LDPC Matrix Lifting for Flexible Code Length and Rate Adaptation
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Solution Overview
Problem
Existing LDPC code systems face challenges in supporting encoding and decoding of information bit sequences of various lengths and meeting flexible code length and code rate requirements in communication systems.
Innovation Solution
The proposed solution involves using a specific structure for the LDPC matrix, comprising submatrices A, B, C, and D, with a base graph that includes specific weight distributions and orthogonal structures, and utilizing lifting factors to generate different base matrices for varying code block lengths, allowing for flexible code rate and length adaptation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed LDPC matrix structure is used, then the encoding and decoding process is simple, but it cannot support information bit sequences of various lengths and flexible code rate requirements
Solution Approach 1:
The LDPC matrix is divided into multiple submatrices (A, B, C, D, E) with specific structures. Each submatrix serves a particular function, allowing the overall matrix to be adapted to different code lengths and rates by selectively configuring these modular components rather than using a single fixed structure.
Solution Approach 2:
The patent employs a dynamic base graph configuration where the LDPC matrix structure can be adjusted based on the required code length and rate. By using a base graph with specifically designed submatrices and applying lifting factors, the system dynamically adapts the matrix dimensions and properties to match various transmission requirements.
2Adaptability or versatility
If the LDPC matrix is designed to support various code lengths and rates, then adaptability is improved, but the complexity of encoding and decoding increases
Solution Approach 1:
The base graph with its structured submatrices serves as a universal foundation that can generate multiple LDPC matrices for different code lengths and rates. This multi-functional design allows a single base structure to handle various communication scenarios without requiring separate specialized matrices for each case.
Solution Approach 2:
The patent utilizes lifting factors as key parameters to transform the base graph into specific LDPC matrices. By changing the lifting factor value, the system can generate matrices with different dimensions and properties, enabling flexible adaptation to various code lengths and rates while maintaining a consistent encoding and decoding methodology.
3Productivity
If a simple LDPC matrix structure is used, then encoding and decoding are computationally efficient, but the system cannot meet flexible code rate requirements
Solution Approach 1:
The base graph is pre-designed with specific submatrix structures (A, B, C, D, E) that are optimized for efficient processing. This preliminary structuring allows the system to maintain computational efficiency while achieving adaptability, as the pre-configured submatrices can be systematically combined and scaled using lifting factors to meet different code rate requirements without fundamental redesign.
Data Source
AI summary
A low density parity check (LDPC) channel encoding method is used in a wireless communications system. A communication device encodes an input bit sequence by using an 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. The base matrix may be one of eight exemplary designs. The encoding method can be used in various communications systems including fifth generation (5G) telecommunication systems, and can support various encoding requirements for information bit sequences with different code lengths.