Construction of low density parity check codes: BIBD and vandermonde

Abstract

In this presentation we shall go briefly through the properties of LDPC-codes and discuss two methods for constructing LDPC matrices. One of these methods is based on BIBD, which we explain in the first part of the presentation. We shall go through the definition of BIBD and introduce the general methods of finding them. Then we shall explain one particular method called symmetrically repeated differences SRD and explain several designs based on this method. We shall then show how to use BIBD in LDPC construction. Go through the performance of some LDPC-codes based on BIBD [ 1, 21. The second part of the presentation introduces a simple method to construct quasicyclic LDPC codes. It is based on Vandermonde matrix [4] and we compare it with BIBD method [ 3 ] .