Raptor-Like LDPC Base Graph Selection for Variable Code Rates
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Solution Overview
Problem
Raptor-like LDPC base graphs in 5G communications systems face challenges in ensuring encoding and decoding performance across a wide range of code lengths and code rates, lacking flexibility and efficiency in supporting both high and low code rates.
Innovation Solution
A data transmission method that allows a base station to select and indicate a target Raptor-like LDPC base graph from a set of base graphs based on current service requirements, such as latency or performance needs, to optimize encoding and decoding performance for varying code lengths and rates, enabling flexible code rate and length support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single Raptor-like LDPC base graph is used to support a wide range of code lengths and code rates, then the system can cover more scenarios, but the encoding and decoding performance cannot be ensured across different code block lengths and code rates
Solution Approach 1:
The patent divides the single base graph into multiple base graphs (first base graph and second base graph), each optimized for specific code rate ranges. The first base graph is used for code rates ≤ 1/3, while the second base graph is used for code rates > 1/3. This segmentation allows each base graph to be specialized for its intended range, ensuring optimal performance within each segment while collectively covering a wide range of code rates and lengths.
2Adaptability or versatility
If a single Raptor-like LDPC base graph is used to support both high code rates and low code rates, then the system can handle diverse traffic types, but the performance of both high-code-rate encoding/decoding and low-code-rate encoding/decoding cannot be ensured
Solution Approach 1:
The patent applies local quality by making different parts of the system (different base graphs) have different properties optimized for their specific function. The first base graph is specifically designed with properties optimal for low code rates (≤ 1/3), while the second base graph is designed with properties optimal for high code rates (> 1/3). This allows each base graph to have locally optimized quality for its intended code rate range, ensuring high performance for both high and low code rate scenarios.
3Adaptability or versatility
If multiple base graphs are used to provide code size and code rate flexibility, then the range of supported code rates and lengths is enhanced, but the complexity of selecting and managing base graphs increases
Solution Approach 1:
The patent uses parameter changes (specifically code rate thresholds) to automatically select the appropriate base graph. The selection is based on comparing the actual code rate against a predefined threshold (1/3). This simple parameter-based selection mechanism maintains low complexity while providing the flexibility of multiple base graphs, as the selection rule is straightforward and does not require complex management or decision-making processes.
Data Source
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AI summary
This application provides a data transmission method, a base station, and a terminal device. The method includes: determining, by a base station, a target base graph in N Raptor-like LDPC base graphs; and sending, by the base station, indication information to a terminal device, where the indication information is used to indicate the terminal device to use the target base graph to perform LDPC encoding and decoding. Based on the foregoing technical solution, the base station may determine a target base graph in a plurality of Raptor-like LDPC base graphs that may be used to perform LDPC encoding and decoding, and indicate the target base graph to the terminal device. Further, for one code rate or one code length, the base station may select different base graphs as required.