Polar-Code HARQ Retransmission Using Differently Encoded Bits
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Solution Overview
Problem
Existing polar code-based Hybrid Automatic Repeat Request (HARQ) schemes in wireless communication systems do not effectively improve channel polarization, leading to suboptimal error correction and increased re-transmission sessions due to inefficient information bit allocation and decoding processes.
Innovation Solution
A method and apparatus for performing HARQ using polar codes, where information bits are optimally allocated for both the first and second packets, and bits encoded differently are preferentially selected for re-transmission, reducing error likelihood and computation complexity by utilizing a processor with a first and second encoder for efficient bit allocation and re-transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polar code-based HARQ schemes are used, then implementation is simpler, but channel polarization is not improved and error correction is suboptimal
Solution Approach 1:
The encoding process is segmented into two distinct encoders: a first encoder for initial transmission and a second encoder for re-transmission. Each encoder processes different input bit configurations, allowing optimization of channel polarization for each transmission phase while maintaining manageable complexity through functional division.
Solution Approach 2:
The system dynamically switches between different encoding configurations based on transmission phase. The first encoder uses one polar code configuration for initial transmission, while the second encoder uses a different polar code configuration optimized for re-transmission, adapting the coding strategy to the specific needs of each transmission attempt.
2Productivity
If information bits are not optimally allocated, then encoding is simpler, but re-transmission sessions increase
Solution Approach 1:
The system performs preliminary optimization of information bit allocation before transmission. The first encoder and second encoder are pre-configured with optimized polar code constructions that maximize channel polarization, ensuring that the most important information bits are transmitted with the highest reliability in the initial transmission and subsequent re-transmissions.
3Reliability
If bits encoded differently are not preferentially selected for re-transmission, then selection process is simpler, but decoding error likelihood increases
Solution Approach 1:
The bit selection process for re-transmission applies local quality optimization by preferentially selecting specific bits from the second output bits based on their encoding characteristics. Bits that were encoded differently in the first transmission are identified and prioritized for re-transmission, ensuring that the most critical uncoded information is transmitted again with appropriate redundancy.
Data Source
AI summary
Provided are a method and an apparatus for performing a HARQ based on a polar code in a wireless communication system. The apparatus transmits multiple first output bits, which are generated from multiple first input bits, to a receiver. Upon receiving a retransmission request, the apparatus generates multiple second output bits from multiple second input bits. The apparatus selects multiple third output bits from among the multiple second output bits, and transmits the selected multiple third output bits to the receiver. Bits, which are encoded differently from the multiple first output bits among the multiple second output bits, are preferentially selected as the multiple third output bits.