Method for constructing LDPC codes

Abstract

The invention discloses a method for constructing LDPC codes. The method comprises the following steps that: step 1, the size of a check matrix of the LDPC codes is set, specifically, the number of lines, the number of columns and the size of circulatory sub blocks of the check matrix are set; step 2, according to the number of the lines, the number of the columns and the size of the circulatory sub blocks, the number of the circulatory sub blocks contained in the check matrix is calculated, and optimal line-column distribution is searched, and the optimal line-column distribution uniquely determines the column degree value of each circulatory sub block; a code table of the LDPC codes is set, such that each circulatory sub block is corresponding to one line in the code table, and the number of the figures of the corresponding line is equal to the column degree value of the circulatory sub block; and a step 3, values of the figures in the code table are determined. Codes constructed by using the method of the invention are irregular codes; with the design of column weight distribution and a short-cycle elimination algorithm adopted, the performance of the codes is close to Shannon limit; with double diagonal form-degree two-node design adopted, the implementation of an encoder can be simplified; and considerations are given to the regularization of line weight, such that the error floor of the codes can be decreased.

Description

technical field [0001] The invention relates to a method for constructing codewords, in particular to a method for constructing codewords for LDPC codes. Background technique [0002] The LDPC code was first proposed by Gallager in his doctoral dissertation in 1963. At the same time, Gallager also proposed the probabilistic decoding algorithm of the LDPC code. However, due to the complexity of the probabilistic iterative decoding calculation, it was difficult to realize the technical development level at that time, so LDPC The code quickly disappeared in the communication world at the time. Afterwards, except for Tanner who used a bipartite graph to describe iterative decoding in the 1980s, few scholars paid more attention to LDPC codes. [0003] In 1993, the proposal of Turbo code made people see a coding scheme that can approach the Shannon limit for the first time after 45 years. So far people have begun to notice the excellent performance of iterative decoding. At the ...

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Problems solved by technology

[0005] However, due to the late development of LDPC, it missed the third-generation mobile communication. However, in the future 4G mobile com

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