Mitigating the Effects of Track Mis-Registration in Bit-Patterned Media

In bit-patterned media (BPM) aimed at magnetic recording densities of 1 Tbit/in² and higher, adjacent tracks may become very close leading to significant inter-track interference (ITI). Read-head offset or track mis-registration (TMR) can further degrade the performance of the channel. To investigate the effects of ITI and TMR on the performance of the channel, we have developed a two-dimensional (2D) pulse response simulator for BPM. Simulation results using these pulse responses suggest that equalizers and detectors optimized for zero TMR may not perform well in the presence of TMR. To mitigate the effects of TMR, we propose a modified trellis for the Viterbi algorithm (VA). The modified VA (MVA) takes into account the ITI while computing branch metrics. Simulation results show that the MVA can improve the bit error rate in the presence of TMR.