Block LDPC Child Matrix Structure for Flexible Code Rates
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Solution Overview
Problem
Block Low Density Parity Check (LDPC) codes in communication systems are limited by their fixed code rate, which restricts high-speed, high-capacity data transmission and makes it difficult to implement optimal performance due to cycle structures and hardware implementation restrictions.
Innovation Solution
The method generates a child parity check matrix from a parent parity check matrix to support variable code rates, allowing for the transmission and reception of signals with different code rates by adding or puncturing parity bits, thereby enabling flexible encoding and decoding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If block LDPC codes with fixed code rate (1/2 or 1/3) are used, then encoding and decoding can be implemented, but the code rate cannot be varied to support high-speed, high-capacity data transmission
Solution Approach 1:
The parity check matrix is segmented into multiple sub-matrices (first sub-matrix, second sub-matrix, third sub-matrix) corresponding to different code rates. Each sub-matrix can be independently selected based on the required code rate, enabling variable code rate support without requiring a completely different encoding/decoding structure for each rate.
Solution Approach 2:
A single encoding/decoding apparatus is designed to handle multiple code rates (1/3, 1/2, 2/3) by selecting from pre-defined sub-matrices. The same hardware structure performs encoding and decoding operations across different code rates, eliminating the need for separate dedicated structures for each code rate.
2Reliability
If optimal degree distribution is calculated using density evolution scheme, then low code rate performance can be achieved, but implementation is difficult due to cycle structure and hardware restrictions
Solution Approach 1:
The optimal degree distribution and corresponding parity check matrix structures are pre-calculated using density evolution scheme for different code rates. These pre-computed sub-matrices are stored in the apparatus, allowing the system to directly select the appropriate pre-optimized structure without performing complex calculations during real-time operation, thus achieving both optimal performance and implementation feasibility.
3Productivity
If variable code rate is supported, then high-speed, high-capacity data transmission can be enabled, but the encoding complexity increases
Solution Approach 1:
The encoding apparatus dynamically selects the appropriate sub-matrix based on the required code rate. This dynamic selection allows the system to adapt to different data throughput requirements by choosing the most suitable code rate and corresponding matrix structure, enabling high-speed transmission when needed while maintaining manageable encoding complexity through the use of pre-optimized sub-matrices.
Data Source
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Figure 3A~3B
AI summary
The present invention provides an apparatus and method of transmitting/receiving a signal supporting a plurality of code rates in a communication system using a block LDPC code. The child parity check matrix used for encoding/decoding includes a plurality of parity blocks comprising permutation or zero matrixes in order to facilitate encoding. Furthermore, the used child parity check matrix has an extended structure of a parent parity check matrix. Puncturing can be employed in order to obtain more code rates. Hence a parent codeword, a child codeword having code rate less that the code rate of the parent codeword, and a child codeword having code rate greater than the code rate of the parent codeword can be generated by only using the child parity check matrix.