Construction of LDPC convolutional codes via difference triangle sets

In this paper, a construction of [Formula: see text] LDPC convolutional codes over arbitrary finite fields, which generalizes the work of Robinson and Bernstein and the later work of Tong is provided. The sets of integers forming a (k, w)-(weak) difference triangle set are used as supports of some columns of the sliding parity-check matrix of an [Formula: see text] convolutional code, where [Formula: see text] , [Formula: see text] . The parameters of the convolutional code are related to the parameters of the underlying difference triangle set. In particular, a relation between the free distance of the code and w is established as well as a relation between the degree of the code and the scope of the difference triangle set. Moreover, we show that some conditions on the weak difference triangle set ensure that the Tanner graph associated to the sliding parity-check matrix of the convolutional code is free from [Formula: see text] -cycles not satisfying the full rank condition over any finite field. Finally, we relax these conditions and provide a lower bound on the field size, depending on the parity of [Formula: see text] , that is sufficient to still avoid [Formula: see text] -cycles. This is important for improving the performance of a code and avoiding the presence of low-weight codewords and absorbing sets.