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Wyszukujesz frazę "Khalaf, Ashraf A. M." wg kryterium: Autor

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    Wyświetlanie 1-9 z 9
    Tytuł:
    PAPR reduction using a combination between precoding and non-liner companding techniques for ACO-OFDM-based VLC systems
    Autorzy:
    Mohammed, Nazmi A.
    Elnabawy, M. M.
    Khalaf, Ashraf A. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818212.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    visible light communication
    light emitting diode
    peak-to-average power ratio
    bit error rate
    Opis:
    Peak-to-average power ratio reduction techniques for visible light communication broadcasting systems are designed, simulated, and evaluated in this work. The proposed techniques are based on merging non-linear companding techniques with precoding techniques. This work aims to nominate an optimum novel scheme combining the low peak-to-average power ratio with the acceptable bit error rate performance. Asymmetrically clipped optical orthogonal frequency division multiplexing with the low peak-to-average power ratio performance becomes more attractive to real-life visible light communication applications due to non-linearity elimination. The proposed schemes are compared and an optimum choice is nominated. Comparing the presented work and related literature reviews for peak-to-average power ratio reduction techniques are held to ensure the proposed schemes validity and effectiveness.
    Źródło:
    Opto-Electronics Review; 2021, 29, 2; 59--70
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dimming control schemes combining IEEE 802.15.7 and SC-LPPM modulation schemes with an adaptive M-QAM OFDM for indoor LOS VLC systems
    Autorzy:
    Mohammed, Nazmi A.
    Badawi, Kareem A.
    Khalaf, Ashraf A. M.
    El-Rabaie, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/1818236.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    visible light communication
    sub-carrier pulse position modulation
    lightning topologies
    bit error rate
    Opis:
    The presented work proposes a new dimming control schemes for indoor visible light communication which combines variable pulse-position modulation, colour shift keying as key schemes of IEEE 802.15.7 standard, and sub carrier-pulse-position modulation as a pulse-position modulation variant with orthogonal frequency division multiplexing. These schemes are then compared with traditional merging schemes utilizing pulse-width modulation and multiple pulse-position modulation with m-ary quadrature amplitude modulation OFDM. The proposed schemes are investigated in a typical room with a different lighting layout (i.e., distinctive and uniform lighting layout), followed by an illumination investigation to evaluate the performance of the proposed schemes, especially the enhanced achieved data rates, and to determine their limitations as reliable visible light communication systems that can satisfy both communication and illumination requirements.
    Źródło:
    Opto-Electronics Review; 2020, 28, 4; 203--212
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Intelligent transportation : a hybrid FSO/VLC-assisted relay system
    Autorzy:
    EL-Garhy, Suzan M.
    Khalaf, Ashraf A. M.
    Aly, Moustafa H.
    Abaza, Mohamed
    Powiązania:
    https://bibliotekanauki.pl/articles/2174852.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    intelligent transportation systems
    infrastructure-to-vehicle
    vehicle-to-vehicle
    relay
    Opis:
    Various intelligent transportation systems are proposed in different forms of wireless communication technologies. Recently, the importance of visible light communication and free-space optics has been demonstrated in accomplishing vehicle-to-vehicle and infrastructure-to-vehicle communication systems, due to power efficiency, free licenses, and safety for human health. In this paper, a new hybrid relay system supported by free-space optics/visible light communication with two scenarios is proposed. The first one is that the data are transferred from the source to the relay through a free-space optics communication link and are then directed to the destination through a visible light communication link. The second scenario is that the data are transmitted from the source to the destination passing through two different relays to ensure larger coverage. A 10‾⁶ bit error rate is achieved at a distance of 900 m for the first scenario with a remarkable signal-to-noise ratio of ~25.5 dB, while the largest distance that can be covered by the second scenario is 1200 m with a signalto- noise ratio of ~30 dB.
