Inter-Layer Interference (ILI) Suppression in Dual-Layer Bit-Patterned Magnetic Recording Systems

Abstract

Dual-layer bit-patterned magnetic recording (DL-BPMR) systems are promising for achieving higher areal densities (ADs). However, they face significant challenges, including inter-symbol interference (ISI), inter-track interference (ITI), and inter-layer interference (ILI). To address these issues, this work proposes integrating a sum-soft-information (SSI) technique and an ILI suppression method to enhance detection reliability. The SSI technique is initially used to improve the reliability of the log-likelihood ratio (LLR) for the bottom layer signal by leveraging the mutual information derived from a staggered array reader configuration. The enhanced data sequence of the bottom layer is subsequently utilized to suppress ILI by applying a weighting before being removed from the mixed readback signal. The separated readback signal of the top layer is then processed using well-predesigned equalizers and detectors. Simulation results demonstrate that the proposed method significantly improves bit error rate (BER) performance compared to conventional single-layer and DL-BPMR systems, particularly at a user density of 4.0 Tb/in2, making it a promising approach for next-generation high-density magnetic recording.