A Class of Non-Binary Doubly-Generalized LDPC codes for Moderate and High Code Rates

In this paper, a new class of doubly-generalized LDPC codes is proposed. The particular point of the proposed construction is the presence of a small fraction of single parity-check codes at the variable nodes side. Together with the use of extended alphabets, the existence of such a fraction has been shown to improve the asymptotic decoding threshold, without harming the minimum distance behaviour of the code ensemble. Note that the improvement is more significant in cases where the code initially contains check nodes of high degrees, which corresponds to the region of moderate and high code rates.