LDPC Rate Matching by Check-Bit Confidence for IR-HARQ
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Solution Overview
Problem
Current WLAN standards cannot effectively meet the requirement of continuously increasing redundant bits through retransmission in the IR-HARQ mechanism to reduce channel coding rate and improve decoding performance.
Innovation Solution
A rate matching method is provided where the transmit end performs rate matching on an LDPC codeword based on the priority order of puncturing the check bits of the mother code, related to the confidences of the check bits, to obtain a codeword with a higher or lower code rate, thereby improving decoding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current WLAN LDPC coding scheme is used, then the system maintains compatibility with existing standards, but it cannot continuously increase redundant bits through retransmission to reduce channel coding rate and improve decoding performance
Solution Approach 1:
The patent introduces dynamic rate matching capability that allows the LDPC code to adaptively adjust the number of redundant bits during retransmission. The system can dynamically select different puncturing patterns and code rates based on channel conditions and retransmission round, enabling continuous increase of redundant bits to improve decoding performance while maintaining standard compatibility.
Solution Approach 2:
The patent changes key parameters of the LDPC coding scheme including code rate, block length, and puncturing patterns. By introducing a mother code concept and deriving multiple code rates from it through systematic puncturing, the system can continuously adjust the amount of redundant information transmitted during IR-HARQ retransmissions, thereby improving decoding performance without requiring completely new code structures.
2Productivity
If check bits are punctured during rate matching, then the code rate increases and transmission efficiency improves, but the reliability of individual check bits decreases
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different check bits based on their positions and roles in the LDPC code structure. Systematic check bits are preserved with higher priority while other check bits are punctured according to specific patterns. This selective puncturing strategy ensures that critical check bits maintain reliability while allowing overall code rate increase for improved transmission efficiency.
Solution Approach 2:
The patent performs preliminary arrangement of check bits into systematic and non-systematic categories before rate matching. By pre-identifying which check bits are essential for decoder convergence and which can be punctured, the system can confidently increase code rate through selective puncturing while maintaining sufficient check bit reliability for successful decoding.
3Reliability
If the number of redundant bits is increased through retransmission, then the channel coding rate decreases and decoding performance improves, but the system complexity and retransmission overhead increase
Solution Approach 1:
The patent segments the redundant bits into structured groups based on the mother code framework. Each retransmission carries a specific portion of redundant information according to predefined puncturing patterns, allowing the receiver to systematically accumulate redundant bits across multiple transmissions. This segmentation reduces complexity by providing a clear structure for both transmission and accumulation of redundant information.
Solution Approach 2:
The patent uses the mother code as a template that is repeatedly applied and modified through systematic puncturing for different code rates. Instead of designing completely new codes for each retransmission scenario, the system copies and adapts the mother code structure, significantly reducing system complexity while enabling flexible adjustment of redundant bit quantity across multiple retransmissions.
Data Source
AI summary
This application provides a rate matching method and a communication apparatus. A transmit end punctures an LDPC codeword based on a priority order of check bits of a mother code of an LDPC code. The priority order of the check bits of the mother code indicates a priority order of puncturing the check bits in a rate matching process, and the priority order is related to confidences of the check bits. The confidences of the check bits indicate degrees to which the check bits are affected by noise in a channel transmission process. In addition, puncturing the check bits can ensure restorability of a system variable node, and a check bit with a higher confidence is more likely to be correctly restored, so that more valid information can be provided for another system variable node during decoding iteration.