LDPC Base Graph Truncation for Low-Latency NR URLLC Coding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current LDPC codes used in New Radio (NR) ultra-reliable low-latency communications (URLLC) face challenges such as increased complexity and latency due to large variable and check nodes, error floors at certain block sizes, and limitations in supporting low code rates and low-latency requirements, while also requiring efficient reuse of existing codes to avoid significant hardware changes.
Innovation Solution
The solution involves truncating LDPC base graph #1 to support higher code rates, introducing a new base graph #3 with reduced dimensions, and limiting shift sizes to reduce complexity and error floors, allowing for efficient reuse of existing LDPC codes by defining three options for coding transport blocks using LDPC base graphs #2, truncated #1, and new #3, with reduced hardware complexity and improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LDPC base graph #1 is used to support high to low code rates and block sizes up to 8448, then code rate flexibility is improved, but hardware complexity and decoding latency increase due to large variable and check nodes
Solution Approach 1:
The patent segments the code rate support into two distinct base graphs: BG#2 for medium to lower code rates with reduced dimensions, and BG#1 for high code rates. This segmentation allows each base graph to be optimized independently, reducing overall hardware complexity while maintaining code rate flexibility across different operating conditions.
Solution Approach 2:
The patent introduces dynamic base graph selection based on code rate conditions. The system dynamically switches between BG#2 and BG#1 depending on the required code rate, allowing optimal performance for each operating point while avoiding the complexity of using the larger BG#1 for all code rates.
2Adaptability or versatility
If LDPC base graph #1 is used for low code rates, then code rate coverage is improved, but error floors occur at certain block sizes
Solution Approach 1:
The patent applies local quality by designing BG#2 with specific structural optimizations tailored for medium to lower code rates. The base graph includes carefully designed parity check matrices with specific column weights and structures that locally optimize performance for the target code rate range, eliminating error floors that would occur with generic base graphs.
3Adaptability or versatility
If full LDPC base graph #1 is used, then support for low code rates is improved, but latency increases due to large number of variable and check nodes
Solution Approach 1:
The patent extracts and removes unnecessary components from the full LDPC base graph #1 structure when operating at medium to lower code rates. By using the truncated BG#2 with fewer columns and optimized parity check matrices, the system eliminates redundant variable and check nodes that would increase decoding latency, while still maintaining support for low code rates through the appropriate base graph selection.
Data Source
AI summary
Various communication systems may benefit from suitable coding schemes. For example, certain wireless communication systems may benefit from using low density parity check and other reliability mechanisms. A method can include communicating at least one transport block for ultra-reliable low-latency communications between a sending device and a receiving device. The transport block can be coded using a base graph according to one of the following three options: using only low density parity check base graph #2; using only low density parity check base graph #2 and truncated low density parity check base graph #1; or using low density parity check base graph #2, truncated low density parity check base graph #1, and low density parity check base graph #3.