Flexible code rate compatible coding method based on low-code-rate generalized LDPC (Low Density Parity Check) code

Abstract

The invention discloses a flexible code rate compatible coding method based on a low-code-rate generalized LDPC (Low Density Parity Check) code, and belongs to the field of digital signal processing. The implementation method comprises the following steps: an original signal enters an information processing unit to output an original bit sequence, and the original bit sequence is sent to an LDPC coding unit; and the original information bits generate LDPC code words containing the original information bits and the check bits. The check bits and the information bits are subjected to a Hadamard encoding operation. And randomly deleting the coded 1-degree Hadamard variable nodes according to a preset code rate and channel conditions so as to realize flexible adjustment of the code rate. And performing parallel-to-serial operation on the punched low-bit-rate generalized LDPC code word to form a final coding bit sequence, namely realizing flexible code rate compatible coding of the low-bit-rate generalized LDPC code. According to the invention, flexible code rate compatibility can be realized, the degree of adaptation between the encoder and different channel environments is increased, the transmission efficiency and the channel adaptability are significantly improved, and the communication reliability under variable channel conditions is ensured.

Description

Technical Field

[0001] The invention relates to a flexible code rate compatible coding method based on low code rate generalized LDPC code, and belongs to the field of digital signal processing. Background Art

[0002] With the rapid development of communication technology, there is an increasing demand for coding schemes that can adapt to different channel conditions and effectively utilize spectrum resources. In modern communication systems, especially in environments with limited spectrum resources and changing channel conditions, how to ensure the reliability and efficiency of communication while maintaining high data transmission rates has become an important research topic. Low-density parity-check (LDPC) codes are widely used in various communication systems due to their excellent error correction capabilities. However, traditional LDPC codes have limitations in code rate adaptability, especially under dynamically changing channel conditions, where their performance may be limited. In addition, Hadamard codes are known for their unique repetitive structure and strong anti-interference capabilities, but they also have limitations when used alone. In response to these challenges, this patent proposes a flexible code rate compatible coding method based on low code rate generalized LDPC codes. The core innovation of this coding method lies in utilizing the characteristics of the 1-degree Hadamard variable nodes of low code rate generalized LDPC codes and adopting a puncturing technique, which achieves dynamic adjustment of the code rate by deleting some of the encoded bits during the coding process. This flexible code rate compatible method enables the encoder to flexibly adjust the code rate according to the real-time changes in channel conditions, effectively improving the coding efficiency while maintaining high reliability of data transmission. By combining the efficient error correction capability of LDPC codes and the strong anti-interference ability of Hadamard codes, and cleverly applying puncturing technology, the coding method in this patent not only improves the communication efficiency under limited spectrum resources, but also maintains a high communication quality under dynamic channel conditions. In addition, the flexible code rate compatible design enables the encoder to dynamically adjust the coding strategy according to the actual channel conditions, thereby maximizing the utilization efficiency of spectrum resources while ensuring communication quality, which has important practical application value for modern communication systems. Summary of the invention

[0003] In order to solve the problem that traditional coding methods cannot dynamically adapt to different channel conditions under an environment with limited spectrum resources and changeable channel conditions, resulting in limited encoder performance, the purpose of the present invention is to provide a flexible rate-compatible coding method based on low-rate generalized LDPC codes. Under the error correction capability and low code rate of the low-rate generalized LDPC codes themselves, the encoder can dynamically adjust the code rate of the LDPC codes by puncturing the 1st-degree Hadamard variable nodes to adapt to the complex and changeable channel environment.

[0004] The object of the present invention is achieved through the following technical solutions.

