Researcher:
Uyrus, Ali

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Ali

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Uyrus

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Uyrus, Ali

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2018 - 201952020 - 20212

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Researcher Of Publications: search.filters.isAuthorOfPublication.93330735-4eb1-44ac-9712-9e374f7c8828

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    Location-aware adaptive physical layer design for vehicular visible light communication
    (IEEE, 2019) Department of Electrical and Electronics Engineering; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Gürbilek, Gökhan; Koca, Mertkan; Uyrus, Ali; Soner, Burak; Başar, Ertuğrul; Ergen, Sinem Çöleri; Researcher; Master Student; PhD Student; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; College of Sciences; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 149116; 7211
    Vehicular visible light communication (V2LC) is expected to complement radio frequency (RF) technologies for higher reliability in vehicular connectivity. Since high mobility makes the line-of-sight V2LC channel very dynamic, an adaptive physical layer (PHY) design is required for realizing a rate-optimal and reliable V2LC system. Existing studies on adaptive PHY designs have mostly considered indoor scenarios with low mobility and require a feedback channel for both reporting the received signal-to-noise ratio (SNR) to the transmitter and channel equalization (CE), which increases system complexity and introduces overhead. This paper presents a novel low-complexity adaptive PHY design that provides rate-optimal and reliable V2LC without a feedback channel. The proposed design utilizes a priori measurements of the BER with respect to SNR, which are static for V2LC on the road. SNR is predicted in real-time based on the relative locations of the transmitting (TX) and receiving (RX) vehicles using a path loss model based on a priori measurements of the SNR-distance relationship and the polar beam pattern for a given TX/RX pair, in a given setting. The proposed design is validated via night-time experiments with On-Off-Keying (OOK), 4-Pulse-Position Modulation (4-PPM) and Direct Current-Biased Optical OFDM (DCO-OFDM). The proposed location-aware adaptive PHY design can be expanded for general reliable rate-optimal V2LC use by updating the path loss model with additional measurements for different settings.
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    Vehicular VLC frequency domain channel sounding and characterization
    (IEEE, 2018) N/A; Department of Electrical and Electronics Engineering; Department of Electrical and Electronics Engineering; Turan, Buğra; Gürbilek, Gökhan; Uyrus, Ali; Ergen, Sinem Çöleri; PhD Student; Researcher; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 7211
    Vehicular visible light communication (V2LC) has recently gained popularity as a complementary technology to radio frequency (RF) based vehicular communication schemes due to its low-cost, secure and RF-interference free nature. In this paper, we propose outdoor vehicular visible light communication (V2LC) frequency domain channel sounding based channel model characterization under night, sunset and sun conditions with the usage of vector network analyzer (VNA) and commercial off-the-shelf (COTS) automotive light emitting diode (LED) light. We further bring forward a new practical system bandwidth criterion named as effective usable bandwidth (EUB) for an end-to-end V2LC system with respect to the real world measurements. We demonstrate outdoor static V2LC channel measurement results, taking into account vehicle light emitting diode (LED) response, road reflections from nearby vehicles and various daylight conditions with respect to varying inter-vehicular distances. Measurement results indicate that, sunlight decreases system effective usable bandwidth due to the limited dynamic range of avalanche photodiode (APD), nearby vehicles cause constructive interference whereas road reflections change time dispersion characteristics of the V2LC channel.
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    PublicationMetadata only
    Machine learning aided path loss estimator and jammer detector for heterogeneous vehicular networks
    (Ieee, 2021) N/A; N/A; N/A; N/A; N/A; Department of Electrical and Electronics Engineering; Turan, Buğra; Uyrus, Ali; Koç, Osman Nuri; Kar, Emrah; Ergen, Sinem Çöleri; PhD Student; PhD Student; Other; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; N/A; N/A; College of Engineering; Koc University Ford Otosan Automotive Technologies Laboratory (KUFOTAL); N/A; N/A; N/A; N/A; 7211
    Heterogeneous vehicular communications aim to improve the reliability, security and delay performance of vehicle-to-vehicle (V2V) communications, by utilizing multiple communication technologies. Predicting the path loss through conventional fitting based models and radio frequency (RF) jamming detection through rule based models of different communication schemes fail to address comprehensive mobility and jamming scenarios. In this paper, we propose a machine learning based adaptive link quality estimation and jamming detection scheme for the optimum selection and aggregation of IEEE 802.11p and Vehicular Visible Light Communications (V-VLC) technologies targeting reliable V2V communications. We propose to use Random Forest regression and classifier based algorithms, where multiple individual learners with diversity are trained by using measurement data and the final result is obtained by averaging outputs of all learners. We test our framework on real-world road measurement data, demonstrating up to 234 dB and 0.56 dB Mean Absolute Error (MAE) improvement for V-VLC and IEEE 802.11p path loss prediction compared to fitting based models, respectively. The proposed jamming presence detection scheme yields 88.3% accuracy to detect noise interference injection for IEEE 802.11p links, yielding 3% better prediction performance than previously proposed deep convolutional neural network (DCNN) based scheme.
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    PublicationOpen Access
    Location-aware adaptive physical layer design for vehicular visible light communication
    (Institute of Electrical and Electronics Engineers (IEEE), 2019) Department of Electrical and Electronics Engineering; Gürbilek, Gökhan; Koca, Mertkan; Uyrus, Ali; Soner, Burak; Ergen, Sinem Çöleri; Başar, Ertuğrul; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; N/A; 7211; 149116
