Elektrik Elektronik Mühendisliği Bölümü Yayın Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/411

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Author: search.filters.author.Gokce, Muhsin CanerSubject: search.filters.subject.Optical Wireless Communication

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Now showing 1 - 5 of 5
  • Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Coupling Efficiency of Multimode Beam To Fiber in Atmospheric Turbulence
    (Pergamon-elsevier Science Ltd, 2023) Baykal, Yahya; Ata, Yalcin; Gokce, Muhsin Caner
    Atmospheric turbulence causes wavefront distortions in the propagated laser beam. By the beam shaping of the transmitted laser, wavefront distortions can be mitigated effectively. In this paper, we consider a shaped laser modeled by multimode beams at the transmitter and investigate the coupling of the light wave to a single-mode fiber under the atmospheric turbulence effect. We derive the light power on the coupling lens and light power accepted by the fiber core using the extended Huygens-Fresnel princi-ple. Then, the fiber coupling efficiency (FCE) is scrutinized for different system parameters such as the number of modes of the transmit laser, link distance, structure constant of atmosphere, focal length and radius of the coupling lens, wavelength, source size, and the number of speckles (NOS).(c) 2023 Elsevier Ltd. All rights reserved.
  • Article
    Citation - WoS: 2
    Citation - Scopus: 1
    Signal-To Ratio With Adaptive Optics Compensation in Non-Kolmogorov Weak Turbulent Atmosphere
    (Taylor & Francis Ltd, 2021) Baykal, Yahya; Gokce, Muhsin Caner; Ata, Yalcin
    This study investigates the average signal-to-noise ratio < SNR > at the shot-noise limited receiver of an optical wireless communication system (OWC) that uses collimated Gaussian beam with adaptive optics correction in non-Kolmogorov weak turbulent atmosphere. < SNR > and the variation in the percentage < SNR > are calculated and the results are presented against various adaptive optics correction modes, non-Kolmogorov power-law exponent, receiver aperture size, Gaussian beam source size, photodetector quantum efficiency, electronic bandwidth, link length, and turbulence strength. Adaptive optics correction is analyzed for tilt, defocus, astigmatism, coma and trefoil modes and their variations. The effects of adaptive optics compensation are examined that cause an increase in SNR, hence improve the performance of an OWC system using collimated Gaussian beam and operating in the non-Kolmogorov weak turbulent atmosphere.
  • Article
    Citation - WoS: 5
    Effect of Anisotropy on Performance of M-Ary Phase Shift Keying Subcarrier Intensity-Modulated Optical Wireless Communication Links Operating in Strong Oceanic Turbulence
    (Iop Publishing Ltd, 2020) Baykal, Yahya; Ata, Yalcin; Gokce, Muhsin Caner
    In strong oceanic turbulence, the performance of M-ary phase shift keying subcarrier intensity-modulated optical wireless communication (OWC) links is investigated in terms of the bit-error-rate (BER) by considering the effect of anisotropy of the oceanic channel. To calculate the BER of the OWC link, a gamma-gamma statistical channel model is adopted. The extended Huygens-Fresnel principle and the asymptotic Rytov theory are used to obtain the received optical power and the large-scale and small-scale log-intensity variances, respectively. Our graphical illustrations include the BER versus anisotropic factor for various system parameters such as the modulation order, filter bandwidth, link distance, peak amplitude of each subcarrier and the oceanic turbulence parameters.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 11
    Error Performance of Optical Wireless Communication Systems Exercising Bpsk Subcarrier Intensity Modulation in Non-Kolmogorov Turbulent Atmosphere
    (Elsevier Science Bv, 2019) Baykal, Yahya; Gokce, Muhsin Caner; Ata, Yalcin
    Subcarrier intensity modulation (SIM) scheme is preferred due to efficient bandwidth usage superiority over other modulation techniques such as on-off keying (OOK), pulse position modulation (PPM). In this paper, we investigate the bit error rate (BER) performance of optical wireless communication (OWC) system using binary phase shift keying (BPSK) SIM in non-Kolmogorov turbulent atmosphere. We pay attention to the weak turbulence conditions by using Rytov approximation and considering that the receiver is a PIN photodetector. Propagating beam type is Gaussian. It is seen that BER performance of the BPSK SIM OWC is significantly affected from non-Kolmogorov power law exponent, load resistor, responsivity of the PIN photodetector, bandwidth, beam source size, turbulence strength and noise factor.
  • Article
    Citation - WoS: 32
    Citation - Scopus: 40
    Performance Analysis of M-Ary Pulse Position Modulation in Strong Oceanic Turbulence
    (Elsevier Science Bv, 2018) Baykal, Yahya; Ata, Yalcin; Gokce, Muhsin Caner
    In this paper, we consider an underwater wireless optical communication (UWOC) system which consists of an M-ary pulse position modulated (PPM) Gaussian optical beam at the transmitter and an avalanche photodiode (APD) at the receiver. In strong oceanic turbulence, we aimed at investigating the system performance in terms of bit error rate (BER) by the help of gamma-gamma channel model. For this purpose, the average power and the aperture averaged scintillation at the finite sized detector are derived by using the extended Huygens-Fresnel principle and the asymptotic Rytov theory, respectively. BER variations are examined versus the average APD gain, modulation order, bit rate as well as the oceanic turbulence parameters, i.e., the rate of dissipation of kinetic energy per unit mass of fluid, the rate of dissipation of mean-squared temperature and the ratio of temperature to salinity contributions to the refractive index spectrum.