Wszystkie pola: Free Space Optical - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: SAC-OCDMA over Hybrid FTTx Free Space Optical Communication Networks
Autorzy:: Sahbudin, R. K. Z.
Chun, T. T. K.
Anas, S. B. A.
Hitam, S.
Mokhtar, M.
Powiązania:: https://bibliotekanauki.pl/articles/308402.pdf
Data publikacji:: 2015
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Tematy:: Hybrid FTTx free space optical
Khazani-Syed code
SAC-OCDMA
Spectral direct decoding
Opis:: This paper presents an investigation of Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) over hybrid Fiber-to-the-x (FTTx) Free Space Optical (FSO) link under different weather conditions. FTTx and FSO are the last mile technologies that complement each other in delivering secure and high speed communication to customers' residence or office. SAC-OCDMA is one of the potential multiplexing techniques that has become a research area of interest in optical communications and considered a promising technique for FTTx access networks. It is based on Khazani-Syed (KS) code with Spectral Direct Decoding (SDD) technique. All the components involved in the network were specied according to the available market product in order to simulate the actual environment as close as possible. The result shows that for bit error rate (BER) of 10‾9, the network is able to perform with 20 km Single Mode Fiber (SMF) spanning from the central office (CO) and 1.48 km FSO range with transmission rate of 1.25 Gb/s during heavy rain.
Źródło:: Journal of Telecommunications and Information Technology; 2015, 2; 52-58
1509-4553
1899-8852
Pojawia się w:: Journal of Telecommunications and Information Technology
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Performance probability distribution function for modeling visibility for free space optical link in Nigeria
Autorzy:: Ojo, Joseph Sunday
Olakunle Lawrence, Ojo
Ibitola, Gilbert Akin
Powiązania:: https://bibliotekanauki.pl/articles/1163564.pdf
Data publikacji:: 2018
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:: Free Space Optical
Nigeria
distribution functions
lognormal
visibility
Opis:: This paper attempt to assess the performance of the most appropriate distribution function for modeling atmospheric visibility over five selected locations (Akure, Enugu, Ikeja, Jos and Port-Harcourt) in Nigeria. The distribution functions are tested based on 5-year (2010-2014) visibility data obtained from Nigeria Meteorological Agency (NIMET). Five distribution functions are tested to determine most suitable one based on four different metric measures. The associated parameters of the most suitable fitted distribution are estimated and the trends in the characteristic of the visibility are deduced. The result shows that lognormal distribution present the best probability distribution function for modeling visibility over the selected locations. A typical result for one of the locations (Akure) show that the lognormal distribution has Root Mean Square Error (RMSE) of 0.0766 km, Mean Absolute Error (MAE) of 0.0095 km, Mean Absolute Percentage Error (MAPE) of 17.8 % and coefficient of determination (R2) of 0.87. When compared with other distribution functions, the same trend could be seen in other locations although with different values of RMSE, MAE, MAPE and R2. The location and the scale parameters for the total distribution varies seasonal-wise and are location depended. The overall result will be useful for predicting future visibility over the locations. It will also be a good tool for free space optical link design in Nigeria.
Źródło:: World Scientific News; 2018, 109; 211-234
2392-2192
Pojawia się w:: World Scientific News
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Comparative BER Analysis of Free Space Optical System Using Wavelength Diversity over Exponentiated Weibull Channel
Autorzy:: Shah, Dhaval
Joshi, Hardik
Kothari, Dilipkumar
Powiązania:: https://bibliotekanauki.pl/articles/2055211.pdf
Data publikacji:: 2021
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: bit error rate
exponentiated weibull distribution
free space optics
FSO
wavelingth diversity
optimal combining
Opis:: Atmospheric turbulence is considered as major threat to Free Space Optical (FSO) communication as it causes irradiance and phase fluctuations of the transmitted signal which degrade the performance of FSO system. Wavelength diversity is one of the techniques to mitigate these effects. In this paper, the wavelength diversity technique is applied to FSO system to improve the performance under different turbulence conditions which are modeled using Exponentiated Weibull (EW) channel. In this technique, the data was communicated through 1.55 µm, 1.31 µm, and 0.85 µm carrier wavelengths. Optimal Combining (OC) scheme has been considered to receive the signals at receiver. Mathematical equation for average BER is derived for wavelength diversity based FSO system. Results are obtained for the different link length under different turbulence conditions. The obtained average BER results for different turbulence conditions characterized by EW channel is compared with the published result of average BER for different turbulence which is presented by classical channel model. A comparative BER analysis shows that maximum advantage of wavelength diversity technique is obtained when different turbulence conditions are modeled by EW channel.
Źródło:: International Journal of Electronics and Telecommunications; 2021, 67, 4; 665--672
2300-1933
Pojawia się w:: International Journal of Electronics and Telecommunications
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: An approach to investigating the feasibility of free-space optical communication technology deployment under scintillation effects
Autorzy:: Mahmood, Aras S.