    Vehicular visible light communication (V2LC) is expected to complement radio frequency (RF) technologies for higher reliability in vehicular connectivity. Since high mobility makes the line-of-sight V2LC channel very dynamic, an adaptive physical layer (PHY) design is required for realizing a rate-optimal and reliable V2LC system. Existing studies on adaptive PHY designs have mostly considered indoor scenarios with low mobility and require a feedback channel for both reporting the received signal-to-noise ratio (SNR) to the transmitter and channel equalization (CE), which increases system complexity and introduces overhead. This paper presents a novel low-complexity adaptive PHY design that provides rate-optimal and reliable V2LC without a feedback channel. The proposed design utilizes a priori measurements of the BER with respect to SNR, which are static for V2LC on the road. SNR is predicted in real-time based on the relative locations of the transmitting (TX) and receiving (RX) vehicles using a path loss model based on a priori measurements of the SNR-distance relationship and the polar beam pattern for a given TX/RX pair, in a given setting. The proposed design is validated via night-time experiments with On-Off-Keying (OOK), 4-Pulse-Position Modulation (4-PPM) and Direct Current-Biased Optical OFDM (DCO-OFDM). The proposed location-aware adaptive PHY design can be expanded for general reliable rate-optimal V2LC use by updating the path loss model with additional measurements for different settings.
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    PublicationOpen Access
    Visible light and mmWave propagation channel comparison for vehicular communications
    (Institute of Electrical and Electronics Engineers (IEEE), 2019) Department of Electrical and Electronics Engineering; Uyrus, Ali; Turan, Buğra; Ergen, Sinem Çöleri; Başar, Ertuğrul; Other; PhD Student; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 7211; 149116
    Future connected vehicles are expected to require fast and reliable exchange of road information to increase safety and enable cooperative driving. Currently, standardized vehicular communication technologies aim to enable basic safety message exchanges with limited bandwidth. Recently, alternative technologies, based on millimeter-wave (mmWave) and visible light spectrum are proposed as complementary vehicle-to-everything (V2X) communication schemes, provisioned to support future connected vehicles with high bandwidth and increased security. However, the understanding of channel propagation characteristics is the key to achieve reliability, due to higher path loss compared to 5.8 GHz band. In this work, we compare channel path loss characteristics of mmWave and vehicular visible light communication (VVLC) schemes to provide an overview regarding technology selection in an indoor parking garage. Path loss measurements are conducted with respect to various inter-vehicular distances, receiver angles, nearby vehicle existence, and lane occupation scenarios. Measurement results indicated path loss of 21.47 dB for VVLC from 3 m to 20 m distances. Moreover, path loss for mmWave 26.5 GHz and 38.5 GHz channels increased 12.5 dB, and 12.7 dB, respectively. Nearby vehicles are shown to decrease path loss of 26.5 GHz and 38.5 GHz signals up to 9.78 dB, and 9.56 dB, respectively, whereas VVLC channel path loss decreases 0.4 dB at the same scenario. Channel frequency response (CFR) measurements indicated frequency flat behavior of VVLC channels while mmWave channel exhibits frequency selectivity induced dispersion due to parking garage structure. Obstructed line-of-sight (OLoS) measurements further reveal that blocking vehicle interrupts VVLC signals while selecting a favorable antenna location leads up to 30 dB less path loss for mmWave signals.
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    PublicationOpen Access
    Modeling and analysis of reconfigurable intelligent surfaces for indoor and outdoor applications in future wireless networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Yıldırım, İbrahim; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Uyrus, Ali; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 149116; N/A
    Reconfigurable intelligent surface (RIS)-empowered communication is one of the promising 6G technologies that allows the conversion of the wireless channel into an intelligent transmit entity by manipulating the impinging waves using man-made surfaces. In this paper, the potential benefits of using RISs are investigated for indoor/outdoor setups and various frequency bands (from sub 6 GHz to millimeter-waves). First, a general system model with a single RIS is considered and the effect of the total number of reflecting elements on the probabilistic distribution of the received signal-to-noise ratio and error performance is investigated under Rician fading. Also for this case, the path loss exponent is analyzed by considering empirical path loss models. Furthermore, transmission models with multiple RISs are developed and analyzed for indoor and outdoor non line-of-sight (NLOS) scenarios. The conventional RIS selection strategies are also integrated for systems equipped with multiple RISs for the first time. Through extensive simulations, it is demonstrated that the RIS-assisted systems provide promising solutions for indoor/outdoor scenarios at various operating frequencies and exhibit significant results in error performance and achievable data rates even in the presence of system imperfections such as limited range phase adjustment and imperfect channel phase estimation at RISs.
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    PublicationOpen Access
    Vehicular VLC frequency domain channel sounding and characterization
    (Institute of Electrical and Electronics Engineers (IEEE), 2018) Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Turan, Buğra; Uyrus, Ali; Gürbilek, Gökhan; Faculty Member; Other; PhD Student; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; 7211; N/A; N/A; N/A
    Vehicular visible light communication (V2LC) has recently gained popularity as a complementary technology to radio frequency (RF) based vehicular communication schemes due to its low-cost, secure and RF-interference free nature. In this paper, we propose outdoor vehicular visible light communication (V2LC) frequency domain channel sounding based channel model characterization under night, sunset and sun conditions with the usage of vector network analyzer (VNA) and commercial off-the-shelf (COTS) automotive light emitting diode (LED) light. We further bring forward a new practical system bandwidth criterion named as effective usable bandwidth (EUB) for an end-to-end V2LC system with respect to the real world measurements. We demonstrate outdoor static V2LC channel measurement results, taking into account vehicle light emitting diode (LED) response, road reflections from nearby vehicles and various daylight conditions with respect to varying inter-vehicular distances. Measurement results indicate that, sunlight decreases system effective usable bandwidth due to the limited dynamic range of avalanche photodiode (APD), nearby vehicles cause constructive interference whereas road reflections change time dispersion characteristics of the V2LC channel.