Polar Code Check-Bit Placement for More Accurate List Decoding
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Solution Overview
Problem
The decoding performance of Polar codes is poor when the code length is small or medium, leading to decreased user experience due to suboptimal decoding quality in existing communication systems.
Innovation Solution
An encoding method that adjusts the position of check bits within the information bits based on a sorting value, followed by a second-level encoding process, and a decoding method that decodes the adjusted encoded code word to output survivor paths, improving decoding performance and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If SC decoding method is used for Polar codes, then encoding complexity is low and Shannon capacity is achieved, but decoding performance is poor when code length N is small or medium
Solution Approach 1:
The patent segments the decoding process into multiple stages: initial SC decoding to generate candidate paths, followed by CRC verification to filter valid paths, and iterative refinement. This segmentation allows the system to maintain low encoding complexity while improving decoding performance through structured multi-stage processing.
Solution Approach 2:
The patent performs preliminary CRC check on the transmitted code word before full decoding. This preliminary action identifies likely error-free code words early in the process, allowing the decoder to focus computational resources on verifying and refining candidate paths rather than processing all possibilities equally.
2Ease of manufacture
If check bits are appended at the end of information bits, then encoding is simple, but decoding accuracy is reduced for small or medium code lengths
Solution Approach 1:
The patent performs preliminary CRC verification on candidate paths during the decoding process. By checking CRC validity at intermediate stages rather than only at the end, the system can eliminate invalid paths early, improving decoding accuracy without significantly complicating the encoding process.
Solution Approach 2:
The patent implements feedback mechanisms where CRC check results from candidate paths are used to guide subsequent decoding iterations. Valid paths identified through CRC feedback are prioritized for further processing, while invalid paths are discarded, creating a feedback-driven refinement process that improves accuracy.
3Loss of information
If all survivor paths are processed through full decoding, then decoding completeness is maintained, but computational resources are wasted on invalid paths
Solution Approach 1:
The patent extracts and verifies candidate paths using CRC checks before committing to full decoding processing. By separating the verification step from the full decoding process, the system can identify and discard invalid paths early, extracting only the necessary information to determine path validity without performing complete decoding on all candidates.
Solution Approach 2:
The patent discards invalid survivor paths that fail CRC verification, preventing waste of computational resources on further processing of these paths. The system recovers and continues processing only with valid paths that pass the CRC check, maintaining decoding completeness for valid candidates while eliminating unnecessary computation for invalid ones.
Data Source
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AI summary
Embodiments of the present invention provide an encoding/decoding method, apparatus, and system, and relate to the communications field. The present invention may improve decoding performance and improve accuracy of a survivor path. The method includes: encoding information bits according to a first-level encoding method to obtain a first-level encoded code word; obtaining a sorting value of each check bit of the first-level encoded code word, and adjusting each check bit to a corresponding position according to the sorting value of each check bit, where the sorting value refers to a value of S when the check bit is related to first S information bits of the information bits in the first-level encoded code word, and S is a non-zero integer; and performing, according to a second-level encoding method, second-level encoding on the first-level encoded code word after positions of the check bits are adjusted, thereby obtaining a second-level encoded code word. The present invention is applicable to various communication systems.