Modulation Codes for Multi-wavelength and Multi-Level Photochromic Optical Recording Channel

概要

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Multi-wavelength and multi-level optical recording with photochromic materials is a novel way to increase recording density and data transfer rate significantly. Modulation codes for multi-wavelength and multi-level recording channel are discussed. Firstly, two-dimensional (2-D) run-length-limited (RLL) $(d_{x},d_{y},k;n)$ codes are introduced for multi-wavelength recording. An example of 2-D $\mathrm{RLL}(1,1,6;2)$ code is shown to effectively combat the crosstalk in a two-wavelength recording model. Then, a DC-free four-ary $\mathrm{RLL}(2,8)$ code is designed with code rate of 8/10 (bits/symbol), and a partial-response maximum-likelihood (PRML) detector is used for the four-level $\mathrm{RLL}(2,8)$ modulation recording channel. We also introduce 2-D $\mathrm{RLL}(M,1,\infty)$ codes for the joint multi-wavelength multi-level recording channel. Some numerical results on the capacities are derived, and an example of 2-D $(5,1,\infty)$ code is constructed via state splitting algorithm. These proposed codes show great potential to be applicable in high-density 2-D and multi-level optical recording channels.
2006-02-15