Summary

International Symposium on Extremely Advanced Transmission Technologies

2019

Session Number:P

Session:

Number:P-24

Quasi-Nyquist WDM Networks Using Widely Deployed Wavelength-Selective Switches

Ryuta Shiraki,  Yojiro Mori,  Hiroshi Hasegawa,  Ken-ichi Sato,  

pp.-

Publication Date:2019/5/29

Online ISSN:2188-5079

DOI:10.34385/proc.31.P-24

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Summary:
"To cost-effectively process growing traffic carried through photonic networks, the spectral efficiency must be improved by employing highly dense wavelengthdivision multiplexing (WDM) such as quasi-Nyquist WDM. In such systems, however, signals suffer from spectrum narrowing caused by traversing wavelengthselective switches (WSSs) placed in optical nodes; the small guardband width results in severe spectrum narrowing [1]. Furthermore, the limited WSS-passband resolution is another factor that interferes the improvement of spectral efficiency; widely deployed WSSs cannot process optical paths on a wavelength basis if the channel frequencies are aligned more finely than a 12.5-GHz granularity determined by ITU-T. In this paper, we demonstrate a photonic-network architecture that enables widely deployed WSSs to support quasi-Nyquist WDM transmission. Its effectiveness is confirmed through transmission experiments and network simulations. In order to complement the limited WSS-passband resolution, multiple channels consecutive in the frequency domain are bundled so that the aggregated bandwidth of each bundle matches the WSS-passband resolution. Additionally, the maximum number of spectrumnarrowing events triggered by adjacent paths, Ns, is controlled by our wavelength-assignment algorithm. Consequently, we can accommodate three 400-Gbps dual-carrier DP-16QAM signals aligned with 66.6-GHz spacing within a 200-GHz bandwidth even while complying with the two restrictions [2]."