Self-synchronization decoding method based on polarization code

Abstract

The invention relates to the technical field of communication, in particular to a self-synchronization decoding method based on a polarization code. The method comprises the following steps: when a transmitting end constructs a polar code coding structure, selecting a partially frozen bit position to embed a preset synchronous identification sequence, and introducing a synchronous auxiliary capability on the premise of keeping a non-information bearing attribute. And in the bit stream receiving process, a receiving end identifies a plurality of synchronous candidate initial positions based on the frozen bit symbol stability change trend and the path metric value mutation characteristics. And carrying out limited depth decoding on each candidate point, calculating a Hamming consistency score of a frozen bit and a synchronization sequence, carrying out weighted fusion with a path metric value to construct a synchronization confidence coefficient function, judging an optimal synchronization starting point, then executing a complete polarization code decoding process, and recovering original information bits. The method does not need independent synchronization fields, has high synchronization accuracy and decoding efficiency, and is suitable for low-delay and low-resource-occupation scenes in high-speed communication.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a self-synchronization decoding method based on polar codes. Background Art

[0002] The development of high-performance communication systems such as 5G and the Internet of Things (IoT) has placed higher demands on the decoding efficiency and synchronization accuracy of channel coding methods. Polar codes, a channel coding scheme adopted by the 5G standard, have attracted widespread attention due to their capacity-approximating performance and structural programmability.

[0003] Existing polar code communication systems often rely on dedicated synchronization fields such as preambles and frame headers for frame synchronization. This approach not only consumes channel resources and reduces the effective code rate, but is also susceptible to noise interference, leading to synchronization errors. Furthermore, traditional synchronization mechanisms are separated from the decoding process and cannot dynamically adjust synchronization judgments based on feedback from the actual decoding path. This leads to increased error rates and synchronization delays, making it unsuitable for low-latency synchronization requirements in high-speed dynamic scenarios. Therefore, a mechanism that can integrate path behaviors and achieve simultaneous synchronization and decoding without relying on external synchronization sequences is urgently needed to improve the efficiency and robustness of the overall communication system.

[0004] Therefore, the present invention provides a self-synchronous decoding method based on polar codes. Summary of the Invention

[0005] The present invention provides a polar code-based self-synchronization decoding method. This method does not require an additional synchronization field, can identify the frame start position in real time during reception, and complete information restoration. This method reduces channel resource overhead and improves synchronization accuracy and decoding efficiency.

[0006] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a self-synchronous decoding method based on polar codes, comprising: When constructing the polar code structure at the transmitter, some frozen bits are selected to embed a preset synchronization identification sequence. The frozen bits are set to predefined non-zero values ​​while maintaining their non-information-carrying role, for synchronization-assisted identification at the decoder. When receiving the polar code bit stream at the receiving end, multiple synchronization start position candidates are identified in real time based on the symbol stability change trend of the frozen bits during path extension and the mutation characteristics of the path metric value. For each candidate position, a restricted path decoding operation is performed to extract the frozen bit restoration value and compare it with the preset synchronization recognition sequence to obtain a consistency score; The path metric and consistency score are weightedly fused to construct a synchronization confidence function. The position with the highest score is selected as the synchronization starting point. The complete polar code decoding process is performed starting from this synchronization starting point, and the restored information bit sequence is output.

[0007] As a preferred technical solution of the present invention, the synchronization identification sequence is composed of a fixed-length binary sequence. This sequence is generated by a linear feedback shift register and embedded in selected frozen bit positions. During embedding, the sequence is distributed in a bit-interval manner to avoid significant interference with the overall structural performance of the polar code.

[0008] As a preferred technical solution of the present invention, the position selection of the frozen bits includes the following steps: Based on the code length parameter of the polar code, the reliability of each bit channel is estimated using the Bhattacharyya parameter method, and a bit channel reliability ranking list is generated. According to the set bit rate, the bits with the highest reliability ranking are selected from the sorting table as information bits, and the remaining positions are defined as the frozen bit set; In the frozen bit set, frozen bits whose reliability parameter values ​​are not less than a set value are selected to embed the synchronization identification sequence, taking into account both structural integrity and decoding recognizability, and distributed in a fixed interval manner; The bit value of the preset synchronization identification sequence is embedded into the embedding position, so that the part of frozen bits has a synchronization auxiliary function but does not carry valid information.

