain an original code word. Other code words with higher code rate than the mother code are called as intercepted code words, and are obtained by intercepting the original code words after the mother code is coded, part of bits are intercepted from the original code words and are spliced together for transmission, the rest bits are not transmitted, and the specifically intercepted bits are given by an intercepted bit code table. The multi-point cooperative communication system requires that the LDPC code words can be independently coded and decoded, and simultaneously, the code words with different code rates can be combined together for joint decoding, so that performance gain is obtained. The code word structure and the coding method provided by the invention can well meet the requirement.

Description

Middle and high code rate LDPC code word structure and coding method for multi-point cooperative communication system

Technical Field

The invention relates to the technical field of communication coding, in particular to a medium and high code rate LDPC code word structure and a coding method suitable for a multi-point cooperative communication system.

Background

The LDPC codeword was first proposed by bolager in 1963, and provided with a codeword and a corresponding iterative decoding algorithm, but the initial iterative decoding algorithm was complex, and the development of the integrated circuit technology was slow, so the LDPC codeword was not considered at that time. In a later period of time, few scholars have much attention paid to LDPC codewords, except that Tanner visualizes the iterative decoding of LDPC with bipartite graphs. Subsequently, in the last 90 th century, Turbo codes based on iterative decoding mechanism were found to be a coding scheme that can approach Shannon limit, so far people began to pay attention to the excellent performance of iterative decoding. Meanwhile, the iteration theory based on the bipartite graph (Tanner graph) also makes a great breakthrough: spielman explains the error correction process as a process of gradually reducing errors, proves that a bipartite Graph-based coding and decoding algorithm has linear complexity, on the basis, scholars propose conditions and a method for generating a bipartite Graph with certain error correction capability by using an Expander Graph, then Kschischang and the like establish the theory of a Factor Graph (Factor Graph), further deepens the Graph theory basis based on LDPC iterative decoding, and on the basis of the researches, Wiber proposes an LDPC iterative decoding algorithm based on a Graph. All these theories are proposed, so that in 1995, Mackay and Neal discovered that LDPC codes have performance approaching the shannon limit as Turbo codes, thereby causing a hot tide of research on LDPC codes.

Through deep research on LDPC code words, the LDPC code is found to have advantages in all aspects compared with Turbo code, has better decoding performance and lower realization complexity, and can meet the requirements of high-speed data transmission and high performance of a future system, thereby being widely applied. Currently, communication systems using LDPC codewords include: the european second generation digital broadcast television transmission standard DVB2 series; IEEE802.11 n wireless local area network standard; the ieee802.11e wireless wide area network standard; the terrestrial transmission standard for digital television (DTTB) in china, and the near-earth, deep space communication systems of the north american CCSDS, and the like.

At present, the theoretical basis of LDPC is indeed gradually perfected, and the research on the code words is gradually shifted from pure theory to the research on the requirement of theory combined application. Specific LDPC code words are designed to meet specific application scenarios and application requirements. In the coordinated multi-point communication system, a plurality of base stations encode and transmit the same content, so as to ensure the coverage rate in complex terrain, and therefore, if a receiving end receives a signal of any one of the base stations, the receiving end can directly decode the signal. However, when a receiving end receives signals transmitted by a plurality of base stations, if the information carried in the signals cannot be fully utilized for joint decoding, a large amount of spectrum waste is caused, so that the multi-point cooperative communication system requires that the LDPC code words transmitted by any base station can be decoded independently, and simultaneously, the LDPC code words transmitted by different base stations can be decoded jointly, the information carried in the signals transmitted by different base stations is fully utilized, and the performance of joint decoding is greatly improved compared with the performance of independent decoding. For the above application requirements, the code word and the corresponding coding method need to be designed separately to meet the requirements.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a medium and high code rate (code rate greater than or equal to 1/2) LDPC code word structure and a coding method suitable for a multipoint cooperative communication system, which are used for meeting the requirement that different code rate code words can be jointly decoded in the multipoint cooperative communication system.

