GCD constraint-based short-loop-free SC-LDPC code construction method

Abstract

The invention provides a construction method of a short-ring-free SC-LDPC code based on GCD constraint, and the method comprises the steps: constructing an initial cyclic shift matrix of which the column number is an even number according to the code length and code rate of a to-be-constructed SC-LDPC code through employing the GCD constraint; based on a preset cutting rule, performing cutting translation processing on the initial cyclic shift matrix to obtain a target coupling block; constructing a target cyclic shift matrix according to the target coupling block; according to the method, the target cyclic shift matrix is subjected to hash processing to obtain the check matrix, and the SC-LDPC code is constructed based on the check matrix, so that short rings such as four rings and six rings can be avoided, and meanwhile, the method has the advantages of simple coupling structure, simple coding structure, small decoding delay, good decoding performance and the like.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a method for constructing a short-loop-free SC-LDPC code based on GCD constraints. Background Art

[0002] Spatially Coupled Low-Density Parity-Check (SC-LDPC) is a type of coupled code that can achieve better performance than Low-Density Parity-Check (LDPC) block codes. The check matrix of SC-LDPC code is coupled by the check matrix of LDPC block code. SC-LDPC code couples adjacent LDPC block codes together, which can be regarded as a local coupling relationship. Compared with LDPC block codes, SC-LDPC codes not only have better decoding performance, but also have a relatively simple coding structure.

[0003] Facing the future 6G mobile communication and space-land-sea integration strategy, SC-LDPC code, as a new coupling code, has excellent waterfall performance and low error floor due to its special convolution structure characteristics. At the same time, the application of sliding window decoding algorithm also greatly reduces the decoding delay and storage space requirements. However, traditional SC-LDPC codes are affected by short loops (such as 4-loop and 6-loop) and often have certain performance losses. Therefore, it is necessary to study the construction scheme of spatial coupling codes that eliminate short loops.

[0004] RS code is a maximum distance separable code that can effectively correct random symbol errors and random burst errors. It has been widely used in many fields such as deep space communication, mobile communication, data storage, computer communication, etc. Although the SC-LDPC code constructed based on RS code has better decoding performance and simpler coding structure than the traditional block LDPC code, the simple coupling relationship destroys the original degree distribution, making it lose its original advantage in eliminating 4 rings. At the same time, the existing 6 rings also cause certain performance losses. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides an ordered statistics decoding method, device and apparatus based on a belief propagation list, which specifically include:

[0006] In a first aspect, the present invention provides a method for constructing a short-cycle-free SC-LDPC code based on GCD constraints, characterized in that it includes:

[0007] Using the GCD constraint, an initial cyclic shift matrix with an even number of columns is constructed according to the code length and code rate of the SC-LDPC code to be constructed;

[0008] Based on the preset cropping rule, the initial cyclic shift matrix is ​​cropped and translated to obtain the target coupling block;

[0009] According to the target coupling block, construct a target cyclic shift matrix;

[0010] The target cyclic shift matrix is ​​hashed to obtain a check matrix, and an SC-LDPC code is constructed based on the check matrix.

[0011] In a second aspect, the present invention further provides a construction device for a short-cycle-free SC-LDPC code based on a GCD constraint, comprising:

[0012] A construction module, used to construct an initial cyclic shift matrix using GCD constraints;

[0013] A cutting module, used for cutting and translating the initial cyclic shift matrix based on a preset cutting rule to obtain a target coupling block;

[0014] The construction module is further used to construct a target cyclic shift matrix according to the target coupling block;

[0015] The construction module is also used to perform hash processing on the target cyclic shift matrix to obtain a check matrix, and to construct an SC-LDPC code based on the check matrix.

[0016] In a third aspect, the present invention further provides an electronic device, comprising a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0017] Memory, used to store computer programs;

[0018] The processor is used to implement any method provided in the first aspect when executing a program stored in the memory.

[0019] In a fourth aspect, the present invention provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, any one of the methods provided in the first aspect is implemented.

