Browsing by Author "Ekin, S."

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    ArticlePublicationOpen Access
    Hybrid RF/VLC systems: A comprehensive survey on network topologies, performance analyses, applications, and future directions
    (IEEE, 2021) Abuella, H.; Elamassie, Mohammed; Uysal, Murat; Xu, Z.; Serpedin, E.; Qaraqe, K. A.; Ekin, S.; Electrical & Electronics Engineering; ELAMASSIE, Mohammed; UYSAL, Murat
    Wireless communications refer to data transmissions in unguided propagation media through the use of wireless carriers such as radio frequency (RF) and visible light (VL) waves. The rising demand for high data rates, especially, in indoor scenarios, overloads conventional RF technologies. Therefore, technologies such as millimeter waves (mmWave) and cognitive radios have been adopted as possible solutions to overcome the spectrum scarcity and capacity limitations of the conventional RF systems. In parallel, visible light communication (VLC) has been proposed as an alternative solution, where a light source is used for both illumination and data transmission. In comparison to RF links, VLC links present a very high bandwidth that allows much higher data rates. VLC exhibits also immunity to interference from electromagnetic sources, has unlicensed channels, is a very low power consumption system, and has no health hazard. VLC is appealing for a wide range of applications including reliable communications with low latency such as vehicle safety communication. Despite the major advantages of VLC technology and a variety of its applications, its use has been hampered by its cons such as its dependence on a line of sight connectivity. Recently, hybrid RF/VLC systems were proposed to take advantage of the high capacity of VLC links and better connectivity of RF links. Thus, hybrid RF/VLC systems are envisioned as a key enabler to improve the user rates and mobility on one hand and to optimize the capacity, interference and power consumption of the overall network on the other hand. This paper seeks to provide a detailed survey of hybrid RF/VLC systems. This paper represents an overview of the current developments in the hybrid RF/VLC systems, their benefits and limitations for both newcomers and expert researchers.
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    ViLDAR-Visible light sensing-based speed estimation using vehicle headlamps
    (IEEE, 2019-11) Abuella, H.; Miramirkhani, F.; Ekin, S.; Uysal, Murat; Ahmed, S.; Electrical & Electronics Engineering; UYSAL, Murat
    The introduction of light emitting diodes (LED) in automotive exterior lighting systems provides opportunities to develop viable alternatives to conventional communication and sensing technologies. Most of the advanced driver-assist and autonomous vehicle technologies are based on Radio Detection and Ranging (RADAR) or Light Detection and Ranging (LiDAR) systems that use radio frequency or laser signals, respectively. While reliable and real-time information on vehicle speeds is critical for traffic operations management and autonomous vehicles safety, RADAR or LiDAR systems have some deficiencies especially in curved road scenarios where the incidence angle is rapidly varying. In this paper, we propose a novel speed estimation system so-called the Visible Light Detection and Ranging (ViLDAR) that builds upon sensing visible light variation of the vehicle's headlamp. We determine the accuracy of the proposed speed estimator in straight and curved road scenarios. We further present how the algorithm design parameters and the channel noise level affect the speed estimation accuracy. For wide incidence angles, the simulation results show that the ViLDAR outperforms RADAR/LiDAR systems in both straight and curved road scenarios.
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    ViLDAR: a novel speed estimation system using visible light in vehicles
    (IEEE, 2017) Abuella, H.; Ekin, S.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat
    In this paper, we introduce Visible Light Detection and Ranging (ViLDAR): a novel speed estimation system that utilizes visible light variation during a known time difference. The use of light emitting diodes (LED) in vehicles lighting systems has become increasingly common in the automotive industry. Concurrently, monitoring drivers' speeds constitutes a critical issue for safety regulation agencies. Most of the speed monitoring systems are based on measuring the speed of vehicles using wellknown RADAR or LiDAR systems that use radio frequency or laser signals, respectively. However, these systems have certain limitations, e.g., the requirement of line-of-sight for accurate results in RADAR and LiDAR, and narrow beam-width and deficient performance in curved roads in RADAR. We present a simple as well as novel estimation method for the speed of an approaching vehicle given only the received light intensity information. Assuming a Lambertian channel model for the light wave propagation, the performance of the estimator is compared in different angle of incidences between the vehicle and the detector. The proposed method outperforms RADAR/LiDAR systems in terms of speed estimation accuracy for a wide range of incidence angles.