A Generalized Algebraic Approach to Optimizing SC-LDPC Codes

Abstract

Spatially coupled low-density parity-check (SC-LDPC) codes are sparse graph codes that have recently become of interest due to their capacity-approaching performance on memoryless binary input channels. In this paper, we unify all existing SC-LDPC code construction methods under a new generalized description of SC-LDPC codes based on algebraic lifts of graphs. We present an improved low-complexity counting method for the special case of $(3,3)$-absorbing sets for array-based SC-LDPC codes, which we then use to optimize permutation assignments in SC-LDPC code construction. We show that codes constructed in this way are able to outperform previously published constructions, in terms of the number of dominant absorbing sets and with respect to both standard and windowed decoding.