A New Read Channel Model for Patterned Media Storage

Abstract

It is conceivable that early generations of patterned media will utilize read heads whose dimensions are several times larger than an "island" of magnetization. For such a scenario, we propose a "multiple islands per read head" model where the output from the read head is a function of the magnetization from several independently written tracks of islands. In particular, we focus on a "3 islands per read head" model where the output from the read head is a function of the magnetization from three independently written tracks of islands. The readback signal is determined from a finite track-width magnetoresistive (MR) head model using reciprocity calculations, and two noise sources - island position jitter and AWGN electronics noise - are considered. By sampling the noisy signal at intervals corresponding to the down-track island separation, we obtain a discrete-time readback channel model whose performance is obtained under maximum-likelihood sequence detection.