LDPC Encoding with Shortening Patterns for Flexible Codeword Lengths
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Solution Overview
Problem
Current LDPC codes in communication systems, such as DVB-S2, are limited to only two codeword lengths, which restricts their adaptability and flexibility, especially in systems requiring various data rates and high-order modulation schemes, leading to inefficiencies in error correction for high-order modulation symbols.
Innovation Solution
A method and apparatus for generating LDPC codes with varying codeword lengths using a single parity-check matrix by applying shortening or puncturing patterns optimized for specific modulation schemes, such as 16-QAM and 64-QAM, to accommodate different bit reliabilities and error correction needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single parity-check matrix is used for LDPC coding, then memory efficiency and device complexity are improved, but the ability to support various codeword lengths and code rates deteriorates
Solution Approach 1:
The patent divides the single parity-check matrix into multiple sub-matrices corresponding to different codeword lengths and code rates. By segmenting the matrix structure, the system can selectively use appropriate sub-matrices for different transmission conditions, thereby supporting various codeword lengths while maintaining a unified overall matrix framework that reduces storage complexity.
Solution Approach 2:
The patent implements dynamic selection of codeword lengths and code rates based on channel conditions and transmission requirements. The system can adaptively adjust the LDPC coding parameters by selecting different sub-matrices from the parity-check matrix structure, enabling flexible adaptation to varying communication demands without requiring multiple complete parity-check matrices.
2Reliability
If LDPC codes are designed for specific codeword lengths, then error correction performance is improved, but system extendibility and flexibility deteriorate
Solution Approach 1:
The patent designs a universal parity-check matrix structure that can serve multiple functions for different codeword lengths and code rates. This single matrix structure is engineered to support various LDPC code configurations, allowing the system to maintain optimal error correction performance across different operating conditions while providing system extendibility without requiring separate dedicated matrices for each code configuration.
Solution Approach 2:
The patent enables parameter changes in codeword length and code rate by utilizing different sub-matrices or sub-structures within the unified parity-check matrix. By changing the active portion of the matrix structure, the system can adapt to different transmission requirements while maintaining the mathematical properties necessary for effective error correction, thus achieving both reliability and extendibility.
3Adaptability or versatility
If multiple parity-check matrices are stored for different codeword lengths, then codeword length adaptability is improved, but memory usage and device complexity worsen
Solution Approach 1:
The patent merges multiple parity-check matrices into a single unified matrix structure by combining them as sub-matrices or blocks within one overall matrix. This merging approach allows the system to support multiple codeword lengths and code rates using a single stored matrix structure, significantly reducing memory storage requirements compared to storing separate complete matrices for each configuration.
Solution Approach 2:
The patent implements a nested structure where smaller parity-check matrices for different codeword lengths are embedded within a larger unified parity-check matrix framework. This nesting allows the system to store only one matrix structure while having access to multiple effective parity-check matrices by selecting different portions or sub-structures, thereby supporting various codeword lengths with minimal memory overhead.
Data Source
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AI summary
A method and apparatus for encoding using a Low-Density Parity-Check (LDPC) code, the LDPC involving a parity check matrix, the parity check matrix comprising an information part and a parity part. The encoding method includes dividing information bits into a plurality of bit groups, determining a length K2, where K2 denotes a length of information bits to be obtained by shortening, determining a number of bit groups to be shortened, based on the length K2, shortening information bits in the determined number of bit groups according to a predetermined order of bit groups, and encoding shortened information bits.