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“Multi-Dimensional Modulation Coding for Page-Oriented Optical Data Storage Systems”
by Dhawat "Eddie" Pansatiankul
May 2002
Page-oriented optical data storage (PODS) technology has great potential benefit for future computer applications that require tremendous data storage capacity and very high data transfer rates. As with any conventional data storage technology, PODS systems operating near their maximum capabilities need modulation coding to facilitate their recording and retrieving processes and, consequently, to improve their overall system performance. However, the modulation coding scheme designed for a specific data storage technology is generally inappropriate for others. This dissertation contains a comprehensive analysis of suitable modulation coding schemes and corresponding modulation codes for PODS systems that use two-photon absorption technology.
We present several two-dimensional (2-D) mathematical models for various two-photon PODS systems. Using these 2-D models, we describe the nature of intersymbol interference (ISI) in two-photon PODS systems and find that its characteristics are different from ISI in conventional data storage systems. To overcome the inherent ISI in two-photon PODS systems, we present a novel 2-D modulation coding scheme. We also present a number of fixed-length and variable-length 2-D modulation codes with diverse properties based on our 2-D modulation coding scheme. The bit-error-rate (BER) performance of these 2-D modulation codes is investigated and compared.
In addition to the ISI, the interpage interference (IPI) may also be significant in two-photon PODS systems. We present many three-dimensional (3-D) mathematical models for a variety of two-photon PODS systems to examine IPI and its effects. In order to overcome the effects of ISI and the effects of IPI in two-photon PODS systems simultaneously, we present a new 3-D modulation coding scheme that is an extension of our 2-D modulation coding scheme. Examples of 3-D modulation codes derived from our 3-D modulation coding scheme are also presented. Finally, we discuss techniques to encode and extract clock information in two-photon PODS systems.