Modeling and simulation of optical wireless communication channels in IoUT considering water types turbulence and transmitter selection.

The Internet of Underwater Things (IoUT) is revolutionizing underwater communication by enabling real-time data exchange, environmental monitoring, and exploration in aquatic environments. Among emerging technologies, optical wireless communication (OWC) has gained prominence due to its high-speed data rates and superior efficiency compared to traditional acoustic and radio frequency (RF) methods. This paper presents a comprehensive study of OWC channel modeling and simulation tailored for IoUT applications. The research investigates the physical characteristics of underwater optical channels, focusing on the effects of absorption, scattering, turbulence, and various noise sources on light propagation across diverse water types, including pure seawater, clear coastal waters, and turbid harbor waters. A central aspect of the study is the comparative evaluation of two transmitter types-light-emitting diode photo sources (LED-PS) and laser diode photo sources (LD-PS)-both operating at a 520 nm wavelength (green light). Their performance is assessed under varying environmental conditions, incorporating three turbulence models: log-normal, generalized gamma, and Weibull distributions. Simulation models are developed and implemented using MATLAB and Python to analyze key parameters such as transmission distance, water type, transmitter characteristics, wavelength, and turbulence intensity. Performance metrics, including received optical power, signal-to-noise ratio (SNR), and bit error rate (BER), are evaluated to provide in-depth insights into system behavior. Results show that LD-PS consistently outperforms LED-PS across all scenarios. For instance, at a received power threshold of - 53.4 dBm, LD-PS achieves a communication distance of up to 68.39 m in pure seawater (compared to 27.36 m for LED-PS), while in turbid harbor, the range is reduced to 3.08 m. At a BER of 10, LD-PS reaches 67.69 m in pure seawater and 3.18 m in turbid harbor conditions. Under a fixed SNR of 50 dB, LD-PS achieves a maximum range of 73.34 m in pure sea. The minimum SNR required to maintain a BER of 10 is 12.19 dB in pure seawater and rises to 91.94 dB in turbid harbor conditions. These findings advance the development of OWC systems by providing practical guidelines for optimizing underwater communication performance. The insights presented serve as a foundation for designing robust and efficient IoUT networks capable of reliable data transmission across a range of aquatic environments.