• Title/Summary/Keyword: Multi-level holographic data storage

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12/16 Modulation Code for 4-Level Holographic Data Storage (4-레벨 홀로그래픽 데이터 저장장치를 위한 12/16 변조부호)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.10
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    • pp.10-14
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    • 2016
  • Holographic data storage (HDS) features short access times, high storage capacities, and fast transfer rates since the data is recorded and read not by lines but by pages within a volume of holographic material. Furthermore, a single pixel can store more than 1 bit if it is multi-level. However, there is a problem of inter-symbol interference (ISI) between the adjacent symbols if the level difference between neighboring symbols is large. Hence, one should avoid side by side placement of the smallest level symbol and the largest level symbol in any direction. This paper proposes a 12/16 modulation code for 4-level holographic data storage, so that the largest symbol is 3 and the smallest symbol is 0, in order to reduce the ISI.

4-level 3/4 Modulation Code for Holographic Data Storage (홀로그래픽 데이터 저장장치를 위한 4레벨 3/4 변조부호)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.9
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    • pp.8-12
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    • 2015
  • A Holographic data storage has some advantage of fast transmission, short access time and high storage capacity. However, it has several problems such as inter-symbol interference, inter-page interference and misalignment. Especially, for multi-level holographic data storage system, since one pixel contains more than 1bit, the system is more vulnerable to the error. In this paper, we propose a 3/4 modulation code which mitigate inter-symbol interference for 4-level holographic data storage.

1 Bit/Pixel Modulation Codes for Multi-Level Holographic Data Storage System (멀티레벨 홀로그래픽 데이터 저장장치를 위한 1비트/픽셀 변조부호)

  • Jeong, Seongkwon;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.9
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    • pp.1667-1671
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    • 2015
  • Multi-level holographic data storage is a candidate for the next generation data storage system, since it can store more than one bit per pixel. It is possible to increase the number of codewords if the number of levels is increased, and the code with an appropriate selection of codewords can also increase the minimum distance. In this paper, we propose three multi-level modulation codes of the code rate 1 bit/pixel and compare the performance according to the minimum distance. The result shows that the code with small number of levels is better than that of large number of levels because it is hard to detect threshold value.

4-Level 4/6 Modulation Code with Trellis Encoding on Holographic Data Storage (홀로그래픽 데이터 저장장치에서 트렐리스 인코딩을 이용한 4-레벨 4/6 변조부호)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.6
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    • pp.11-16
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    • 2017
  • Multi-level holographic data storage requires modulation codes for avoiding two dimensional inter-symbol interference (2D-ISI). Modulation codes can remove the fatal ISI pattern of neighboring the largest and the smallest symbols. In this paper, we propose a 4-level 4/6 modulation code and its trellis encoding for error correction. The proposed 4/6 modulation code prevents that the symbol 0 and 3 are not adjacent in any direction. Also, we compare the proposed modulation code with the same code rate modulation codes for four-level holographic data storage.

Adaptive Threshold Detection Using Expectation-Maximization Algorithm for Multi-Level Holographic Data Storage (멀티레벨 홀로그래픽 저장장치를 위한 적응 EM 알고리즘)

  • Kim, Jinyoung;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37A no.10
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    • pp.809-814
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    • 2012
  • We propose an adaptive threshold detector algorithm for multi-level holographic data storage based on the expectation-maximization (EM) method. In this paper, the signal intensities that are passed through the four-level holographic channel are modeled as a four Gaussian mixture with unknown DC offsets and the threshold levels are estimated based on the maximum likelihood criterion. We compare the bit error rate (BER) performance of the proposed algorithm with the non-adaptive threshold detection algorithm for various levels of DC offset and misalignments. Our proposed algorithm shows consistently acceptable performance when the DC offset variance is fixed or the misalignments are lower than 20%. When the DC offset varies with each page, the BER of the proposed method is acceptable when the misalignments are lower than 10% and DC offset variance is 0.001.

