LDPC Base Matrix Lifting for Flexible Wireless Code Blocks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current LDPC code systems face challenges in supporting flexible code lengths and code rates, particularly in wireless communication systems, where existing methods struggle to efficiently encode and decode information sequences with varying lengths effectively.
Innovation Solution
The proposed solution involves using a low-density parity-check (LDPC) matrix obtained through a lifting factor Z and a base matrix, which includes specific row and column transformations to support different code block lengths, allowing for flexible encoding and decoding of input sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed LDPC matrix structure is used, then the decoding complexity is low, but the system cannot support flexible code lengths and code rates
Solution Approach 1:
The LDPC matrix is segmented into a base matrix and multiple expanded matrices corresponding to different code lengths. The base matrix contains fundamental structure information, while expanded matrices are generated by lifting operations with different lifting factors to support various code lengths (e.g., 512, 1024, 2048 bits). This segmentation allows the system to maintain a compact base structure while providing flexibility for different code lengths.
Solution Approach 2:
The patent implements dynamic selection of LDPC matrices based on the actual code length requirements. The system dynamically chooses the appropriate expanded matrix from multiple pre-generated matrices or generates them on-demand through lifting operations. This dynamic adaptation enables the system to optimize between decoding complexity and code length support flexibility.
2Adaptability or versatility
If multiple LDPC matrices are stored for different code lengths, then code length flexibility is improved, but memory usage and system complexity increase
Solution Approach 1:
The patent employs a nested structure where multiple expanded LDPC matrices are generated from a single base matrix through lifting operations. The base matrix is nested within the expanded matrices, which are further nested within the complete encoding system. This nesting allows the system to store only the compact base matrix and generate larger matrices as needed, significantly reducing memory requirements while maintaining support for multiple code lengths and rates.
Solution Approach 2:
Instead of storing multiple complete LDPC matrices, the system creates copies of the base matrix structure through lifting operations to generate expanded matrices for different code lengths. This copying approach with transformation allows the system to derive multiple code length variants from a single source, reducing storage requirements while providing code rate flexibility.
3Productivity
If conventional Turbo codes are used, then the system is simpler to implement, but the throughput is lower
Solution Approach 1:
The patent performs preliminary organization of LDPC matrices in a base graph format with defined lifting factors before actual encoding/decoding operations. The base matrices are pre-structured to enable efficient parallel decoding operations. This preliminary preparation allows the system to achieve high throughput through parallel processing while managing complexity through structured matrix design.
Solution Approach 2:
The patent changes key parameters of the LDPC code system, including lifting factors, base matrix dimensions, and code lengths, to optimize the balance between throughput and complexity. By adjusting these parameters, the system can achieve higher throughput through parallel decoding operations while controlling implementation complexity through careful parameter selection.
Data Source
AI summary
Embodiments of this application disclose provides a low density parity check (LDPC) channel encoding method for use in a wireless communications system. A communication device encodes an input bit sequence by using a LDPC matrix, to obtain an encoded bit sequence for transmission. The LDPC matrix is obtained based on a lifting factor Z and a base matrix. Embodiments of the application provide eight particular designs of the base matrix. The encoding method provided in the embodiments of the application can be used in various communications systems including the fifth generation (5G) telecommunication systems, and can support various encoding requirements for information bit sequences with different code lengths.