[0009] As a preferred technical solution of the present invention, the symbol stability change trend includes: The receiving end continuously monitors the decoded values ​​of the frozen bits in the decoding path and, within each sliding window, counts the symbol consistency changes of the frozen bit positions in the path list within the window range. If the consistency of frozen bit symbols in a sliding window decreases significantly, which is manifested as significant inconsistency in the decoding values ​​of most frozen bits between candidate paths, and this phenomenon continues to exceed the set amplitude threshold, the starting position of the current window is determined to be the synchronization candidate starting point.

[0010] As a preferred technical solution of the present invention, the mutation behavior of the path metric value includes: During the decoding process, the path metric change trend of each candidate path is continuously monitored. When the average path metric value in the path set corresponding to the current moment changes by more than the set change threshold relative to the previous moment, or when the number of retained valid paths decreases by more than the set ratio in a single bit decision during the path expansion process, the position corresponding to the decoding moment is determined as a synchronization candidate starting position.

[0011] As a preferred technical solution of the present invention, the consistency comparison includes the following steps: For each candidate starting position, perform partial path decoding of the polar code to obtain the restored value of the frozen bits in the current path. Compare the frozen bit restoration value with the synchronization identification sequence embedded by the transmitter bit by bit, and calculate the Hamming distance between them as the consistency score; The smaller the Hamming distance is, the higher the matching degree is, and the more likely the corresponding candidate starting position is to be the true synchronization starting point.

[0012] As a preferred technical solution of the invention, the synchronization confidence function includes: It is constructed by fusing two types of information: path metric information and frozen bit consistency score; Among them, the path metric information is used to reflect the overall confidence level of the decoding path and form a relative credibility ranking among different candidate paths; The consistency score is used to measure the consistency between the frozen bits and the preset synchronization identification sequence in the decoding path. The consistency score is obtained by performing restricted depth path decoding on each candidate synchronization start position. The above two types of information are integrated according to a preset weighting strategy to form a comprehensive scoring index for synchronization starting point determination; The comprehensive scoring result is used to sort multiple candidate synchronization start positions and select the position with the highest score as the final synchronization start point.

[0013] As a preferred technical solution of the invention, the complete polar code decoding process includes: Adopt SCL method and combine CRC to judge the correctness of multiple candidate decoding paths; The step of verifying the validity of the synchronization start point includes: after completing polar code list decoding at the selected synchronization start position, if there is at least one path in the decoding path set that passes the CRC check, confirming that the current synchronization start point is a valid synchronization point and outputting the corresponding decoding result; If all paths fail the CRC check, the current synchronization starting point is abandoned, and the next candidate synchronization position is selected in the order of synchronization confidence score, and the complete decoding and verification process is performed again; When all candidate synchronization positions fail the CRC check, it is determined that the synchronization of the current data block has failed, and a system-level resynchronization mechanism is triggered or the system waits for the next identifiable synchronization block.

[0014] The beneficial effects of the present invention are: 1. The synchronization mechanism described in this invention fully exploits the polar code decoding path information and does not rely on additional synchronization frame headers or preamble structures. Through synchronous reconstruction of frozen bits, path statistical analysis, and score fusion mechanisms, the self-synchronization process can be executed in conjunction with the standard SCL decoding process, adapting to existing hardware platform architectures. This method provides enhanced robustness and synchronization flexibility, especially in communication environments with multipath interference, frame boundary drift, or uncertain reception status, significantly improving the system's overall anti-desynchronization capability and decoding success rate.

[0015] 2. The synchronization starting point selection of the present invention is based on a weighted fusion of the frozen bit Hamming consistency score and the path metric value, taking into account both local sequence matching accuracy and overall path credibility. Compared with synchronization methods with a single structure or unidirectional criteria, it has higher accuracy and is particularly suitable for high-speed communication applications with strict bit error rate control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 1 is a flow chart of a self-synchronous decoding method based on polar codes provided by the present invention; DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0018] Example 1: A self-synchronous decoding method based on polar codes, such as Figure 1 As shown, including: When constructing the polar code structure at the transmitter, some frozen bits are selected to embed a preset synchronization identification sequence. The frozen bits are set to predefined non-zero values ​​while maintaining their non-information-carrying role, for synchronization-assisted identification at the decoder. Furthermore, the synchronization identification sequence is composed of a binary sequence of fixed length, which is generated by a linear feedback shift register and embedded in selected frozen bit positions. The sequence is distributed in a bit interval manner during embedding to avoid significant interference with the overall structural performance of the polar code.

