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Joint timing and frequency synchronization in coherent optical OFDM systems

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Abstract

In this paper, we review our joint timing and frequency synchronization algorithms in coherent optical orthogonal frequency division multiplexing (CO-OFDM) systems. We first present a timing estimation method by designing the pattern of the training symbol, whose timing metric has a sharp and clear peak, to ensure accurate timing offset (TO) estimation performance. Then we provide both data-aided (DA) and blind (BL) approaches to estimate the carrier frequency offset (CFO). For the DA algorithm, we utilize the same training symbol structure as the timing estimation does, while for the BL algorithm, we utilize the zero-subcarrier power (ZSP) to achieve full-range CFO estimation. Note that our joint timing and frequency synchronization approaches require only one OFDM symbol, which ensure not only the data transmission efficiency, but also the TO and CFO estimation performance. A modified BL ZSP algorithm is proposed to further improve the CFO estimation performance by taking the power average over a series of OFDM symbols. The effectiveness of the TO estimation algorithm, and both the DA and BL CFO estimation algorithms are verified and demonstrated in both simulations and experiments.

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Acknowledgements

The authors would like to thank the supports of Grants 61501313, 61571316 and 61302112 from NSFC and Grant 1-ZE5K from the Hong Kong Polytechnic University.

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Authors and Affiliations

  1. Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583, Singapore

    Xinwei Du & Pooi-Yuen Kam

  2. National University of Singapore (Suzhou) Research Institute, Suzhou, 21512, China

    Xinwei Du

  3. Department of Electrical and Information Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    Xinwei Du & Changyuan Yu

Authors
  1. Xinwei Du
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  2. Pooi-Yuen Kam
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  3. Changyuan Yu
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Corresponding author

Correspondence to Changyuan Yu.

Additional information

Dr. Changyuan Yu received his Ph.D. degree in Electrical Engineering from the University of Southern California, USA in 2005. He was a visiting researcher at NEC Labs America in Princeton, USA in 2005. He then joined the faculty of National University of Singapore (NUS) in 12/2005, where he served as the founding leader of Photonic System Research Group in Department of Electrical and Computer Engineering. He was also a joint senior scientist with Institute for Infocomm Research (I2R), Agency for Science, Technology and Research (A*STAR) in Singapore. In 12/2015, he joined The Hong Kong Polytechnic University as an associate professor in Department of Electronic and Information Engineering. And he also continues as an adjunct associate professor of NUS. His research focuses on photonic devices, subsystems, optical fiber communication and sensor systems, and biomedical instruments. As the PI/co-PI, he secured over 5 million US dollars grants, and supervised 10 postdocs and 20 PhD students. He has authored/co-authored 1 US patent, 6 book chapters, 400 + journal and conference papers (75 invited, including OFC2012 in USA). His group won 6 best paper awards in conferences and the championship in biomedical area in the 3rd China Innovation and Entrepreneurship Competition in 2014.

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Du, X., Kam, PY. & Yu, C. Joint timing and frequency synchronization in coherent optical OFDM systems. Front. Optoelectron. 12, 4–14 (2019). https://doi.org/10.1007/s12200-019-0868-7

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  • DOI: https://doi.org/10.1007/s12200-019-0868-7

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