Browsing by Author "Coleri Ergen, S."

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    Broadcasting brake lights with MIMO-OFDM based vehicular VLC
    (IEEE, 2016) Turan, B.; Narmanlıoğlu, Ömer; Coleri Ergen, S.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Narmanlıoğlu, Ömer
    Inter-vehicular connectivity to enhance road safety and enable highly autonomous driving is increasingly becoming popular. Despite the prevalent works on radio-frequency (RF) based vehicular communication schemes, visible light communication (VLC) is considered to be a promising candidate for vehicular communications due to its low complexity and RF interference-free nature. This paper investigates applicability of VLC to enhance road safety based on real world measurements. Deployment of multiple light emitting diodes (LEDs) enables multiple-input multiple-output (MIMO) transmission in the context of vehicular VLC. We consider direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) based MIMO transmission scheme and evaluate the performances of different MIMO modes including repetition code (RC) and spatial multiplexing (SM), different modulation orders and different transmitter-receiver selection. The results reveal that selection of the closest transmitters to the receivers, provide better performance due to high signal-to-noise-ratio (SNR) requirements for RC mode. However, usage of all possible transmitters does not always yield better performance due to power division at the transmitter side. Moreover, SM suffers from channel correlation whereas the performance of RC shows more degradation on higher-order modulations that are required to yield the same throughput with SM.
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    On the performance of MIMO OFDM-based intra-vehicular VLC networks
    (IEEE, 2016) Turan, B.; Narmanlıoğlu, Ömer; Coleri Ergen, S.; Uysal, Murat; Electrical & Electronics Engineering; NARMANLIOĞLU, Ömer; UYSAL, Murat; Narmanlıoğlu, Ömer
    Vehicular hotspots for on-board Internet access using Long Term Evolution (LTE) as the backhaul network has recently gained popularity. Currently, Wi-Fi is the most common technology to provide in-vehicle access, where data has been relayed through on board LTE receiver. Despite its wide acceptance, coexistence and contention based data rate limitations with Wi-Fi necessitates alternatives for in-vehicle data access schemes. This paper investigates the performance of hybrid LTE and visible light communication (VLC) networks using LTE as the backhaul and VLC as the on-board access network.Under the consideration of vehicle interior unique channel characteristics and light emitting diode (LED) deployment flexibility, best transmitter configuration using repetition coding (RC) and spatial multiplexing (SM) multiple input multiple output (MIMO)modes is determined. Proposed configurations based on direct current biased optical orthogonal frequency-division multiplexing(DCO-OFDM) are compared with respect to their bit-error-rate (BER) performances. Furthermore, the performance of intravehicular VLC networks for single and multi-user scenarios is investigated.
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    Physical layer implementation of standard compliant vehicular VLC
    (IEEE, 2017) Turan, B.; Narmanlioglu, Omer; Coleri Ergen, S.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Narmanlioglu, Omer
    Visible light communication (VLC) has recently gained popularity as a complementary technology to radio frequency (RF) based alternatives for vehicular communications as a low-cost, secure and RF interference free technology. In this paper, we propose IEEE 802.15.7 standard-compliant physical layer (PHY) implementation and experimental evaluation, using commercial off-the-shelf (COTS) automotive light emitting diode (LED) fog light for the purpose of low-latency safety message dissemination. We first show that the standard is applicable to line of sight (LoS) vehicle-to-vehicle (V2V) VLC. We then demonstrate that the proper selection of modulation coding schemes (MCS) plays an important role in order to minimize bit-error- rate (BER) for the reliable transmission with varying inter-vehicle distances. We also addressed the angular limitations of COTS automotive LED light for viable vehicular VLC.
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    Poster: on-board camera video transmission over vehicular VLC
    (IEEE, 2017) Narmanlioglu, Omer; Turan, B.; Kebapci, Burak; Coleri Ergen, S.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Narmanlioglu, Omer; Kebapci, Burak
    Vehicular connectivity is envisaged to extend vehicle on-board camera videos to the nearby vehicles in order to increase drivers' road awareness. This paper demonstrates the possibilities of video transmission captured by vehicle on-board forward-looking camera via visible light communications (VLC) using taillights to provide see-beyond the front vehicle assistance. Line of sight (LoS) inter-vehicular video transmission using direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) based VLC with the data rate of 6.42 Mbps and lower latency than 32 msec is validated through experiments.