Powiązania:: https://bibliotekanauki.pl/articles/27315698.pdf
Data publikacji:: 2023
Wydawca:: Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:: free-space optical communication
atmospheric turbulence
scintillation attenuation
refractive index structure parameter (Cn²)
Opis:: Local weather conditions have an impact on the availability of free-space optical (FSO) communication. The variation in meteorological parameters, such as temperature, humidity, and wind speed, leads to variations of the refractive index along the transmission path. These refractive index inhomogeneities produced by atmospheric turbulence induce optical turbulence which is responsible for random fluctuations in the intensity of the laser beam that carries the signal (irradiance) called scintillations that can significantly degrade the performance of FSO systems. This paper aims to investigate the feasibility of deploying FSO communication technology under scintillation effects in any urban region and atmospheric environment. To achieve that, firstly by utilizing the Hufnagel-Vally day with the Sadot and Kopeika models together, the scintillation strength for a specified region, Sulaimani City in north-eastern Iraq as an example, has been estimated through the calculation of the refractive index structure parameter (Cn²) over a period of 10 years and it was found to be at the strong turbulence level. Secondly, from the same estimated parameter, the scintillation attenuation of the signal carrying the laser beam intensity can be calculated to investigate the feasibility of FSO communication using Optysistem-7 software. The optimal link distance for northeastern Iraq (Sulaimani City) has been found to be within the limit of about 5.5 km. Analysing the max. Q-factor, bit-error rate and signal to noise ratio for an average of 120 months between 2013-2022 assessed the best and worst seasons for FSO.
Źródło:: Opto-Electronics Review; 2023, 31, 3; art. no. e147037
1230-3402
Pojawia się w:: Opto-Electronics Review
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Investigation of Free Space Optical Detection Module Operating at the Wavelength Range of 8-12 μm
Autorzy:: Gutowska, M.
Nowakowski, M.
Bielecki, Z.
Mikolajczyk, J.
Szabra, D.
Paliwoda, R.
Pedzinska, M.
Pawluczyk, J.
Gawron, W.
Powiązania:: https://bibliotekanauki.pl/articles/1506789.pdf
Data publikacji:: 2010-12
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:: 07.07.Df
85.60.Bt
Opis:: The paper presents the construction and test results of a long-term radiation detector module for free space optical communication operated at the wavelength range of 8-12 μm. In the module a Polish detector manufactured in the company Vigo System S.A. was applied. High sensitivity of the detection module was achieved through a multi-layered heterostructure HgCdTe with immersion lens, which is optimized for the radiation detection at the wavelength of 10 μm. Detector noises were reduced as a result of detector cooling by means of four-stage thermoelectric cooler. The developed detection module is dedicated to design a next-generation optical data link. The link will be characterized by a greater range in difficult weather conditions in relation to the currently offered links operating at the shorter wavelengths.
Źródło:: Acta Physica Polonica A; 2010, 118, 6; 1143-1147
0587-4246
1898-794X
Pojawia się w:: Acta Physica Polonica A
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Average capacity analysis of FSO system with Airy beam as carrier over exponentiated Weibull channels
Autorzy:: Li, Yi
Chu, Xingchun
Han, Zhongxiang
Tang, Hanling
Song, Xinkang
Powiązania:: https://bibliotekanauki.pl/articles/2202763.pdf
Data publikacji:: 2023
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: Airy beam
free-space optical communication
channel capacity
exponentiated Weibull model
Opis:: Based on scintillation index of Airy beam and exponentiated Weibull channel model, analytical expressions of average channel capacity for free-space optical (FSO) communication links with Airy beam as signal carrier under weak atmospheric turbulence and on-off keying modulation scheme are derived. The average capacity at various propagation distances, transverse scale factors and exponential decay factors has been evaluated. And we compared the average capacity of FSO links with Airy beam and Gaussian beam as signal carrier. The results show that the average capacity of FSO links with Airy beam as carrier increases with the increase of mean signal-to-noise ratio and decreases uniformly with the increase of propagation distance. When the transverse scale factor of Airy beam is about 2 cm, a higher average capacity can be obtained. And the smaller the exponential decay factor of Airy beam, the larger the average capacity. Under the same source power or source width, the average capacity of FSO links with Airy beam as carrier is significantly higher than that of FSO links with Gaussian beam as carrier. The results of this research have some reference significance for the application of Airy beam in FSO communication system.
