Constellation Rearrangement for HARQ Bit Grouping
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Solution Overview
Problem
Existing bit grouping methods for high-order modulations in IEEE 802.16e and 802.16m standards, such as 16 QAM and 64 QAM, suffer from sub-optimal reliability and complexity, particularly when using Hybrid Automatic Repeat Request (HARQ), leading to performance degradation due to same-constellation mapping in re-transmissions.
Innovation Solution
A simple two-version constellation rearrangement method involving a 1-bit right circular shift for in-phase and quadrature components in a QAM scheme, allowing for efficient bit grouping and constellation re-arrangement, which can be implemented in a single permutation, thereby improving reliability and reducing implementation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the same constellation mapping is used for re-transmission in HARQ, then implementation is simple, but decoding performance degrades significantly due to low-reliability bit positions
Solution Approach 1:
The patent applies dynamics by making the constellation mapping adaptive rather than static. Different constellation mappings are selected based on the transmission attempt number, allowing the system to dynamically adjust bit-to-symbol mapping to optimize reliability for each re-transmission while maintaining manageable complexity through predefined mapping patterns.
Solution Approach 2:
The patent changes the mapping parameter between different transmission attempts. By varying which bits map to which constellation points based on the transmission attempt number, the system improves reliability by ensuring that bits are not consistently placed in low-reliability positions across re-transmissions, while the complexity remains controlled through systematic parameter variation.
2Reliability
If complex constellation re-arrangement schemes are used to improve reliability, then decoding performance improves, but implementation complexity increases
Solution Approach 1:
The patent uses dynamics by selecting from multiple predefined constellation mappings based on transmission attempt number. This approach improves bit reliability by adapting the mapping to each transmission context while controlling implementation complexity through the use of a finite set of predetermined mappings rather than arbitrary complex transformations.
Solution Approach 2:
The patent systematically changes mapping parameters between transmissions by selecting different constellation mappings based on the transmission attempt number. This parameter variation improves reliability by preventing consistent placement of bits in vulnerable positions, while the complexity is managed through systematic selection from predefined options rather than complex real-time optimization.
3Reliability
If traditional bit grouping methods are used for high-order modulations, then implementation is straightforward, but reliability is sub-optimal
Solution Approach 1:
The patent applies dynamics by adapting the bit grouping and constellation mapping based on the transmission attempt number. This dynamic approach improves reliability by optimizing the mapping for each re-transmission context while maintaining reasonable complexity through the use of systematic, predefined grouping patterns that vary with transmission state.
Solution Approach 2:
The patent changes the grouping and mapping parameters based on transmission attempt number, improving reliability by ensuring optimal bit-to-symbol mapping for each transmission context. The complexity is controlled through systematic parameter variation from a finite set of predefined patterns rather than requiring complex real-time optimization algorithms.
Data Source
AI summary
Methods and systems for subpacket generation using a convolutional turbo code in hybrid automatic repeat request re-transmissions that includes separating a codeword into subblocks of bits, interleaving the subblocks, and performing a permutation to group the bit streams and rearrange a symbol constellation such that bits are assigned to bit positions based on a number of re-transmissions.