Symmetric information rate estimation and bit aspect ratio optimization for TDMR using Generalized Belief Propagation

Abstract

In this paper, we propose a method for estimating the Symmetric Information Rate (SIR) for Two Dimensional Magnetic Recording (TDMR) channel by using the Generalized Belief Propagation (GBP) algorithm. We consider the Voronoi model as the channel model of a TDMR system. The dominant component of noise in TDMR caused by the imperfections of the medium is called “media noise”. The nature of the media noise is data-dependent, however, the media noise can be closely approximated by additive white Gaussian noise (AWGN) with variance and mean dependent on channel bits written on the magnetic medium. Lower and upper bounds on the SIR are obtained by using the GBP algorithm. In addition, it is shown that the accuracy of the SIR estimation can be adjusted for sufficient size of the magnetic medium. Finally, the bit aspect ratio of a TDMR system is optimized by maximizing the SIR per unit area.