Low density odd-even check code iterative sequencing statistical decoding method

Abstract

The iterative ranking statistical decoding method for low density parity check codes is suitable for soft decision decoding of low density parity check (LDPC) codes. In the iterative decoding process of low-density parity-check codes, according to the magnitude of the cumulative value of the likelihood ratio output by all variable nodes in previous iterations, the sorting statistical decoding method is used to assist iterative decoding, that is, each variable node will The node likelihood ratio output is accumulated, and the absolute value of the cumulative likelihood ratio is defined as the node reliability of the current iteration, and the nodes and the columns of the check matrix are sorted in ascending order according to the reliability, and the column-sorted matrix is ​​Gaussian eliminated; combined The system generation matrix obtained by Gaussian elimination encodes the reliable node information sequence after the previous two sortings to obtain a set of candidate codewords; if the iterative decoding does not get the final output, select from the previous sets of candidate codewords The one with the smallest Euclidean distance to the received sequence is used as the decoding output. The error correction performance of the LDPC code is greatly enhanced.

Description

technical field [0001] The invention relates to a soft-judgment decoding method of a low-density parity check code, and belongs to the technical field of channel error correction coding decoding. Background technique [0002] Among the decoding methods of LDPC codes, the iterative soft-decision decoding method based on bipartite graph, that is, BP decoding, has a good bit error rate performance. For longer irregular LDPC codes, it can achieve performance close to the Shannon limit. However, in practical applications, the system often uses code blocks of short and medium lengths, and the bipartite graph corresponding to the finite-length LDPC code no longer has asymptotically acyclic characteristics, so in this case, BP decoding still has a comparative advantage compared with MLD decoding. big gap. The OSD decoding method is also a kind of soft-decision decoding that was applied to linear block codes earlier, and is suitable for short codes with a certain algebraic structure...

AI Technical Summary

Problems solved by technology

Since the complexity of the OSD decoding method is proportional to N 2 , OSD decoding is performed on the output soft information of each iteration, which will add a lot of delay to each iteration and destroy the high-speed decoding characteristics of LDPC codes

If OSD decoding is started in a certain iteration in the middle of BP decoding, the performance gain obtained by OSD decoding is very small due to the oscillation phenomenon in the soft information output by the current iteration.

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