22 January 2010 NLMS-based PMD equalization with improved adaption speed
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Abstract
The still increasing demand for data bandwidth in short-haul transmission as well as in long- haul transmission implicates the development of optical high-speed communication systems that carry 40 Gbit/s and higher. This step is limited mainly by the polarization mode dispersion (PMD) of the fiber infrastructure. Direct detection transmission systems are state of the art. At this the square-law detection of the photo diode transforms linear distortions into nonlinear effects, which makes linear equalization principles less effective. Coherent detection on the other hand delivers amplitude, phase and polarization information of the field and thus enables advanced PMD-compensation in the electrical domain. We realize PMD-compensation by means of least mean squares based adaptive electronic equalizers. The drawback of adaptive equalization principles is the setting of the adaption step-size. Small step-sizes lead to very accurate results, but are very time-consuming. By contrast large step-sizes can accelerate the adaption process but lead to inaccurate equalizer settings. Accordingly, it is desirable to resize the step-size during the adaption process. For these reasons different step-size control algorithms are implemented, analyzed and adapted to the requirements of an optical PMD affected transmission system. It shows that step-size control algorithms are able to accelerate the adaption-process significantly.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Daniel Goelz, Peter Meissner, "NLMS-based PMD equalization with improved adaption speed", Proc. SPIE 7621, Optical Metro Networks and Short-Haul Systems II, 76210P (22 January 2010); doi: 10.1117/12.841940; https://doi.org/10.1117/12.841940
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