Correlation-sensitive adaptive sequence detection

In high density magnetic recording, noise samples corresponding to adjacent signal samples are heavily correlated as a result of front-end equalizers, media noise, and signal nonlinearities combined with nonlinear filters to cancel them. This correlation significantly deteriorates the performance of detectors at high densities. In this paper, we propose a novel sequence detector that is correlation sensitive and adaptive to the nonstationary signal sample statistics. We derive the correlation-sensitive maximum likelihood detector. It can be used with any Viterbi-like receiver (e.g., partial response maximum likelihood, fixed delay tree search, multilevel decision feedback equalization) that relies on a tree/trellis structure. Our detector adjusts the metric computation to the noise correlation statistics. Because these statistics are nonstationary, we develop an adaptive algorithm that tracks the data correlation matrices. Simulation results are presented that show the applicability of the new correlation-sensitive adaptive sequence detector.

[1]  Lineu C. Barbosa.  Toward the detection of signals in presence of signal-dependent noise , 1995, Other Conferences.

[2]  Jaekyun Moon,et al.  Performance comparison of detection methods in magnetic recording , 1990 .

[3]  Jian-Gang Zhu,et al.  Noise Characteristics of Interacting Transitions in Longitudinal Thin Film Media , 1994, Digest of the Magnetic Recording Conference.

[4]  Lennart Ljung,et al.  System Identification: Theory for the User , 1987 .

[5]  Roger W. Wood,et al.  Viterbi Detection of Class IV Partial Response on a Magnetic Recording Channel , 1986, IEEE Trans. Commun..

[6]  H. Thapar,et al.  A class of partial response systems for increasing storage density in magnetic recording , 1987 .

[7]  A. Kavcic.  Experimental Validation of The Triangle Zig-Zag Transition Model , 1997, 1997 IEEE International Magnetics Conference (INTERMAG'97).

[8]  Jian-Gang Zhu,et al.  Impact of medium noise correlation on various partial response channels , 1995 .

[9]  N.M. Zayed,et al.  Comparison Of Equalization & Detection For Very High Density Magnetic Recording , 1997, 1997 IEEE International Magnetics Conference (INTERMAG'97).

[10]  Peter K. George,et al.  Noise in high performance thin-film longitudinal magnetic recording media , 1985 .

[11]  José M. F. Moura,et al.  The Viterbi algorithm and Markov noise memory , 2000, IEEE Trans. Inf. Theory.

[12]  José M. F. Moura,et al.  Expedient media noise modeling: isolated and interacting transitions , 1996 .

[13]  R. R. Spencer,et al.  Comparison of different detection techniques for digital magnetic recording channels , 1995 .

[14]  G. David Forney,et al.  Maximum-likelihood sequence estimation of digital sequences in the presence of intersymbol interference , 1972, IEEE Trans. Inf. Theory.

[15]  D. Lindholm,et al.  Magnetic fields of finite track width heads , 1977 .

[16]  J.J. Wang,et al.  An Experimental MDFE Detector , 1997, 1997 IEEE International Magnetics Conference (INTERMAG'97).

[17]  Jian-Gang Zhu,et al.  Recording and transition noise simulations in thin film media , 1988 .

[18]  Jaekyun Moon,et al.  Improved equalization for digital recording using nonlinear filtering and error confinement , 1994 .

[19]  José M. F. Moura,et al.  Statistical study of zig-zag transition boundaries in longitudinal digital magnetic recording , 1997, IEEE Transactions on Magnetics.

[20]  K. C. Bracken,et al.  Adaptive continuous-time equalization and FDTS/DF sequence detection , 1995 .

[21]  L.R. Carley,et al.  Adaptive Continuous-Time Equalization Followed By FDTS/DF Sequence Detection , 1994, Digest of the Magnetic Recording Conference.

[22]  Yaw-Shing Tang.  Explicit formula for thin film disk noise based on zig-zag domain transitions , 1988 .

[23]  Emanuele Viterbo,et al.  Compensation of nonlinearities in high-density magnetic recording channels , 1994 .

[24]  Jaekyun Moon,et al.  Modified Viterbi algorithm for a jitter-dominant 1-D/sup 2/ channel , 1992 .

[25]  J. Cioffi,et al.  Performance analysis of the modified maximum likelihood sequence detector in the presence of data-dependent noise , 1992, [1992] Conference Record of the Twenty-Sixth Asilomar Conference on Signals, Systems & Computers.

[26]  David B. Bogy,et al.  Measurement of head/disk spacing with a laser interferometer , 1988 .

[27]  J. G. Kenney,et al.  Multi-level decision feedback equalization: an efficient realization of FDTS/DF , 1995 .

[28]  S. Nakagawa,et al.  A study on detection methods of NRZ recording , 1980 .

[29]  R. Baugh,et al.  Measurement of noise in magnetic media , 1983 .