Ring-Linked CC-QC-LDPC Decoder for Long Codes With Lower Complexity
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Solution Overview
Problem
Existing LDPC block codes face limitations in achieving long code lengths due to high decoder complexity, which restricts error performance, especially in high signal-to-noise regions, and require significant storage, whereas LDPCCCs offer better error performance but with complex decoders and large storage needs.
Innovation Solution
The development of CC-QC-LDPC codes, which are formed by cyclically coupling QC-LDPC sub-codes, allowing for a prolonged code length with lower decoder complexity by introducing a convolutional nature to block codes, using a generator matrix G and parity-check matrix H that satisfy HGT=0, and employing a decoder architecture with sub-decoders arranged in a ring shape for concurrent decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDPC block codes are used to achieve long code lengths for better error performance, then error performance is improved, but decoder complexity becomes very high
Solution Approach 1:
The patent divides the long LDPC block code into multiple shorter QC-LDPC sub-codes and couples them cyclically. This segmentation allows the decoder to process smaller units independently while maintaining the benefits of long code length through the cyclic coupling structure, thereby reducing overall decoder complexity while preserving error performance.
Solution Approach 2:
The patent introduces a dynamic decoding architecture where sub-decoders can be selectively activated based on the required code length and error performance requirements. This dynamic approach allows the system to adapt between using fewer sub-decoders for lower complexity or more sub-decoders for higher performance, providing flexibility to balance the contradiction between error performance and decoder complexity.
2Reliability
If LDPCCCs are used to achieve better error performance in waterfall region and lower error floor, then error performance is improved, but storage requirements increase significantly
Solution Approach 1:
The patent segments the parity-check matrix into multiple QC-LDPC sub-matrices that can be stored and processed separately. This segmentation reduces the peak memory storage requirements compared to storing the complete parity-check matrix of an LDPCCC, while the cyclic coupling structure maintains the error performance benefits.
Solution Approach 2:
The patent employs an iterative decoding process where intermediate results are discarded and regenerated in each iteration rather than being stored permanently. This approach significantly reduces storage requirements while maintaining the error performance characteristics of LDPCCCs through the cyclic coupling of sub-codes.
3Length of moving object
If LDPCCC decoder processes data in continual manner to achieve long code length, then code length is extended, but storage space increases linearly with number of decoding iterations
Solution Approach 1:
The patent divides the long code into multiple shorter sub-codes that are processed in parallel by separate sub-decoders. This segmentation allows the system to achieve the equivalent of long code length processing without requiring storage space that increases linearly with iterations, as each sub-decoder handles a smaller portion independently.
Solution Approach 2:
The patent creates multiple copies of the same QC-LDPC sub-code structure with different parity-check matrices, allowing parallel processing of different code segments. This copying approach enables long code length functionality while maintaining bounded storage requirements, as the same structural template is reused across multiple sub-decoders.
Data Source
AI summary
This invention provides a cyclically-coupled (CC-) quasi-cyclic (QC-) low-density parity-check (LDPC) code and its decoder architecture. The essence of the invention is to introduce the convolutional nature to a plurality of individual block codes internally so as to form a resultant block code with a prolonged code length while slightly increasing the hardware complexity in decoder realization. The CC-QC-LDPC code is formed by cyclically coupling a plurality of sub-codes each being a QC-LDPC code such that overlapping of some variable nodes between two consecutive sub-codes results. The decoder comprises plural sub-decoders each configured to decode the channel messages for one sub-code. The sub-decoders are arranged in a ring shape such that an individual sub-decoder is configured to communicate edge messages with two neighboring sub-decoders adjacent to said individual sub-decoder in the decoding of the channel messages. The sub-decoders are configured to operate concurrently for simultaneously decoding individual sub-codes.