QC-LDPC Low Code Rates for Low-SNR Long-Distance Links
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Solution Overview
Problem
Current channel coding technologies, such as those used in the 802.11n standard for WiFi, lack LDPC codes with low code rates (e.g., 1/6, 1/4, 1/3), which are necessary for low signal-to-noise ratio and long-distance transmission environments.
Innovation Solution
The development of QC-LDPC codes with code rates of 1/6, 1/4, and 1/3, which can be multiplexed with existing LDPC codes of higher code rates, enabling their use in various communication systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC codes with higher code rates (e.g., 1/2, 2/3, 3/4, 5/6) are used as in the 802.11n standard, then device complexity is reduced by leveraging existing hardware infrastructure, but reliability deteriorates in low signal-to-noise ratio and long-distance transmission environments
Solution Approach 1:
The patent creates a universal LDPC coding system where a single hardware infrastructure can support multiple code rates (1/6, 1/4, 1/3, 1/2, 2/3, 3/4, 5/6) through configurable generating matrices and check matrices. This allows the same physical device to adapt to different transmission conditions without requiring separate hardware for each code rate, thus improving reliability in low SNR environments while maintaining device complexity at acceptable levels through multi-functionality.
2Reliability
If new LDPC codes with low code rates (1/6, 1/4, 1/3) are developed, then reliability improves for low signal-to-noise ratio transmission, but device complexity increases due to additional coding structures
Solution Approach 1:
The patent merges the implementation of multiple LDPC code rates into a unified system by defining standardized generating matrices and check matrices for code rates 1/6, 1/4, and 1/3 that can be integrated with existing 802.11n hardware. The merging approach allows low code rate options to be added to the existing code rate set (1/2, 2/3, 3/4, 5/6) without creating entirely separate coding systems, thus improving reliability while controlling the increase in device complexity through consolidation.
Solution Approach 2:
The patent introduces dynamic selection capability where the system can choose appropriate code rates (1/6, 1/4, 1/3, 1/2, 2/3, 3/4, 5/6) based on transmission conditions such as signal-to-noise ratio and distance. This dynamic adaptation allows the system to use lower code rates (higher redundancy) when reliability is critical in poor conditions, while switching to higher code rates when conditions are favorable, thus improving overall reliability without permanently increasing device complexity.
3Reliability
If channel coding with higher redundancy is implemented, then reliability improves for long-distance transmission, but productivity decreases due to increased processing overhead
Solution Approach 1:
The patent implements dynamic code rate selection where the system can adaptively choose between code rates 1/6, 1/4, 1/3, 1/2, 2/3, 3/4, and 5/6 based on channel conditions. When transmission reliability is critical (low SNR, long distance), the system selects lower code rates with higher redundancy. When channel conditions are good, it selects higher code rates with less redundancy, thus maintaining productivity. This dynamic adjustment resolves the contradiction by making redundancy variable rather than fixed.
Solution Approach 2:
The patent changes the redundancy parameter (code rate) as a variable that can be adjusted according to transmission requirements. By defining standardized generating matrices and check matrices for multiple code rates including 1/6, 1/4, and 1/3, the system can modify the redundancy level without changing the underlying hardware architecture. This parameter change approach allows the system to increase reliability through higher redundancy when needed while maintaining productivity by using lower redundancy when conditions permit.
Data Source
AI summary
There are provided a channel coding method, a processing device, a communication method and a device. The channel coding method includes: using a generating matrix or a check matrix of QC-LDPC codes to channel-encode or channel-decode a code stream, wherein a code rate of the generating matrix or the check matrix is 1/6, 1/4 or 1/3. The method can be used in a transmission environment with a low signal-noise ratio and a long distance.