Iterative Two-Dimensional Soft Output Viterbi Algorithm for Patterned Media

We introduce an iterative two-dimensional (2-D) soft output Viterbi algorithm (SOVA) for patterned media storage. Patterned media storage has enormous 2-D intersymbol interference (ISI), which includes ISI from neighboring symbols and intertrack interference (ITI) from adjacent tracks, since there is a small space between adjacent tracks and neighboring symbols. Thus, conventional one-dimensional (1-D) detection schemes have difficulty overcoming the 2-D ISI problem. To combat 2-D ISI, it is natural to consider a 2-D detection scheme. Since the complexity of pure 2-D Viterbi detection is quite high, we propose a 2-D SOVA using two 1-D SOVAs. We also propose an iterative scheme between two 1-D SOVAs to achieve its best performance without error correcting codes.