Hybrid IRSNOMA Framework for Turbulence Resilient Underwater Visible Light Communication

Abstract

Underwater Visible Light Communication (UVLC) offers high data rates, low latency, and strong physical-layer security, making it as an alternative to acoustic and RF systems for real-time underwater applications. However, its performance is severely degraded by absorption, scattering, and turbulence-induced fading. To enhance link reliability, recent advances in Non-Orthogonal Multiple Access (NOMA) and Intelligent Reflecting Surfaces (IRS) are being integrated into UVLC systems. NOMA enables simultaneous multiuser access through power-domain multiplexing, improving spectral efficiency and connectivity, while IRS enhances signal strength and coverage by intelligently reflecting and directing optical beams. Motivated by these benefits, we propose a hybrid IRSNOMA framework for UVLC to improve link reliability and mitigate turbulence effects. A composite channel model is formulated by combining direct and IRS-reflected paths under absorption, scattering, and turbulence modeled using the Exponential Generalized Gamma (EGG) distribution with pointing errors. Closed-form expressions for the outage probability and average bit error rate (ABER) are derived in terms of the Meijer-G function. System performance is evaluated under various configurations, and Monte Carlo simulations validate the analytical results, demonstrating excellent match and highlighting the effectiveness of the proposed IRSNOMA-assisted UVLC design.