NR LDPC Base Graph Switching for Short Code Block Avoidance
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Solution Overview
Problem
The existing proposal for selecting base graph #2 (BG2) for code rates just below 1/3 in 5G wireless communication systems results in poorer performance compared to base graph #1 (BG1) due to increased code block segmentation and shorter code block lengths, especially for transport block sizes greater than 3840.
Innovation Solution
Instead of always selecting BG2 for code rates less than 1/3, the method determines a threshold (R_threshold) between 1/5 and 1/3, and selects BG2 only if the code rate is below this threshold, otherwise choosing BG1, to optimize performance based on code rate and block length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If base graph #2 (BG2) is selected for code rates just below 1/3, then the code rate requirement is met, but performance deteriorates due to increased code block segmentation and shorter code block lengths
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the base graph selection based on code rate thresholds. Instead of fixed selection, the system changes the base graph parameter (BG1 or BG2) based on the calculated code rate, achieving optimal performance for different code rate ranges without excessive segmentation
Solution Approach 2:
The patent implements dynamic base graph selection where the choice between BG1 and BG2 is not static but adapts based on real-time code rate calculations. This dynamic approach allows the system to switch between different base graphs depending on the specific code rate requirement, avoiding the performance degradation associated with rigid segmentation rules
2Reliability
If base graph #2 (BG2) is used for transport block sizes greater than 3840, then the code rate can be maintained, but the code block length decreases leading to poorer performance
Solution Approach 1:
The patent changes the base graph parameter based on code rate and transport block size conditions. By monitoring these parameters and switching between BG1 and BG2 appropriately, the system maintains optimal code block lengths for different TBS values, preventing performance degradation from excessive segmentation
3Device complexity
If base graph #1 (BG1) is selected for higher code rates, then code block segmentation is reduced, but the code rate capability is limited
Solution Approach 1:
The patent implements multi-functionality by making both BG1 and BG2 available in the system, with selection based on code rate requirements. This universal approach allows the system to handle both lower code rates (where BG2 excels) and higher code rates (where BG1 performs better), achieving versatility across different operational conditions
Solution Approach 2:
The system dynamically selects between BG1 and BG2 based on code rate thresholds, allowing it to adapt to different code rate requirements. This dynamic selection optimizes the balance between segmentation overhead and code rate capability, using BG1 when lower segmentation is needed and BG2 when lower code rates are required
Data Source
AI summary
According to some embodiments, a method for use in a wireless transmitter of encoding a transport block comprises, upon determining a code rate for transmitting a transport block is less than or equal to R_threshold (R_threshold is between ⅕ and ⅓), selecting new radio (NR) low-density parity-check (LDPC) base graph 2 for encoding the transport block. Otherwise, the method comprises selecting NR LDPC base graph 1 for encoding the transport block, unless a transport block size (TBS) of the transport block is less than or equal to a size threshold (X) and a code rate for transmitting the transport block is less than or equal to ⅔, in which case the method may comprise selecting base graph 2. The method further comprises encoding the transport block using the selected base graph and transmitting the encoded transport block to a wireless receiver.