Browsing by Author "Tadayyoni, Hamed"

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    Characterization of orbital angular momentum-multiplexed FSO channel in the presence of pointing errors
    (IEEE, 2023) Elamassie, Mohammed; Tadayyoni, Hamed; Uysal, Murat; Electrical & Electronics Engineering; ELAMASSIE, Mohammed; UYSAL, Murat; Tadayyoni, Hamed
    Free space optical communication (FSO) uses laser transmitters at near-infrared wavelengths for line-of-sight wireless communication. Through the use of advanced laser beams instead of the conventional Gaussian-shaped beam, orbital angular momentum (OAM) allows taking advantage of higher degrees of freedom in the FSO link design. OAM enables the simultaneous transmission of multiple data streams due to the orthogonality between beams of different spatial modes. However, in practice, atmospheric turbulence and pointing errors may destroy the orthogonality. Pointing errors may result in crosstalk between modes and power disparities as a result of shifting the received beam. In this paper, we consider Laguerre-Gaussian beams and investigate the effect of random pointing errors on crosstalk coefficients.
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    Ultraviolet communications for ground-to-air links
    (IEEE, 2019) Tadayyoni, Hamed; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Tadayyoniahrab, Hamed
    Ultraviolet (UV) communication enables non-line-of-sight (NLOS) wireless connectivity through strong molecular and aerosol scattering. Due to their NLOS nature, UV links bring robustness to blockage or shadowing and relax the pointing, acquisition and tracking requirements. This feature is particularly appealing for unmanned aerial vehicle (UAV) networks. In this paper, we consider the uplink of a ground sensor network where a number of sensor nodes are placed on the ground in a serial manner and with equal intra-distances. A UAV periodically visits the area and collects the sensor data from ground nodes. For the uplink transmission under consideration, we investigate the performance of UV-based system and determine the maximum UAV coverage to maintain a pre-defined bit error rate performance.
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    Ultraviolet communications for unmanned aerial vehicle networks
    (IEEE, 2022) Tadayyoni, Hamed; Ardakani, M. H.; Heidarpour, A. R.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Tadayyoni, Hamed
    Due to the strong scattering, ultraviolet (UV) communication links enable non-line-of-sight (NLOS) outdoor connectivity and relax the pointing, acquisition, and tracking requirements encountered in infrared links. This feature makes the UV communications attractive, in particular, for unmanned aerial vehicle (UAV) networks where link alignment is hard to realize. In this letter, we study the performance of the uplink of a ground sensor network where a UAV periodically visits the area to receive the data from serial sensor nodes. The transmission from the closest sensor to the flying UAV is the desired signal while the received signals from other nodes are treated as interference. We derive the bit error rate for the uplink airborne UV in the presence of interference. Numerical results are provided to validate our theoretical analysis and investigate the effect of interferers on the system performance.