LDPC Channel Encoding with Column Group Shortening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current LDPC code systems, such as DVB-S2, are limited to only two codeword lengths, which restricts their extendibility and flexibility, particularly in adaptive communication systems requiring various data rates, and storing separate parity-check matrices for each codeword length reduces memory efficiency.
Innovation Solution
A method and apparatus for generating LDPC codes with different codeword lengths using shortening or puncturing techniques, allowing for flexible code rate adjustment by grouping columns in a parity-check matrix and applying predetermined shortening or puncturing patterns, including the incorporation of BCH parity bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate parity-check matrices are stored for each codeword length, then code flexibility and adaptability are improved, but memory storage requirements increase
Solution Approach 1:
A single parity-check matrix is designed to serve multiple codeword lengths through column group shortening. The matrix can generate codes with different code rates and codeword lengths by selectively shortening different numbers of column groups, making one matrix universal for multiple coding scenarios instead of requiring separate matrices for each length.
Solution Approach 2:
The code rate and codeword length are adjusted by changing the shortening parameter (number of column groups to shorten) rather than changing the fundamental parity-check matrix structure. This allows dynamic adaptation of code parameters from a single base matrix, reducing memory requirements while maintaining flexibility.
2Device complexity
If only two fixed codeword lengths are supported, then system complexity is reduced, but adaptability to various data rates is limited
Solution Approach 1:
The system transitions from static support of only two fixed codeword lengths to dynamic support of multiple variable lengths. By introducing the column group shortening mechanism with configurable shortening counts, the system can adaptively select different codeword lengths and code rates based on channel conditions and data rate requirements, achieving dynamic adaptability without substantial complexity increase.
Solution Approach 2:
The parity-check matrix columns are organized into column groups that can be independently shortened. This segmentation allows flexible combination of shortened and non-shortened column groups to achieve various codeword lengths, enabling the system to support multiple data rates by selectively applying shortening to different numbers of column groups.
3Adaptability or versatility
If column-by-column shortening is applied to achieve various codeword lengths, then code flexibility is improved, but encoding complexity and processing time increase
Solution Approach 1:
Columns are grouped into manageable units that can be shortened in bulk rather than individually processed. This column group segmentation allows the encoder to efficiently handle shortening operations by working with groups of columns simultaneously, reducing the per-column processing overhead while maintaining the ability to achieve various codeword lengths through different shortening counts.
Data Source
AI summary
A method for encoding a channel in a communication system using a Low-Density Parity-Check (LDPC) code. The method includes generating a plurality of column groups by grouping (categorizing) columns corresponding to an information word in a parity-check matrix of the LDPC code, and ordering the column groups; determining a range of an information word desired to be obtained by performing shortening; based on the determined range of the information word, performing column group-by-column group shortening on the column groups in order according to a predetermined shortening pattern; and LDPC encoding the shortened information word.