한국통신학회논문지 (The Journal of Korean Institute of Communications and Information Sciences)

한국통신학회 (The Korean Institute of Commucations and Information Sciences)
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멀티레벨 홀로그래픽 저장장치를 위한 적응 EM 알고리즘

Adaptive Threshold Detection Using Expectation-Maximization Algorithm for Multi-Level Holographic Data Storage

  • 김진영 (숭실대학교 정보통신전자공학부 정보저장 및 통신 연구실) ;
  • 이재진 (숭실대학교 정보통신전자공학부 정보저장 및 통신 연구실)
  • 투고 : 2012.10.16
  • 심사 : 2012.10.23
  • 발행 : 2012.10.30
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초록

본 논문은 멀티레벨을 가지는 홀로그래픽 저장 장치에서 EM (Expectation-maximization) 알고리즘을 이용한 적응 문턱전압검출기를 제안한다. 멀티레벨을 이용한 홀로그래픽 저장 장치의 경우 DC 오프셋의 정도에 따라 비적응 문턱전압검출기의 성능에 매우 심각한 영향을 미친다. EM 방법은 채널을 통과한 데이터를 이용해 Expectation step과 maximization step을 반복하면서 평균과 분산을 추정하는 방법이다. DC 오프셋이 있는 상황에서 제안된 방법을 적용하여 문턱값을 찾아내서 검출한 결과 일정한 한도 내의 DC 오프셋의 경우는 DC 오프셋이 없는 경우와 동일한 성능을 보였다.

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.

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참고문헌

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