According to a first aspect of the present invention, there is provided a medium and high code rate LDPC codeword structure suitable for a coordinated multi-point communication system, including:

mother code: the code word with the lowest code rate is an LDPC code word with a QC-IRA structure, and an original code word is obtained by encoding according to a mother code encoding code table through an encoding method of the QC-IRA structure;

intercepting a code word: except the mother code, other code rate code words are obtained by intercepting the original code words after the mother code is coded.

Further, the mother code is directed at a QC-IRA structure LDPC code word having an information bit length of K and a code word length of N, and includes a check matrix H, where N-K rows represent check nodes and N columns represent variable nodes;

the check matrix H is composed of₁And H₂Left and right parts, H₁At left, H₂Spliced together side by side on the right, wherein:

H₁the matrix comprises N-K rows and K columns, which are composed of L rows and J columns, and L x J submatrices in total, and are obtained after row-column transformation, each submatrix is a Z x Z square matrix of Z rows and Z columns, the submatrix is a zero matrix or a circulant, and the weight of the circulant is 1;

H₂the array is a double diagonal array with N-K rows and N-K columns.

In one embodiment, the code rate of the mother code is 1/2, the code length is 69120, and the size of the submatrix is 360 × 360, and the code of the mother code is shown in appendix I. The intercepted code rates are 3/5A, 3/5B, 3/5C, 2/3A, 2/3B, 3/4A, 3/4B, 3/4C, 6/7A, 6/7B, 6/7C, 6/7D, 6/7E and 6/7F respectively, meanwhile, the code length of the code word with code rate 3/5 is 57600, the code length of the code word with code rate 2/3 is 51840, the code length of the code word with code rate 3/4 is 46080 and the code length of the code word with code rate 6/7 is 40320, and the corresponding intercepted code is shown in appendix II.

Furthermore, the LDPC code words with medium and high code rates can be independently decoded and can also be jointly decoded in a multi-point cooperative communication system, and one set of code words comprises a plurality of medium and high code rates; in the multi-point cooperative communication system, a plurality of base stations encode the same content, if a receiving end receives a signal of any one of the base stations, the decoding can be carried out, if the receiving end receives signals sent by the plurality of base stations, information carried in the signals is fully utilized to carry out combined decoding, and the combined decoding performance is greatly improved compared with that of single decoding.

According to a second aspect of the present invention, there is provided a method for encoding a medium/high code rate LDPC codeword suitable for a coordinated multi-point communication system, including:

step one, initializing a check bit;

step two, circularly accumulating the information bits to the check bits according to a coding code table, wherein the coding code table is determined by the position of the circulant and the offset of 1 in the circulant;

and step three, accumulating the check bits to obtain the encoded LDPC mother code words.

And step four, intercepting the mother code word according to the intercepted code table to obtain the final intercepted code word.

In the above four steps, the mother code codeword can be obtained after the third step is completed, and the intercepted codeword can be obtained after the fourth step is completed.

Compared with the prior art, the code word scheme in the invention can better meet the following requirements of a multipoint cooperative communication system:

1. LDPC code words sent by any base station can be decoded independently;

2. the LDPC codes sent by different base stations can be decoded together, information carried in signals sent by different base stations is fully utilized, and the performance of joint decoding is greatly improved compared with that of independent decoding.

In the multi-point cooperative communication system, a plurality of base stations can carry out coding transmission on the same content, and the transmission coverage rate in complex terrain is ensured, so that if a receiving end receives a signal of any one of the base stations, the code word can be directly decoded. When a receiving end receives signals sent by a plurality of base stations, the code words can fully utilize information carried in the signals to carry out combined decoding, and frequency spectrums are fully utilized.

However, most of the LDPC codeword schemes in the prior art are designed separately, and therefore joint decoding cannot be performed effectively, and when a receiving end receives signals transmitted by a plurality of base stations, information carried in the signals cannot be fully utilized for joint decoding, which causes a great amount of waste of frequency spectrum

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a diagram illustrating an exemplary method for encoding an intercepted code according to the present invention;

fig. 2 is a schematic structural diagram of a check matrix H of an LDPC codeword in an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

The invention provides a set of intercepting LDPC code word structure based on a multi-point cooperative communication system, a corresponding coding code table and an intercepting code table, and a detailed description of the corresponding code word structure and the coding method.

