Polar Code HARQ Retransmission with Segmented Bit Re-Encoding
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Solution Overview
Problem
Conventional polar code retransmission methods in HARQ systems exhibit low retransmission performance due to the same encoding process being used for both initial and retransmitted data, leading to suboptimal decoding and reliability issues.
Innovation Solution
The method involves determining specific information bit sets and indices for a polar code transmitted for the first time, followed by modulo-2 addition to generate a distinct third polar code for retransmission, enhancing the code distance and retransmission performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same encoding process is used for both initial and retransmitted polar codes, then the encoding complexity is low and the process is simple, but the retransmission performance is poor and reliability is reduced
Solution Approach 1:
The information bit set A is segmented into two parts: the first K1 information bits remain unchanged between initial transmission and retransmission, while the second K2 information bits are updated for retransmission. This segmentation allows the retransmitted code to differ from the initial code, improving reliability without requiring complete re-encoding of all bits.
Solution Approach 2:
The encoder pre-determines the first K1 information bits that will be used in both initial transmission and retransmission. This preliminary selection of common information bits enables the system to quickly generate retransmission codes by only updating the remaining K2 bits, rather than performing full re-encoding.
2Reliability
If conventional chase combining HARQ is used, then the implementation is simple, but the decoding reliability is insufficient and frame error rates are high
Solution Approach 1:
The encoding parameters are made dynamic based on transmission status. For initial transmission, all K information bits are encoded. For retransmission, only the updated K2 information bits are encoded and combined with the previously transmitted K1 bits. This dynamic approach adapts the encoding process to the specific retransmission scenario, improving decoding reliability.
Solution Approach 2:
The retransmitted polar code is generated by merging the first K1 information bits (shared between initial and retransmission) with the updated K2 information bits. This combining approach allows the receiver to accumulate information from both transmissions, improving decoding reliability through incremental redundancy.
Data Source
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AI summary
The present invention relates to the field of communications network technologies, and discloses a polar code retransmission method and apparatus, which can improve HARQ performance. In embodiments of the present invention, some information bits of a first polar code are encoded to obtain a second polar code, where the first polar code is a code word that is transmitted for the first time; modulo-2 addition is performed on the first polar code and the second polar code to obtain a third polar code; and the third polar code is sent as a to-be-retransmitted code word. The solutions provided in the embodiments of the present invention are applicable when a polar code is retransmitted.