Symbol Mapping by Bit Reliability for Lower Block Error Rates
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Solution Overview
Problem
Conventional symbol mapping methods degrade receiving performance by failing to distinguish and utilize the reliability differences between information bits and redundancy bits in binary bit streams, particularly in modulation techniques like 16 QAM and 64 QAM.
Innovation Solution
A symbol mapping method and apparatus that interleaves information bits and redundancy bits based on their log likelihood ratio (LLR) values, allowing for differential reliability mapping, utilizing an encoder, first and second interleavers, and a symbol mapper to allocate bits according to their reliability, thereby enhancing the reliability of information bits over redundancy bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional symbol mapping is used without distinguishing bit reliability, then the mapping process is simple, but receiving performance degrades
Solution Approach 1:
The patent segments the binary bit stream into information bits and redundancy bits based on their different reliability characteristics (LLR values). This segmentation allows differential mapping where information bits are mapped to more reliable symbol positions and redundancy bits to less reliable positions, thereby improving overall receiving performance without requiring complex adaptive processing
Solution Approach 2:
The patent applies local quality by assigning different mapping qualities to different bit types. Information bits are mapped to symbol positions with higher reliability (better LLR characteristics) while redundancy bits are mapped to positions with lower reliability. This localized optimization of bit-to-symbol mapping improves receiving performance while maintaining a relatively simple mapping structure
2Reliability
If bits are mapped without considering LLR values, then the mapping operation is straightforward, but information reliability is not optimized
Solution Approach 1:
The patent performs preliminary action by calculating and storing LLR (log likelihood ratio) values for each bit position before the actual mapping operation. These pre-calculated reliability metrics are then used to guide the mapping of information bits and redundancy bits to appropriate symbol positions, optimizing information reliability while keeping the mapping operation itself relatively simple through lookup-based assignment
Data Source
AI summary
In a symbol mapping method, transmission data is encoded to generate information bits and redundancy bits. An average LLR value of bits on which the information bits are mapped is different from an average LLR value of bits on which the redundancy bits are mapped.