Design and Optimization of Tail-Biting Spatially Coupled Protograph LDPC Codes Under Shuffled Belief-Propagation Decoding

In this letter, we conduct a comprehensive investigation on tail-biting (TB) spatially coupled protograph (SC-P) low-density parity-check (LDPC) codes under shuffled belief-propagation (BP) decoding. We first propose a shuffled extrinsic information transfer (S-EXIT) algorithm tailored for the shuffled decoding. Exploiting the proposed algorithm, we accurately predict the convergence performance (i.e., decoding thresholds) for TB-SC-P codes under such a schedule and demonstrate that their convergence performance can be further improved. Based on the S-EXIT analysis, we develop an optimization method to generate a new type of TB-SC-P codes, called improved TB-SC double-protograph (I-TB-SC-DP) codes, which can inherit the superiorities of two mother protograph codes and possess more desirable decoding thresholds. Theoretical analyses and simulated results illustrate that the proposed I-TB-SC-DP codes exhibit better error performance than the existing counterparts.