CN-115694516-B - Quick continuous counteraction decoding method and device for special node of polarization code

CN115694516BCN 115694516 BCN115694516 BCN 115694516BCN-115694516-B

Abstract

The invention provides a quick continuous cancellation decoding method of a special node of a polarization code, which comprises the steps of determining special nodes in a target decoding tree of continuous cancellation decoding according to distribution of information bits and frozen bits of the polarization code, wherein the special nodes comprise a first pair constraint and a second pair constraint, performing hard decision on a log likelihood ratio sequence of the special nodes to obtain a first estimated codeword sequence, calculating a check value of the first pair constraint, overturning a bit estimated value in the first estimated codeword sequence according to the check value of the first pair constraint to obtain a second estimated codeword sequence, calculating a check value of the second pair constraint, constructing a set formed by overturning bit pairs according to the check value of the second pair constraint, selecting a bit pair with minimum measurement in the set, and overturning a bit estimated value of a corresponding position of the bit pair in the second estimated codeword sequence to obtain the target estimated codeword sequence. The method of the invention greatly reduces the decoding time delay under the condition of ensuring the lossless performance, and is convenient for the realization of a hardware platform.

Inventors

LU YANG
ZHAO MINGMIN
LEI MING
ZHAO MINJIAN

Assignees

浙江大学

Dates

Publication Date: 20260505
Application Date: 20221109

Claims (10)

1. A quick continuous cancellation decoding method of a polarization code special node is characterized by comprising the following steps: Determining special nodes in a target coding tree for continuously canceling coding according to the distribution of the information bits and the frozen bits of the polarization code, wherein the special nodes comprise a first pair constraint and a second pair constraint; Hard decision is carried out on the log likelihood ratio sequence of the special node to obtain a first estimated codeword sequence; Calculating the check value of the first dual constraint, and turning over the bit estimated value in the first estimated codeword sequence according to the check value of the first dual constraint to obtain a second estimated codeword sequence; Calculating the check value of the second dual constraint, constructing a set formed by turning bit pairs according to the check value of the second dual constraint, selecting the bit pair with the smallest measurement in the set, turning over the bit estimation value of the bit pair corresponding position in the second estimation codeword sequence, and obtaining the target estimation codeword sequence.
2. The method of claim 1, wherein the special node is a polar code sub-code comprising a source node and a sequence of code rate one or single even check sub-nodes.
3. The method of claim 1, wherein hard-deciding the log likelihood ratio sequence of the particular node to obtain a first estimated codeword sequence comprises: When the log-likelihood ratio is greater than 0, the hard decision result is 0, otherwise, the hard decision result is 1.
4. The method of claim 1, wherein calculating the check value of the first dual constraint comprises: calculating a log-likelihood ratio sequence of a source node in the special node, and decoding the source node according to the log-likelihood ratio sequence to obtain a source node estimated codeword sequence; And calculating a check value of the first dual constraint according to the source node estimated codeword sequence.
5. The method of claim 4, wherein the obtaining the source node estimated codeword sequence comprises: If the source node has a special structure, calculating to obtain an estimated codeword sequence of the source node through a quick decoding algorithm corresponding to the source node; If the source node has a general structure, the estimated codeword sequence of the source node is obtained through calculation by a traditional serial cancellation decoding algorithm.
6. The method of claim 1, wherein said flipping bit estimates in said first estimated codeword sequence according to the parity value of said first dual constraint comprises: If the codeword sequence meets the first type dual check value, not performing bit flipping operation; If the codeword sequence does not satisfy the first type of dual check value, bit flipping is performed on the bit having the smallest log likelihood ratio absolute value.
7. The method of claim 1, wherein constructing the set of flipped bit pairs from the parity values of the second dual constraint comprises: The collection is generated in an offline manner.
8. A quick continuous cancellation decoding device of a polarization code special node is characterized by comprising the following modules: The acquisition module is used for determining special nodes in a target coding tree for continuous cancellation decoding according to the distribution of the polarization code information bits and the frozen bits, wherein the special nodes comprise a first pair constraint and a second pair constraint; The judging module is used for carrying out hard judgment on the log likelihood ratio sequence of the special node to obtain a first estimated codeword sequence; The first verification module is used for calculating the verification value of the first dual constraint, and turning over the bit estimation value in the first estimated codeword sequence according to the verification value of the first dual constraint to obtain a second estimated codeword sequence; and the second checking module is used for calculating the check value of the second dual constraint, constructing a set formed by turning bit pairs according to the check value of the second dual constraint, selecting the bit pair with the smallest measurement in the set, turning over the bit estimation value of the bit pair corresponding position in the second estimation codeword sequence, and obtaining the target estimation codeword sequence.
9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing a method for fast successive cancellation decoding of a specific node of a polar code according to any one of claims 1-7 when the computer program is executed by the processor.
10. A computer readable storage medium having stored thereon a computer program, which when executed by a processor implements a method of fast successive cancellation decoding of a polarization specific node according to any one of claims 1 to 7.

