LDPC Puncturing Scheme for Filling 802.11ax MCS Gaps
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Solution Overview
Problem
The IEEE 802.11ax standard for wireless local area networks (WLANs) experiences significant performance gaps between adjacent coding levels due to limited code rates, leading to suboptimal channel capacity utilization.
Innovation Solution
A method and system for encoding data using punctured low-density parity-check (LDPC) codes, which involves forming unpunctured codewords, removing punctured bits to create punctured codewords, and transmitting them based on thresholds, thereby reducing gaps between coding levels by introducing additional Modulation and Coding Scheme (MCS) levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fixed code rates are used in IEEE 802.11ax, then implementation is simple, but performance gaps between adjacent coding levels are significant
Solution Approach 1:
The patent implements dynamic code rates by combining a base code rate with puncturing ratios. Instead of using fixed discrete code rates, the system dynamically adjusts the effective code rate by selectively removing (puncturing) parity bits from the encoded stream. This creates a continuous spectrum of code rates between the base rate and higher rates, eliminating performance gaps while maintaining adaptability to channel conditions.
Solution Approach 2:
The patent changes the code rate parameter continuously by varying the puncturing ratio. By controlling what fraction of parity bits are removed (punctured), the system can achieve any code rate within a range, transforming the discrete parameter selection into a continuous adjustment mechanism that fills performance gaps between traditional coding levels.
2Productivity
If punctured bits are removed to increase code rate, then channel capacity utilization improves, but error correction capability deteriorates
Solution Approach 1:
The patent applies partial puncturing where only a portion of the parity bits are removed rather than all or none. By controlling the puncturing ratio to be partial (between 0 and 100%), the system achieves intermediate code rates that balance spectral efficiency gains with sufficient error correction capability remaining in the transmitted bits.
Solution Approach 2:
The system dynamically adjusts the puncturing level based on channel conditions. When channel quality is good, more bits can be punctured to increase spectral efficiency. When channel quality degrades, fewer bits are punctured to maintain error correction capability, creating a dynamic balance between the two competing objectives.
Data Source
AI summary
A method for encoding or transmitting. In some embodiments, the method includes forming a set of one or more unpunctured codewords by coding a plurality of payload bits at a mother code rate, removing a plurality of punctured bits from the set of one or more unpunctured codewords to form a set of one or more punctured codewords, and transmitting the set of one or more punctured codewords. In some embodiments, the number of punctured bits exceeds a first threshold, or the number of punctured bits exceeds a second threshold.