[0019] The frozen bit position selection comprises the following steps: Based on the code length parameter of the polar code, the reliability of each bit channel is estimated using the Bhattacharyya parameter method, and a bit channel reliability ranking list is generated. According to the set bit rate, the bit positions whose Bhattacharyya parameter values ​​are lower than the first preset threshold are selected from the sorted list as information bits, and the remaining positions are used as frozen bit sets; In the frozen bit set, a number of frozen bits with Bhattacharyya parameter values ​​higher than a second preset threshold are selected as embedding positions of the synchronization identification sequence, and are evenly distributed in the codeword in a fixed interval manner; The bit value of the preset synchronization identification sequence is embedded into the embedding position, so that the part of frozen bits has a synchronization auxiliary function but does not carry valid information.

[0020] Specifically, first, set the code length parameter of the polar code , that is, the total number of coded bits, and set the target number of information bits , thus determining the total number of frozen bits to be .

[0021] Then, the length is calculated by using the Bhattacharyya parameter method. The reliability of each polarized bit channel is estimated, generating an ordered list of bit channel reliability values. Based on the channel transfer function, the algorithm recursively calculates the Bhattacharyya upper bound for each bit channel. A smaller value indicates a more reliable bit channel.

[0022] Sort the results by reliability value and select the top The most reliable bit position is used as the information bit, and the rest bit positions are defined as frozen bit positions. These frozen bit positions are recorded as a set .

[0023] In the frozen bit set In the sequence, sort the bits from low to high according to the Bhattacharyya value again, and select the bit positions with the lowest reliability as the embedding positions of the synchronization identification sequence. Set the synchronization identification sequence length to , then take out from the frozen bit set frozen bits as embedding sites, denoted as the set , which satisfies .

[0024] In order to reduce the disturbance of embedding on the performance of polar code structure, the above embedding sites are selected in a fixed bit interval manner. For example, in the frozen bit set Middle step length Select from the end forward so that the embedding positions are evenly distributed throughout the codeword. According to the code length and recognition sequence length Calculations confirm that the coverage is approximately uniform. Then, a linear feedback shift register (LFSR) generator is used to generate a set of fixed synchronization recognition sequences as binary sequence vectors. The feedback polynomial and initial state of the LFSR are pre-shared between both communicating parties to ensure that the synchronization sequence can be restored at the receiving end.

[0025] Finally, in the process of constructing the polar code, the synchronization identification sequence generated above is Each bit value of Embedded into the corresponding freezing sites in sequence The embedding process keeps the bits on other frozen bits set to all zeros, thereby ensuring that the structure of the entire polar code still meets the basic design constraints.

[0026] Through the above steps, the transmitter completes the synchronization assistance function of some frozen bits in the polar code encoding structure, enabling them to mark the synchronization position without carrying any information bits. This facilitates the receiver to achieve accurate synchronization identification without the need for an auxiliary synchronization sequence.

[0027] When receiving the polar code bit stream at the receiving end, multiple synchronization start position candidates are identified in real time based on the symbol stability change trend of the frozen bits during path extension and the mutation characteristics of the path metric value. Furthermore, the symbol stability change trend includes: The receiving end continuously monitors the decoded values ​​of the frozen bits in the decoding path and, within each sliding window, counts the symbol consistency changes of the frozen bit positions in the path list within the window range. If the consistency of frozen bit symbols in a sliding window decreases significantly, which is manifested as significant inconsistency in the decoding values ​​of most frozen bits between candidate paths, and this phenomenon continues to exceed the set amplitude threshold, the starting position of the current window is determined to be the synchronization candidate starting point.

[0028] The mutation behavior of the path metric value includes: During the decoding process, the path metric change trend of each candidate path is continuously monitored. When the average path metric value in the path set corresponding to the current moment changes by more than the set change threshold relative to the previous moment, or when the number of retained valid paths decreases by more than the set ratio in a single bit decision during the path expansion process, the position corresponding to the decoding moment is determined as a synchronization candidate starting position.

