Polar Mother Code Length Selection for Low-Complexity Rate Matching
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Solution Overview
Problem
Existing polar coding methods face challenges in balancing encoding gain and complexity, particularly in rate matching processes where large mother code lengths increase complexity and decrease performance, while smaller code lengths result in higher encoding gains but lower complexity, necessitating a method to efficiently adjust code lengths and reduce overheads.
Innovation Solution
The proposed method involves determining a mother code length that is an integer power of 2, either less than or equal to the target code length, and using repetition or puncturing to achieve the target code length, with a preset condition-based approach to select between repetition-based and shortening/puncturing-based rate matching, thereby balancing encoding gain and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large mother code length is used to achieve the target code length, then the encoding gain is improved, but the complexity of encoding and decoding increases and buffer size requirements increase
Solution Approach 1:
The patent segments the rate matching process into two distinct approaches: repetition for low code rates and puncturing for high code rates. This segmentation allows the system to optimize complexity by selecting the appropriate method based on code rate, avoiding the need to always use large mother code lengths with puncturing.
Solution Approach 2:
The patent changes the parameter of mother code length selection based on code rate. By dynamically adjusting whether to use repetition or puncturing based on the code rate threshold, the system optimizes the balance between encoding gain and complexity without being constrained to fixed mother code lengths.
2Reliability
If a large mother code length is used to achieve the target code length, then the encoding gain is improved, but the buffer size requirements increase
Solution Approach 1:
The patent segments the rate matching process into two distinct approaches: repetition for low code rates and puncturing for high code rates. This segmentation allows the system to optimize complexity by selecting the appropriate method based on code rate, avoiding the need to always use large mother code lengths with puncturing.
Solution Approach 2:
Instead of always using puncturing with large mother code lengths, the patent inverts the approach for low code rates by using repetition with smaller mother code lengths. This inversion reduces buffer size requirements while maintaining encoding gain through the alternative mechanism of repeating coded bits.
3Adaptability or versatility
If rate matching by puncturing is applied to achieve target code length, then the code length is adjusted, but the overheads increase and complexity increases
Solution Approach 1:
The patent introduces dynamic selection between repetition and puncturing methods based on code rate. This dynamic approach allows the system to adapt to different code rates optimally, using repetition for low code rates to avoid the overhead and complexity associated with puncturing, while maintaining the ability to adjust code length.
Solution Approach 2:
The patent changes the parameter of mother code length selection based on code rate. By dynamically adjusting whether to use repetition or puncturing based on the code rate threshold, the system optimizes the balance between encoding gain and complexity without being constrained to fixed mother code lengths.
4Device complexity
If repetition is used to achieve the target code length, then the complexity is reduced, but the encoding gain may be compromised
Solution Approach 1:
The patent applies different quality characteristics to different code rate regions: repetition is applied locally to low code rate scenarios where simplicity is prioritized, while puncturing is applied locally to high code rate scenarios where encoding gain is prioritized. This local quality approach ensures optimal performance for each operating condition.
Solution Approach 2:
The patent changes the parameter of mother code length selection based on code rate. By dynamically adjusting whether to use repetition or puncturing based on the code rate threshold, the system optimizes the balance between encoding gain and complexity without being constrained to fixed mother code lengths.
Data Source
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AI summary
Embodiments of this application provide a rate matching method, an encoding apparatus, a decoding apparatus, and a communication apparatus. The method includes: obtaining an information bit sequence and a target code length M of a polar code; and when the target code length M meets a preset condition, using a polar code with a first mother code length N1 to encode the information bit sequence, to output a first encoded bit sequence, where N1 is less than or equal to M, and N1 is an integer power of 2, and repeating at least some bits in the first encoded bit sequence, to obtain a first target polar code with a length M; or when the target code length M does not meet the preset condition, using a polar code with a second mother code length N2 to encode the information bit sequence, to output a second encoded bit sequence, where N2 is greater than or equal to M, and N2 is an integer power of 2, and shortening or puncturing the second encoded bit sequence, to obtain a second target polar code with a length M. When an encoding gain loss is quite low, a repetition-based rate matching manner is used, to reduce encoding and decoding complexity.