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Asynchronous Multitrack Detection With a Generalized Partial-Response Maximum-Likelihood Strategy | IEEE Journals & Magazine | IEEE Xplore

Asynchronous Multitrack Detection With a Generalized Partial-Response Maximum-Likelihood Strategy


Abstract:

The industry standard for single-track detection in magnetic recording is partial-response equalization followed by a trellis-based sequence detector. We extend for the f...Show More

Abstract:

The industry standard for single-track detection in magnetic recording is partial-response equalization followed by a trellis-based sequence detector. We extend for the first time the partial-response paradigm to the case of multitrack detection when the multiple tracks being jointly detected were written asynchronously, with different bit phases and bit rates. We propose a multiple-input multiple-output (MIMO) partial-response equalizer that equalizes the unsynchronized samples of the multiple readback waveforms to a time-varying MIMO target, thereby enabling a trellis-based rotating-target (ROTAR) detector that accounts for the asynchrony. We evaluate the proposed equalization strategy on a two-dimensional magnetic-recording channel, and find that the proposed receiver outperforms a conventional receiver that detects one track at a time, by a 30% reduction in the bit-error rate, and that it closely matches the performance of a fictitious system in which the tracks are perfectly synchronous.
Published in: IEEE Transactions on Communications ( Volume: 70, Issue: 3, March 2022)
Page(s): 1595 - 1605
Date of Publication: 15 December 2021

ISSN Information:


I. Introduction

Improving areal density and throughput in magnetic recording systems [1], [2] motivates the development of multitrack detection in which multiple neighboring tracks are detected jointly [3]–[5]. Existing multitrack detection algorithms, with only two recent exceptions [2] and [3], assume that the tracks being detected are written synchronously [4]–[7]. In practice, however, variations in disk rotational speeds can lead to slightly different bit rates from one track to the next, as illustrated in Fig. 1 for the case of two overlapping readers detecting two neighboring tracks.

An illustration of how neighboring tracks can have different bit rates (the difference is exaggerated for emphasis), with a pair of readers for recovering the bits from both tracks.

References

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