LDPC Code Block Segmentation by Base Graph and TB Size
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing communication systems face challenges in efficiently encoding and transmitting data channels using LDPC codes, particularly in handling transport blocks with varying code rates and sizes, which can lead to inefficiencies in resource allocation and performance.
Innovation Solution
An apparatus and method that attach transport block-level CRC bits to a TB, select an LDPC base graph based on code rate and TB size, determine the number of code blocks, segment the TB into CBs, pad zeros to the last CB, attach CB-level CRC bits, and encode each CB using the selected LDPC base graph for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fixed LDPC base graph is used for all code rates and block sizes, then device complexity is reduced, but encoding performance and resource utilization deteriorate
Solution Approach 1:
The system dynamically selects between first and second LDPC base graphs based on code rate ranges and transport block size conditions. The base graph selection is not fixed but adapts to the specific encoding parameters, allowing optimal performance for different code rates (e.g., using first base graph for lower code rates and second base graph for higher code rates) while maintaining manageable complexity through predefined selection criteria.
Solution Approach 2:
The invention changes the parameters of the LDPC base graph selection based on code rate and transport block size. By monitoring these parameters and selecting appropriate base graphs accordingly, the system optimizes encoding performance for different operational conditions without requiring a single complex base graph to handle all scenarios.
2Device complexity
If transport block is segmented into fixed number of code blocks, then segmentation process is simplified, but encoding performance deteriorates for varying code rates and block sizes
Solution Approach 1:
The number of code blocks and their sizes are dynamically determined based on the selected LDPC base graph, code rate, and transport block size. Rather than using a fixed segmentation scheme, the system adapts the segmentation parameters to match the specific encoding requirements, improving data transmission quality by optimizing the code block structure for each encoding scenario.
Solution Approach 2:
The segmentation parameters (number of code blocks, size of each code block) are changed based on the selected base graph and encoding conditions. This allows the system to adjust segmentation to achieve optimal performance for different code rates and block sizes while maintaining manageable complexity through rule-based determination.
3Reliability
If CRC bits are attached at both TB and CB levels, then error detection capability is improved, but overhead and processing complexity increase
Solution Approach 1:
The error detection mechanism is segmented into two levels: TB-level CRC for overall transport block integrity and CB-level CRC for individual code block verification. This segmentation allows the system to provide comprehensive error detection capability while enabling selective processing - CB-level CRC can be used for fine-grained error detection and TB-level CRC for overall validation, reducing the need to process all CRC bits in every scenario.
Solution Approach 2:
Different CRC processing is applied at different levels: CB-level CRC provides local error detection for individual code blocks, while TB-level CRC provides global error detection for the entire transport block. This local quality approach allows the system to optimize error detection for specific needs without uniformly applying maximum processing complexity throughout.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
An apparatus and method are described. The apparatus includes a transceiver and processor, which attach transport block (TB) level CRC bits to a TB, select an LDPC base graph (BG) based on a code rate (CR) and TB size of the TB including TB level CRC bits, determine a number of code blocks (CBs) to use for segmenting the TB including TB level CRC bits depending on the selected LDPC BG, determine a single CB size for each of the CBs based on the number of CBs, segment the TB including TB level CRC bits into the CBs based on the number of CBs and CB size, pad zeros to a last CB of the CBs in the segmented TB, attach CB level CRC bits to each CB in the segmented TB, encode each CB in the segmented TB using the selected LDPC base graph, and transmit the encoded CBs.