LDPC Mother Matrix Encoding for Adaptive IR-HARQ Code Rates
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Solution Overview
Problem
The existing WLAN standards cannot meet the requirement of increasing redundant bits through retransmission in the IR-HARQ mechanism to decrease the channel coding rate, thereby limiting the improvement of decoding performance for LDPC codes.
Innovation Solution
An LDPC code encoding method that uses a mother matrix to generate check matrices of different sizes, allowing for the selection of a check matrix corresponding to a required code rate during LDPC encoding. In the IR-HARQ mechanism, a check matrix with a lower code rate is used during retransmissions to increase redundant bits and decrease the channel coding rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed check matrix is used for LDPC encoding in existing WLAN standards, then the encoding structure is simple and device complexity is low, but the channel coding rate cannot be dynamically adjusted to increase redundant bits during retransmission
Solution Approach 1:
The check matrix is segmented into a basic matrix and an extension matrix. The basic matrix contains the core LDPC encoding structure, while the extension matrix provides additional rows that can be selectively included to increase the number of redundant bits. This segmentation allows the system to maintain a simple base structure while enabling flexible adaptation of code rate by including or excluding extension matrix rows during retransmission.
Solution Approach 2:
The encoding structure transitions from a fixed check matrix to a dynamic check matrix composition. The system can dynamically adjust the code rate by selecting different numbers of extension matrix rows to include in the final check matrix used for encoding. This dynamic adjustment capability enables the IR-HARQ mechanism to increase redundant bits during retransmission while maintaining a relatively simple base encoding structure.
2Reliability
If the channel coding rate is maintained at a higher level for faster transmission, then transmission speed is improved, but the decoding success rate decreases and more retransmissions are required
Solution Approach 1:
The system changes the code rate parameter dynamically based on transmission needs. During initial transmission, a higher code rate is used for faster transmission. When retransmission is required, the system changes the parameter by including extension matrix rows to create a lower effective code rate, thereby increasing redundant bits and improving decoding success rate without permanently sacrificing transmission efficiency.
3Adaptability or versatility
If multiple separate check matrices are stored for different code rates, then code rate flexibility is achieved, but memory requirements and device complexity increase significantly
Solution Approach 1:
A single universal mother matrix is designed to serve multiple code rate requirements. The mother matrix contains both the basic matrix and extension matrix components, which can be combined in different ways to generate check matrices for various code rates. This universal structure eliminates the need to store multiple separate check matrices, significantly reducing memory requirements while maintaining code rate flexibility for IR-HARQ operations.
Data Source
AI summary
This application provides an LDPC code encoding method and a communication apparatus, to meet a requirement of increasing redundant bits through retransmission in an IR-HARQ mechanism, so as to decrease a channel coding rate, and improve decoding performance of an LDPC code. In the method, a check matrix of the LDPC code is used as a basic matrix, and the basic matrix is extended to obtain a mother matrix compatible with a plurality of code rates. During LDPC encoding, a transmit device reads, from the mother matrix, a check matrix corresponding to a required code rate, and performs LDPC encoding on an information bit sequence based on the read check matrix. LDPC encoding is performed on the information bit sequence by using check matrices of different sizes, to obtain different quantities of redundant bits.