[0029] Specifically, the sliding window length is set to , the path list size is , that is, the number of retained decoding paths is , the frozen bit set is , which contains a total of frozen bit positions.

[0030] As the bit streams arrive one by one, the receiver uses sequential scanning to expand the decoding path. Each time a new bit is received, a new path set is constructed. bit moments, trace back a length of Sliding window, that is, the inspection position interval All the bits in the frozen bit set The bit index set of .

[0031] For each frozen bit in the sliding window , from the currently reserved Extract the decoded value at that position in the decoding path , count the symbol consistency of the position. The specific method is: Let the bit value that appears the most times on the frozen bit be , define the symbol consistency score of this position as: ; in is an indicator function that takes the value 1 if the value inside the brackets is true, and takes the value 0 otherwise.

[0032] The consistency scores of all frozen bit positions in the sliding window are averaged to obtain the consistency index of the current window: ; Continuously record the average consistency index of multiple sliding windows. If the current window Compared to the previous window The reduction exceeds the set threshold , that is, satisfying: ; The current window starting position Marks a potential synchronization candidate starting position.

[0033] The path metric is defined in the form of log-likelihood cost under the polar code serial cancellation list decoding path. Specifically, for any path , in the judgment bits, let the corresponding log-likelihood ratio be , the path metric update formula is as follows: ; in For the path in bits The decision value at is the log-likelihood ratio of the bit, ensuring that the path update is consistent with the decoding bias information direction.

[0034] At the same time, monitor the path metric mean of the decoding path. Bit position, corresponding to The path metric mean of the first path is There are significant mutations at the following positions: ; in is the average path metric value of the current location, is the mutation threshold.

[0035] If the consistency of the frozen bit symbol drops by more than And the path metric mutation amplitude exceeds , then the position is determined as a valid synchronization candidate starting point, recorded and used for subsequent partial path decoding and synchronization scoring operations.

[0036] For each candidate position, a restricted path decoding operation is performed to extract the frozen bit restoration value and compare it with the preset synchronization recognition sequence to obtain a consistency score; Furthermore, the consistency comparison includes the following steps: For each candidate starting position, perform partial path decoding of the polar code to obtain the restored value of the frozen bits in the current path. Compare the frozen bit restoration value with the synchronization identification sequence embedded by the transmitter bit by bit, and calculate the Hamming distance between them as the consistency score; The smaller the Hamming distance is, the higher the matching degree is, and the more likely the corresponding candidate starting position is to be the true synchronization starting point.

[0037] Specifically, the restricted decoding depth is set to , which means that in the bit stream starting at each candidate starting position, only the first The decoding operation is performed on the bits.

[0038] At the candidate starting position Start polar code path extension decoding at the beginning, use simplified SCL decoder, only extend In this process, the corresponding frozen bit position set in the decoding path is extracted The bit-restored values ​​of , constitute the frozen bit-restored sequence: ; The synchronization identification sequence is a binary sequence preset by the transmitter and embedded in the frozen bit position, which is expressed as: ; in , which indicates the number of frozen bits used for synchronization identification.

[0039] Restore the frozen bits in the path decoding result to their values Synchronize recognition sequence with preset Perform a bit-by-bit comparison and use the Hamming distance to measure the number of inconsistent bits: ; in is an indicator function that takes the value 1 if the value inside the brackets is true, and takes the value 0 otherwise.

[0040] Normalize the Hamming distance and then reversely map it to the consistency score : ; The closer the consistency score is to 1, the higher the matching degree between the frozen bit restoration value and the synchronization identification sequence is, and the greater the possibility that the corresponding candidate starting point is the true synchronization starting point.

[0041] The scores of all candidate positions Output is used for subsequent construction of the synchronization confidence function and selection of the final synchronization starting point.

[0042] The path metric and consistency score are weightedly fused to construct a synchronization confidence function. The position with the highest score is selected as the synchronization starting point. The complete polar code decoding process is performed starting from this synchronization starting point, and the restored information bit sequence is output.

