Polar Code Bit Reduction With Partial Interleaving for IR-HARQ
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Solution Overview
Problem
Conventional polar codes lack sufficient flexibility for fine-grained adaptation to varying channel conditions, particularly in supporting advanced communication features like IR-HARQ, due to limitations in rate matching and bit assignment.
Innovation Solution
Implementing partially interleaved encoded bit reduction and adaptive bit assignment in polar coding, involving a subset of bit indices for encoding and decoding, to reduce the number of encoded bits while maintaining performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional polar codes are used with traditional rate matching, then the coding structure is simple and easy to implement, but the flexibility for fine-grained adaptation to channel conditions is insufficient
Solution Approach 1:
The patent segments the polar code structure by dividing the N encoded bits into multiple subsets, where each subset corresponds to a specific subset of bit indices. This segmentation enables selective rate matching on different subsets independently, providing fine-grained adaptation to channel conditions while maintaining the overall polar code framework. The segmented approach allows the system to apply different rate matching patterns to different subsets based on channel quality requirements.
Solution Approach 2:
The patent introduces dynamic adaptability by enabling the system to flexibly select which subsets of encoded bits to transmit based on varying channel conditions. The rate matching parameters and subset selections can be dynamically adjusted according to channel quality measurements, allowing the coding scheme to adapt in real-time without changing the fundamental polar code structure. This dynamic behavior provides the needed flexibility while keeping the base structure intact.
2Reliability
If all encoded bits are transmitted, then the error correction performance is maximized, but the number of transmitted bits is large reducing spectral efficiency
Solution Approach 1:
The patent extracts and transmits only the most essential encoded bits by selecting specific subsets of bit indices for transmission. Instead of transmitting all N encoded bits, the system identifies and transmits only the critical subsets that provide the necessary error correction performance for the given channel conditions. This extraction approach reduces the number of transmitted bits while maintaining adequate reliability through selective subset transmission.
Solution Approach 2:
The patent changes the transmission parameter from fixed full-rate transmission to variable-rate transmission by adjusting which subsets of encoded bits are transmitted. The system can dynamically modify the set of transmitted bit indices based on channel conditions, effectively changing the code rate and number of transmitted bits while maintaining the polar code structure. This parameter adjustment enables optimization of the trade-off between reliability and spectral efficiency.
3Productivity
If rate matching is applied to reduce encoded bits, then spectral efficiency improves, but the flexibility for advanced features like IR-HARQ is insufficient
Solution Approach 1:
The patent creates a universal rate matching framework that serves multiple functions simultaneously. The same subset-based rate matching mechanism supports both basic spectral efficiency optimization and advanced features like incremental redundancy HARQ. By defining rate matching in terms of flexible subset selections, the system can achieve simple rate adaptation for spectral efficiency while also enabling complex HARQ operations by selectively transmitting different subsets across retransmissions. This multi-functional approach eliminates the need for separate mechanisms for different features.
Data Source
AI summary
Polar codes for wireless communications are constructed to adapt to channel conditions. Input bits are encoded by a polar code to obtain a number of encoded bits, and a reduced number of the encoded bits are decoded to obtain decoded input bits. The polar code provides or includes bit indices for bit values, and the bit indices include a first set of bit indices for values of the input bits and a second set of bit indices for a predetermined bit value. Encoded bits in a subset, which includes fewer than all of the encoded bits and is for reducing the number of the encoded bits, are interleaved.