[0020] In a fifth aspect, the present invention provides a program product, which includes computer program instructions, and when the computer program instructions are executed, they can implement any of the methods provided in the first aspect.

[0021] Beneficial effects of the present invention:

[0022] The present invention provides a method for constructing a short-loop SC-LDPC code based on GCD constraints. By adopting the GCD constraints, according to the code length and code rate of the SC-LDPC code to be constructed, an initial cyclic shift matrix with an even number of columns is constructed; based on a preset pruning rule, the initial cyclic shift matrix is ​​pruned and shifted to obtain a target coupling block; according to the target coupling block, a target cyclic shift matrix is ​​constructed; and the target cyclic shift matrix is ​​hashed to obtain a check matrix. The SC-LDPC code constructed based on the check matrix can avoid the occurrence of short loops such as 4-loops and 6-loops, and has the advantages of simple coupling structure, simple coding structure, small decoding delay, good decoding performance, and the like.

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic flow chart of a method for constructing a short-cycle-free SC-LDPC code based on GCD constraints provided by the present invention;

[0025] Figure 2 A schematic diagram of the partitioning result of an initial cyclic shift matrix provided by the present invention;

[0026] Figure 3 A schematic diagram of the translation result of an initial cyclic shift matrix provided by the present invention;

[0027] Figure 4 A schematic diagram of the structure of a target cyclic shift matrix provided by the present invention;

[0028] Figure 5 A schematic diagram of the structure of a construction device for a short-cycle-free SC-LDPC code based on GCD constraints provided by the present invention;

[0029] Figure 6 A schematic diagram of a simulation result provided by the present invention;

[0030] Figure 7 Another schematic diagram of simulation results provided by the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0032] In order to solve the problems existing in the prior art, the present invention proposes a short-loop-free SC-LDPC code construction method based on GCD constraints. The method makes full use of the structural advantage of the Greatest Common Divisor Constraint (GCD) constraint to construct a short-loop-free structure, and cuts and translates the original cyclic shift matrix while ensuring that the matrix degree distribution remains unchanged. The original cyclic shift matrix is ​​used as a coupling block to construct the final cyclic shift matrix, and then the SC-LDPC code is constructed. The SC-LDPC code can not only avoid the occurrence of 4-loops and 6-loops, but also take into account the simple coding structure of the coupling structure.

[0033] Figure 1 A method for constructing a short-cycle-free SC-LDPC code based on GCD constraints provided by the present invention includes:

[0034] S101. Using the GCD constraint, construct an initial cyclic shift matrix with an even number of columns according to the code length and code rate of the SC-LDPC code to be constructed.

[0035] The GCD constraint can be used to construct a type of cyclic shift matrix without 4-rings and 6-rings. Optionally, the GCD constraint is used to construct the initial cyclic shift matrix, which is expressed as:

[0036]

[0037] Where J represents the number of rows of the initial cyclic shift matrix, L represents the number of columns of the initial cyclic shift matrix, L is the number of columns, J and L are both positive integers greater than or equal to 3, and the data items a0~a in each element of the matrix J-1 Satisfy 0≤a0 <a1<…<a J-1 .

[0038] S102: Based on a preset cropping rule, perform cropping and translation processing on the initial cyclic shift matrix to obtain a target coupling block.

[0039] Optionally, based on a preset cropping rule, the initial cyclic shift matrix is ​​cropped and translated to obtain a target coupling block, including: dividing the initial cyclic shift matrix into 4 sub-matrices with equal column widths, namely, sub-matrix A1 located at the upper left corner, sub-matrix B1 located at the lower left corner, sub-matrix A2 located at the upper right corner, and sub-matrix B2 located at the lower right corner, wherein sub-matrix A1 and sub-matrix A2 have the same row height; sub-matrix A2 is translated to directly below sub-matrix B2 to obtain the target coupling block.

