NR Code Block Segmentation With Dynamic LDPC Base Graph Selection
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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 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 transport block size and code rate conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If base graph #2 (BG2) is selected for code rates just below 1/3, then the code rate requirement is met, but the performance deteriorates due to increased code block segmentation and shorter block lengths
Solution Approach 1:
The patent introduces a threshold parameter R_threshold (between 1/5 and 1/3) that dynamically determines base graph selection. When code rate R is below R_threshold, BG2 is selected; otherwise BG1 is selected. This parameter-based decision mechanism resolves the contradiction by adapting the base graph choice to the specific code rate condition, ensuring optimal performance across different operating points.
Solution Approach 2:
The base graph selection is made dynamic rather than static. The system transitions from a fixed rule (always use BG2 for R<1/3) to a dynamic selection process that evaluates the code rate against R_threshold and adjusts the base graph choice accordingly. This dynamic approach allows the system to optimize performance by selecting the appropriate base graph based on real-time code rate conditions.
2Manufacturing precision
If base graph #2 (BG2) is used for transport block sizes greater than 3840, then the code block size constraint is satisfied, but the performance loss increases due to segmentation
Solution Approach 1:
The patent uses the code block size parameter (3840) in combination with the code rate threshold to determine base graph selection. When TBS>3840 and R>R_threshold, BG1 is selected despite the size constraint, because the performance benefit of avoiding segmentation outweighs the code block size consideration. This resolves the contradiction by prioritizing performance metrics under specific conditions.
Solution Approach 2:
Different base graphs are applied to different regions of the parameter space (TBS, code rate). For the specific region where TBS>3840 and R>R_threshold, BG1 provides locally optimal performance by avoiding segmentation penalties. The patent applies local optimization rather than a global rule, selecting the base graph that best suits the specific operating conditions.
3Length of stationary object
If base graph #1 (BG1) is selected for code rates above 1/3, then the code block length is maintained, but the code rate requirement cannot be met
Solution Approach 1:
The R_threshold parameter enables continuous adaptation between BG1 and BG2 based on code rate requirements. When R<R_threshold, BG2 is selected to meet the lower code rate requirement; when R>R_threshold, BG1 is selected to maintain code block length benefits. This parameter-driven approach resolves the contradiction by allowing the system to meet code rate requirements while preserving code block length advantages when applicable.
Data Source
AI summary
Methods, systems, and apparatus are provided for encoding code blocks for transmission in a wireless communication system. An example encoding method in a wireless communication system includes determining, for one or more code blocks of a transport block, that at least one of a plurality of criteria is met, wherein the plurality of criteria includes that a coding rate (R) is less than or equal to 1/4 or that a transport block size (TBS) is less than or equal to 3824 bits and the R is less than or equal to 2/3. The one or more code blocks are encoded using low-density parity-check (LDPC) base graph 2, wherein a maximum code block size is 3840 bits. The one or more encoded code blocks are transmitted over the wireless network.