2/3 Modulation Code and Its Vterbi Decoder for 4-level Holographic Data Storage (4-레벨 홀로그래픽 저장장치를 위한 2/3 변조부호와 비터비 검출기)

  • Kim, Gukhui;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.38A no.10
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    • pp.827-832
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    • 2013
  • Holographic data storage system is affected by two dimensional intersymbol interference and inter-page interference. Especially, for multi-level holographic data storage system, since one pixel contains more than 1 bit, the system is more vulnerable to the error. In this paper, we propose a 2/3 modulation code for 4-level holographic data storage system. The proposed modulation code with error correcting capability could be compensated these interferences. Also, in this paper, we proposed a Viterbi decoder for 2/3 modulation code. The proposed Viterbi decoder eliminates unnecessary calculation. As a result, proposed 2/3 modulation code and Viterbi decoder has shown better performance than conventional one.

Performance Analysis of Holographic Data Storage Depending on the Number of Levels Per Pixel of the Code Rate 1/2 Modulation Codes (부호율 1/2인 변조부호의 픽셀당 레벨 수에 따른 홀로그래픽 데이터 저장장치 성능 분석)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.10
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    • pp.16-20
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    • 2015
  • We propose three multi-level modulation codes of the code rate 1/2 for holographic data storage considered as a promising candidate for next generation storage systems. Since a pixel with multi-levels can represent more than 1 bit, it is possible to increase the storage capacity and have many codewords. Thus, we can choose a code that the minimum distance is as far as possible. When we compare the codes with the code rate 1/2, the performance of the code with small number of levels is better than that of large number of levels.

Performance of 4-level Modulation Code for Holographic Data Storage (홀로그래픽 데이터 저장장치를 위한 4-레벨 변조 부호의 성능 비교)

  • Park, Keunhwan;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.9
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    • pp.1672-1677
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    • 2015
  • The multi-level holographic storage system can store more than one bit per pixel. In this paper, we introduce a 6-pixel 4-level modulation code and compare with 4-level 6/9 modulation code and 2/3 modulation code. The proposed 6-pixel modulation code has the minimum Euclidean distance 3. The 6-pixel modulation code is approximately 1dB better than the other modulation codes.

4-Level Balanced Modulation Code for the Mitigation of Two-Dimensional Intersymbol Interference in Holographic Data-Storage Systems (홀로그래픽 데이터 저장장치에서 2차원 심볼 간 간섭을 완화하기 위한 4-레벨 균형 변조부호)

  • Park, Keunhwan;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.53 no.9
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    • pp.12-17
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    • 2016
  • In the holographic data storage system (HDSS), the data regarding the volume of a storage medium are recorded and read by the page, and the transmission rate and storage capacity can be increased because of two-dimensional, page-oriented data processing; furthermore, the multi-level HDSS can store more than one bit per pixel. For this same reason, however, and unlike conventional data-storage systems, the HDSS is hampered by two-dimensional (2D) intersymbol interference (ISI) and interpage interference (IPI). Progress regarding the published papers on 2D ISI, which is more severe in the multi-level HDSS, continues; however, mitigation of both 2D ISI and IPI in terms of the multi-level HDSS has not yet been studied. In this paper, we therefore propose a 4-level balanced-modulation code that simultaneously mitigates 2D ISI and IPI.

4-level 6/9 Modulation Code for Holographic Data Storage (홀로그래픽 데이터 저장장치를 위한 4레벨 6/9 변조부호)

  • Kim, Byungsun;Park, Keunhwan;Lee, Jaejin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.10
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    • pp.574-578
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    • 2014
  • A holographic data storage (HDS) has some advantages of high storage capacity, fast transmission, and short access time. However, there are two major concerns with the system which are two-dimensional (2D) inter-symbol interference (ISI) and inter-page interference (IPI). Thus, this paper proposes a 4-level 6/9 modulation code which mitigate inter-symbol interference (ISI).