[0005] The present invention discloses a flexible rate-compatible coding method based on a low-rate generalized LDPC code. The original signal enters an information processing unit to output an original bit sequence, which is then sent to an LDPC coding unit. In the LDPC coding unit, the original information bits generate an LDPC codeword containing the original information bits and a check bit. The check bit and the information bit are sent to a Hadamard coding unit for Hadamard coding operations to enhance the anti-interference performance and error correction capability of the codeword. In a puncturing unit, according to a predetermined code rate and channel condition, the encoded 1-degree Hadamard variable nodes are randomly deleted to achieve flexible adjustment of the code rate. The encoded bit sequence obtained after Hadamard coding and puncturing is sent to an integration unit. In the integration unit, the low-rate generalized LDPC coded codeword that has been punctured is converted from parallel to serial to form a final coded bit sequence, thereby achieving flexible rate-compatible coding of a low-rate generalized LDPC code. The present invention combines LDPC coding, Hadamard coding and puncturing technology to achieve low code rate coding while combining the error correction capability brought by LDPC code. The puncturing technology is used to achieve flexible code rate compatibility, increase the adaptability of the encoder to different channel environments, significantly improve transmission efficiency and channel adaptability, and ensure communication reliability under variable channel conditions.

[0006] The present invention discloses a flexible rate-compatible coding method based on a low-rate generalized LDPC code, comprising the following steps:

[0007] Step 1: The information processing unit quantizes the original signal into original information bits, and outputs the original information bits in parallel to the LDPC encoding unit in multiple channels.

[0008] Step 2: The LDPC encoding unit performs LDPC encoding on the original information bits input in step 1, and outputs the LDPC encoding in parallel to the Hadamard encoding unit.

[0009] The LDPC code length is n, the information sequence length is k, and the check matrix is ​​H. The codeword c satisfies Hc T = 0. The check matrix H is transformed into a form satisfying equation (1) by Gaussian elimination:

[0010]

[0011] I is the identity matrix, and P is a random sparse matrix. If H is full rank, there is no row with all zeros. Transpose the check matrix H to get the generator matrix of the LDPC code:

[0012] G=[P k×(n-k) I k×k ] (2)

[0013] The original information bit sequence is u = [u1, u2, ..., u k ], then c=uG is the codeword after LDPC coding, and the LDPC coding is output to the Hadamard coding unit.

[0014] Step 3: Perform Hadamard coding on the check bits and information bits to enhance the anti-interference performance and error correction capability of the codeword.

[0015] In LDPC coding, the connection corresponding to each check node satisfies the parity check relationship, which can be regarded as an SPC code. By further encoding the SPC code into a Hadamard code, the constraint relationship of the SPC code is enhanced.

[0016] The rows and columns of the Hadamard matrix are composed of orthogonal code groups. Let H represent a length of 2 r , Hadamard matrix carrying (r+1) bits of information, the codeword set is composed of ±H n The column structure is constructed using {±h j :j=0,1,...,2 r In Hadamard coding, the codeword consists of the original information bits, whose indexes are {0, 1, 2, 4, ..., 2 r -1}.

[0017] Its Hadamard constraints satisfy:

[0018]

[0019] Represents the exclusive-OR operator. Hadamard codes of order r can be used with systematic coding to generate 2 r -r-2 Hadamard parity bits, which are connected to the check nodes in the LDPC to form a Hadamard variable node of degree 1.

[0020] Step 4: In the puncturing unit, according to the predetermined code rate and channel conditions, the encoded 1-degree Hadamard variable nodes are randomly deleted to achieve flexible adjustment of the code rate.

[0021] After constructing the low-rate generalized LDPC code, the low-rate generalized LDPC code is used as the mother code and combined with the puncturing technology to design the rate compatible code. When puncturing, since all Hadamard variable nodes are 1-degree nodes, only the Hadamard variable nodes are punctured by random puncturing.

[0022] Step 5: The integration unit performs a parallel-to-serial operation on the original information bits and the encoder coded symbols of the multi-path output, and outputs the punctured low-rate generalized LDPC coded symbols.

[0023] The original information bits and the punctured Hadamard coded symbols of the multiple outputs are converted from parallel to serial, and the final flexible code rate compatible low code rate generalized LDPC coded symbols are output.