[0040] For example, Figure 2 As shown, the initial cyclic shift matrix P FLRMThe four sub-matrices A1, A2, B1 and B2 are divided into equal column widths, that is, the column widths of A1, A2, B1 and B2 are the same. It should be noted that the number of rows of the two adjacent sub-matrices on the left and right is the same, and the number of rows of the two adjacent sub-matrices on the top and bottom can be the same or different. Different division methods can obtain different code rates. That is, the number of rows and columns of A1 and A2 are the same, the number of rows and columns of B1 and B2 are the same, the number of columns of A1 and B1 is the same, but the number of rows is not necessarily the same, and the number of columns of A2 and B2 is the same, but the number of rows is not necessarily the same.

[0041] Further, such as Figure 3 As shown, the matrix A2 is translated to just below the matrix B2 to obtain the target coupling block.

[0042] Through the cutting coupling scheme of the basic matrix, the original degree distribution is kept unchanged during the splicing process, thereby ensuring that the ring distribution remains unchanged.

[0043] S103: construct a target cyclic shift matrix according to the target coupling block.

[0044] Optionally, a target cyclic shift matrix is ​​constructed according to the target coupling block, including: according to a preset code length, copying the target coupling block multiple times, and splicing each target coupling block in sequence to form a quasi-diagonal band structure to obtain a target cyclic shift matrix, in which the submatrix A2 in the previous target coupling block is connected to the submatrix A1 in the subsequent target coupling block.

[0045] Exemplarily, in combination with the above example, according to the preset code length, the target coupling block is copied multiple times, and each coupling block is connected in pairs through the matrix A2 and A1 to form the following Figure 4 The target cyclic shift matrix of the quasi-diagonal band structure is shown.

[0046] S104. Perform hashing on the target cyclic shift matrix to obtain a check matrix, and construct an SC-LDPC code based on the check matrix.

[0047] Optionally, hashing the target cyclic shift matrix to construct a check matrix, including: constructing a cyclic permutation matrix according to the initial cyclic shift matrix; and hashing the target cyclic shift matrix through the cyclic permutation matrix to construct a check matrix.

[0048] Further, according to the initial cyclic shift matrix, a cyclic permutation matrix is ​​constructed, including the following steps 1)-3):

[0049] 1) Determine a first threshold value according to an initial cyclic shift matrix.

[0050] Among them, the first threshold is expressed as:

[0051] Z + =(aJ-1 -a0)(L-1)+1,

[0052] Z + represents the first threshold;

[0053] 2) Traverse each element of the initial cyclic shift matrix to determine a positive integer that meets a preset condition and is less than a first threshold.

[0054] The preset condition is expressed as:

[0055]

[0056] Z represents the value to be solved, Z∈[2,Z + ], mod means modular operation, p i,j Represents any element in the initial cyclic shift matrix, i=i0,i1,i2,...., j=j0,j1,j2,....

[0057] 3) Determine the size of the circulant permutation matrix as the smallest positive integer, and construct the circulant permutation matrix.

[0058] Optionally, the method further includes: decoding the constructed SC-LDPC code by using a sliding window decoding algorithm.

[0059] The SC-LDPC code constructed based on the method provided by the present invention has a spatially coupled structure (ie, SC), so it can be decoded using a sliding window decoding algorithm, thereby reducing decoding delay and storage space requirements, improving decoding efficiency, and reducing resource consumption.

[0060] The present invention provides a method for constructing a short-loop SC-LDPC code based on GCD constraints. By adopting the GCD constraints, according to the code length and code rate of the SC-LDPC code to be constructed, an initial cyclic shift matrix with an even number of columns is constructed; based on a preset pruning rule, the initial cyclic shift matrix is ​​pruned and shifted to obtain a target coupling block; according to the target coupling block, a target cyclic shift matrix is ​​constructed; and the target cyclic shift matrix is ​​hashed to obtain a check matrix. The SC-LDPC code constructed based on the check matrix can avoid the occurrence of short loops such as 4-loops and 6-loops, and has the advantages of simple coupling structure, simple coding structure, small decoding delay, good decoding performance, and the like.

