Two-dimensional Polar code communication transmission method, device and equipment

Abstract

The invention discloses a communication transmission method, device and equipment of a two-dimensional Polar code. On an encoder, inner code Polar coding with the code rate of 1 is adopted to balance the error probability of each outer code, so that the error probability of a total code block is reduced, a Double Gaussian Application (DGA) algorithm is proposed to optimize the Design SNR used when the outer codes are constructed, and the accuracy of reliability estimation of sub-channels of the outer codes is improved. On a decoder, a Selective Successive Cancellation (SSCL) decoder combining inner code SCL decoding and outer code SC selection path re-decoding is adopted, a relatively reliable path obtained by inner code decoding is reserved and is used as a candidate path during re-decoding after decoding failure, and the decoding reliability is improved through re-decoding of multiple re-selection paths. Meanwhile, a plurality of inner code SCL decoders decode at the same time, and additional complexity is almost not introduced under the working signal-to-noise ratio by selecting and re-decoding, so that the overall decoding time delay is reduced.

Description

Technical Field

[0001] The present invention relates to a forward error correction (FEC) technology in an industrial communication scenario, and in particular to a low-latency Polar coding scheme suitable for short and medium codes. Background Art

[0002] In 1948, Shannon proved that error-free transmission of data is possible in communication channels affected by noise. He proved that in these cases, reliable transmission can be achieved by transmitting data at a code rate R that is lower than the channel capacity (also known as the Shannon limit), and FEC technology is one of the common methods to solve this problem.

[0003] Arikan designed Polar code in the late 2000s, providing the first FEC technology that can achieve channel capacity. Polar code transfers the capacity of some sub-channels to other sub-channels through channel polarization, thus achieving the transfer of channel capacity. In the end, the information bits are placed on the more reliable sub-channels, and the remaining channels are placed with frozen bits known to the sender and receiver, which is equivalent to not transmitting information.

[0004] The SCL (Successive Cancellation List) algorithm copes with the error transmission problem of the SC algorithm by retaining the split path. When the list is large enough, the performance of the SCL decoder is close to that of the ML decoder. In order to solve the problem that the code distance of Polar code is inherently worse than that of RM code and other existing codes, the CRC-assisted SCL (CA-SCL) algorithm is proposed. CA-SCL determines the final surviving path through the path metric PM and CRC check, reducing the impact of the poor code distance of Polar code on performance. The SCF (Successive Cancellation Flipping) algorithm selects the first possible error bit flip when the CRC check fails, and continues SC decoding until the check succeeds. It can also reduce the impact of error transmission in the SC algorithm, and the computational complexity and delay are similar to those of the SC algorithm when the signal-to-noise ratio is high, while achieving performance close to that of the SCL decoder. However, the traditional SC-based decoder is a sequential decoder, and the decoding delay increases linearly with the code length. Under medium and long codes, the decoding delay is somewhat different from the parallel decoding LDPC code. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing solutions, and to provide a two-dimensional Polar code encoding and decoding solution based on path selection retranslation, which is used to achieve reliable decoding of Polar codes with low latency in medium and short code scenarios.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: a communication transmission method of a two-dimensional Polar code, comprising the following steps: The sending end encodes the bit sequence to be coded using the two-dimensional Polar code constructed by the DGA optimized outer code, generates the codeword sequence to be sent, and then sends it out; The receiving end obtains the information to be decoded; The receiving end decodes the received information to be decoded using the SSCL decoder.

[0007] Furthermore, the following steps are specifically adopted to generate a codeword sequence to be sent by encoding the two-dimensional Polar code constructed by DGA optimization of the outer code of the sequence to be encoded: (1) Treating the coded bit sequence Add CRC check bits to generate a new sequence ; (2) The new sequence generated in step (1) The length of each outer code information bit constructed according to the same error probability criterion Split into Outer Code Information Sequence ; (3) The outer code information sequence obtained in step (2) is constructed through the DGA algorithm to construct the outer code codeword ; (4) Convert the external code word The jth bit of the inner code sequence , perform inner code encoding to obtain the inner code word All internal code words Construct the codeword sequence to be sent , Where N is the code length, K is the information length, is the CRC length, N I is the inner code length.

