A Detector-Aware LDPC Code Optimization for Ultra-High Density Magnetic Recording Channels

In this paper, a detector-aware low-density parity-check (LDPC) code optimization algorithm is proposed for the ultra-high density magnetic recording channel, such as bit-patterned magnetic recording and two-dimensional magnetic recording, where a 2-D detector (2D-DET) is employed to combat 2-D intersymbol interference (2D-ISI) effects, by acquiring the variance of the 2D-ISI channel log-likelihood ratios corresponding to the specific 2D-DET. The new parameter builds a bridge of LDPC code optimization between the ISI-channel and the additive white Gaussian noise channel. Numerical results show that our proposed algorithms are more efficient in running time than other recently proposed optimization algorithms. Moreover, the protograph-based quasi-cyclic (QC) codes using the proposed optimization strategy, which have a low-complexity QC encoder structure with an effectual parallelizable protograph decoder composition, enjoy up to one order of magnitude performance gain in bit error rate over the other random codes that suffer from high error floors.