A middle and high code rate LDPC code word structure suitable for a multi-point cooperative communication system is disclosed, wherein the code word with the lowest code rate is a mother code which is an LDPC code word with a QC-IRA (Quasi-Cyclic Irregular Repeat Accumulate) structure, and an original code word is obtained by coding according to a mother code coding code table through a coding method of the structure. Other code words with a higher code rate than the mother code are called as intercepted code words and are obtained by intercepting the original code words after the mother code is encoded, wherein the intercepting mode is as shown in fig. 1, a part of bits (white parts in fig. 1) are intercepted from the original code words and are spliced together for transmission, the rest bits (gray parts) are not transmitted, and the specifically intercepted bits are given by an intercepted bit code table.

A specific LDPC codeword structure can be completely represented by its check matrix, and in a set of truncated LDPC codewords, because the final codeword of the truncated code is obtained by truncation after the mother code is encoded, although there are multiple code rates, there is only one specific codeword, i.e., the mother code, and the truncated code has no specific codeword, but its encoding method explains how to obtain the corresponding codeword.

The mother code structure is a QC-IRA structure. In a check matrix H of QC-IRA structure LDPC code word with information bit length K and code word length N, N-K rows represent check nodes, N columns represent variable nodes, and the H matrix is formed by H₁And H₂The left part and the right part are formed as shown in figure 2. Wherein H₁There are N-K rows and K columns. It is composed of L x J submatrices P and is obtained after row-column transformation. Namely:

submatrix P_l,jThe matrix is a square matrix of Z and Z, the sub-matrixes are all zero matrixes or circulants, and the weight of the circulant is 1. l, j represents the position of the submatrix when P_l,jIn the case of non-zero matrices, by P_l,jI denotes the offset of the circulant, i.e.: (suppose Z is 4)

H₂The array is a double diagonal array with N-K rows and N-K columns. Namely:

in a specific embodiment, the mother code has a code rate of 1/2, an information bit length of 34560, a code length of 69120, and a circulant size of 360 × 360. Therefore we use (i)₀，i₁，…i₃₄₅₅₉) Represents an information bit, (p)₀，p₁，…p₃₄₅₅₉) Representing the check bits, and thus obtaining the final codeword (i)₀，i₁，…i₃₄₅₅₉，p₀，p₁，…p₃₄₅₅₉) A. For the mother code of this particular embodiment, the encoding method is as follows:

step one, initializing the check bit. Instant p₀＝p₁＝p₂＝…＝p₃₄₅₅₉＝0。

And step two, circularly accumulating the information bits to the check bits according to an encoding code table of the LDPC code words with code rate of 1/2 and code length of 69120 in the appendix I. According to the code table, the bit value i of the first information bit is set₀Accumulating to check bit with address as first row digit of code table, the following 359 information bit values i_mM 1, 2, 3 … 359 to an address of

(x+(mmod360)*96)mod34560

Wherein x represents the number of the first row of the code table. Circulating by taking 360 information bits as a circulating block, and then performing the operation once for each circulating block, wherein each circulating block corresponds to one row in a code table, namely 1 st to 360 th rows

The information bits correspond to the first row of the code table, the 361 st to 720 th information bits correspond to the second row of the code table, and so on.

And step three, accumulating the check bits to obtain the coded code word. I.e. p₀And keeping the same, starting from i equal to 1,the following operations were sequentially performed

Obtaining the final mother code word (i)₀，i₁，…i₃₄₅₅₉，p₀，p₁，…p₃₄₅₅₉)。

In this embodiment, since the code rate of the mother code is 1/2, the code length is 69120, the information bit length is 34560, and the extracted code is obtained by extracting from the mother code, the decoded information bit lengths are the same, the code lengths of the extracted codes corresponding to code rates 3/5, 2/3, 3/4, and 6/7 are 57600, 51840, 46080, and 40320, respectively, and the information bit lengths of the above code rates are the same and are 34560.