[0008] Furthermore, the generating polynomial of CRC in step (1) is ,in This is the CRC length.

[0009] Furthermore, the length of each outer code information bit in step (2) is The construction of is done by following the steps below: 2.1 Using formula 1 to estimate the mean value of the soft acceptance The error probability of the subchannel is: (1) in The code rate is The weight coefficient of the codeword, d is the Hamming distance; 2.2 Error probability for a specified subchannel , use the bisection method to approximate the solution of equation 2: (2) Thus construct .

[0010] Furthermore, in step (3), the outer codeword is constructed by the DGA algorithm by specifically adopting the following steps: 3.1 According to the preset design SNR, the code length is The GA algorithm estimates the soft value mean of each sub-channel ; 3.2 The equivalent signal-to-noise ratio of each subchannel is obtained by formula 3: (3) When designing the SNR of each sub-channel separately GA algorithm, construct the external code sequence to be encoded and Multiply them to get the outer code word.

[0011] Furthermore, the received information to be decoded is decoded by using the SSCL decoder, specifically by the following steps: (1) Select the outer code current decoding subchannel i=0; use The parallel SC decoders perform inner code decoding in parallel and calculate the codeword softness of the outer code subchannel i; (2) The codeword soft quantity of the outer code subchannel i is decoded by SCL, and the candidate paths, select the most reliable path as the outer code decoding result ; (3) Decode the external code Re-encode to get the estimated outer codeword , and used as the i-th decoding result of each inner code for subsequent inner code decoding; (4) If ,but And enter Step 1, otherwise the decoded Combined into decoded CRC codeword .

[0012] Furthermore, decoding also includes decoding CRC codewords Perform CRC check. If the check passes, the decoding is successful. If the check fails, re-decode from step (1). The number of re-decoding is within the set T times.

[0013] An electronic device, comprising: at least one processor; and a memory connected to the at least one processor in communication; wherein: The memory stores a computer program that can be executed by the at least one processor. The computer program is executed by the at least one processor so that the at least one processor can perform any one of the methods described above.

[0014] A computer-readable storage medium stores computer instructions, wherein the computer instructions are used to enable a processor to implement any of the above methods when executed.

[0015] Based on the two-dimensional Polar code encoding and decoding scheme of path selection retranslation, the transmitter uses the two-dimensional Polar code encoding constructed by DGA optimized outer code. The two-dimensional Polar code encoding first performs CRC encoding, where is the CRC length. The CRC codeword is divided into The DGA algorithm is used to construct the sequences to be encoded for each outer code and encode them to obtain the outer code word. Then, the bits at the same subchannel position of the outer code word are taken and encoded with an inner code rate of 1 to obtain the inner code word. All the inner code words constitute the transmitted bits. The receiving end adopts the proposed SSCL decoder and uses The SC decoders perform inner code decoding in parallel. After completing the SC decoding of one bit, the output soft quantities of all SC decoders are used as the soft quantities of the outer code words, and the outer code decoding is performed through the SCL decoder. After all the outer code words are decoded, the decoding results are subjected to CRC check. If they pass, the decoding is successful. Otherwise, a less reliable path is selected from the candidate paths generated by the SCL decoder as the outer code decoding result for re-translation until the CRC check passes or the number of re-translation exceeds the threshold.

[0016] Polar code, combined with the SCL decoding algorithm, has shown excellent performance in short packet communications and has been selected as the NR control channel decoding method. However, since the SC decoder is essentially serial, its delay is inferior to modern coding methods such as LDPC codes with iterative decoding. Many improved SC decoder-based technologies have been proposed to reduce decoding delays, including hypothesis testing-based methods that make direct hard decisions on reliable unstructured nodes in Polar codes, thereby simplifying the decoding operation. The decoding efficiency is improved by reducing the number of nodes that require decoding calculations. And through the node aggregation method, parallel decoding is achieved by constructing long and reliable component codes. This method not only enhances the reliability of the coding, but also significantly reduces the decoding delay.

