LDPC Check Matrix Switching for Code Rate Without Puncturing
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Solution Overview
Problem
The method for improving error correction capability in LDPC codes by changing code rates, as described in Japanese Patent No. 5875713, leads to increased power consumption and a deterioration in error correction capability due to the use of puncturing techniques.
Innovation Solution
A transmitter that generates code words using a check matrix capable of switching between a first and a second check matrix, with the second check matrix being derived from the first by masking cyclic permutation matrices and adding rows with column weights equal to or less than a threshold, allowing efficient code rate changes without compromising error correction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If puncturing technique is used to change code rate from low to high, then code rate increases, but error correction capability deteriorates and power consumption increases
Solution Approach 1:
The patent applies dynamics by making the check matrix structure changeable through a control signal. The encoding unit can switch between different check matrices (first check matrix for low code rate, second check matrix for high code rate) based on transmission conditions. This dynamic reconfiguration allows the system to adapt code rate without using puncturing, thereby maintaining error correction capability while changing code rate.
Solution Approach 2:
The patent changes the structural parameters of the check matrix itself rather than merely removing parity bits. By modifying the check matrix structure (masking cyclic permutation matrices and adding rows with specific column weights), the system achieves different code rates with optimized error correction performance for each rate, avoiding the degradation inherent in puncturing methods.
2Adaptability or versatility
If puncturing technique is used to change code rate, then code rate increases, but power consumption increases due to increased operating frequency or reduced iterative decoding times
Solution Approach 1:
The encoding unit dynamically switches between different check matrices based on the desired code rate. This dynamic approach allows the system to achieve high code rates without the need for increased operating frequency or reduced iterative decoding times, thereby avoiding the associated power consumption increase.
Solution Approach 2:
By changing the check matrix structure parameters rather than using puncturing, the system achieves efficient encoding at different code rates with optimized computational requirements, preventing unnecessary power consumption increases.
3Adaptability or versatility
If puncturing technique is used to change code rate, then code rate increases, but the capability to correct errors deteriorates
Solution Approach 1:
The system dynamically selects appropriate check matrices based on transmission conditions and desired code rates. Each check matrix is specifically designed to maintain optimal error correction capability for its intended code rate, ensuring that error correction performance is preserved even when code rate changes.
Solution Approach 2:
The patent modifies the check matrix structure parameters (masking cyclic permutation matrices, adding rows with column weights ≤ threshold) to create specialized check matrices for different code rates. This ensures that each code rate has an optimized check matrix structure that maintains high error correction capability, unlike puncturing which degrades performance.
Data Source
AI summary
A transmitter according to the disclosure includes: an encoding unit that generates a code word by performing coding with a low-density parity-check code using a check matrix, the encoding unit being capable of switching the check matrix for use in generating the code word, between a first check matrix with a first code rate and a second check matrix with a second code rate smaller than the first code rate, the first check matrix containing a plurality of cyclic permutation matrices, the encoding unit generating the second check matrix by masking the cyclic permutation matrix at a predetermined position in the first check matrix and adding a row with a column weight equal to or less than a threshold; and a transmission unit that transmits the code word.