Źródło:: Optica Applicata; 2023, 53, 1; 35--48
0078-5466
1899-7015
Pojawia się w:: Optica Applicata
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Variable antennas positions solution to reduce pointing errors due to wind speed and temperature coupled effects during free space optical link using matrix Rician pointing error model
Autorzy:: Teuma Mbezi, Michel
Eke, Samuel
Som, Idelette Hermine Judith
Mouangue, Ruben Martin
Powiązania:: https://bibliotekanauki.pl/articles/27310098.pdf
Data publikacji:: 2023
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: atmospheric turbulence
pointing error
free space optical transmission
Rician pointing error model
Opis:: Pointing errors (PE) during free space optical (FSO) transmission can be caused by laser beam wander due to thermal and wind dynamic instability. The aim of this work is to study the coupled effects of temperature and wind speed on PE using matrix Rician pointing error (MRPE) model; then show how variable antennas height can reduce PE due to wind speed and temperature coupled effects. To achieve this purposes, average PE expression was established using MRPE model. Then considering a Gaussian beam wave and Monin–Obukhov similarity functions for the structure parameters of temperature, explicit relationship was established between average PE, temperature and wind speed. It comes out of this study that under dynamic turbulence, one can appropriately modify temperature to reduce PE due to dynamic instability and reciprocally. Depending on turbulence large cells or frozen turbulence eddies distribution, PE can be reduced by appropriately modified antennas height or the distance between transmitter and receiver. That is why this work suggests to install variable or dynamic antennas (rather than fixed ones) which could intelligently modify its positions according to laser beam wander created by atmospheric turbulence.
Źródło:: Optica Applicata; 2023, 53, 3; 393--406
0078-5466
1899-7015
Pojawia się w:: Optica Applicata
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Indoor localization based on visible light communication and machine learning algorithms
Autorzy:: Ghonim, Alzahraa M.
Salama, Wessam M.
Khalaf, Ashraf A. M.
Shalaby, Hossam M. H.
Powiązania:: https://bibliotekanauki.pl/articles/2063908.pdf
Data publikacji:: 2022
Wydawca:: Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:: free-space optical communication
visible light communication
neural networks
random forests
machine learning
Opis:: An indoor localization system is proposed based on visible light communications, received signal strength, and machine learning algorithms. To acquire an accurate localization system, first, a dataset is collected. The dataset is then used with various machine learning algorithms for training purpose. Several evaluation metrics are used to estimate the robustness of the proposed system. Specifically, authors’ evaluation parameters are based on training time, testing time, classification accuracy, area under curve, F1-score, precision, recall, logloss, and specificity. It turned out that the proposed system is featured with high accuracy. The authors are able to achieve 99.5% for area under curve, 99.4% for classification accuracy, precision, F1, and recall. The logloss and precision are 4% and 99.7%, respectively. Moreover, root mean square error is used as an additional performance evaluation averaged to 0.136 cm.
Źródło:: Opto-Electronics Review; 2022, 30, 2; art. no. e140858
1230-3402
Pojawia się w:: Opto-Electronics Review
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: The improvement of fiber-detection method to enhance the output of amplify-received relaying on FSO communications
Autorzy:: Darusalam, Ucuk
Priambodo, Purnomo Sidi
Zulkifli, Fitri Yuli
Rahardjo, Eko Tjipto
Powiązania:: https://bibliotekanauki.pl/articles/27311966.pdf
Data publikacji:: 2023
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:: amplify-received relaying
optical relaying network
free-space optical communication
noise suppression
optical spatial filter
scintillation
Opis:: The performance of free-space optical (FSO) communications that using an optical amplifier (OA) in the scheme of an amplify-received (AR)-relaying has a major drawback in the detection of input signal quality under the effects of turbulence. As an OA is based on a fiber-detection (FD) method to receive and delivers a signal at the amplification process stage, there is an opportunity to implement an optical spatial filter (OSF) to improve the quality of an input signal. In this paper, as the continuation of previous work on the direct-detection, the OSF is applied on the AR-relaying. The novelty proposed in this work is the improvement of FD method where the OSF is designed as the integration of cone reflector, pinhole and multi-mode fiber with an OA. The OSF produces an optical signal, the input of the OA, which minimizes the effects of turbulence, background noise and signal fluctuation. Thus, OA in AR-relaying produces signal output with high power and rise up below threshold level. Additionally, an OSF with a lower pinhole diameter produces the best quality of the signal spectral to be delivered into an EDFA. Through this implementation, the performance of optical relaying on FSO can be significantly improved.
Źródło:: International Journal of Electronics and Telecommunications; 2023, 69, 2; 325--333
2300-1933
Pojawia się w:: International Journal of Electronics and Telecommunications
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Analysis of Free-Space Optics Development
Autorzy:: Mikołajczyk, J.
Bielecki, Z.
Bugajski, M.
Piotrowski, J.
Wojtas, J.
Gawron, W.
Szabra, D.
Prokopiuk, A.
Powiązania:: https://bibliotekanauki.pl/articles/221245.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: optical communications
open path laser communications
line of sight communications
free space optics
Opis:: The article presents state of work in technology of free-space optical communications (Free Space Optics - FSO). Both commercially available optical data links and their further development are described. The main elements and operation limiting factors of FSO systems have been identified. Additionally, analyses of FSO/RF hybrid systems application are included. The main aspects of LasBITer project related to such hybrid technology for security and defence applications are presented.
Źródło:: Metrology and Measurement Systems; 2017, 24, 4; 653-674
0860-8229
Pojawia się w:: Metrology and Measurement Systems
Dostawca treści:: Biblioteka Nauki

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