Description

Quick continuous counteraction decoding method and device for special node of polarization code Technical Field The invention relates to the technical field of wireless communication. Background Polarization codes are a channel coding scheme which has been theoretically proven to reach shannon capacity, and have been adopted by the fifth generation mobile communication system (5G). The decoding algorithm has great influence on the error correction capability of the polarization code in practical application, wherein the decoding algorithm based on serial cancellation (Successive Cancellation, SC) adopts a bit-by-bit decoding mode, can effectively utilize the polarization effect, shows good error correction performance, and is widely focused in academia and industry. However, SC decoding algorithms have two major drawbacks. On the one hand, according to the polarization theory, the polarized codes under SC decoding can reach the channel capacity only when the code length is approaching infinity, so in practice, SC decoding cannot provide reasonable error correction performance for polarized codes with limited code length. Serial cancellation list (Successive Cancellation List, SCL) decoding greatly improves the error correction performance of SC decoding by maintaining a list that retains multiple most reliable codeword sequences. By concatenating the polar code with a cyclic redundancy Check (Cyclic Redundancy Check, CRC), the decoding performance provided by a CRC-assisted SCL (CA-SCL) decoder may approach that of a Maximum-Likelihood (ML) decoder, which makes the polar code a powerful competitor to other currently most advanced channel coding, such as Low-DENSITY PARITY-Check (LDPC) codes and Turbo codes. On the other hand, the bit-by-bit sequency of SC decoding causes very high decoding delay and Low throughput performance, which hinders the application of SC decoding in Low-delay communication scenarios such as Ultra-Reliable Low-Latency Communication, URLLC. In order to realize efficient decoding, a common idea is to parallelize the decoding process, namely decoding at the middle node level of the decoding tree instead of the leaf node level, so that the traversing of the whole code tree is avoided and the decoding speed is improved. In order to ensure that the decoding performance is not degraded, constraint conditions caused by information in nodes and distribution characteristics of frozen bits are required to be considered in decoding at the node level, so that a decoding result is effective. Therefore, the higher the number of decoding tree layers where the node is located, the higher the parallelism, the lower the decoding delay and the higher the throughput, but at the same time, the more bits the node contains, the more complex the constraint condition, and the difficulty is brought to the realization of the decoding algorithm with lossless performance. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the invention aims to provide a quick continuous cancellation decoding method of a special node of a polarization code, which is used for reducing decoding delay. To achieve the above objective, an embodiment of a first aspect of the present invention provides a method for fast and continuous cancellation decoding of a specific node of a polarization code, including: Determining special nodes in a target coding tree for continuously canceling coding according to the distribution of the information bits and the frozen bits of the polarization code, wherein the special nodes comprise a first pair constraint and a second pair constraint; Hard decision is carried out on the log likelihood ratio sequence of the special node to obtain a first estimated codeword sequence; Calculating the check value of the first dual constraint, and turning over the bit estimated value in the first estimated codeword sequence according to the check value of the first dual constraint to obtain a second estimated codeword sequence; Calculating the check value of the second dual constraint, constructing a set formed by turning bit pairs according to the check value of the second dual constraint, selecting the bit pair with the smallest measurement in the set, turning over the bit estimation value of the bit pair corresponding position in the second estimation codeword sequence, and obtaining the target estimation codeword sequence. In addition, the method for fast and continuous cancellation decoding of the special node of the polarization code according to the above embodiment of the present invention may further have the following additional technical features: further, in one embodiment of the present invention, the special node is a polar code sub-code comprising a source node and a sequence of code rate one or single even check sub-nodes. Further, in an embodiment of the present invention, the hard decision on the log likeli