Subband Constellation Shaping for Frequency-Selective Fading
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Solution Overview
Problem
Existing wireless communication systems do not effectively consider frequency selective fading channels in constellation shaping, leading to inefficiencies in resource utilization and communication reliability.
Innovation Solution
Implement subband level constellation shaping by using multiple distribution matchers, where each subband index is associated with a specific encoding parameter set, allowing for tailored modulation orders and distribution matcher parameters to enhance communication efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single distribution matcher is used for constellation shaping, then device complexity is reduced, but spectral efficiency and communication reliability deteriorate due to inability to adapt to frequency selective fading channels
Solution Approach 1:
The patent divides the frequency band into multiple subbands and applies separate distribution matchers to each subband. This segmentation allows the system to handle frequency selective fading differently across subbands, improving communication reliability while maintaining manageable complexity through modular processing.
Solution Approach 2:
The patent introduces dynamic adaptation by selecting different distribution matcher parameters (such as shaping modulus and constellation size) based on channel conditions for each subband. This dynamic parameter selection enables the system to optimize performance for varying frequency selective fading conditions.
2Productivity
If multiple distribution matchers with different parameters are applied to different subbands, then spectral efficiency improves through adaptive modulation, but device complexity increases due to multiple encoding parameter sets
Solution Approach 1:
The patent applies different encoding parameters (modulation order, coding rate, distribution matcher parameters) to different subbands based on their specific channel conditions. This local optimization allows each subband to use parameters best suited to its characteristics, maximizing spectral efficiency while the patent manages complexity through systematic parameter selection.
Solution Approach 2:
The patent changes key parameters including modulation order, coding rate, and distribution matcher parameters across different subbands. By systematically varying these parameters based on channel quality, the system achieves higher spectral efficiency while maintaining tractable complexity through structured parameter management.
3Productivity
If higher modulation orders are used to improve data rate, then productivity increases, but reliability decreases due to greater susceptibility to channel fading
Solution Approach 1:
The patent dynamically adjusts modulation order based on channel conditions in each subband. In subbands with good channel quality, higher modulation orders are used to increase data rate, while in subbands with poor quality, lower modulation orders with more robust coding are applied to maintain reliability. This dynamic adaptation resolves the trade-off between productivity and reliability.
Solution Approach 2:
The patent simultaneously changes modulation order and coding rate parameters across subbands. By coordinating these parameter changes, the system achieves higher overall data rates while maintaining acceptable error rates through adaptive error correction capability in each subband.
Data Source
AI summary
Methods, systems, and devices for wireless communication at a user equipment (UE) are described. A user equipment (UE) may receive a configuration indicating a mapping between a set of multiple subband indices and a set of multiple encoding parameter sets. The UE may apply, at a first distribution matcher, a first encoding parameter set to a first subset of a bit stream. The UE may also apply, at a second distribution matcher, a second encoding parameter set to a second subset of the bit stream. The a first encoding parameter set may be associated with a first subband index and the second encoding parameter set may be associated with a second subband index. The UE may then transmit a first modulated bit stream on a first subband, and a second modulated bit stream on a second subband.