Rate-Compatible LDPC Parity Check Matrix Design
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Solution Overview
Problem
Conventional RC-LDPC encoding schemes face increased complexity in encoding and decoding due to high density of the parity check matrix, leading to higher decoding complexity and time delays, particularly in diagonal and general extension schemes.
Innovation Solution
The proposed solution involves a new parity check matrix structure with a stair-wise lower triangular or partial dual-diagonal structure, optimizing the extension part to reduce the density of '1' and simplify encoding and decoding processes, while maintaining error correction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional RC-LDPC encoding schemes (diagonal or general extension schemes) are used, then code rate compatibility is achieved, but encoding and decoding complexity increases due to high density of the parity check matrix
Solution Approach 1:
The patent applies local quality by making different parts of the parity check matrix have different structures. Specifically, the extension part (rows R-K+1 to R) is designed with a stair-wise lower triangular structure having lower density, while the base part (rows 1 to R-K) can have higher density. This localized structural differentiation allows the matrix to maintain code rate compatibility while reducing overall decoding complexity, as the lower density extension part requires fewer computational operations during belief propagation decoding.
Solution Approach 2:
The patent segments the parity check matrix into distinct functional parts: a base matrix for high code rates and an extension part for lower code rates. The extension part is further segmented into multiple sections with stair-wise structure. This segmentation allows independent optimization of each part's density and structure, enabling code rate compatibility through the extension mechanism while controlling complexity by keeping the extension part's density lower than conventional schemes.
2Reliability
If high density parity check matrix is used in RC-LDPC encoding, then error correction capability is maintained, but decoding time delay increases
Solution Approach 1:
The patent applies local quality by creating a heterogeneous density structure within the parity check matrix. The extension part uses a stair-wise lower triangular structure with deliberately reduced density compared to conventional high-density matrices. This localized density reduction in the extension part decreases the number of non-zero elements that require processing during decoding, thereby reducing decoding time delay while the base part maintains sufficient density to preserve error correction capability.
Solution Approach 2:
The patent changes the density parameter of the parity check matrix in the extension part by imposing a stair-wise lower triangular structure constraint. This structural parameter change reduces the average number of ones per row in the extension part, directly reducing the computational complexity and time required for belief propagation decoding operations, while the base matrix parameters are optimized to maintain error correction performance.
3Adaptability or versatility
If conventional extension schemes are used for RC-LDPC, then rate compatibility is achieved, but the structure becomes too complex for practical implementation
Solution Approach 1:
The patent applies local quality by assigning a specific simple structure (stair-wise lower triangular) to the extension part of the parity check matrix, while allowing the base matrix to have a more flexible structure. This localized structural simplification in the extension part makes the overall encoder structure more tractable for practical implementation, as the stair-wise pattern is easier to generate and process than conventional high-density extension structures, while still achieving rate compatibility through the extension mechanism.
Data Source
AI summary
A 5th generation (5G) or pre-5G communication system for supporting a data transmission rate higher than that of a 4th generation (4G) communication system such as long term evolution (LTE) is disclosed. The present disclosure relates to a rate compatible low-density parity-check (RC-LDPC) encoding method and device therefor. The encoding method includes using LDPC in a communication system, including the operations of LDPC encoding information bits by a first encoding rate, and performing a concatenated single parity check (SPC) encoding for the encoded bits by at least one second encoding rate lower than the first encoding rate.