    Źródło:
    Opto-Electronics Review; 2022, 30, 4; art. no. e144260
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    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
    Artykuł
    Tytuł:
    Dimming control schemes combining IEEE 802.15.7 and SC-LPPM modulation schemes with an adaptive M-QAM OFDM for indoor LOS VLC systems
    Autorzy:
    Mohammed, Nazmi A.
    Badawi, Kareem A.
    Khalaf, Ashraf A. M.
    El-Rabaie, El-Sayed
    Powiązania:
    https://bibliotekanauki.pl/articles/1818230.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    visible light communication
    sub-carrier pulse position modulation
    lightning topologies
    bit error rate
    Opis:
    The presented work proposes a new dimming control schemes for indoor visible light communication which combines variable pulse-position modulation, colour shift keying as key schemes of IEEE 802.15.7 standard, and sub carrier-pulse-position modulation as a pulse-position modulation variant with orthogonal frequency division multiplexing. These schemes are then compared with traditional merging schemes utilizing pulse-width modulation and multiple pulse-position modulation with m-ary quadrature amplitude modulation OFDM. The proposed schemes are investigated in a typical room with a different lighting layout (i.e., distinctive and uniform lighting layout), followed by an illumination investigation to evaluate the performance of the proposed schemes, especially the enhanced achieved data rates, and to determine their limitations as reliable visible light communication systems that can satisfy both communication and illumination requirements.
    Źródło:
    Opto-Electronics Review; 2020, 28, 4; 203--212
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A proposed preamble channel estimation scheme for flip FBMC-based indoor VLC systems
    Autorzy:
    El-Ganiny, Mohamed Y.
    Khalaf, Ashraf A. M.
    Hussein, Aziza I.
    Hamed, Hesham F. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2063904.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    channel estimation
    filter bank multicarrier
    IEEE 802.15.7 standard
    interference approximation method
    visible light communication
    Opis:
    Filter bank multicarrier waveform is investigated as a potential waveform for visible light communication broadcasting systems. Imaginary inter-carrier and/or inter-symbol interference are causing substantial performance degradation in the filter bank multicarrier system. Direct current-biased optical filter bank multicarrier modulation overcomes all the problems of direct current-biased optical-orthogonal frequency division multiplexing modulation approaches in terms of speed and bandwidth. However, it also wastes a lot of energy while transforming a true bipolar signal into a positive unipolar signal by adding direct current-bias. In this paper, a flip-filter bank multicarrier-based visible light communication system was introduced to overcome this problem. In this system, a bipolar signal is converted to a unipolar signal by isolating the positive and negative parts, turning them to positive and then delivering the signal. Also, a new channel estimation scheme for a flip-filter bank multicarrier system is proposed which improves the channel estimation performance compared to that of each of the conventional schemes. The proposed system performance is measured in terms of bit error rate, normalized mean squared error, and constellation diagram. The superiority of the proposed scheme over other conventional structures has been successfully verified by MATLAB 2020b simulation experiments results. These results are evaluated under indoor visible light communication standard.
    Źródło:
    Opto-Electronics Review; 2022, 30, 1; art. no. e140859
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hybrid PAPR reduction schemes for different OFDM-based VLC systems
    Autorzy:
    El-Ganiny, Mohamed Y.
    Khalaf, Ashraf A. M.
    Hussein, Aziza I.
    Hamed, Hesham F. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174839.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    visible light communication
    peak-to-average power ratio
    bit error rate
    Opis:
    Orthogonal frequency division multiplexing has been widely used in many radio frequency wireless communication standards as a preferable multicarrier modulation scheme. The modulated signals of a conventional orthogonal frequency division multiplexing system are complex and bipolar. In intensity-modulated direct detection optical wireless communications, transmitted signals should be real and unipolar due to non-coherent emissions of an optical light emitting diode. In this paper, different hybrid optical systems have been proposed to satisfy real and unipolar signals. Peak-to-average power ratio is one of the biggest challenges for orthogonal frequency division multiplexing-based visible light communications. They are based on a combination of non-linear companding techniques with spreading or precoding techniques. Simulation evaluation is performed under direct current-biased optical orthogonal frequency division multiplexing, asymmetrically clipped optical orthogonal frequency division multiplexing, and Flip-orthogonal frequency division multiplexing systems in terms of peak-to-average power ratio, bit error rate, and spectral efficiency. The proposed schemes are investigated to determine a scheme with a low peak-to-average power ratio and an acceptable bit error rate. MATLABTM software has been successfully used to show the validity of the proposed schemes.
