HARQ LDPC Parity Check Matrix Selection for Flexible Code Rates
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Solution Overview
Problem
Structured LDPC codes in next-generation communication systems are inflexible in terms of coding rates due to their fixed parity check matrix size, making it difficult to change the length of the codes and support various code rates required for high-speed large-capacity data transmission/reception in systems like HARQ and AMC schemes.
Innovation Solution
The method involves using a signal transmission apparatus that generates a codeword vector by encoding an information vector with a first parity check matrix of LDPC codes, where the matrix includes multiple square matrix columns of size L×L, allowing for different numbers of information vector square matrix columns, and selecting a parity check matrix based on the length of the information vector and a lifting element L to support various coding rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed-size parity check matrix is used for structured LDPC codes, then the decoding structure is simplified and parallel implementation is enabled, but the code rate flexibility is reduced
Solution Approach 1:
The parity check matrix is segmented into multiple sub-matrices (information vector sub-matrices and parity vector sub-matrices). By selectively including or excluding specific sub-matrices based on the desired code rate, the system achieves code rate flexibility while maintaining the structured LDPC decoding advantages. The information vector square matrix columns are divided into multiple groups that can be selectively activated.
Solution Approach 2:
The system dynamically selects which sub-matrices to include in the encoding/decoding process based on the required code rate. The number of information vector square matrix columns is adjusted dynamically by selecting different combinations of sub-matrices from the predefined set, allowing adaptation to various code rates while using the same base parity check matrix structure.
2Quantity of substance
If the number of square matrix columns is increased to support longer code lengths, then the data transmission capacity is improved, but the complexity of managing multiple parity check matrices increases
Solution Approach 1:
A single base parity check matrix structure serves multiple functions by supporting various code lengths and rates through selective sub-matrix inclusion. The same parity check matrix framework can generate LDPC codes of different lengths by activating different numbers and combinations of sub-matrices, eliminating the need to store and manage completely separate parity check matrices for each code length.
Data Source
AI summary
An apparatus and method for transmitting a signal in a communication system using a Hybrid Automatic Repeat reQuest (HARQ) scheme are provided. The method includes generating a codeword vector by encoding an information vector by using a first parity check matrix of Low Density Parity Check (LDPC) codes, generating a transmission vector by processing the codeword vector, and transmitting the transmission vector. When the first parity check matrix includes a plurality of square matrix columns, each square matrix includes a size of L×L, the first parity check matrix is one of p parity check matrixes stored in the signal transmission apparatus, the p parity check matrixes support different numbers of information vector square matrix columns, and each of the numbers of information vector square matrix columns indicates the number of square matrix columns corresponding to the information vector from among the plurality of square matrix columns. The first parity check matrix is a parity check matrix supporting the number of information vector square matrix columns determined by using the length of the information vector and the value L from the p parity check matrixes, and the value L is determined by using p and the length of the information vector.