Symbol Mapping Scheme for HARQ Bit Reliability
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Solution Overview
Problem
Current symbol mapping methods in wireless communication systems, such as those using 16-QAM and 64-QAM, fail to distinguish reliability differences between information bits and redundancy bits, leading to high block error rates (BLER) due to uniform bit reliability mapping, which is exacerbated by retransmission schemes like HARQ.
Innovation Solution
A symbol mapping method and apparatus that employs different mapping schemes for initial and retransmission, where information bits and redundancy bits are mapped based on their respective reliability levels, with the second mapping scheme differing from the first to prioritize high-reliability bits during retransmissions, thereby enhancing bit reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same symbol mapping scheme is used for both initial transmission and retransmission, then the mapping process is simple and consistent, but the block error rate remains high because reliability differences between bits are not addressed
Solution Approach 1:
The patent applies dynamics by making the mapping scheme adaptive rather than static. The system dynamically selects between first and second mapping schemes based on transmission type (initial or retransmission), allowing the mapping configuration to change according to operational conditions. This enables the system to optimize bit reliability for each transmission scenario without requiring a completely complex new system.
Solution Approach 2:
The patent changes mapping parameters (which specific bits are mapped to which symbol positions) based on transmission type. For initial transmission, one mapping scheme is applied, while for retransmission, a different mapping scheme is used. This parameter change allows the system to address reliability differences between information bits and redundancy bits in different transmission contexts, thereby reducing block error rate without fundamental system redesign.
2Reliability
If different mapping schemes are used for initial transmission and retransmission, then bit reliability is improved by addressing reliability differences, but the system complexity increases
Solution Approach 1:
The patent segments the transmission process into distinct phases (initial transmission and retransmission) and applies different mapping schemes to each segment. This segmentation allows the system to optimize for bit reliability in each phase independently - using appropriate mapping configurations for information bits during initial transmission and for redundancy bits during retransmission - without requiring the entire system to be redesigned for each scenario.
Solution Approach 2:
The system performs preliminary classification of transmission types before applying mapping schemes. By determining whether a transmission is initial or retransmission beforehand, the system can pre-select the appropriate mapping scheme, avoiding complex real-time decisions and simplifying the overall system architecture while still achieving improved bit reliability through differentiated mapping.
3Reliability
If reliability differentiation is not applied in symbol mapping, then the mapping process is straightforward, but the block error rate is high due to uniform treatment of all bits
Solution Approach 1:
The patent applies local quality by treating different bits differently based on their reliability characteristics. Instead of uniformly mapping all bits, the system identifies which bits have higher reliability requirements (information bits vs. redundancy bits) and applies appropriate mapping strategies locally - such as mapping information bits to more reliable symbol positions during initial transmission and redundancy bits to reliable positions during retransmission. This localized differentiation reduces block error rate without requiring complete system complexity.
Data Source
AI summary
In a symbol mapping method, transmission data is encoded to output information bits and redundancy bits. The information bits and the redundancy bits are mapped to a symbol according to a first mapping scheme at a first transmission, and the information bits and the redundancy bits are mapped to a symbol according to a second mapping scheme at a second transmission.