Low density check code check matrix constructing method based on shift matrix classified extension

Abstract

A method for LDPC check matrix configuration based on circular shift matrix grading extension, which comprises configuring a master matrix exclusive of loops with the length of 4, then searching the distribution of loop 6, 8 and 10 in the master matrix, adopting grading expansion method to fill the displacement parameters of the circular shift matrix in the position of 1 element in the master matrix, and finally using circular shift matrix and all 0 matrix to fill the master matrix expansion according to the positions of displacement parameter matrix and 0 element so as to generate check matrix. For timely and effective discovery of good codes with secondarily maximized minimum loop length and average minimum loop length, the invention only requires graded optimization of the combinationof the master matrix with very small code length and the circular shift matrix; compared with the method of random circular shift configuration check matrix followed by comparing average minimum looplength, the search volume is significantly reduced. The check matrix not only has excellent performance, but also further reduces average iteration times. The invention is suitable for all methods that adopt circular shift matrix to constitute check matrix.

Description

technical field [0001] The present invention relates to a method in the technical field of channel coding, in particular to a method for constructing a check matrix of an LDPC code based on hierarchical expansion of a cyclic shift matrix. Background technique [0002] Low Density Parity Check (LDPC) codes were first proposed by Gallager in 1962, but due to the limitation of technical conditions at that time, people did not pay attention to them. After nearly 30 years of silence, Mackay and Neal rediscovered that LDPC codes have good performance in 1996. LDPC code is a special linear block code, which can be expressed by check matrix and generator matrix. Among them, the non-zero elements in the check matrix are very rare, so it is called "low density". According to whether the row weight (the number of non-zero elements in each row) and the column weight (the number of non-zero elements in each column) of the check matrix are constant values, LDPC codes can be divided into...

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Problems solved by technology

Although the random search method is the most effective way to find the LDPC code with the minimum ring length and the average minimum ring length maximization, its huge computational complexity makes it impractical when the code length is large

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