A Two Dimensional Partial-Response Maximum-Likelihood Technique for Holographic Data Storage Systems

Jeong

et al. 2013

In a practical holographic data storage system, the reconstruction process for a data page should account for the processing time as well as the bit error rate (BER) performance. To improve both aspects, we introduce two-dimensional (2D) partial response maximum likelihood composed of a 2D partial response (PR) target including diagonal elements and a 2D soft output Viterbi algorithm (SOVA) with a variable reliability factor. The 2D SOVA performs two one-dimensional (1D) SOVAs in structural accordance with the 2D PR target where extrinsic information uses the expected value calculated on a synchronization pattern. Finally, the 2D SOVA exports a weighted average using the reliability factor that is updated similarly as the optimization scheme for each page. The simulation results show that the proposed method has superior BER performance, despite using only two 1D SOVAs as compared with the modified 2D SOVA composed of four 1D SOVAs.

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Soft Output Viterbi Algorithm with a Variable Reliability Factor for Holographic Data Storage

Koo

Jeong

et al. 2013

“…[3][4][5] There have been many attempts to reconstruct a degraded data page without error bits. To solve these problems, the 2D equalizer, 6,7) 2D PRML, [8][9][10][11][12] 2D modulation code, 13,14) 2D ECC, 15) tone controllable codes, [16][17][18] etc. have been proposed in recent papers, in terms of the data page.…”

Section: Introductionmentioning

confidence: 99%

Modified Two-Dimensional Soft Output Viterbi Algorithm with Two-Dimensional Partial Response Target for Holographic Data Storage

Koo

2012

A brief review of established methods shows that only with the Berthelot technique is it possible to see a finite volume of liquid in sustained mechanical tension. A short discussion of the practice and theory reveals two uncertainties with the conventional technique : that of the determination of a true filling temperature, and the influence of compliance by the glass on the tension developed. A description is then given of a modified apparatus with which these difficulties do not arise. The tube is formed into a coil which deflects sufficiently to indicate internal pressure or tension, and by monitoring these deflections with a distance meter a record of pressure/ tension against temperature can be made. The course of a typical run is shown from which the excess pressure, filling temperature and limiting tension may all be estimated with much greater precision than befoie. The orders of magnitude of the results obtained are indicated, and a possible influence of non-uniform gaseous supersaturation is suggested.

“…1) Second, interpage interference (IPI) arises since data pages are recorded into a volume of the storage medium. 1) To manage these two problems, many kinds of equalizers, [3][4][5][6][7][8] modulation codes, [9][10][11][12][13][14] and error correcting codes were developed. [15][16][17] To compensate for data distortion, we propose two types of 2D iterative decoding (ID) schemes.…”

Section: Introductionmentioning

confidence: 99%

Two-Dimensional Iterative Decoding Schemes for Holographic Data Storage Systems

Kong

Choi³

2012

Two iterative decoding (ID) schemes, which are the ID using a single parity bit (ID-SPB) and ID using a modulation code (ID-MC), are proposed for holographic data storage systems. In the ID-SPB, a single two-dimensional parity bit is employed to conduct ID, whereas in the ID-MC, the inherent constraint of the modulation code is utilized to conduct ID. In both schemes, a data page is iteratively decoded by exchanging extrinsic information between the horizontal and vertical data bits in the page. In particular, in the ID-SPB, by adding more parity bits to each row and column of the interleaved page, we can conduct the ID within a page as well as between the original and interleaved pages. Thus, additional performance gain can be achieved in the ID-SPB. On the other hand, the ID-MC has a performance gain without loss of data rate since parity bits are not required for ID. The simulation results show that the proposed ID-SPB and ID-MC have about 2-4 and 1-2 dB performance gains in terms of bit error rate compared with the system without ID, respectively. #