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Open Access Research Article

Graph-Based Channel Detection for Multitrack Recording Channels

Jun Hu1, Tolga M Duman2* and M Fatih Erden3

Author Affiliations

1 Qualcomm Inc., San Diego, CA 92121, USA

2 Electrical Engineering Department, Ira A. Fulton School of Engineering, Arizona State University, Tempe, AZ 85287-5706, USA

3 Seagate Technology, Pittsburgh, PA 15222-4215, USA

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EURASIP Journal on Advances in Signal Processing 2008, 2008:738281  doi:10.1155/2008/738281

The electronic version of this article is the complete one and can be found online at: http://asp.eurasipjournals.com/content/2008/1/738281


Received:26 March 2008
Accepted:28 November 2008
Published:20 January 2009

© 2008 The Author(s).

This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We propose a low complexity detection technique for multihead multitrack recording systems. By exploiting sparseness of two-dimensional partial response (PR) channels, we develop an algorithm which performs belief propagation (BP) over corresponding factor graphs. We consider the BP-based detector not only for partial response channels but also for more practical conventional media and bit-patterned media storage systems, with and without media noise. Compared to the maximum likelihood detector which has a prohibitively high complexity that is exponential with both the number of tracks and the number of intersymbol interference (ISI) taps, the proposed detector has a much lower complexity and a fast parallel structure. For the multitrack recording systems with PR equalization, the price is a small performance penalty (less than one dB if the intertrack interference (ITI) is not too high). Furthermore, since the algorithm is soft-input soft-output in nature, turbo equalization can be employed if there is an outer code. We show that a few turbo equalization iterations can provide significant performance improvement even when the ITI level is high.

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