Robust channel estimation for coherent optical orthogonal chirp-division multiplexing with pulse compression and noise rejection
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Accepted version
Date
2018-10-22
Authors
Ouyang, Xing
Antony, Cleitus
Talli, Giuseppe
Townsend, Paul D.
Journal Title
Journal ISSN
Volume Title
Publisher
Institute of Electrical and Electronics Engineers (IEEE)
Published Version
Abstract
Orthogonal chirp-division multiplexing (OCDM) was recently proposed as a promising modulation technique for high-speed fiber-optic communications due to its resilience to transmission impairments. By exploiting the pulse-compression property of the chirped waveforms, in this paper we propose a channel estimation algorithm compatible with the coherent optical (CO) OCDM system. In the proposed algorithm, a chirp from the orthogonal basis of the Fresnel transform is employed as the pilot signal. At the receiver, noise-rejection windowing is adopted in the Fresnel domain to remove the excessive noise after pulse compression, and then dispersions can be effectively compensated by efficient single-tap equalizers. It is shown that the proposed estimator is unbiased as long as the width of the noise-rejection window is wider than the maximum excess delay of the system. Moreover, the optimal window function achieving the minimum mean square error is derived in closed form. With these desired properties, it is shown that the proposed estimator outperforms conventional estimators, such as the intrasymbol frequency-domain average estimator, especially when the dispersion is severe. Finally, numerical results are provided to confirm the advantages of the CO-OCDM system with the proposed channel estimation algorithm.
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Keywords
Channel estimation , Chirp modulation , Equalisers , Frequency-domain analysis , Least mean squares methods , Optical fibre communication , Optical fibre dispersion , Optical modulation , Maximum excess delay , Optimal window function , Intrasymbol frequency-domain average estimator , CO-OCDM system , Channel estimation algorithm , Robust channel estimation , Coherent optical orthogonal chirp-division multiplexing , Pulse compression , Noise rejection , High-speed fiber-optic communications , Transmission impairments , Pulse-compression property , Chirped waveforms , Coherent optical OCDM system , Orthogonal basis , Fresnel transform , Noise-rejection windowing , Fresnel domain , Noise-rejection window , Modulation technique , Chirp , Discrete Fourier transforms , Code division multiplexing , Receivers , Intra-symbol frequency-domain average (ISFA) , Optical coherent detection , Orthogonal chirp-division multiplexing (OCDM) , Orthogonal frequency-division multiplexing (OFDM)
Citation
Ouyang, X., Antony, C., Talli, G. and Townsend, P. D. (2018) 'Robust Channel Estimation for Coherent Optical Orthogonal Chirp-Division Multiplexing With Pulse Compression and Noise Rejection', Journal of Lightwave Technology, 36(23), pp. 5600-5610. doi: 10.1109/JLT.2018.2877305
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