Article

Minimum-Latency Tracking of Rapid Variations in Two-Dimensional Storage Systems

IEEE Transactions on Magnetics (Impact Factor: 1.42). 02/2007; DOI: 10.1109/TMAG.2006.886844
Source: IEEE Xplore

ABSTRACT The trend of increasing storage densities results in growing sensitivity of system performance to variations of storage channel parameters. To counteract these variations, more adaptivity is needed in the data receiver. Accurate tracking of rapid variations is limited by latencies in the adaptation loops. These latencies are largely governed by delays of the bit detector. In two-dimensional storage systems, data are packaged in a group of adjacent tracks or rows, and for some of the rows the detection delays can increase dramatically with respect to one-dimensional systems. As a result, the effective latencies in the adaptation loops preclude the tracking of rapid variations and really limit the performance of the system. In this paper, a scheme is proposed that overcomes this problem and that can be used for timing recovery, automatic gain control, and other adaptive circuits. Rapid variations for all the rows are tracked using control information from rows for which detector latency is smallest. This works properly if rapid variations are common across the rows as is the case, for example, for the two-dimensional optical storage (TwoDOS) system. Experimental results for TwoDOS confirm that the scheme yields improved performance with respect to conventional adaptation schemes

0 Bookmarks
 · 
109 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We introduce two detection methods for uncoded two-dimensional (2-D) intersymbol interference (ISI) channels. The detection methods are suitable for a special case of 2-D ISI channels where the channel response is separable. In this case, the 2-D ISI is treated as the concatenation of two one-dimensional ISI channels. The first method uses equalization to reduce the ISI in one of the two dimensions followed by use of a maximum a posteriori (MAP) detector for the ISI in the other dimension. The second method employs modified MAP algorithms to reduce the ISI in each dimension. The implementation complexity of the two methods grows exponentially in the ISI length in either the row or column dimension. We develop two iterative decoding schemes based on these detection methods and low-density parity-check codes as error correction codes. Simulation results show that the bit-error-rate performance loss caused by the 2-D ISI for the separable channel response considered is less than 1 dB over a channel without ISI. This motivates equalizing a general 2-D ISI channel response to a nearby separable matrix.
    IEEE Transactions on Magnetics 08/2003; · 1.42 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper describes an architecture for a read channel which can be used to recover data from a multi-track optical medium. The multi-track format allows for a higher density of data storage as well as a higher data transfer rate for applications such as high density DVDs. The proposed channel is based on a 2D partial response over a hexagonal lattice and employs a 2D nonlinear equalizer and 2D data detection. Bit error measurements based on sampled data from a prototype disc and optics, and offline software read channel are presented and show satisfactory performance.
    IEEE Transactions on Consumer Electronics 12/2004; · 1.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel data detection scheme is proposed for two-dimensional data storage systems. This scheme is designed to reduce the complexity of two-dimensional Viterbi detector by constraining intertrack interference to be causal and by exploiting the principle of decision feedback. Its application to the two-dimensional optical data storage system is investigated, and further simplifications are also developed.
    IEEE Transactions on Consumer Electronics 03/2005; · 1.09 Impact Factor

Full-text

View
0 Downloads
Available from