HARQ LDPC Coding for Flexible Block Length Retransmission
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Solution Overview
Problem
Existing communication systems face challenges in efficiently using polar codes due to the power of 2 restriction on coded block lengths, which requires puncturing and affects code construction and decoding schemes.
Innovation Solution
The use of LDPC and polar codes in communication systems, specifically employing rate-compatible LDPC codes based on protographs and adapting polar codes for HARQ schemes by varying the number of information bits and using different puncturing schemes for retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polar codes are used with power of 2 restriction on coded block lengths, then code construction is simplified, but puncturing is required which affects code construction and decoding schemes
Solution Approach 1:
The patent changes the fundamental parameter of coded block length from power of 2 restriction to arbitrary lengths by using LDPC codes with configurable block lengths. This eliminates the need for puncturing while maintaining code construction simplicity through the use of protograph-based LDPC code families that can be configured for any block length.
Solution Approach 2:
The patent extracts and removes the puncturing operation from the code construction process by adopting LDPC codes that naturally support arbitrary block lengths. This eliminates the harmful effect of puncturing on code construction and decoding schemes while preserving the ability to adapt to different transmission requirements.
2Adaptability or versatility
If puncturing is applied to meet power of 2 restriction, then coded block length requirement is satisfied, but code construction and decoding schemes are affected
Solution Approach 1:
The patent changes the approach by using LDPC codes with configurable block lengths that can directly accommodate any coded block length requirement without puncturing. The protograph-based construction allows flexible parameter adjustment while maintaining simple and unified code construction schemes.
3Ease of manufacture
If fixed code parameters are used, then code construction is simple, but adaptability to varying channel conditions and retransmission needs is reduced
Solution Approach 1:
The patent introduces dynamic adaptability through rate-compatible LDPC code families based on protographs, where code parameters such as block length and coding rate can be dynamically adjusted according to channel conditions and retransmission needs. This maintains simple construction through the underlying protograph structure while enabling flexible adaptation.
Solution Approach 2:
The patent creates a universal code construction framework using protograph-based LDPC codes that can serve multiple functions: initial transmission, retransmissions, and adaptation to various channel conditions, all while maintaining a unified and simple construction approach through the protograph template.
Data Source
AI summary
A method may comprise receiving a first signal comprising first LDPC bits including systematic bits and parity bits and transmitting information indicating that the first signal was incorrectly received. A second signal comprising second LDPC bits may be received in response to the transmitting. The second signal may include LDPC bits according to a lifting size of an LDPC base graph.