[0061] Figure 5 A schematic diagram of a structure of a construction device for a short-cycle-free SC-LDPC code based on GCD constraints provided by the present invention is shown in FIG. Figure 5 As shown, the device comprises:

[0062] The construction module 51 is used to construct an initial cyclic shift matrix using the GCD constraint.

[0063] The cropping module 52 is used to perform cropping and translation processing on the initial cyclic shift matrix based on a preset cropping rule to obtain a target coupling block.

[0064] The construction module 51 is further configured to construct a target cyclic shift matrix according to the target coupling block.

[0065] The construction module 51 is further used to perform hash processing on the target cyclic shift matrix to obtain a check matrix, and to construct an SC-LDPC code based on the check matrix.

[0066] In order to further demonstrate the beneficial effects of the present invention, the present invention also provides a set of simulation data, as follows:

[0067] The RS structure and GCD constraint are used to construct the initial cyclic shift matrix before pruning, and the parameters are shown in Table 1.

[0068] Table 1 Construction parameters

[0069] Construction method J×L <![CDATA[(n1,m,b,l)]]> Bitrate CPM Size Code length code1 GCD 5×10 (2,5,4,8) 0.45 143 5720 code2 GCD 4×12 (2,6,4,8) 0.625 144 6912 code3 RS 5×10 (2,5,4,8) 0.45 149 5960 code4 RS 4×12 (2,6,4,8) 0.625 149 7152

[0070] Among them, b and l represent the number of coupling blocks and the coupling length respectively, n1 represents the number of upper half rows when the initial cyclic shift matrix is ​​pruned, m represents the number of left half columns when the initial cyclic shift matrix is ​​pruned, that is, half of the number of columns of the initial cyclic shift matrix, J represents the number of rows of the initial cyclic shift matrix, L represents the number of columns of the initial cyclic shift matrix, and l=2×b is satisfied under the pruning method of the present invention.

[0071] The simulation environment adopts binary phase shift keying (BPSK) modulation under Gaussian channel, the decoding algorithm adopts sliding window decoding, the window size is set to 4 and 8 (i.e. no sliding window), and the maximum number of decoding iterations is set to 50. The performance comparison of bit error rate (BER) and frame error rate (BLER) is as follows: Figure 6 , 7 shown.

[0072] When the window size is 4, the short-cycle-free SC-LDPC code based on GCD constraint proposed in the present invention is better than the traditional SC-LDPC code based on RS code at a BER of 10 -4 Both code rates have a performance gain of 0.45dB when BLER is 10 -2 Both bit rates have a performance gain of 0.7dB.

[0073] When the window size is 8, the short-cycle-free SC-LDPC code based on GCD constraint proposed in the present invention is better than the traditional SC-LDPC code based on RS code at a BER of 10-6 When the bit rate is 0.45 and 0.625, the performance gain is 1.05 and 1.0dB respectively. -4 The performance gains are 1.1 and 1.25 dB at 0.45 bit rate and 0.625 bit rate respectively.

[0074] Therefore, the GCD-constrained short-loop SC-LDPC code proposed in the present invention reduces the decoding performance loss caused by short loops (such as 4 loops and 6 loops), has a simple coding structure and a small decoding delay.

[0075] The present invention also provides a structure of an electronic device, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus.

[0076] Memory, used to store computer programs;

[0077] The processor is used to implement the steps provided in the above method embodiment when executing the program stored in the memory.

[0078] The communication interface is used for communication between the above electronic device and other devices.

[0079] The method provided in the embodiment of the present invention can be applied to electronic devices. Specifically, the electronic device can be: a desktop computer, a portable computer, an intelligent mobile terminal, a server, etc. This is not limited here, and any electronic device that can implement the present invention belongs to the protection scope of the present invention.

[0080] The present invention also provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the steps provided in the above method embodiment are implemented.

[0081] The present invention also provides a program product, which includes computer program instructions. When the computer program instructions are executed, the steps provided in the above method embodiment can be implemented.

