Polar Code Rate Reduction for Fine-Grained IR-HARQ Adaptation
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Solution Overview
Problem
Existing channel coding methods, particularly polar codes, lack the flexibility to adapt code length and rate in a fine-grained manner to effectively handle varying channel conditions, limiting their performance in advanced communication scenarios like IR-HARQ.
Innovation Solution
Implement partial code rate reduction techniques, including adaptive and piece-wise approaches, using an implicit reliability sequence-based method to allocate information bits and reduce the number of encoded bits, while maintaining flexibility and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polar codes use conventional rate matching techniques (puncturing and shortening), then code rate can be adjusted, but the flexibility is not enough to support fine-grained incremental-redundancy hybrid automatic repeat request (IR-HARQ)
Solution Approach 1:
The code is divided into multiple segments, each with its own code rate. This segmentation allows independent adjustment of code rates for different segments, enabling fine-grained control for IR-HARQ while maintaining the overall coding structure. The patent applies this by dividing the polar code into segments that can be selectively punctured or shortened based on channel conditions and HARQ requirements.
Solution Approach 2:
The code rate for each segment can be dynamically adjusted based on channel conditions and HARQ feedback. This dynamic adaptability allows the system to optimize performance for varying channel conditions while supporting fine-grained IR-HARQ operations. The patent implements this through configurable code rates for different segments that can be adapted in real-time.
2Reliability
If polar codes are designed to adapt to channel conditions with fine-grained flexibility, then error correction performance improves, but the inherent coding structure may be compromised
Solution Approach 1:
Different segments of the code are assigned different code rates and puncturing patterns based on their specific requirements. This local optimization allows each segment to be tailored for optimal error correction performance while maintaining overall code adaptability. The patent applies this by assigning different code rates to different segments based on channel conditions and information bit importance.
Solution Approach 2:
The code rate, code length, and puncturing patterns are changed as parameters to adapt to different channel conditions. This parameter-based approach allows flexible adaptation without compromising the fundamental polar code structure. The patent implements this by varying code rate parameters across segments and using configurable puncturing patterns to achieve fine-grained adaptability.
3Ease of manufacture
If conventional rate matching is used for polar codes, then implementation is straightforward, but code construction latency is not reduced
Solution Approach 1:
Puncturing patterns and code rate configurations are pre-calculated and stored for different channel conditions and code rates. This preliminary preparation eliminates the need for complex real-time calculations during code construction, reducing latency while maintaining implementation simplicity. The patent applies this by pre-computing puncturing patterns for various scenarios and storing them for quick retrieval during encoding.
Solution Approach 2:
Instead of calculating optimal puncturing patterns for all possible conditions, the patent uses a subset of pre-defined patterns that cover the most common scenarios. This partial approach reduces complexity and latency while providing sufficient adaptability for practical applications. The patent implements this by selecting and pre-storing only the most frequently needed puncturing patterns rather than all possible configurations.
Data Source
AI summary
Polar codes for wireless communications are constructed to adapt to channel conditions. The polar code construction includes a partial code rate reduction. Input bits are encoded by a polar code to obtain a number of encoded bits, and the number of the encoded bits on bit indices in a first segment of encoded bit indices of the encoded bits is reduced. The polar code includes or provides a first set of bit indices for values of the input bits, a second set of bit indices for a predetermined bit value, and a third set of bit indices corresponding to the first segment of encoded bit indices. The second set and the third set of bit indices include a first bit index on which the predetermined bit value is placed to reduce a code rate of the first segment.