[0043] Furthermore, the synchronization confidence function includes: Fusion construction based on path metric information and frozen bit consistency score; Among them, the path metric information is used to reflect the overall confidence level of the decoding path and form a relative credibility ranking among different candidate paths; The consistency score is used to measure the consistency between the frozen bits and the preset synchronization identification sequence in the decoding path. The consistency score is obtained by performing restricted depth path decoding on each candidate synchronization start position. The above two types of information are integrated according to a preset weighting strategy to form a comprehensive scoring index for synchronization starting point determination; The comprehensive scoring result is used to sort multiple candidate synchronization start positions and select the position with the highest score as the final synchronization start point.

[0044] Specifically, for each candidate synchronization start position , select the path with the highest score in its restricted depth decoding , and extract the corresponding path at depth The path metric value under Given that the path metric is in the form of negative log-likelihood accumulation, it needs to be normalized and reversed. Suppose the maximum metric of all candidate paths is , the minimum is , then for each candidate position calculate: ; in , the larger the value, the better the path.

[0045] In order to ensure the consistency of the physical meaning of the fusion score, the path confidence of the reverse normalization process is Consistency score with frozen bits Perform weighted fusion to obtain synchronization confidence score: ; in is the preset fusion weight coefficient.

[0046] Score set for all candidate points Sort and get the highest-scoring candidate synchronization point index: ; Determine its corresponding position The final synchronization starting point.

[0047] Furthermore, the SCL method is used to Starting with , perform full polar code decoding on the received code stream, using a list width of SCL decoder; and combined with the CRC check mechanism to determine the validity of each decoding path; The steps for verifying the validity of the synchronization starting point include: After completing polar code decoding at the selected synchronization start position, if there is at least one path in the decoding path set that passes the CRC check, the current synchronization start point is confirmed to be a valid synchronization point, and the corresponding decoding result is output; If all paths fail the CRC check, the current synchronization starting point is abandoned, and the next candidate synchronization position is selected in the order of synchronization confidence score, and the complete decoding and verification process is performed again; When all candidate synchronization positions fail the CRC check, it is determined that the current data block synchronization has failed and the system waits for the next identifiable synchronization block.

[0048] Through the above-mentioned fusion mechanism and the complete decoding path verification process, reliable synchronization starting point determination and decoding result recovery can be achieved without the help of additional synchronization sequences, thereby improving the overall system anti-interference ability and communication efficiency.

[0049] Example 2: In order to verify the advantages of the self-synchronous decoding method of the present invention in significantly improving synchronization accuracy and system efficiency without introducing additional synchronization sequences, this embodiment uses polar code , number of information bits Based on this, a complete self-synchronous decoding process is described, from the construction at the sending end to the synchronous identification and decoding output at the receiving end. The specific steps are as follows: Constructing a frozen set after sorting using Bhattacharyya parameters , from which 16 frozen bits with reliability parameter values ​​not lower than the set value range are selected to form a synchronous recognition embedding set .

[0050] Using LFSR to generate synchronization recognition sequence , in the frozen position The remaining frozen bits are still set to 0.

[0051] After the bit stream is received, the candidate synchronization starting point is scanned with a sliding window with a step size of 1 , and map the frozen bit positions according to the polar code construction rules.

[0052] At each candidate starting point, the execution depth is Path extension to get only the frozen bits The corresponding decoded value.

[0053] Synchronize the restored value with the sender Calculate the Hamming distance and get the consistency score . Extract path metrics at the same time , normalized to , fusion score: ; The final synchronization starting point is the highest scoring position If decoding fails after the synchronization starting point, the next best candidate point will be tried in order of confidence.

[0054] At the synchronization start point The full SCL list decoding is performed at the node with a path width of L=8 and a CRC check. If the check passes, the information bit is output; if it fails, the candidate point is switched.

[0055] On the basis of the same channel conditions and consistent code length, compared with the traditional frame synchronization scheme, the present invention shows: the synchronization accuracy is significantly improved; the average synchronization judgment time is significantly advanced; the system does not occupy additional bit resources, and the channel utilization rate is effectively improved.

