Spatially Coupled LDPC Codes With Small Constraint Length and Low Error Floor

In this letter, we design time-invariant spatially coupled low-density parity-check (SC-LDPC) codes with small constraint length and low error floor. For this, we modify the codes in the literature that have (close to) minimal constraint length for a given degree distribution and girth, to improve their error floor. This is performed by eliminating (or minimizing the multiplicity of) some of the dominant trapping sets (TSs) of the codes and/or increasing the minimum distance. To reduce the multiplicity of the TSs effectively and efficiently, we devise a technique based on the parent/child relationship between TSs that aims at successively minimizing the multiplicity of TSs depending on their harmfulness.