QC-LDPC (Quasi-Cyclic Low Density Parity Check) code constructing method

Abstract

The invention relates to a QC-LDPC code constructing method which comprises the following steps of: initializing the line displacement values corresponding to all nonzero units of a basic matrix; traversing each column of the basic matrix according to the sequence from left to right and finding out all rings containing each nonzero unit of the current column; sequentially setting the line displacement value of each nonzero unit contained in each ring to satisfy a set constraint condition; selecting the nonzero unit with the minimum line displacement value in each ring, reserving the change of the line displacement value thereof and restoring the line displacement values of other nonzero units to original values; and when all the columns are traversed, finally determining the line displacement values corresponding to all the nonzero units of the basic matrix so as to construct a QC-LDPC code matrix. The method can maximize the minimum circumferential value of a QC-LDPC code, thereby enhancing the performance of the QC-LDPC code, so that the constructed QC-LDPC code can be more rapidly converged and achieve a lower error floor.

Description

technical field [0001] The present invention relates to the technical field of channel coding, in particular to a method for constructing a Quasi Cyclic-Low Density Parity Check (QC-LDPC) code. Background technique [0002] Due to random noise, multipath attenuation, track loss of magnetic memory, etc., data errors often occur during data transmission in wireless or wired communication. Therefore, the method of channel coding is usually used to code and correct the data. Among the currently existing coding methods, LDPC has attracted people's attention due to its excellent performance, and has been widely used in many fields, such as the satellite TV transmission standard DVB-S2, China's high-definition TV standard and so on. [0003] How to construct LDPC codes to obtain excellent decoding performance has been a research topic of many units. In order to study LDPC codes better, Tanner Graph is usually used to represent LDPC codes, and information soft value iterative prop...

AI Technical Summary

Problems solved by technology

The LDPC code constructed by this matrix construction method is called QC-LDPC code. QC-LDPC code is a very important branch of LDPC code research. It is a kind of structured LDPC code. Its check matrix H adopts quasi-cyclic structure, has the characteristics of low implementation complexity, and it can be easily implemented on hardware, but if this LDPC code is not properly designed, it will not improve the minimum cycle characteristics, and can only guarantee the entire QC-LDPC matrix The minimum circumference of is not less than the minimum circumference of its fundamental matrix

For example, if the minimum circumference of the fundamental matrix is ​​4, the final constructed QC-LDPC matrix may contain a large number of matrices with a circumference of 4, resulting in poor performance of the QC-LDPC code

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