I. Introduction
Shingled magnetic recording (SMR) and two-dimensional magnetic recording (TDMR) have been proposed for pushing storage densities beyond 1 (Terabits/sq. inch) [1]. Conventional recording is expected to reach a limiting density at about this point and all of the alternative technologies under consideration appear very challenging [2]. Shingle-writing takes advantage of the high fields and gradients associated with the corner of a wide write head. Tracks are written such that they overlap one another yielding a track pitch much less than the head-width [1]–[5]. The track-pitch and bit aspect ratio can readily be pushed far below that of a conventional system, to the point where inter-track interference (ITI) necessitates the use of 2-dimensional (2D) read-back and signal-processing [6]–[9].