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Photonic Network Communications

, Volume 31, Issue 2, pp 294–304 | Cite as

DFT-based optical offset-QAM OFDM: analytical, numerical, and experimental studies

  • Jian ZhaoEmail author
Article

Abstract

We investigate discrete Fourier transform-based offset quadrature amplitude modulation (offset-QAM) orthogonal frequency division multiplexing (OFDM) technology. We derive a closed-form expression for the de-multiplexed signal and analyze the influence of crosstalk on implementation algorithms and system performance. It is found that channel estimation in offset-QAM OFDM is different from that in conventional OFDM (C-OFDM) due to the residual crosstalk terms and requires particular study. We propose simple and efficient channel estimation algorithms and show, in a 38-Gbit/s offset-16QAM OFDM experiment with 840-km single-mode fiber, that these algorithms can enable the system performance close to the theoretical limit. By using these algorithms, we compare this technology with C-OFDM and Nyquist FDM (N-FDM) and numerically and experimentally show that DFT-based offset-QAM OFDM can greatly enhance the net data rate for fiber transmissions compared to C-OFDM and exhibit lower complexity than N-FDM. These advantages together with the successfully developed implementation algorithms make this technology very promising for optical communication systems.

Keywords

Optical orthogonal frequency division multiplexing Coherent detection Dispersion Crosstalk 

Notes

Acknowledgments

This work was supported by the Science Foundation Ireland under Grant Number 11/SIRG/I2124 and 13/TIDA/I2718, and EU \(7\mathrm{th}\) Framework Program under grant agreement 318415 (FOX-C).

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Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  1. 1.Photonic Systems Group, Tyndall National Institute and Department of PhysicsUniversity College CorkCorkIreland

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