Polar Code HARQ Retransmission Using XOR Re-Encoded Codewords
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Solution Overview
Problem
Conventional polar code retransmission methods using Hybrid Automatic Repeat reQuest (HARQ) technology result in relatively low retransmission performance due to the same polar code being transmitted again, which does not effectively improve decoding reliability.
Innovation Solution
The method involves encoding information bits of a first polar code to obtain a second polar code, performing modulo-2 addition with the first polar code to generate a third polar code, and sending the third code as a retransmitted word, where the first information bit set and index set are determined to create a distinct retransmitted code different from the initial transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same polar code is retransmitted using conventional HARQ technology, then the retransmission process is simple, but the decoding reliability does not improve effectively
Solution Approach 1:
The patent changes the parameter of the polar code by performing modulo-2 addition between the original polar code and a re-encoded version of the same information bits. This transforms the code parameters to create a new code word with different properties, specifically increasing the code distance, while still using the same information bits. This resolves the contradiction by improving decoding reliability through parameter transformation without requiring completely new encoding schemes.
Solution Approach 2:
The patent introduces dynamic re-encoding where the second polar code is generated by re-encoding the same information bits through the polar encoding process again. This dynamic generation of a variant code allows the system to adapt the code properties for retransmission, improving reliability while maintaining a manageable encoding complexity through the use of the same encoder structure.
2Reliability
If information bits are re-encoded to create a distinct retransmitted code, then the code distance increases and HARQ performance improves, but the encoding process becomes more complex
Solution Approach 1:
The patent merges two polar code words (the original and the re-encoded version) through modulo-2 addition to create a third polar code for retransmission. This combining operation leverages the properties of both code words to produce a result with enhanced code distance and improved HARQ performance, while the merging process itself can be efficiently implemented using existing XOR operations in the encoder.
3Reliability
If modulo-2 addition is performed on the first polar code and the second polar code, then the code distance of the retransmitted code increases, but the processing complexity increases
Solution Approach 1:
The patent replaces complex processing operations with a simple modulo-2 addition (XOR) operation to combine the first and second polar codes. This substitution of a potentially complex merging process with a fundamental bitwise operation achieves the goal of increasing code distance while minimizing the increase in processing complexity, as XOR operations are computationally efficient and can be implemented with simple logic gates.
Data Source
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.