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1

Evaluation of a high-speed hybrid OAM-OFDM-MDM multiplexed coherent FSO system under desert conditions

Sinha Shivaji, Kumar Chakresh

Optica Applicata

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2023

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Vol. 53, nr 3

431--445

EN

To meet the needs of future wireless optical networks, this paper introduces a high-speed, hybrid multiplexed, coherent free-space optical (FSO) communication system that integrates an orbital angular momentum (OAM) multiplexed signal with an orthogonal frequency division multiplexing (OFDM) technique. Two independent QAM polarized beams, each carrying in-phase and quadrature (I/Q) phase 16-QAM-OFDM modulated data, are combined using mode division multiplexing (MDM) to increase the capacity of the proposed system. The reason of choosing OFDM is its capability to support higher data rate, and mitigating intersymbol interference (ISI). The signal is detected using a coherent detection-based digital signal processing (DSP) algorithm at the receiver end. The proposed hybrid FSO system is evaluated in low and heavy dust environments using bit error rate (BER), link distance, optical signal-to-noise ratio (OSNR), and received optical power performance matrices. The simulation results demonstrate the successful transmission of a 120 Gb/s single carrier over the longest link ranges of 1.5 and 0.40 km, respectively, under low and heavy dust weather environments below the signal degradation threshold value (forward error correction (FEC) limit) of BER 2.2 × 10–3 in strong turbulent conditions.

2

Simultaneous monitoring of chromatic dispersion and optical signal to noise ratio in optical links using convolutional neural network and asynchronous delay-tap sampling

Mrozek Tomasz, Perlicki Krzysztof, Jakubiak Andrzej

Optica Applicata

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2020

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Vol. 50, nr 3

331--341

EN

The article presents a method for image analysis using asynchronous delay-tap sampling (ADTS) technique and convolutional neural networks (CNNs), allowing simultaneous monitoring of many phenomena occurring in the physical layer of the optical network. The ADTS method makes it possible to visualize the course of the optical signal in the form of characteristics (so-called phase portraits), which change their shape under the influence of phenomena (including chromatic dispersion, amplified spontaneous emission noise and other). Using the VPI photonics software,a simulation model of the ADTS technique was built. After the simulation tests, 10000 images were obtained, which after proper preparation were subjected to further analysis using CNN algorithms. The main goal of the study was to train a CNN to recognize the selected impairment (distortion); then to test its accuracy and estimate the impairment for the selected set of test images. The input data consisted of processed binary images in the form of two-dimensional matrices, with the position of the pixel. This article focuses on the analysis of images containing simultaneously the phenomena of chromatic dispersion and optical signal to noise ratio.

3

The use of convolutional neural networks for simultaneous monitoring of chromatic dispersion and Optical to Signal Noise Ratio in the physical layer of the optical network

Mrozek Tomasz, Perlicki Krzysztof

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2019

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nr 3

67--72

EN

The article presents a method for image analysis using Asynchronous Delay Tap Sampling (ADTS) technique and Convolutional Neural Networks (CNN), allowing simultaneous monitoring of many phenomena occurring in the physical layer of the optical network. The ADTS method makes it possible to visualize the course of the optical signal in the form of characteristics (so-called phase portraits), which change their shape under the influence of phenomena (including chromatic dispersion, amplified spontaneous emission noise and others). Using the VP Iphotonics software, a simulation model of the ADTS technique was built. After the simulation tests, 10000 images were obtained, which after proper preparation were subjected to further analysis using convolutional neural networks algorithms. The main goal of the study was to train a convolutional neural network to recognize the selected impairment (distortion); then to test its accuracy and estimate the impairment for the selected set of test images. The input data consisted of processed binary images in the form of two-dimensional matrices, with the position of the pixel. This article focuses on the analysis of images containing simultaneously the phenomena of chromatic dispersion and optical to noise signal ratio.

PL

Przedstawiono metodę analizy obrazu za pomocą technik: Asynchronous Delay Tap Sampling (ADTS) i Convolutional Neural Networks (CNN), umożliwiającą równoczesne monitorowanie wielu zjawisk zachodzących w warstwie fizycznej sieci optycznej. Metoda ADTS umożliwia wizualizację przebiegu sygnału optycznego w postaci charakterystyk (tzw. portrety fazowe), które zmieniają swój kształt pod wpływem zjawisk (w tym dyspersji chromatycznej, OSNR i innych). Za pomocą oprogramowania VP Iphotonics zbudowano model symulacyjny techniki ADTS. Po testach symulacyjnych uzyskano 10 000 obrazów, które po odpowiednim przygotowaniu poddano dalszej analizie za pomocą algorytmówk konwolucyjnych sieci neuronowych. Głównym celem badań było nauczenie konwolucyjnej sieci neuronowej rozpoznawania równocześnie występujących zaburzeń. Dane wejściowe składały się z przetworzonych obrazów binarnych w postaci macierzy dwuwymiarowych. Artykuł skupia się na analizie obrazów zawierających jednocześnie zjawisko dyspersji chromatycznej i OSNR.

4

An 80 Gbps multi-band access radio over fiber link with single side band optical millimeter-wave dispersion-tolerant transmission without FBG and optical filter

Ashaa R. S., Jayasree V. K., Mhatli S.

Opto-Electronics Review

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2017

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Vol. 25, No. 4

311--317

EN

We are presenting a new low-cost Single Sideband (SSB) modulated Radio-over Fiber (RoF) communication system for millimeter (mm)-wave multiband wireless communication at the frequencies of 40 GHz,80 GHz and 120 GHz. Its principle lies in the Carrier Suppressed modulation through a nested dual electrode Mach–Zehnder Modulator (MZM) and product modulator based baseband signal decomposition. In this novel method, the optical signal is decomposed into different SSB signals using a power splitter and product modulators at the base station. This proposed method uses a different technique for a baseband signal decomposition from the existing method. The proposed signal decomposition technique has reduced the nonlinearities due to the FBGs. The proposed method is compared with the existing method in terms of BER, data rate and OSNR. The simulation results disclose that our proposed scheme outperforms the existing methods at a higher data rate of 80 Gbps with a minimum BER and privileged Q factor.