On the Optimization of Integrated Terrestrial-Air-Underwater Architecture Using Optical Wireless Communication for Future 6G Network

Optical wireless communication (OWC) is one of the promising solution to enhance the capacity of the next generation cellular as well as fiber-wireless (FiWi) broadband access networks. The proposed work aims to complement an OWC system by utilizing unmanned aerial vehicles (UAV) to improve the performance of an integrated terrestrial-air-underwater (TAU) communication framework. Specifically, an integrated FiWi based UAV assisted hybrid free-space optical (FSO) and underwater wireless optical communication (UWOC) system is proposed to meet high data rate requirement between a terrestrial ground station and an autonomous underwater vehicle (AUV). The performance of the proposed scheme is compared against the conventional radio frequency (RF) based TAU communication framework. We also optimize the divergence angle of the optical beam of FSO link using a novel COgnition-based divergence angle tracking (CODAT) algorithm such that the outage probability of FSO links is minimized and the data rate requirement of AUV is also satisfied. The impact of the position of over-sea surface (OSS) relay and UAV altitude on the performance of the proposed system is also analyzed. Through the obtained results it has been shown that the proposed OWC based integrated TAU communication framework outperforms the conventional RF based TAU communication framework.