Two-Dimensional Pulse Response and Media Noise Modeling for Bit-Patterned Media

Abstract

In high density bit-patterned media (BPM), bits or magnetic islands are very close leading to significant inter-track interference (ITI) in addition to inter-symbol interference (ISI). Also, in BPM, major sources of media noise are the fluctuations in the location of the magnetic islands and fluctuations in the sizes of the magnetic islands. The location fluctuations can happen in both along-the-track and in cross-track directions. The size fluctuations affect both ISI and ITI. In order to obtain a more realistic channel model that includes the 2-D interference and the 2-D impact of media noise, we have developed a 2-D pulse response simulator for BPM. Utilizing the 2-D pulse response, we model the ITI and the media noise. Simulation results show that to achieve an acceptable bit error rate (BER), the location and size fluctuations should be smaller than 8% of the bit period at a density of 1.5 Tb in 2 .Index Terms-Bit-patterned media, media noise modeling, 2-D pulse response.

Effective Generalized Partial Response Target and Serial Detector for Two-Dimensional Bit-Patterned Media Recording Channel Including Track Mis-Registration

“…Therefore, changes in TMR values also change the performance of the proposed model. Finally, we simulated our proposed scheme with a 6% fluctuation in the position [17]. In this case, the coefficients are changed according to the position of the bit island.…”

“…However, two methods of soft-output achieve almost the same result because position fluctuation causes the target coefficients to lose the formats given in (1) and (3). Finally, we simulated our proposed scheme with a 6% fluctuation in the position [17]. In this case, the coefficients are changed according to the position of the bit island.…”

A two-dimensional coding design for staggered islands bit-patterned media recording

“…11 Here, we assume that there is only the along-track location fluctuation in the system (i.e., D z ¼ 0), and it is modeled as a truncated Gaussian probability distribution function with zero mean and r 2 j , where r j is specified as percentage of the bit period T x . Next, the readback data sequence r l;k is equalized by a 2D equalizer to obtain the data sequence s l;k and is fed to the 2D Viterbi detector to determine the most likely input sequence.…”

Magnetic interactions in 2D and 3D arrays

“…Based on those amplitudes, a 0.6/3.4 · 100% = 16% relative error in (magnetic) area fluctuations would be falsely deduced comparing the slopes in figure 4.4.a and b. Although small, such an error in size jitter is readily significant in BPM recording systems [Nabavi et al, 2008] and must be avoided in media noise characterization.…”