Quasi-Cyclic LDPC Encoding With Variable Lifting Factors for 5G
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Solution Overview
Problem
Current LDPC code designs face challenges in supporting flexible code lengths and code rates, particularly in wireless communication systems, where existing methods struggle to maintain high encoding performance and avoid error floors across varying block lengths.
Innovation Solution
The proposed solution involves using a base matrix with specific structures, such as those shown in FIGs. 3b-1 to 3b-8, and determining lifting factors Z to generate LDPC matrices that can be transformed or offset to accommodate different code block lengths, ensuring performance across multiple block lengths by adjusting lifting factors and shift values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed LDPC base matrix is used, then the encoding structure is simple, but the code length and code rate cannot be flexibly adjusted
Solution Approach 1:
The patent applies dynamics by making the lifting factor Z variable rather than fixed. Different lifting factors are selected based on the required code length and code rate, allowing the LDPC code parameters to adapt dynamically to different transmission scenarios while maintaining a consistent base matrix structure.
Solution Approach 2:
The patent changes the parameter Z (lifting factor) to achieve different code lengths and code rates. By varying Z while keeping the base matrix structure fixed, the system can flexibly adjust code parameters without redesigning the entire encoding structure, thus resolving the contradiction between adaptability and complexity.
2Reliability
If different base matrices are used for different lifting factors, then code performance can be optimized for specific lengths, but the system complexity increases
Solution Approach 1:
The patent makes the single base matrix universal by designing it to work with multiple lifting factors. The base matrix structure is crafted such that it can generate optimal LDPC codes for various code lengths and rates through parameter adjustment alone, eliminating the need for multiple specialized base matrices and reducing system complexity.
Solution Approach 2:
Instead of changing the base matrix structure, the patent changes the lifting factor parameter Z to achieve different code performances. This parameter-based approach allows one base matrix to serve multiple functions across different operating conditions, optimizing reliability without increasing matrix management complexity.
3Adaptability or versatility
If lifting factor Z is increased to support longer code blocks, then code length flexibility improves, but decoding complexity increases
Solution Approach 1:
The patent segments the LDPC code design into a fixed base matrix component and a variable lifting factor component. This segmentation allows the complex aspect (base matrix structure) to be pre-computed and fixed, while the lifting factor Z handles the adaptation to different code lengths, thereby managing decoding complexity more efficiently.
Solution Approach 2:
The patent uses parameter changes in the lifting factor Z to support different code block lengths. By adjusting Z rather than redesigning the base matrix, the system achieves code length flexibility while keeping the decoding structure relatively consistent, thus controlling decoding complexity growth.
Data Source
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AI summary
This application discloses an encoding method, an apparatus, a communications device, and a communications system. The method includes: encoding an input bit sequence by using a low density parity check (LDPC) matrix, where the LDPC matrix is obtained based on a lifting factor Z and a base matrix, and the base matrix includes row 0 to row 6 and column 0 to column 16 in one of matrices shown in FIG. 3b-1 to FIG. 3b-8, or the base matrix includes row 0 to row 6 and some columns of column 0 to column 16 in any matrix shown in FIG. 3b-1 to FIG. 3b-8. The encoding method, the apparatus, the communications device, and the communications system in this application can support an encoding requirement for information bit sequences with a plurality of lengths.