• 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.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.38A no.9
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• pp.739-743
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• 2013

In this paper, a two-dimensional (2-D) channel code for magnetic patterned media is proposed. Patterned media records an information bit on a magnetized dot. Since the space between adjacent tracks is narrow in order to increase the storage density, inter-track interference (ITI) and inter-symbol interference (ISI) can be problems. The amplitude of a bit signal can be corrupted by the 2-D ISI. The signal of the bit surrounded by the same value can be especially destructive, i.e. when its value is the same as the values of the eight surrounding bits. The proposed modulation coding scheme improves the decoding performance of patterned media by preventing this worst case and provides a better code rate than conventional channel codes.

• 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.