[0017] The method of the present invention is based on the cascade scheme of two-dimensional Polar codes, which divides the longer codewords to be decoded into several inner code sub-blocks that can be decoded in parallel, thereby reducing the decoding delay. However, in traditional two-dimensional Polar code decoders, the traditional Polar code GA construction method has the problem of inaccurate estimation of the sub-channel signal-to-noise ratio of the inner code, and the SC decoder used for both the inner and outer codes has insufficient performance due to insufficient polarization, which is inferior to the traditional Polar code. In order to solve this problem, the present invention takes into account the reliability changes of the outer code sub-channel caused by the polarization of the inner code through the method of double Gaussian estimation DGA in encoding, thereby ensuring the optimality of the outer code construction; in decoding, the utilization rate of the SCL decoding list is improved by retaining reliable paths and selecting re-translation, thereby further improving the decoding performance while decoding in parallel. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is an implementation flow chart of the SSCL decoder in the embodiment of the present invention.

[0019] Figure 2 It is an implementation flow chart of the DGA algorithm in an embodiment of the present invention.

[0020] Figure 3 is the bit rate in the implementation case of the present invention , , , , The CA-SCL algorithm used in 5G-Polar code and the proposed two-dimensional Polar code encoding and decoding algorithm based on path selection retranslation (PT-Polar) are compared. The performance of the BPSK through AWGN channel is 2.1347 W / m2 and 2.313 W / m2 respectively. . DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0022] It should be noted that the terms "including" and "having" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or apparatuses.

[0023] The following is combined with Figure 1 , attached Figure 2 The present invention will be further described.

[0024] Implementation scenario: Linear block code , the code length is , the information bit length is The internal code length is , the length of the outer code is ,in The CRC generator polynomial is ,in is the CRC length. Let the information sequence of the cascaded CRC be Divided into External code information sequence ,in The sequence length is ,satisfy , the code words of the outer code and inner code are and , the polar code generation matrix of the inner code is , the polar code generation matrix of the outer code is , external code word Composition of the generated codeword after encoding . Select the retranslation path set as , the list size is , the maximum number of selected re-translations is .

[0025] 1). The 2D Polar code encoding scheme includes the following steps: Step 1: Information bit sequence Add CRC check bit generation .

[0026] Step 2: Construct the length of each outer code information bit according to the same error probability criterion For the acceptance soft quantity mean value The error probability of the subchannel is approximately estimated as ,in The code rate is The weight coefficient of the codeword is d, and the Hamming distance is d. , use the bisection method to approximate the solution of the equation , thus constructing . And will according to Split into Outer Code Information Sequence .

[0027] Step 3: Construct the outer codeword according to the DGA algorithm. First, the code length is The GA algorithm estimates the soft value mean of each sub-channel , and then calculate the equivalent signal-to-noise ratio of each sub-channel , design SNR for each sub-channel separately GA algorithm, construct the external code sequence to be encoded and Multiply to get the outer code word .

[0028] Step 4: Take The jth bit of the inner code sequence , perform external code encoding to obtain the external code word All external code words Construct the codeword to be sent .

[0029] 2). The SSCL decoder algorithm is implemented as follows: Step 1: Initialize the number of re-translation times t=0, and the current decoding sub-channel of the outer code i=0.

[0030] Step 2: The parallel SC decoders perform inner code decoding in parallel, calculate the codeword soft quantity of the outer code subchannel i, and input the codeword soft quantity into the SCL decoder to decode and obtain candidate paths. , then from Select from the paths The sub-reliable paths are added to the selected re-translation set .

[0031] Step 3: If the subchannel selected for retranslation for the tth time is i, that is , then from The most reliable path is selected as the outer code decoding result Otherwise, select from Select the The candidate paths are used as the outer code decoding results .

