• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.459-464
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• 2013

In this paper, we introduce a modulation code design problem where best selection of two-dimensional codewords are determined to reduce two-dimensional (2D) intersymbol interference (ISI) and interpage interference (IPI). Codeword selection problem is formulated as a quadratic integer programming model that minimizes intra- and inter-symbol differences subject to uniform symbol usage and minimal Hamming distance violations. Second integer programming model detects the occurrence of isolated pixel pattern in the selected codewords. The proposed models are applied to 4-level and 2-level 6/8 codes.

• 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).

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.9-14
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• 2016

In the holographic data storage system, the data can be stored more than one bit per pixel and the storage capacity and transmission rate can be increased. In this paper, we proposed a sparse-ON pixel 4/6 balanced-modulation code that the code rate is 1.33 (bit/pixel) with uniform page density. Even though the performance of the proposed sparse-ON pixel 4/6 balanced-code is similar to 2/3 and 6/9 modulation codes, it can increase the storage capacity more than these modulation codes and also store more pages in a volume by reducing the rate of ON pixels to mitigate IPI (inter-page interference).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.465-470
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• 2013

In this paper, we introduce a modulation code design problem where best selection of two-dimensional codewords are determined to reduce two-dimensional (2D) Intersymbol Interference (ISI) and Interpage Interference (IPI), while when these codewords are randomly arranged on the storage, isolated pixel cannot be formed. Codeword selection problem and isolated pixel detection problem are formulated as integer program models and we develop a cutting plane algorithm where a valid cut is generated to remove current feasible solution to avoid isolated pixel by solving the isolated pixel detection subproblem. Using the proposed method, $4{\times}2$ 6/8 codewords with non-isolated pixel are found.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.8
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• pp.1976-1988
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• 1996

This paper describes TCM(trellis coded modulation) schemes using 32VSB signal for digital CATV system. First we design optimum encoder with code rate 4/5 for 32VSB by using one dimenstional signal constellation and obtain 0.75-4.38 dB coding gains over the existing uncoded 16VSB. Second by using two dimensional signal constellation we design TCM encoders with code rate 9/10, which are better in the power efficienty (0.5-2.27 dB) and the transmission rate(12.5%), and we also design TCM encoders which have more coding gains than one dimensional TCM encoders for the larger number of states(more than 8 states).

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.6
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• pp.10-14
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• 2015

In holographic data storage systems, data is recorded and read by page on a volume of storage medium, and it can increase transmission rate and storage capacity because of two-dimensional page-oriented data processing by charge-coupled devices. However, HDS suffers two-dimensional intersymbol interference unlike conventional data storages. In this paper, we propose a preprocessing method of decreasing ISI before read data in HDS pass to detector. This method has some advantage when we collaborate with the preprocessing for reducing misalignment error and modulation code.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11A
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• pp.1073-1077
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• 2010

This paper proposes a new 4-dimensional(4D) constellation-rotation(CR) method which obtains diversity gain of 4 under Rayleigh fading channels. The proposed scheme uses two consecutive CR operations for the constellation of QAM signals unlike a conventional 2-dimensional(2D) CR method using only one CR operation. The computer simulation results show that the new method outperforms the conventional one even more as both the channel code rate and the erasure ratio increase. In a point of system flexibility, the proposed scheme has a great advantage since the conventional 2D CR scheme can be simply implemented by only changing rotation angle values used in the proposed scheme.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.229-231
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• 1988

In this paper, we design adaptive DPCM by the two dimensional linear prediction using the covariance method and propose adaptive algorithm which determines analysis frame size by the compassion of the local standard deviation and the global standard deviation of images.