[0082] As for the device / electronic device / storage medium / program product embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the specific contents and beneficial effects and other related matters can be referred to the partial description of the method embodiments.

[0083] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0084] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for constructing a short-cycle-free SC-LDPC code based on GCD constraints, characterized in that: include: Using the GCD constraint, an initial cyclic shift matrix with an even number of columns is constructed according to the code length and code rate of the SC-LDPC code to be constructed; Based on a preset cropping rule, the initial cyclic shift matrix is ​​cropped and translated to obtain a target coupling block; constructing a target cyclic shift matrix according to the target coupling block; The target cyclic shift matrix is ​​hashed to obtain a check matrix, and an SC-LDPC code is constructed based on the check matrix.

2. The method according to claim 1, characterized in that The initial cyclic shift matrix is ​​expressed as: Where J represents the number of rows of the initial cyclic shift matrix, L represents the number of columns of the initial cyclic shift matrix, J and L are both positive integers greater than or equal to 3, and the data items a0 to a1 in each element of the matrix are J-1 Satisfy 0≤a0 <a1<…<a J-1 .

3. The method according to claim 2, characterized in that The method of performing a cropping and translation process on the initial cyclic shift matrix based on a preset cropping rule to obtain a target coupling block includes: Divide the initial cyclic shift matrix into four sub-matrices with equal column widths, namely, sub-matrix A1 located at the upper left corner, sub-matrix B1 located at the lower left corner, sub-matrix A2 located at the upper right corner, and sub-matrix B2 located at the lower right corner, wherein the sub-matrix A1 and the sub-matrix A2 have the same row height; The sub-matrix A2 is translated to be directly below the sub-matrix B2 to obtain the target coupling block.

4. The method according to claim 3, characterized in that The constructing a target cyclic shift matrix according to the target coupling block comprises: According to a preset code length, the target coupling block is copied multiple times, and the target coupling blocks are sequentially spliced ​​to form a quasi-diagonal band structure to obtain the target cyclic shift matrix, in which the submatrix A2 in the previous target coupling block is connected to the submatrix A1 in the subsequent target coupling block.

5. The method according to claim 4, characterized in that The performing hashing on the target cyclic shift matrix to construct a check matrix includes: Constructing a cyclic permutation matrix according to the initial cyclic shift matrix; The target cyclic shift matrix is ​​hashed by using the cyclic permutation matrix to construct the check matrix.

6. The method according to claim 5, characterized in that The step of constructing a cyclic permutation matrix according to the initial cyclic shift matrix comprises: According to the initial cyclic shift matrix, a first threshold is determined, which is expressed as: Z + =(a J-1 -a0)(L-1)+1, Among them, Z + represents the first threshold; Traversing each element of the initial cyclic shift matrix, determining a positive integer that satisfies a preset condition and is less than the first threshold, where the preset condition is expressed as: Among them, Z represents the value to be solved, Z∈[2,Z + ], mod means modular operation, p i,j represents any element in the initial cyclic shift matrix, i=i0,i1,i2,...., j=j0,j1,j2,....; The smallest positive integer is determined as the size of the circulant permutation matrix, and the circulant permutation matrix is ​​constructed.

7. A construction device for a short-cycle-free SC-LDPC code based on GCD constraints, characterized in that: include: A construction module, used to construct an initial cyclic shift matrix using GCD constraints; A cropping module, configured to perform cropping and translation processing on the initial cyclic shift matrix based on a preset cropping rule to obtain a target coupling block; The construction module is further used to construct a target cyclic shift matrix according to the target coupling block; The construction module is also used to perform hash processing on the target cyclic shift matrix to obtain a check matrix, and construct an SC-LDPC code based on the check matrix.

8. An electronic device, characterized in that: It includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus; Memory, used to store computer programs; A processor, for implementing any of the methods described in claims 1-6 when executing a program stored in a memory.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 6 is implemented.

10. A program product, characterized in that The program product comprises computer program instructions, and when the computer program instructions are executed, the method according to any one of claims 1 to 6 can be implemented.

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