Coding and signal processing for ultra-high density magnetic recording channels

New magnetic recording technologies such as bit-patterned media recording (BPMR), heat (or microwave) assisted magnetic recording (HAMR) and shingled writing (SW)/two-dimensional magnetic recording (TDMR) have been proposed to push the storage density of future hard disks beyond 1Tb/in². However, at such high recording density, many new challenges from the magnetic recording medium, read/write head as well as writing and reading channels arise. These challenges hinder the realization of Tb/in² hard disks and should be addressed. In this paper, we review these major challenges from a communication theory perspective, and propose ways to mitigate the channel impairments by using low-complexity two-dimensional (2D) channel detection, new low-density parity-check (LDPC) code design paradigm, as well as re-synchronizable coding schemes.