Latifa Guesmi

Modulation formats recognition technique using artificial neural networks for radio over fiber systems

In this paper, we present and investigate a novel method for modulation formats recognition for radio-over-fiber (RoF) systems. The technique uses the artificial neural network (ANN) in conjunction with the features of asynchronous amplitude histograms of the detected signals at high bit rates using direct detection. The use of ANN method for this purpose mainly driven by its ability to learn complex classification problems and the use of sequential training algorithm to increase the estimation accuracy of all modulation formats. The efficiency of this technique is demonstrated under different transmission impairments such as chromatic dispersion (CD) in the range of 34 to 170 ps/nm, differential group delay (DGD) in the range of 0 - 20 ps and the optical signal to-noise ratio (OSNR) in the range of 4 - 30 dB. The results of numerical simulation for various modulation formats demonstrate successful recognition from a known bit rates with a higher estimation accuracy, which exceeds 99.9%.

Method of joint bit rate/modulation format identification and optical performance monitoring using asynchronous delay-tap sampling for radio-over-fiber systems

Abstract. In the context of carrying a wide variety of modulation formats and data rates for home networks, the study covers the radio-over-fiber (RoF) technology, where the need for an alternative way of management, automated fault diagnosis, and formats identification is expressed. Also, RoF signals in an optical link are impaired by various linear and nonlinear effects including chromatic dispersion, polarization mode dispersion, amplified spontaneous emission noise, and so on. Hence, for this purpose, we investigated the sampling method based on asynchronous delay-tap sampling in conjunction with a cross-correlation function for the joint bit rate/modulation format identification and optical performance monitoring. Three modulation formats with different data rates are used to demonstrate the validity of this technique, where the identification accuracy and the monitoring ranges reached high values.

Automatic modulation format recognition for the next generation optical communication networks using artificial neural networks

A new technique for Automatic Modulation Format Recognition (AMFR) in next generation optical communication networks is presented. This technique uses the Artificial Neural Network (ANN) in conjunction with the features of Linear Optical Sampling (LOS) of the detected signal at high bit rates using direct detection or coherent detection. The use of LOS method for this purpose mainly driven by the increase of bit rates which enables the measurement of eye diagrams. The efficiency of this technique is demonstrated under different transmission impairments such as chromatic dispersion (CD) in the range of -500 to 500 ps/nm, differential group delay (DGD) in the range of 0-15 ps and the optical signal tonoise ratio (OSNR) in the range of 10-30 dB. The results of numerical simulation for various modulation formats demonstrate successful recognition from a known bit rates with a higher estimation accuracy, which exceeds 99.8%.

Polarization mode dispersion monitoring in the presence of XPM effect for high speed WDM communication systems

WDM optical systems and nonlinear effects are experiencing last years a huge investigation for performance evaluation. In this paper, and for high speed phase modulated WDM Nyquist systems, a novel method of PMD and first-order PMD (DGD) monitoring using cross phase modulation effect is presented. This technique demonstrate that in the presence of XPM effect, the states of polarization changes and the group-velocity mismatch operates effectively to evaluate the performance of the proposed method. The results are extended to show the output power variation when the number of WDM channels increase for a giving DGD values.

Comb source generation by dual-tone excitation of a dual-arm MZM

A novel way to generate asymmetric optical comb sources is presented. Optical comb sources are an essential component of Terabit orthogonal frequency-division multiplexing (OFDM) and wavelength division multiplexing-Nyquist (WDM-Nyquist) systems. Each arm of the modulator is excited with the linear combination of two sine waves. An asymmetric output spectrum characterized by a flat region, where spectral ripple less than 1dB and which width ranges from 4 to 32 sub-carriers. The simulated annealing optimization algorithm was used to speed up the search for the aforementioned flat regions. The search results for the entire possibility space are interpolated.

Improved optical performance monitoring technique based on nonlinear optics for high-speed WDM Nyquist systems

The field of fiber optics nonlinearity is more discussed last years due to such remarkable enhancement in the nonlinear processes efficiency. In this paper, and for optical performance monitoring (OPM), a new achievement of nonlinear effects has been investigated. The use of cross-phase modulation (XPM) and four-wave mixing (FWM) effects between input optical signal and inserted continuous-wave probe has proposed for impairments monitoring. Indeed, transmitting a multi-channels phase modulated signal at high data rate (1 Tbps WDM Nyquist NRZ- DP-QPSK) improves the sensitivity and the dynamic range monitoring. It was observed by simulation results that various optical parameters including optical power, wavelength, chromatic dispersion (CD), polarization mode dispersion (PMD), optical signal-to-noise ratio (OSNR), Q-factor and so on, can be monitored. Also, the effect of increasing the channel spacing between WDM signals is studied and proved its use for FWM power monitoring.

Robust modulation formats recognition technique using wavelet transform for high speed optical networks

There is a need, for high speed optical communication networks, in the monitoring process, to determine the modulation format type of a received signal. In this paper, we present a new achievement of modulation format recognition technique, where we proposed the use of wavelet transform of the detected signal in conjunction with the artificial neural network (ANN) algorithm. Besides, wavelet transform is one of the most popular candidates of the time-frequency transformations, where the wavelets are generated from a basic wavelet function by dilations and translations. We proved that this technique is capable of recognizing the multi-carriers modulation scheme with high accuracy under different transmission impairments such as chromatic dispersion (CD), differential group delay (DGD) and accumulated amplified spontaneous emission (ASE) noise with different ranges. Both the theoretical analysis and the simulation results showed that the wavelet transform not only can be used for modulation identification of optical communication signals, but also has a better classification accuracies under appropriate OSNR (optical signal-to-noise ratio) values.

Simultaneous and independent optical impairments monitoring using singular spectrum analysis of asynchronously sampled signal amplitudes

Optical performance monitoring (OPM) becomes an inviting topic in high speed optical communication networks. In this paper, a novel technique of OPM based on a new elaborated computation approach of singular spectrum analysis (SSA) for time series prediction is presented. Indeed, various optical impairments among chromatic dispersion (CD), polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise are a major factors limiting quality of transmission data in the systems with data rates lager than 40 Gbit/s. This technique proposed an independent and simultaneous multi-impairments monitoring, where we used SSA of time series analysis and forecasting. It has proven their usefulness in the temporal analysis of short and noisy time series in several fields, that it is based on the singular value decomposition (SVD). Also, advanced optical modulation formats (100 Gbit/s non-return-to zero dual-polarization quadrature phase shift keying (NRZ-DP-QPSK) and 160 Gbit/s DP-16 quadrature amplitude modulation (DP-16QAM)) offering high spectral efficiencies have been successfully employed by analyzing their asynchronously sampled amplitude. The simulated results proved that our method is efficient on CD, first-order PMD, Q-factor and OSNR monitoring, which enabled large monitoring ranges, the CD in the range of 170-1700 ps/nm.Km and 170-1110 ps/nm.Km for 100 Gbit/s NRZ-DP-QPSK and 160 Gbit/s DP-16QAM respectively, and also the DGD up to 20 ps is monitored. We could accurately monitor the OSNR in the range of 10-40 dB with monitoring error remains less than 1 dB in the presence of large accumulated CD.