In this work, we design and analyse a Slotted ALOHA (SA) solution for Optical Wireless Communication (OWC)-based Internet of Underwater Things (IoUT). In the proposed system, user devices exchange data with an access point (AP) which exploits the capture effect. The space spanned by the IoUT nodes is three-dimensional, i.e., users are located in half-sphere centered at the AP placed at the bottom of a floating object at the water surface level. The analytical expressions for the system throughput and reliability expressed in terms of the outage probability are derived. Based on the simulated signal-to-noise-and-interference-ratio statistics and derived analytical expressions, we present numerical results that investigate the trade-off between the system performance and the IoUT system parameters, such as the number of users, activation probability and type of water medium. The presented conclusions provide valuable insights into the design of an SA-based solution for IoUT communications.

翻译：本文针对基于光学无线通信（OWC）的水下物联网（IoUT）系统，设计并分析了一种时隙ALOHA（SA）方案。在所提出的系统中，用户设备通过接入点（AP）交换数据，该接入点利用了捕获效应。IoUT节点所处的空间为三维结构，即用户分布在水面漂浮物底部AP周围的半球面内。推导了系统吞吐量以及以中断概率表征的可靠性的解析表达式。结合模拟的信噪干扰比统计量与解析表达式，本文给出了数值结果，深入研究了系统性能与IoUT系统参数（如用户数、激活概率和水介质类型）之间的权衡关系。所得结论为基于SA的IoUT通信方案的设计提供了有价值的见解。