Iterative Multihead Multitrack Detection Scheme for Bit-Patterned Media Recording

Abstract

An iterative multi-head multi-track detection scheme for bit patterned media recording is proposed in this paper. The proposed scheme employs two iterative strategies with the multi-head multi-track detection where three tracks are simultaneously processed to accurately estimate the channel with TMR and effectively detect the data by using inter-track interference (ITI) information with high reliability. The first outer iteration aims to compensate for the track misregistration (TMR) effect, and the second inner iteration aims to improve the reliability of the data. In outer iteration, the TMR effect is compensated by modifying the generalized partial response (GPR) target to a channel that reflects the TMR estimated by a TMR estimator using expectation and maximization algorithm. In inner iteration, iterative equalization and decoding (IED) is conducted between the two-dimensional partial response maximum likelihood detector and the low-density parity check decoder based on the revised GPR target. Since each track has different channel performance according to the amount of ITI information in the multi-track detection, we design the GPR target and the code rate separately for each track to maximize the overall channel performance. The bit error rate performances of the proposed IED scheme are compared with the conventional IED scheme when areal density is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$2 Tb/in^{2}$</tex-math></inline-formula> . Simulation results show that the proposed IED scheme has more than 2dB gains compared with the conventional IED scheme for 30 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> TMR.