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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

Improved Prediction of Polar Motions by Piecewise Parameterization

Wu Yuanwei, Zhao Xin, Yang Xinyu

Artificial Satellites : Journal of Planetary Geodesy

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2022

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Vol. 57, Special Issue 1

290--299

EN

Natioinal Time Service Center of Chinese Academy of Sciences, Lintong, Shaanxi, China e-mail: yuanwei.wu@ntsc.ac.cn ABSTRACT. On seanonal timescale, the variation of Earth rotation is mainly regulated by angular momentum exchanges between the solid Earth and the fluidal atmosphere, ocean and hydrosphere. In the 2nd EOP PCC, we developed Dill2019’s method for polar motion prediction, using piecewise autoagressive parameters. The maximum prediction errors within 90 days are 36 and 16 mas for polar motion x and y components, respectively. Compared with Bulletin A, the mean absolute error of polar motion y prediction is improved by 20% in all timescale, and with a maximum improvement of 49% on the 5th day. Whereas, for polar motion x, the performance is slightly better (2% - 8%) within 30 days but worse (−7%∼ −19%) within 30∼90 days. We found that the prediction accuracy is very sensitive to the quality of the angular momentum data. For example, on average, the prediction of polar motion y is around 2 times better than polar motion x. In addition, we found the accuracy of 30-90 days prediction is dramatically decreased in the year 2020. We suspect that such deterioration might be due to the pandemic of coronavirus COVID-19, which suppressed global airline activities by more than 60%, then result in a lose of air-borne meteorological data, which are important for weather forecast.

3

Metoda wykrywania rogue ONU - nieposłusznej jednostki w sieci GPON

Kula Sławomir

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2019

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nr 7

658--663, CD

PL

Referat jest poświęcony wykrywaniu rogue ONU, tak zwanych „nieposłusznych” jednostek ONU sieci GPON.W referacie omówiono sygnalizację alarmową wykazując niemożność jej wykorzystania do wykrywania nieposłusznej jednostki ONU. Przedstawiono dotychczas proponowane lub stosowane metody rozwiązania problemu. Zasadniczą część referatu stanowi przedstawienie nowej efektywnej propozycji rozwiązania problemu nieposłusznej jednostki ONU, zarówno od strony idei, jak i jej realizacji technicznej.

EN

The paper is devoted to detecting the rogue ONU, so called disobedient ONU unit of the GPON network. The paper discusses the alarm signaling showing its impossibility to use it to detect the disobedient ONU unit. So far, proposed or applied methods of solving the problem are presented. The main part of the paper is the presentation of the new effective proposal to solve the problem of the disobedient ONU unit, both of the perspective of the idea and its technical implementation.

4

Mobile MPLS-TP : Support the mobility of terminal devices using OAM channel

Pijanka M. M., Różański G. W.

International Journal of Electronics and Telecommunications

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2016

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Vol. 62, No. 3

215--223

EN

MPLS architecture for transport networks play the significant role in the development of next generation networks, in particular with regard to the guarantee of continuity of communications "end-to-end" through a variety of heterogeneous segments of the telecommunications network. The article presents the concept of Mobile MPLS-TP with the use of OAM channels to support the mobility of users and optimize "Handoff" procedure in a hierarchical network topology.