A scalable and hardware-efficient architecture for digitally adaptive electronic dispersion compensation

Daniel Efinger; Stefan Payer; Halmo Fischer

doi:10.1117/12.852371

25 November 2009 A scalable and hardware-efficient architecture for digitally adaptive electronic dispersion compensation

Daniel Efinger, Stefan Payer, Halmo Fischer

Author Affiliations +

Proceedings Volume 7632, Optical Transmission Systems, Switching, and Subsystems VII; 763206 (2009) https://doi.org/10.1117/12.852371
Event: Asia Communications and Photonics, 2009, Shanghai, Shanghai , China

Abstract

We present a novel hardware architecture for digitally adaptive feed-forward equalization (FFE) suitable to compensate the inter-symbol interference (ISI) caused by chromatic (CD) and time-varying polarization mode dispersion (PMD) in intensity modulated optical links with direct detection (IM/DD). Existing analog tapped delay lines for realizing the equalization filter at a bit rate of 40 Gbit/s commonly use external manual or random dithering approaches for tap weight adjustment^1,2. While manual tap weight adjustment is impractical for systems with randomly time-varying behavior, random dithering of the tap weights to find the optimal setup shows adaptation times above 1s which exceeds the measured PMD variations in installed fibers³ (~10ms) by far. Our solution follows a completely digital implementation approach and it can be scaled to various bit rates using distributed arithmetic (DA) and some parallelization techniques. The digital adaptation unit, which employs a simplified Least-Mean-Square-Algorithm (LMS)⁴, is directly implemented together with the FFE. Measurements in our hardware-in-the-loop testbed with a Virtex-II field programmable gate array (FPGA) from Xilinx have demonstrated that it is able to track time-varying optical channels well within 1 ms at a bit rate of 10.7 Gbit/s.

Citation Download Citation

Daniel Efinger, Stefan Payer, and Halmo Fischer "A scalable and hardware-efficient architecture for digitally adaptive electronic dispersion compensation", Proc. SPIE 7632, Optical Transmission Systems, Switching, and Subsystems VII, 763206 (25 November 2009); https://doi.org/10.1117/12.852371

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