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| A Class of High-Rate Low-Complexity QC-LDPC Codes |
| Jing Long-jiang; Lin Jing-li; Zhu Wei-le |
| College of Electronic Engineering of UESTC, Chengdu 610054, China |
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Abstract This paper proposes a class of Quasi-Cyclic Low-Density Parity-Check (QC-LDPC) codes with high code rates, which is an efficient encoding algorithm due to the almost lower triangular form and simple structure of their parity-check matrices. Since the parity-check matrix of the QC-LDPC code is composed of blocks of circulant matrices, the required memory for storing it can be significantly reduced, compared with randomly constructed LDPC codes. Based on the quasi-cyclic structure of the parity-check matrix, a new approach is proposed to analyze the distribution of the short length cycles of their bipartite graph, and a corresponding construction method of QC-LDPC codes without cycles of length 4 is presented. Simulation results show that the proposed codes not only have low encoding complexity and low error floor but also perform well with iterative decoding.
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Received: 06 November 2006
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2008, Vol. 30 