When the truncated codeword in this embodiment is encoded, the following step four is also required to be completed in addition to the above steps one to three.

And step four, intercepting the mother code words according to an intercepting code table in an appendix II corresponding to the appendix I to obtain final intercepting code words. Namely, according to the interception code table in each interception code rate code table in the appendix II, intercepting the code word (i) of the mother code₀，i₁，…i₃₄₅₅₉，p₀，p₁，…p₃₄₅₅₉) The corresponding bits in the code are spliced together, and the encoding flow is shown in fig. 1.

Appendix I: code table of LDCP codeword with code rate of 1/2 and code length of 69120:

appendix II: and (3) corresponding to each interception code rate code table in appendix I:

assume the original code word of the mother code after being coded is (i)₀，i₁，…i₃₄₅₅₉，p₀，p₁，…p₃₄₅₅₉)

When the code word is intercepted as code word of code rate 3/5A, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₁，p₂，p₄，p₅…，p₃₄₅₅₈，p₃₄₅₅₉) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 ≠ 0.

When the code word is intercepted as code word of code rate 3/5B, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₀，p₂，p₃，p₅…，p₃₄₅₅₇，p₃₄₅₅₉) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 ≠ 1.

When the code word is intercepted as code word of code rate 3/5C, the reserved bit code table is as follows: (i)₀，i₁，…i₃₄₅₅₉，p₀，p₁，p₃，p₄…，p₃₄₅₅₇，p₃₄₅₅₈) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 ≠ 2.

When the code word is intercepted as code word of code rate 2/3A, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₁，p₃，p₅，p₇…，p₃₄₅₅₇，p₃₄₅₅₉) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod2 ≠ 0.

When the code word is intercepted as code word of code rate 2/3B, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p_０，p₂，p₄，p₆…，p₃₄₅₅₆，p₃₄₅₅₈) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod2 ≠ 1.

When the code word is intercepted as code word of code rate 3/4A, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₀，p₃，p₆，p₉…，p₃₄₅₅₄，p₃₄₅₅₇) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 is 0.

When the code word is intercepted as code word of code rate 3/4B, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₁，9₄，p₇，p₁₀…，p₃₄₅₅₅，p₃₄₅₅₈) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 is 1.

When the code word is intercepted as code word of code rate 3/4C, the reserved bit code table is as follows: (i)₀，i₁，…i₃₄₅₅₉，p₂，p₅，p₈，p₁₁…，p₃₄₅₅₆，p₃₄₅₅₉) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod3 ═ 2.

When the code word is intercepted as code word of code rate 6/7A, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₀，p₆，p₁₂…，p₃₄₅₄₈，p₃₄₅₅₄) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 is 0.

When the code word is intercepted as code word of code rate 6/7B, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₁，p₇，p₁₃…，p₃₄₅₄₉，p₃₄₅₅₅) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 is 1.

When the code word is intercepted as code word of code rate 6/7C, the reserved bit code table is as follows: (i)₀，i₁，…i₃₄₅₅₉，p₂，p₈，p₁₄…，p₃₄₅₅₀，p₃₄₅₅₆) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 ═ 2.

When the code word is intercepted as code word of 6/7D rate, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₃，p₉，p₁₅…，p₃₄₅₅₁，p₃₄₅₅₇) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 is 3.

When the code word is intercepted as code word of code rate 6/7E, the reserved bit code table is as follows: (i)₀，i₁，…i₃₄₅₅₉，p₄，p₁₀，p₁₆…，p₃₄₅₅₂，p₃₄₅₅₈) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 is 4.

