Decoding of NB-LDPC codes over Subfields

In this paper, we present a novel method to expand a graph over a finite field into a larger one over one of

the original field’s subfields. This allows a number of different graph expansions for any given graph.

These expansions can be used in various applications, and we focus specifically on the case of decoding

NB-LDPC codes. Using the novel expanded graphs, it is possible to reduce decoding complexity of NB-

LDPC codes significantly with minimal performance losses.