[0032] Step 4: Decode the external code Re-encode to get the estimated outer codeword , as the i-th decoding result of each inner code, for subsequent inner code decoding. ,but And enter Step 2, otherwise the decoded Combined into decoded CRC codeword , proceed to Step 5.

[0033] Step 5: CRC check code word , if it passes, the decoding is successful, otherwise .like ,but And go to Step 2, otherwise the decoding fails.

[0034] Table 1 shows the bit rates in the implementation case. , , , theoretically analyzes the reduction in latency and computational complexity of the present invention compared with 5G-Polar code.

[0035] Table 1

[0036] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

[0037] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A communication transmission method of a two-dimensional Polar code, characterized in that The following steps are involved: The sending end encodes the bit sequence to be coded using the two-dimensional Polar code constructed by the DGA optimized outer code, generates the codeword sequence to be sent, and then sends it out; The receiving end obtains the information to be decoded; The receiving end decodes the received information to be decoded using the SSCL decoder.

2. The communication transmission method of the two-dimensional Polar code according to claim 1, characterized in that: The two-dimensional Polar code encoding of the DGA optimized outer code construction for the coded sequence to generate the codeword sequence to be sent specifically adopts the following steps: (1) Treating the coded bit sequence Add CRC check bits to generate a new sequence ; (2) The new sequence generated in step (1) The length of each outer code information bit constructed according to the same error probability criterion Split into Outer Code Information Sequence ; (3) The outer code information sequence obtained in step (2) is constructed through the DGA algorithm to construct the outer code codeword ; (4) Convert the external code word The jth bit of the inner code sequence , perform inner code encoding to obtain the inner code word All internal code words Construct the codeword sequence to be sent ; Where N is the code length, K is the information length, is the CRC length, N I is the inner code length.

3. The communication transmission method of the two-dimensional Polar code according to claim 2, characterized in that: The generating polynomial of CRC in step (1) is: ,in This is the CRC length.

4. The communication transmission method of the two-dimensional Polar code according to claim 2, characterized in that: The length of each outer code information bit in step (2) The construction of is done by following the steps below: 2.1 Using formula 1 to estimate the mean value of the soft acceptance The error probability of the subchannel is: （1） in The code rate is The weight coefficient of the codeword, d is the Hamming distance; 2.2 Error probability for a specified subchannel , use the bisection method to approximate the solution of equation 2: （2） Thus construct .

5. The communication transmission method of the two-dimensional Polar code according to claim 2, characterized in that: In step (3), the outer code word is constructed by the DGA algorithm by specifically adopting the following steps: 3.1 According to the preset design SNR, the code length is The GA algorithm estimates the soft value mean of each sub-channel ; 3.2 The equivalent signal-to-noise ratio of each subchannel is obtained by formula 3: （3） When designing the SNR of each sub-channel separately GA algorithm, construct the external code sequence to be encoded and Multiply them to get the outer code word.

6. The communication transmission method of the two-dimensional Polar code according to claim 1, characterized in that: The method of decoding the received information to be decoded by using the SSCL decoder specifically adopts the following steps: (1) Select the outer code current decoding subchannel i=0; use The parallel SC decoders perform inner code decoding in parallel and calculate the codeword softness of the outer code subchannel i; (2) The codeword soft quantity of the outer code subchannel i is decoded by SCL, and the candidate paths, select the path as the outer code decoding result ; (3) Decode the external code Re-encode to get the estimated outer codeword , and used as the i-th decoding result of each inner code for subsequent inner code decoding; (4) If ,but And enter Step 1, otherwise the decoded Combined into decoded CRC codeword .

7. The communication transmission method of the two-dimensional Polar code according to claim 6, characterized in that: The decoding also includes decoding the CRC codeword Perform CRC check. If the check passes, the decoding is successful. If the check fails, re-decode from step (1). The number of re-decoding is within the set T times.

8. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory connected to the at least one processor in communication; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can perform the method according to any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the method according to any one of claims 1 to 7 when executed.

Images