Optical Wireless Communication (OWC) underwater characterization for robot communication system

This thesis presents a comprehensive study on the design, optimization, and
evaluation of LED-based Optical Wireless Communication (OWC) systems within
confined pipeline environments, including both air-filled (free-space) and waterfilled
conditions. The investigation begins with an experimental characterization of
light transmission in an empty PVC pipe, where line-of-sight (LOS) and multipath
reflections are assessed using multiple wavelength LEDs. Optical enhancements such
as collimating lenses and reflectors are integrated and analyzed through simulation
and measurement to quantify their effects on received power and frequency
bandwidth.
To address the thermal limitations of high-power LEDs, an optimized heatsink
structure is developed using heat transfer modeling and validated through SolidWorks
CFD simulations. Experimental results confirm that the optimized heatsink
significantly improves LED frequency response and receives optical power, with up
to a 245% enhancement observed in certain wavelengths compared to conventional
cooling solutions.
Subsequently, the thesis focuses on the challenges of underwater optical
transmission. Water-filled pipe environments are investigated through both
theoretical and experimental frameworks, incorporating Fresnel’s reflection theory,
Beer–Lambert law, and Henyey–Greenstein scattering models. A controlled testbed
is used to evaluate LED performance under various water levels, revealing the
wavelength-dependent attenuation behaviors. Simulation results using Ansys Zemax
OpticStudio corroborate experimental findings, demonstrating the impact of beam
divergence, and material interfaces.
The outcomes of this research provide critical insights into the optical,
thermal, and environmental factors influencing OWC in pipeline systems. These
findings inform the development of robust, high-efficiency communication platforms
for applications in pipeline monitoring, submerged robotics, and smart infrastructure
systems.