Two-dimensional magnetic recording (TDMR) is a promising technology for boosting areal densities using sophisticated signal processing algorithms within a systems framework. The read/write channel architectures have to effectively tackle 2D inter-symbol interference (ISI), 2D synchronization errors, media and electronic noise sources as well as thermal asperities resulting in burst erasures. 1D low-density parity check (LDPC) codes are well studied to correct large 1D burst errors/erasures. However, such 1D LDPC codes are not suitable for correcting 2D burst errors/erasures due to the 2D span of errors. In this paper, we propose construction of a native 2D LDPC code to effectively correct 2D burst erasures. We also propose a joint detectiondecoding engine based on the generalized belief propagation (GBP) algorithm to simultaneously handle 2D ISI, as well as correct bit/burst errors for TDMR channels. Our work is novel in two aspects: (a) We propose the construction of native 2D LDPC codes to correct large 2D burst erasures, (b) We develop a 2D joint signal detection-decoder engine that incorporates 2D ISI constraints, modulation code constrains along with LDPC decoding. The native 2D LDPC code can correct > 20% more burst erasures compared to the 1D LDPC code over a 128×256 2D page of detected bits. Also, the proposed algorithm is observed to achieve a signal-to-noise ratio (SNR) gain of > 0.5 dB in bit error rate (BER) performance (translating to 10% increase in areal densities around the 1.8 Tb/in² regime with grain sizes of 9 nm) as compared to a decoupled detector-decoder system configuration over small 2D LDPC code of size 16×16. The efficacy of our proposed algorithm and system architecture is evaluated by assessing areal density (AD) gains via simulations for a TDMR configuration comprising of a 2D generalized partial response (GPR) over the Voronoi media model assuming perfect 2D synchronization.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering