Modified Multitrack Joint Two-Dimensional Viterbi Detectors for Rate-4/5 and Rate-5/6 Modulation Codes in Bit-Patterned Magnetic Recording Systems

For an ultrahigh areal-density bit-patterned magnetic recording, system performance is severely degraded by intertrack interference (ITI). Rate-4/5 and rate-5/6 modulation codes were introduced to avoid data patterns that can cause severe ITI. However, their decoders might not be able to correctly perform for data patterns that do not match with their look-up tables during the decoding process. To further improve system performance, we use a multitrack joint two-dimensional (2-D) Viterbi detector for the recommended systems. We also use a modified trellis structure with lower complexity when compared to a conventional joint 2-D detector, which is designed based on their encoding conditions. Simulation results show that our systems outperform the conventional system, especially when they are investigated in a media-noise environment.