[0024] The present invention discloses a flexible rate-compatible coding method based on a low-rate generalized LDPC code, which is implemented based on a flexible rate-compatible coding system based on a low-rate generalized LDPC code. The flexible rate-compatible coding system based on a low-rate generalized LDPC code is implemented and includes an information processing unit, an LDPC coding unit, a Hadamard coding unit, a puncturing unit, and an integration unit.

[0025] The information processing unit is used to process the original signal and output an original bit sequence.

[0026] The LDPC encoding unit is used to process the original bit sequence output by the information processing unit, and output an LDPC codeword including the original information bits and LDPC check bits.

[0027] The Hadamard encoding unit is used to perform Hadamard encoding processing on the input bit sequence to form a stronger constraint relationship and output a bit sequence that satisfies the Hadamard constraint.

[0028] The puncturing unit is used to perform a puncturing operation on the 1-degree Hadamard variable nodes in the generated low-code rate generalized LDPC code, and dynamically adjust the code rate by deleting random bits.

[0029] The integration unit is used to output the final low-rate generalized LDPC coding codeword by integration and parallel-to-serial conversion, integrating the results of LDPC coding, Hadamard coding and puncturing processing.

[0030] Beneficial effects:

[0031] 1. The present invention discloses a flexible rate-compatible coding method based on a low-rate generalized LDPC code. By combining LDPC coding and Hadamard coding, LDPC coding is used to provide efficient error correction capability and Hadamard coding is used to enhance anti-interference performance, so that the encoder is suitable for variable channel conditions.

[0032] 2. The present invention discloses a flexible rate-compatible coding method based on low-rate generalized LDPC codes, which realizes flexible rate compatibility by introducing puncturing technology, and allows the code rate to be flexibly adjusted according to channel conditions. This feature enables the encoder to maximize the utilization efficiency of spectrum resources while maintaining high data transmission quality.

[0033] 3. The present invention discloses a flexible rate-compatible coding method based on a low-rate generalized LDPC code. The check bits and information bits are sent to a Hadamard coding unit to perform a Hadamard coding operation to enhance the anti-interference performance and error correction capability of the codeword. According to a predetermined code rate and channel condition, the encoded 1-degree Hadamard variable nodes are randomly deleted to achieve flexible adjustment of the code rate. The present invention combines LDPC coding, Hadamard coding and puncturing technology to achieve low-rate coding while combining the error correction capability brought by LDPC codes. The puncturing technology is used to achieve flexible rate compatibility, increase the adaptability of the encoder to different channel environments, significantly improve transmission efficiency and channel adaptability, and ensure communication reliability under variable channel conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solution described in the present invention, the accompanying drawings required for use in the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0035] Figure 1 Schematic diagram of the node structure of a low-rate generalized LDPC code.

[0036] Figure 2 The structure diagram is a specific implementation method of a flexible rate-compatible coding method based on low-rate generalized LDPC codes.

[0037] Figure 3 The present invention is a flow chart of a flexible rate-compatible coding method based on low-rate generalized LDPC codes. DETAILED DESCRIPTION

[0038] Embodiment 1:

[0039] like Figure 2 As shown, this embodiment discloses a flexible rate-compatible coding system based on a low-rate generalized LDPC code, including an information processing unit, an LDPC coding unit, a Hadamard coding unit, a puncturing unit, and an integration unit.

[0040] The information processing unit is used to process the original signal and output an original bit sequence.

[0041] The LDPC encoding unit is used to process the original bit sequence output by the information processing unit, and output an LDPC codeword including the original information bits and LDPC check bits.

[0042] The Hadamard encoding unit is used to perform Hadamard encoding processing on the input bit sequence to form a stronger constraint relationship and output a bit sequence that satisfies the Hadamard constraint.

[0043] The puncturing unit is used to perform a puncturing operation on the 1-degree Hadamard variable nodes in the generated low-code rate generalized LDPC code, and dynamically adjust the code rate by deleting or ignoring specific bits.