[0056] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A self-synchronous decoding method based on polar codes, characterized in that: include: When constructing the polar code structure at the transmitter, some frozen bits are selected to embed a preset synchronization identification sequence. The frozen bits are set to predefined non-zero values ​​while maintaining their non-information-carrying role, for synchronization-assisted identification at the decoder. When receiving the polar code bit stream at the receiving end, multiple synchronization start position candidates are identified in real time based on the symbol stability change trend of the frozen bits during path extension and the mutation characteristics of the path metric value. For each candidate position, a restricted path decoding operation is performed to extract the frozen bit restoration value and compare it with the preset synchronization recognition sequence to obtain a consistency score; The path metric value and the consistency score are weightedly fused to construct a synchronization confidence function. The position with the highest score is selected as the synchronization starting point. The complete polar code decoding process is performed starting from the synchronization starting point to output the restored information bit sequence.

2. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The synchronization identification sequence consists of a binary sequence of fixed length, generated by a linear feedback shift register and embedded in selected frozen bit positions. The sequence is distributed in a bit-interval manner during embedding to avoid significant interference with the overall structural performance of the polar code.

3. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The frozen bit position selection comprises the following steps: Based on the code length parameter of the polar code, the reliability of each bit channel is estimated using the Bhattacharyya parameter method, and a bit channel reliability ranking list is generated. According to the set bit rate, the bit positions whose Bhattacharyya parameter values ​​are lower than the first preset threshold are selected from the sorted list as information bits, and the remaining positions are used as frozen bit sets; In the frozen bit set, a number of frozen bits with Bhattacharyya parameter values ​​higher than a second preset threshold are selected as embedding positions of the synchronization identification sequence, and are evenly distributed in the codeword in a fixed interval manner; The bit value of the preset synchronization identification sequence is embedded into the embedding position, so that the part of frozen bits has a synchronization auxiliary function but does not carry valid information.

4. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The symbol stability change trends include: The receiving end continuously monitors the decoded values ​​of the frozen bits in the decoding path and, within each sliding window, counts the symbol consistency changes of the frozen bit positions in the path list within the window range. If the consistency of frozen bit symbols in a sliding window decreases significantly, which is manifested as significant inconsistency in the decoding values ​​of most frozen bits between candidate paths, and this phenomenon continues to exceed the set amplitude threshold, the starting position of the current window is determined to be the synchronization candidate starting point.

5. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The mutation behavior of the path metric value includes: During the decoding process, the path metric change trend of each candidate path is continuously monitored. When the average path metric value in the path set corresponding to the current moment changes by more than the set change threshold relative to the previous moment, or when the number of retained valid paths decreases by more than the set ratio in a single bit decision during the path expansion process, the position corresponding to the decoding moment is determined as a synchronization candidate starting position.

6. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The consistency comparison comprises the following steps: For each candidate starting position, perform partial path decoding of the polar code to obtain the restored value of the frozen bits in the current path. Compare the frozen bit restoration value with the synchronization identification sequence embedded by the transmitter bit by bit, and calculate the Hamming distance between them as the consistency score; The smaller the Hamming distance is, the higher the matching degree is, and the more likely the corresponding candidate starting position is to be the true synchronization starting point.

7. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The synchronization confidence function includes: It is constructed by fusing two types of information: path metric information and frozen bit consistency score; Among them, the path metric information is used to reflect the overall confidence level of the decoding path and form a relative credibility ranking among different candidate paths; The consistency score is used to measure the consistency between the frozen bits and the preset synchronization identification sequence in the decoding path. The consistency score is obtained by performing restricted depth path decoding on each candidate synchronization start position. The above two types of information are integrated according to a preset weighting strategy to form a comprehensive scoring index for synchronization starting point determination; The comprehensive scoring result is used to sort multiple candidate synchronization start positions and select the position with the highest score as the final synchronization start point.

8. The self-synchronous decoding method based on polar codes according to claim 1, wherein: The complete polar code decoding process includes: Adopt SCL method and combine CRC to judge the correctness of multiple candidate decoding paths; The step of verifying the validity of the synchronization start point includes: after completing polar code list decoding at the selected synchronization start position, if there is at least one path in the decoding path set that passes the CRC check, confirming that the current synchronization start point is a valid synchronization point and outputting the corresponding decoding result; If all paths fail the CRC check, the current synchronization starting point is abandoned, and the next candidate synchronization position is selected in the order of synchronization confidence score, and the complete decoding and verification process is performed again; When all candidate synchronization positions fail the CRC check, it is determined that the current data block synchronization has failed and the system waits for the next identifiable synchronization block.

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