Polar Code Retransmission Using Self-Decodable 2N Redundancy
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Solution Overview
Problem
Wireless communication systems face challenges in ensuring reliable data transmission due to degraded channel conditions and increased interference, where existing coding schemes and hybrid automatic repeat request (HARQ) operations may fail to successfully decode polar encoded data.
Innovation Solution
The implementation of enhanced polar HARQ operation techniques, which involve encoding information bits using a first polar code of size N and generating a second set of encoded bits using a larger polar code of size 2N, with the transmitting device copying information bits to polarized bit channels based on reliability, to ensure self-decodable retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a first polar code of size N is used for encoding, then the transmission speed is maintained, but the decoding reliability deteriorates under degraded channel conditions
Solution Approach 1:
The patent segments the encoding process into two stages: first encoding with a polar code of size N for initial transmission, then encoding with a larger polar code of size 2N for retransmission. This segmentation allows the system to adapt to channel conditions by using different code sizes for different transmission attempts, improving decoding reliability when initial transmissions fail.
Solution Approach 2:
The patent implements dynamic code size adaptation where the encoder switches from a smaller polar code (size N) to a larger polar code (size 2N) based on decoding feedback. This dynamic adjustment allows the system to optimize between transmission efficiency and decoding reliability in real-time according to channel conditions.
2Reliability
If a larger polar code of size 2N is used for retransmission, then the decoding reliability improves, but the transmission overhead increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the bit index sets for both the first polar code (size N) and the second polar code (size 2N) before transmission. This allows the system to quickly switch between code sizes without performing complex calculations during retransmission, reducing the overhead associated with code switching.
Solution Approach 2:
The patent uses copying by reusing the encoded bits from the first polar code transmission in the second polar code transmission. The encoded bits from the first transmission are copied and integrated into the second transmission, reducing the amount of new data that needs to be transmitted while still providing the benefits of the larger code size.
3Ease of operation
If information bits are copied to polarized bit channels based on reliability, then the self-decodability is improved, but the processing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-determining and storing the bit index sets that map information bits to polarized bit channels for both code sizes before transmission. This pre-computation eliminates the need for complex real-time calculations during encoding and decoding operations, reducing processing complexity while maintaining self-decodability.
Solution Approach 2:
The patent changes the parameter of bit channel reliability by selecting different bit index sets based on the code size being used. For the first polar code (size N), one bit index set is used, while for the second polar code (size 2N), a different bit index set is used. This parameter change allows the system to optimize the mapping of information bits to channels based on the specific code being used, improving self-decodability without requiring complex dynamic adjustments.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting device, such as a base station or a user equipment (UE), may generate a first set of encoded bits using a polar code. The transmitting device may transmit the first set of encoded bits to a receiving device, but the receiving device may unsuccessfully receive the transmission. The transmitting device may prepare a retransmission by generating a second set of encoded bits. In some cases, the transmitting device may copy information bits from the first transmission to polarized channels when generating the polar code for the retransmission. The transmitting device may copy information bits based on how the information bits were assigned for the first transmission as well as the block length. The transmitting device may copy information bits such that the retransmission is self-decodable.