Dissertation Defense – Bismillah Nasir Ashfaq (PHDEE)

Bismillah Nasir Ashfaq – Ph.D. Electrical and Electronics Engineering

Prof. Murat Uysal – Advisor

Date: 06.05.26

Time: 11:00

Location: AB4-428

DESIGN, MODELING, AND EXPERIMENTAL VALIDATION OF VEHICULAR VISIBLE LIGHT COMMUNICATION SYSTEMS

Prof. Murat Uysal, Özyeğin University

Assoc. Prof. Evşen Yanmaz Adam, Özyeğin University

Asst. Prof. Çağatay Edemen, Özyeğin University

Assoc. Prof. Muhammed Fatih Toy, Istanbul Medipol University

Prof. Eylem Erdoğan, Izmir Institute of Technology

Abstract:

As vehicular automation advances, reliable Vehicle-to-Vehicle (V2V) communication is essential for applications such as platooning and collision avoidance. While radio frequency (RF)-based systems suffer from congestion and interference in dense traffic, Vehicular Visible Light Communication (VLC) has emerged as a promising alternative by leveraging vehicular LED headlamps for dual-purpose illumination and data transmission in the interference-free optical spectrum. This dissertation presents the design, implementation, and validation of a practical vehicular VLC system, focusing on FPGA-based transceiver design, optical front-end optimization, and performance modelling under realistic sunlight conditions. A high-power 26W vehicular LED module is characterized, and a custom high-current bias-T circuit is developed to enable broadband modulation. A real-time VLC system is implemented on a Zynq-7000 FPGA platform using On-Off Keying (OOK), with full transmitter and receiver pipelines developed in VHDL. Outdoor experiments demonstrate reliable communication over distances of 20 meters under daylight conditions, with lens-assisted reception improving SNR. A closed-form analytical model is developed to quantify electrical SNR under dynamic solar irradiance, accounting for receiver orientation, inter-vehicle geometry, and temporal variations, and validated through outdoor measurements. Building on this, a framework for adaptive aperture control is introduced by relating receiver aperture diameter to a target SNR. Collectively, this work establishes an end-to-end framework and provides key insights toward robust vehicular VLC systems in dynamic outdoor environments.

Bio:

Bismillah Nasir Ashfaq is a Ph.D. candidate in Electrical and Electronics Engineering at Özyeğin University, Istanbul, Türkiye, where he conducts research at OKATEM (The Center of Excellence for Optical Wireless Communications Technologies). He also serves as a Digital Design Team Lead at Yongatek Microelectronics, Istanbul, Türkiye. He received his M.S. degree (EE) from Bilkent University, Ankara, Türkiye, and B.E. degree (EE) from National University of Science and Technology (NUST), Pakistan. His doctoral research focuses on the design, modelling, and experimental validation of vehicular visible light communication (VLC) systems, including solar interference mitigation, FPGA-based real-time prototyping, and adaptive optical front-end design. His research interests include vehicular VLC, FPGA-based communication systems, optoelectronic front-end design, decoder architectures, and advanced 5G/6G system prototyping.