When the code word is intercepted as code word of code rate 6/7F, the reserved bit code table is: (i)₀，i₁，…i₃₄₅₅₉，p₅，p₁₁，p₁₇…，p₃₄₅₅₃，p₃₄₅₅₉) Wherein i_m，m＝0，1，2…34599；p_m，m∈[0，34559]And m mod6 ═ 5.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A medium-high code rate LDPC codeword structure for a coordinated multi-point communication system, comprising:

intercepting a code word: other code rate code words except the mother code are obtained by intercepting the original code word after the mother code is coded;

the mother code comprises a check matrix H aiming at a QC-IRA structure LDPC code word with an information bit length of K and a code word length of N, wherein N-K rows represent check nodes, and N columns represent variable nodes;

H₁the matrix comprises N-K rows and K columns, which are composed of L rows and J columns, and L x J submatrices, and are obtained after row-column transformation, wherein each submatrix is a Z x Z square matrix of Z rows and Z columns, namely N-K = L x Z, K = J x Z; the sub-matrixes are all zero matrixes or circulant, and the weight of the circulant is 1;

H₂the array is a double diagonal array with N-K rows and N-K columns.

2. The LDPC codeword structure of claim 1, wherein the LDPC codewords with medium and high code rates can be independently decoded and jointly decoded in a coordinated multi-point communication system, and a set of codewords comprises a plurality of medium and high code rates; in the multi-point cooperative communication system, a plurality of base stations encode the same content, if a receiving end receives a signal of any one of the base stations, the decoding can be carried out, if the receiving end receives signals sent by the plurality of base stations, information carried in the signals can be fully utilized for carrying out combined decoding, and the combined decoding performance is greatly improved compared with that of single decoding.

3. The LDPC codeword structure with medium and high code rates for use in a coordinated multi-point communication system as claimed in any one of claims 1-2, wherein the mother code has a codeword rate of 1/2, a code length of 69120, and a sub-matrix size of 360 × 360, and the code table thereof is:

692 1185 1735 5494 6481 9193 9459 11862 18926 20176 21874 22237 23132 24113 25136 33959

2587 6757 7440 8082 8815 10269 10728 12931 13887 19514 22276 23388 25453 26628 27896 29080

3054 3179 5627 8907 12424 13257 14607 17118 17881 18663 21177 22048 26715 26769 32717 33478

1173 4972 6176 8026 10944 17891 20759 21215 21418 23956 26255 26307 31557 32006 32062 33247

5189 8568 8669 9306 9834 16940 19574 20550 20612 24053 26681 27618 27998 29633 32770 33420

1544 6283 7573 7873 9453 9559 14227 14345 15122 18227 18324 20878 22634 23511 23932 33986

2991 4333 4794 9737 9970 9992 10845 12810 15072 18469 20770 24240 24869 25018 31671 32588

1039 1579 1694 6183 6758 13316 18987 19156 20519 22044 22174 23776 25545 28972 29874 33943

372 4291 5807 6210 8883 11531 14240 14786 19422 21382 21462 21945 25309 30376 30984 32673

4423 6293 7133 7154 7417 10276 10869 11409 11885 14998 15482 16924 16945 17783 22811 28590

159 1784 3158 3178 6913 7173 10404 13556 15103 19579 21496 23228 24294 29081 30227 31669

5065 5595 5825 6638 9331 10559 11600 18360 23565 24035 25649 27088 29134 31788 32835 33962

6621 7496 9176 11662 11830 12696 13152 16699 20650 21095 22068 27188 27832 29470 30194 31328

