LDPC Matrix Lifting for Flexible Code Length and Error Floor Control
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Solution Overview
Problem
Current LDPC code systems face challenges in supporting flexible code lengths and code rates, particularly in encoding performance and error floor management, especially in wireless communications systems.
Innovation Solution
The proposed solution involves using a lifting factor Z and a base matrix to generate LDPC matrices for encoding and decoding, where the lifting factor Z is determined based on the input sequence length, and the base matrix is transformed to accommodate different block lengths, allowing for flexible code rates and improved encoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed LDPC matrix is used for encoding, then the encoding structure is simple, but the system cannot support flexible code lengths and code rates
Solution Approach 1:
The patent applies dynamics by making the LDPC matrix configurable through a lifting factor Z that can be adjusted based on the input sequence length. The base matrix is transformed dynamically by replacing elements with circulant permutation matrices of different sizes, allowing the encoding structure to adapt to various code lengths and rates without requiring multiple fixed matrices.
Solution Approach 2:
The patent changes the parameter Z (lifting factor) to generate different LDPC matrices for different code lengths and rates. By modifying this single parameter, the system can support flexible coding configurations while maintaining a consistent base matrix structure, thus achieving adaptability without proportionally increasing complexity.
2Reliability
If different base matrices are used for different lifting factors, then code performance is optimized, but the system complexity increases
Solution Approach 1:
The patent makes a single base matrix universal by designing it to work with multiple lifting factors. The base matrix contains elements that can be transformed into circulant permutation matrices of various sizes, allowing one base matrix to serve multiple coding configurations. This reduces the need to store and manage multiple different base matrices while still achieving optimized performance for different code lengths and rates.
3Length of moving object
If the lifting factor Z is increased to support longer code blocks, then the supported code length increases, but the decoding complexity increases
Solution Approach 1:
The patent segments the LDPC matrix into a base matrix and circulant permutation matrices. This segmentation allows the decoding process to exploit the structured nature of circulant matrices, enabling efficient implementation through techniques like butterfly operations. The segmentation maintains manageable complexity even as the lifting factor Z increases to support longer code blocks.
Data Source
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 a row 0 to a row 4 and a column 0 to a column 26 in one of matrices shown in FIG. 3b-1A to FIG. 3b-8B, or the base matrix includes a row 0 to a row 4 and some of a column 0 to a column 26 in one of matrices shown in FIG. 3b-1A to FIG. 3b-8B. According to the encoding method, the apparatus, the communications device, and the communications system, channel coding requirements can be met.