paper

On the Girth of (3,L) Quasi-Cyclic LDPC Codes based on Complete Protographs

arXiv:1504.04975 · doi:10.1109/ISIT.2015.7282491

Abstract

We consider the problem of constructing quasi-cyclic low-density parity-check (LDPC) codes from complete protographs. A complete protograph is a small bipartite graph with two disjoint vertex sets such that every vertex in the variable-node set is connected to every vertex in the check-node set by a unique edge. This paper analyzes the required lifting factor for achieving girths of six or eight in the resulting quasi-cyclic codes with constraints on lifting. The required lifting factors provide lower bounds on the block-length of such codes.

6 pages, 2 figures, 5-page version to appear in the Proceedings of 2015 IEEE International Symposium on Information Theory. Update 1 - 05/29/2015 - Minor changes and added a reference

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