13615 19547 21942 23594 30542

2678 6743 19217 25719 30475

9059 11115 12850 17694 26639

14175 14799 16045 18714 34449

1257 2130 12813 26141 32333

15420 19307 20002 26572 28481

595 4669 4841 10946 18001

5840 11977 13477 25731 28560

533 5557 12250 15289 28948

11628 15263 20418 25864 29054

8040 14433 15077 19269 26497

332 10547 14416 18055 29607

9700 19193 24476 26427 26918

1111 4917 6948 7914 10899

10879 14374 23385 23396 33148

9102 19555 20128 27366 32954

683 7806 12205 20379 32960

3657 4111 7244 10531 11186

876 4310 11278 16441 20123

5835 13613 28151 29713 31093

6313 16431 17856 20316 33254

37 4001 10521 16616 17066

4049 7831 18531 19623 27215

3090 13194 17533 19412 31572

679 5508 10660 12502 29334

3220 14362 20104 25450 32518

5993 16410 16637 18124 26318

7664 11861 21310 27047 32454

707 3199 3326 25614 31160

4672 5928 10460 24861 30867

811 2433 2445 9237 13913

2497 6513 27384 30610 34367

3586 4196 14584 24563 24927

2128 9093 18722 20514 34459

5957 6266 24048 24595 24988

3009 5191 14775 17436 18416

2648 17150 21807 23753 26559

16895 24418 27645 28134 31305

3398 19445 19917 25266 29003

11908 13497 14517 27690 29701

5562 9979 15478 20579 31891

557 1201 8704 9092 24028

11993 12194 18660 28682 34489

3864 12616 27212

8999 10586 19443

4385 22177 28015

10094 16136 23636

937 10755 12250

12562 26443 33303

21100 26815 31114

7484 10991 11632

10381 19613 21056

119 3126 30123

9576 9639 31747

16466 21940 33600

14488 21875 28539

20142 22565 32997

4145 30238 33494

11485 19159 23782

23317 24450 29556

2142 5616 23579

2542 21324 24177

9616 18995 22245

162 9661 18764

6398 25883 29056

9578 22359 22985

18950 19801 28349

13192 18193 28038

3361 18531 31016

1516 12459 27996

14767 16423 19577

11153 17236 17252

3648 5352 32602

21944 27344 29134

13376 16749 16758

10675 14781 19212

223 777 6802

9939 15687 21574

20197 29155 33048

2051 22734 29151

2673 3503 31198

18520 23305 31716

6804 25244 30258。

4. the LDPC codeword structure of any one of claims 1-2, wherein the code rates of the extracted codes are 3/5, 2/3, 3/4 and 6/7, respectively, and meanwhile, the code length of 3/5 code rate codeword is 57600, the code length of 2/3 code rate codeword is 51840, the code length of 3/4 code rate codeword is 46080, and the code length of 6/7 code rate is 40320; the 3/5 code rate adopts three interception modes, namely 3/5A, 3/5B and 3/5C, the 2/3 code rate adopts two interception modes, namely 2/3A and 2/3B, the 3/4 code rate adopts three interception modes, namely 3/4A, 3/4B and 3/4C, and the 6/7 code rate adopts six interception modes, namely 6/7A, 6/7B, 6/7C, 6/7D, 6/7E and 6/7F; the corresponding intercepted code table is:

the original code word of the mother code after being coded is assumed to be

：

When the code word is intercepted as code word of code rate 3/5A, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 3/5B, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 3/5C, the reserved bit code table is as follows:

wherein

；

When the code word is intercepted as code word of code rate 2/3A, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 2/3B, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 3/4A, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 3/4B, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 3/4C, the reserved bit code table is as follows:

wherein

；

When the code word is intercepted as code word of code rate 6/7A, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 6/7B, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 6/7C, the reserved bit code table is as follows:

wherein

；

When the code word is intercepted as code word of 6/7D rate, the reserved bit code table is:

wherein

；

When the code word is intercepted as code word of code rate 6/7E, the reserved bit code table is as follows:

wherein

；

When the code word is intercepted as code word of code rate 6/7F, the reserved bit code table is:

wherein

。

5. A method for encoding a high and medium code rate LDPC mother code codeword for a coordinated multi-point communication system as claimed in any one of claims 1 to 4, wherein: the method comprises the following steps:

step one, initializing a check bit;

and step three, accumulating the check bits to obtain the coded high-code-rate LDPC mother code words.

6. The method for encoding the LDPC intercepted code words with medium and high code rates according to claim 5, wherein the method comprises the following steps: the encoding method of the interception code is to intercept the mother code word obtained after the mother code is encoded, and specific intercepted bits are given by an intercepted bit code table, that is, after the three steps of claim 5 are completed, the following four steps are also required to be performed:

and step four, intercepting the mother code word according to the intercepted bit code table to obtain the final intercepted code word.