A double loop construction method suitable for high code rate qc-ldpc codes

Abstract

According to a quasi-cyclic low density parity check code basis matrix construction method, node distribution acquired through optimization of a density evolution algorithm is used, then a stretch factor Z is set, the circle length of the LDPC code check matrix and external message scale of the circle are jointed optimized, finally, a QC-LDPC code basis matrix with excellent performances is generated through extension. Each element in the basis matrix is corresponding to one Z*Z dimensional all-zero matrix, a unit matrix or a cyclic shift matrix of the unit matrix. But in construction of high code rate QC-LDPC code, the contradiction of limitation of matrix row number and maximum line number usually occurs, namely, the maximum line number is greater than the row number. To solve the problem, the invention provides construction of the basis matrix through a method increasing line number through superposition of a plurality of cyclic shift matrixes, namely, multiple cyclic shift matrixes are embedded in a single block matrix. The "superposition" operation is binary addition, the constructed basis matrix not only guarantees the cycle performance of the QC-LDPC code, but also meets the requirement of optimization of codon performance through increase of minimum code distance.

Description

technical field [0001] The present invention relates to a low-density parity-check code, in particular to a method for constructing a check matrix of a low-density parity-check code. Background technique [0002] Channel coding technology is an indispensable key technology for mobile communication systems, and the low density parity check (Low Density Parity Check, LDPC) code in channel coding technology is generally considered to be a channel coding method with superior performance. It has attracted widespread attention for its performance approaching the Shannon limit (referring to the maximum transmission rate for error-free transmission on a channel with random bit errors), and has been applied in the research of mobile communication systems. LDPC code is a special kind of linear block code. Its particularity lies in the fact that the number of 1s in its parity check matrix is ​​far less than the number of 0s, which is called sparsity, also known as low density. It is a...

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Problems solved by technology

[0014] Purpose of the invention: In order to solve the problem of the limited number of rows and the maximum column weight in the QC-LDPC code base matrix, the present invention proposes a double-cycle construction method suitable for high code rate QC-LDPC codes, by embedding in a single block matrix Multiple cyclic shift matrix to increase the column weight, increase the minimum code distance, so as to achieve the purpose of improving codeword performance

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