Concatenated LDPC-RS Decoding Using Puncturing Information
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Solution Overview
Problem
The decoding performance of concatenated codes composed of Reed-Solomon (RS) and Low Density Parity Check (LDPC) codes in CMMB systems is poor due to limited error correction capabilities in existing decoding algorithms.
Innovation Solution
A decoding method and device that performs LDPC soft decision iterative decoding, check decision using a check matrix, de-byte-interleaving, and selecting a decoding mode based on puncturing information to enhance RS decoding, allowing for error correction or erasure decoding depending on the correctable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LDPC decoding algorithms are used for concatenated codes in CMMB systems, then the decoding process is simple, but the decoding performance and error correction capability are poor
Solution Approach 1:
The patent segments the concatenated code decoding into two distinct stages: first LDPC decoding to correct bit errors, then RS decoding to correct symbol errors. This segmentation allows each decoder to operate optimally within its domain, improving overall decoding performance without requiring a single complex algorithm to handle all error types simultaneously.
Solution Approach 2:
The patent performs preliminary LDPC decoding before RS decoding. By first applying LDPC soft decision iterative decoding to correct bit-level errors and then using RS decoding for symbol-level errors, the system prepares the data in an optimal state for the second decoding stage, maximizing the effectiveness of both decoders in the concatenated structure.
2Reliability
If more redundancy is added to increase error correction capability, then reliability improves, but transmission effectiveness decreases
Solution Approach 1:
The patent changes the parameter of redundancy utilization by employing a concatenated code structure with two different code rates (LDPC 1/2 and RS 240/256). This allows the system to achieve high error correction capability through layered redundancy while maintaining transmission effectiveness by optimizing the information payload ratio at each decoding stage, rather than using uniform high redundancy throughout.
3Reliability
If RS error correction decoding is performed without converting check information to puncturing information, then the decoding process is straightforward, but decoding performance is limited
Solution Approach 1:
The patent introduces an intermediary conversion process that transforms LDPC check information into RS puncturing information. This intermediary step acts as a bridge between the two decoding stages, allowing the RS decoder to utilize the check information from LDPC decoding effectively. The conversion enables the RS decoder to treat certain positions as punctured symbols, significantly improving decoding performance by leveraging the check information from the first stage.
Data Source
AI summary
Disclosed are a decoding method and device for concatenated code, for the decoding of concatenated code composed of low density parity code (LDPC) and Reed-Solomon (RS) code. The method includes carrying out LDPC soft decision iterative decoding on bit de-interleaved data flow, and carrying out check decision on LDPC codeword obtained from decoding by using a check matrix; carrying out de-byte-interleave on an information bit of the LDPC codeword obtained from decoding and converting check information of the LDPC codeword into puncturing information of RS codeword; selecting a decoding mode according to the puncturing information of the RS codeword to carry out RS decoding. By way of the solution of the present invention, the RS decoding performance can be improved without increasing the computation complexity, thus greatly improving the receiving performance of the CMMB terminal as compared to the conventional method.