    Źródło:
    Opto-Electronics Review; 2022, 30, 3; art. no. e141951
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hybrid PAPR reduction schemes for different OFDM-based VLC systems
    Autorzy:
    El-Ganiny, Mohamed Y.
    Khalaf, Ashraf A. M.
    Hussein, Aziza I.
    Hamed, Hesham F. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2174840.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    visible light communication
    peak-to-average power ratio
    bit error rate
    Opis:
    Orthogonal frequency division multiplexing has been widely used in many radio frequency wireless communication standards as a preferable multicarrier modulation scheme. The modulated signals of a conventional orthogonal frequency division multiplexing system are complex and bipolar. In intensity-modulated direct detection optical wireless communications, transmitted signals should be real and unipolar due to non-coherent emissions of an optical light emitting diode. In this paper, different hybrid optical systems have been proposed to satisfy real and unipolar signals. Peak-to-average power ratio is one of the biggest challenges for orthogonal frequency division multiplexing-based visible light communications. They are based on a combination of non-linear companding techniques with spreading or precoding techniques. Simulation evaluation is performed under direct current-biased optical orthogonal frequency division multiplexing, asymmetrically clipped optical orthogonal frequency division multiplexing, and Flip-orthogonal frequency division multiplexing systems in terms of peak-to-average power ratio, bit error rate, and spectral efficiency. The proposed schemes are investigated to determine a scheme with a low peak-to-average power ratio and an acceptable bit error rate. MATLABTM software has been successfully used to show the validity of the proposed schemes.
    Źródło:
    Opto-Electronics Review; 2022, 30, 3; art. no. e141951
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cancelable template generation based on quantization concepts
    Autorzy:
    Nassar, Rana M.
    Khalaf, Ashraf A. M.
    El-Banby, Ghada M.
    El-Samie, Fathi E. Abd
    Hussein, Aziza I.
    El-Shafai, Walid
    Powiązania:
    https://bibliotekanauki.pl/articles/27315703.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
    Tematy:
    cancelable biometrics
    quantization concepts
    DCT
    JPEG
    access control
    authentication
    Opis:
    The idea of cancelable biometrics is widely used nowadays for user authentication. It is based on encrypted or intentionally-distorted templates. These templates can be used for user verification, while keeping the original user biometrics safe. Multiple biometric traits can be used to enhance the security level. These traits can be merged together for cancelable template generation. In this paper, a new system for cancelable template generation is presented depending on discrete cosine transform (DCT) merging and joint photographic experts group (JPEG) compression concepts. The DCT has an energy compaction property. The low-frequency quartile in the DCT domain maintains most of the image energy. Hence, the first quartile from each of the four biometrics for the same user is kept and other quartiles are removed. All kept coefficients from the four biometric images are concatenated to formulate a single template. The JPEG compression of this single template with a high compression ratio induces some intended distortion in the template. Hence, it can be used as a cancelable template for the user acquired from his four biometric traits. It can be changed according to the arrangement of biometric quartiles and the compression ratio used. The proposed system has been tested through merging of face, palmprint, iris, and fingerprint images. It achieves a high user verification accuracy of up to 100%. It is also robust in the presence of noise.
    Źródło:
    Opto-Electronics Review; 2023, 31, 3; art. no. e145940
    1230-3402
    Pojawia się w:
    Opto-Electronics Review
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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