LDPC Base Matrix Lifting for Flexible Wireless Code Blocks
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Solution Overview
Problem
Current LDPC code systems face challenges in supporting flexible code block lengths and code rates, particularly in wireless communication systems, where existing methods struggle to efficiently encode and decode information sequences of 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, allowing for the encoding and decoding of input sequences with different lengths by determining the appropriate lifting factor based on the input sequence length, thereby supporting various code block lengths and rates.
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 block lengths and code rates
Solution Approach 1:
The LDPC matrix is segmented into a base matrix and multiple expanded matrices corresponding to different code block lengths. The base matrix contains fundamental structure information, while expanded matrices are generated by lifting operations with different lifting factors to support various code block lengths (e.g., 512, 1024, 2048 bits). This segmentation allows the system to maintain a compact base structure while providing flexibility for different transmission requirements.
Solution Approach 2:
The patent implements dynamic selection of LDPC matrices based on the actual code block length and code rate requirements. The system dynamically chooses the appropriate lifting factor and base matrix configuration to match the transmission parameters, enabling adaptive support for different code block lengths and rates without requiring a completely different matrix structure for each case.
2Adaptability or versatility
If different LDPC matrices are used for different code block lengths, then the adaptability improves, but the system complexity and overhead increase
Solution Approach 1:
A single base matrix is designed to serve multiple functions by supporting different code block lengths and code rates through systematic lifting operations. The base matrix acts as a universal template that can be expanded to generate appropriate LDPC matrices for various transmission scenarios, eliminating the need to store and manage completely separate matrices for each code rate and block length combination.
Solution Approach 2:
The patent changes key parameters such as the lifting factor Z and the selection of base matrix columns/rows to adapt the LDPC matrix structure to different code block lengths and rates. By systematically varying these parameters rather than changing the entire matrix structure, the system achieves adaptability while keeping the base design reusable and reducing overall complexity.
3Reliability
If the LDPC matrix size is increased to support longer code blocks, then the error correction capability improves, but the decoding time and computational load increase
Solution Approach 1:
The base matrix is pre-designed with optimal structural properties that ensure good error floor performance across different code block lengths. By establishing the correct fundamental structure in advance through careful base matrix construction, the system achieves reliable error correction without requiring excessively large matrix sizes for each specific case, thus reducing decoding complexity while maintaining reliability.
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.