Rate-Compatible LDPC Encoding for IR-HARQ Retransmission
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Solution Overview
Problem
Current WLAN systems supporting IR-HARQ lack rate-compatible LDPC code check matrices, limiting the introduction of new incremental redundant bits and thus restricting decoding performance.
Innovation Solution
The method involves using a rate-compatible LDPC code check matrix by extracting submatrices from an extended check matrix to support varying transmission code rates, allowing for LDPC encoding and retransmission of incremental redundant bits to improve decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rate-compatible LDPC code check matrix is introduced to support IR-HARQ, then decoding performance is improved through incremental redundant bits, but device complexity increases due to the extended check matrix structure
Solution Approach 1:
The extended check matrix H is segmented into multiple submatrices including HMC (base matrix), HIR (incremental redundancy submatrix), and identity matrix blocks. Each submatrix serves a specific function: HMC provides the base code structure, HIR supplies incremental redundant bits for IR-HARQ, and identity matrix blocks maintain rate compatibility. This segmentation allows the system to selectively use different parts of the matrix for different transmission scenarios.
Solution Approach 2:
The rate-compatible LDPC code check matrix employs a nested structure where the base check matrix HMC is embedded within the extended matrix H, which in turn contains additional HIR submatrices. This nested arrangement allows progressive expansion of the code rate from the core HMC structure outward, enabling incremental redundancy transmission while maintaining compatibility with the base code structure.
2Adaptability or versatility
If the check matrix is extended to support multiple code rates, then adaptability for different transmission scenarios is improved, but manufacturing precision requirements increase for matrix construction
Solution Approach 1:
The check matrix structure is designed to be dynamically configurable for different code rates. By adjusting the number of rows and columns in the HIR submatrix and the identity matrix blocks, the system can adapt to various transmission scenarios and channel conditions. The dynamic structure allows the same base matrix HMC to support multiple code rates through controlled expansion.
Solution Approach 2:
The invention changes key parameters of the check matrix including the dimensions of submatrices (HMC, HIR, identity blocks) to achieve different code rates. By modifying parameters such as the number of incremental redundancy bits and the size of identity matrix blocks, the system achieves rate compatibility while maintaining a systematic construction approach that reduces precision requirements.
3Reliability
If incremental redundant bits are transmitted during retransmission, then data transmission reliability is improved, but transmission time increases due to additional retransmission cycles
Solution Approach 1:
The extended check matrix H is constructed in advance with predefined HIR submatrices that contain incremental redundant bits for potential retransmissions. This preliminary preparation allows the transmitter to quickly generate appropriate redundant bits for IR-HARQ without requiring complex real-time calculations, thereby reducing retransmission latency while maintaining reliability improvements.
Data Source
AI summary
The present disclosure relates to low-density parity-check (LDPC) encoding methods and apparatus. One example method includes encoding k information bits by using a submatrix of ((n−k)/Z+j) rows and (n/Z+j) columns at an upper left corner of a check matrix H based on a first transmission code rate R satisfying R=k/(n+j×Z), obtaining a first codeword including the k information bits and (n−k+j×Z) redundant bits, and sending the first codeword to a receive end.