Near-optimal parallel distributed data detection for page-oriented optical memories

Xiaopeng Chen, Keith M. Chugg, Mark A. Neifeld

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

Volume optical storage systems suffer from numerous sources of noise and interference, the effects of which can seriously degrade retrieved data fidelity and produce unacceptable bit-error rates (BER's). We examine the problem of reliable two-dimensional data retrieval in the context of recently developed soft-decision methods for iterative decoding. We describe a novel near-optimal algorithm in which each pixel on the page is treated as a starting point for a simple iterative procedure so that a highly parallel, locally connected, distributed computational model emerges whose operation is well suited to the page-oriented memory (POM) interface format. We study the use of our two-dimensional distributed data detection (2D 4) algorithm with both incoherent (linear) and coherent (nonlinear) finite-contrast POM channel models. We present BER results obtained using the 2D 4 algorithm and compare these with three other typical methods [i.e., simple thresholding (THA), differential encoding (DC) and the decision feedback Viterbi algorithm (DFVA)]. The BER improvements are shown to have a direct impact on POM storage capacity and density and this impact is quantified for the special case of holographic POM. In a Rayleigh resolved holographic POM system with infinite contrast, we find that 2D 4 offers capacity improvements of 84%, 56%, and 8% as compared with DC, THA, and DFVA respectively, with corresponding storage density gains of 85%, 26%, and 9%. In the case of finite contrast (C = 4), similar capacity improvements of 93%, 18%, and 4% produce similar density improvements of 98%, 21%, and 6%. Implementational issues associated with the realization of this new distributed detection algorithm are also discussed and parallel neural and focal plane strategies are considered. A 2 cm 2 λ = 0.1 μm digital VLSI real estate budget will support a 600 × 600 pixel 2D 4 focal plane processor operating at 40 MHz with less than 1.7 W/cm 2 power dissipation.

Original languageEnglish (US)
Pages (from-to)866-879
Number of pages14
JournalIEEE Journal on Selected Topics in Quantum Electronics
Volume4
Issue number5
DOIs
StatePublished - Sep 1 1998

Keywords

  • Distributed detection
  • Iterative method
  • Maximum likelihood detection
  • Optical memories
  • Parallel algorithm

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering

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