[0044] The integration unit is used to output the final low-rate generalized LDPC coding codeword by integration and parallel-to-serial conversion, integrating the results of LDPC coding, Hadamard coding and puncturing processing.

[0045] like Figure 3 As shown, the flexible rate-compatible encoder based on low-rate generalized LDPC code disclosed in this embodiment is specifically implemented as follows:

[0046] Step 1: The information processing unit quantizes the original signal into original information bits, and outputs the original information bits in parallel to the LDPC encoding unit in multiple channels.

[0047] Step 2: The LDPC encoding unit performs LDPC encoding on the original information bits input in step 1, and outputs the LDPC encoding in parallel to the Hadamard encoding unit.

[0048] The LDPC code length is n, the information sequence length is k, and the check matrix is ​​H. The codeword c satisfies Hc T = 0. The check matrix H is transformed into a form satisfying equation (1) by Gaussian elimination:

[0049]

[0050] I is the identity matrix, and P is a random sparse matrix. If H is full rank, there is no row with all zeros. Transpose the check matrix H to get the generator matrix of the LDPC code:

[0051] G=[P k×(n-k) I k×k ] (2)

[0052] The original information bit sequence is u = [u1, u2, ..., u k ], then c=uG is the codeword after LDPC coding, and the LDPC coding is output to the Hadamard coding unit.

[0053] Step 3: Perform Hadamard coding on the check bits and information bits to enhance the anti-interference performance and error correction capability of the codeword.

[0054] In LDPC coding, the connection corresponding to each check node satisfies the parity check relationship, which can be regarded as an SPC code. By further encoding the SPC code into a Hadamard code, the constraint relationship of the SPC code is enhanced.

[0055] The rows and columns of the Hadamard matrix are composed of orthogonal code groups. Let H represent a length of 2 r , Hadamard matrix carrying (r+1) bits of information, the codeword set is composed of ±H n The column structure is constructed using {±h j :j=0,1,...,2 r In Hadamard coding, the codeword consists of the original information bits, whose indexes are {0, 1, 2, 4, ..., 2 r -1}.

[0056] Its Hadamard constraints satisfy:

[0057]

[0058] Represents the exclusive-OR operator. Hadamard codes of order r can be used with systematic coding to generate 2 r -r-2 Hadamard parity bits, which are connected to the check nodes in the LDPC to form a Hadamard variable node of degree 1.

[0059] Step 4: In the puncturing unit, according to the predetermined code rate and channel conditions, the encoded 1-degree Hadamard variable nodes are randomly deleted to achieve flexible adjustment of the code rate.

[0060] After constructing the low-rate generalized LDPC code, the low-rate generalized LDPC code is used as the mother code and combined with the puncturing technology to design the rate compatible code. When puncturing, since all Hadamard variable nodes are 1-degree nodes, only the Hadamard variable nodes are punctured by random puncturing.

[0061] Step 5: The integration unit performs a parallel-to-serial operation on the original information bits and the encoder coded symbols of the multi-path output, and outputs the punctured low-rate generalized LDPC coded symbols.

[0062] The original information bits and the punctured Hadamard coded symbols of the multiple outputs are converted from parallel to serial, and the final flexible code rate compatible low code rate generalized LDPC coded symbols are output.

[0063] The specific description above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flexible rate-compatible coding method based on low-rate generalized LDPC codes, characterized by: The following steps are included: Step 1: The information processing unit quantizes the original signal into original information bits, and outputs the original information bits in parallel to the LDPC encoding unit in multiple channels; Step 2: The LDPC encoding unit performs LDPC encoding on the original information bits input in step 1, and outputs the LDPC encoding in parallel to the Hadamard encoding unit in multiple paths; Step 3: Perform Hadamard encoding on the check bits and information bits to enhance the anti-interference performance and error correction capability of the codeword; Step 4: In the puncturing unit, according to the predetermined code rate and channel conditions, the coded 1-degree Hadamard variable nodes are randomly deleted to achieve flexible adjustment of the code rate; Step 5: The integration unit performs a parallel-to-serial operation on the original information bits and the component encoder coded symbols of the multi-path output, and outputs the punctured low-rate generalized LDPC coded symbols.

