A Study of Iterative Signal Processing Schemes for Double-Layered Bit-Patterned Recording

Abstract

To enhance the areal recording density of an alternated magnetic recording technology, we have proposed iterative signal processing schemes based on a double-layered bit-patterned magnetic recording (BPMR) system. A read/write channel model that ideally integrates the signals from both upper and lower recording media layers was created. A single reader was adopted to retrieve a single readback signal through a combination of upper- and lower-layer readback signals. We first initially recover a signal of the upper layer utilizing the partial response maximum likelihood technique that provides a pair of generalized partial response targets. Then, the estimated recorded data sequence obtained from iterative processing is used to reproduce the individual readback signals and both of them will then be detected with their proper target and equalizer that were designed with each reproduced readback signal. Based on the results, the proposed iterative signal processing schemes have been certified to deliver better bit error rate performance compared to single-layer BPMR systems, taking into account the total areal density at 4.0 Tb/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .