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

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/in² .