Polar Code Rate Matching with Threshold-Based Reliability Segmentation
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Solution Overview
Problem
The natural order-based rate matching scheme for polar codes causes changes in reliability order, leading to poor decoding performance and the formation of 'bad points' where SNR suddenly increases, affecting encoding efficiency.
Innovation Solution
A method to determine a threshold based on the length of the reliability sequence and encoded bit sequence, followed by dividing the sequence into first and second sub-sequences to identify information bits, using methods like puncturing or shortening, thereby maintaining reliability order and avoiding 'bad points'.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If natural order-based rate matching scheme is used, then implementation is simple, but decoding performance deteriorates due to reliability order change
Solution Approach 1:
The patent segments the bit sequence into information bits and frozen bits based on reliability sequences, and further divides them into subsets for different rate matching operations (puncturing, shortening, repetition). This segmentation allows maintaining reliability order while implementing rate matching, resolving the contradiction between simple implementation and good decoding performance.
2Ease of operation
If natural order-based rate matching is applied, then consecutive bits are easy to manage, but bad points are formed causing sudden SNR increase
Solution Approach 1:
The patent applies different rate matching operations (puncturing, shortening, repetition) to different subsets of bits based on their reliability characteristics. By locally optimizing the treatment of different bit subsets rather than applying uniform natural order matching, the method avoids forming bad points while maintaining ease of operation.
3Device complexity
If pre-stored reliability sequence is used with natural order rate matching, then construction is simple, but encoding performance deteriorates in some cases
Solution Approach 1:
The patent dynamically selects rate matching operations and determines bit subset assignments based on code length, information bit length, and reliability sequence characteristics. This dynamic adaptation allows the system to maintain simple construction while achieving good encoding performance across different scenarios, resolving the contradiction between construction simplicity and performance.
Data Source
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AI summary
This application provides a polar code encoding method and an apparatus, to reduce implementation complexity of encoding while ensuring encoding performance. The method includes: determining a threshold based on a length N of a first reliability sequence and a length M of an encoded bit sequence, where N is a positive integer power of 2, and M is a positive integer; determining a first sub-sequence and a second sub-sequence based on a rate matching method of the encoded bit sequence and the first reliability sequence; determining, based on the threshold, the first sub-sequence, the second sub-sequence, the rate matching method of the encoded bit sequence, and the first reliability sequence, K information bits corresponding to the encoded bit sequence, where K is a positive integer less than M; and performing polar encoding to obtain the encoded bit sequence.