2. The flexible rate compatible coding method based on low code rate generalized LDPC code according to claim 1, characterized in that: The implementation method of step 2 is: The LDPC code length is n, the information sequence length is k, and the check matrix is ​​H; the codeword c satisfies H·c T =0; the check matrix H is transformed into a form satisfying equation (1) by Gaussian elimination method: I is the identity matrix, and P is a random sparse matrix. If H is full rank, there is no row with all 0s; transpose the check matrix H to get the generator matrix of the LDPC code: G=[P k×(n-k) I k×k ] (2) The original information bit sequence is u = [u1, u2, ..., u k ], then c=uG is the codeword after LDPC coding, and the LDPC coding is output to the Hadamard coding unit.

3. The flexible rate compatible coding method based on low code rate generalized LDPC code according to claim 2, characterized in that: The implementation method of step three is: In LDPC coding, the connection corresponding to each check node satisfies a parity check relationship, and the parity check relationship is equivalent to an SPC code; by further encoding the SPC code into a Hadamard code, the constraint relationship of the SPC code is enhanced; The rows and columns of the Hadamard matrix are composed of orthogonal code groups; H represents a length of 2 r -1, Hadamard matrix carrying (r+1) bits of information, the codeword set is composed of ±H n The column structure is constructed using {±h j :j=0,1,...,2 r -1}; in Hadamard coding, the codeword consists of the original information bits, whose index is {0, 1, 2, 4, ..., 2 r -1}; Its Hadamard constraints satisfy: represents the exclusive-OR operator; Hadamard codes of order r can be used with systematic coding to generate 2 r -r-2 Hadamard parity bits, which are connected to the check nodes in the LDPC to form a Hadamard variable node of degree 1.

4. The flexible rate compatible coding method based on low code rate generalized LDPC code according to claim 3, characterized in that: In step four, After constructing a low-rate generalized LDPC code, the low-rate generalized LDPC code is used as a mother code in combination with puncturing technology to design a rate-compatible code; when puncturing, since all Hadamard variable nodes are 1-degree nodes, only the Hadamard variable nodes are punctured by random puncturing.

5. The flexible rate compatible coding method based on low rate generalized LDPC code according to claim 4, characterized in that: In step five, The original information bits and the multi-channel output punctured Hadamard coded symbols are converted from parallel to serial; and the final flexible code rate compatible low code rate generalized LDPC coded symbols are output.

6. A flexible rate compatible coding method based on low rate generalized LDPC codes as claimed in claim 1, 2, 3, 4 or 5, characterized in that: Based on a flexible rate-compatible coding system based on a low-rate generalized LDPC code; the flexible rate-compatible coding system based on a low-rate generalized LDPC code comprises an information processing unit, an LDPC coding unit, a Hadamard coding unit, a puncturing unit, and an integration unit; The information processing unit is used to process the original signal and output the original bit sequence; The LDPC encoding unit is used to process the original bit sequence output by the information processing unit, and output an LDPC codeword including the original information bits and LDPC check bits; The Hadamard encoding unit is used to perform Hadamard encoding processing on the input bit sequence to form a stronger constraint relationship and output a bit sequence that satisfies the Hadamard constraint; The puncturing unit is used to perform a puncturing operation on the 1-degree Hadamard variable nodes in the generated low-code rate generalized LDPC code, and dynamically adjust the code rate by deleting random bits; The integration unit is used to output the final low-rate generalized LDPC coding codeword by integration and parallel-to-serial conversion, integrating the results of LDPC coding, Hadamard coding and puncturing processing.

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