Exploring QoS metrics in SDN-based IoUT: A comparative study of 3D topology design techniques

The Internet of Underwater Things (IoUT) has become a pivotal domain for advancing underwater communication and monitoring systems. However, achieving efficient and reliable communication in 3D underwater environments remains challenging due to constraints such as limited bandwidth, high energy consumption, and severe signal attenuation. This paper investigates Quality of Service (QoS) optimization in Software-Defined Networking (SDN)-based IoUT environments through the implementation and analysis of various 3D topology design algorithms, including Cubic, Hexagonal Prism, Rhombic Dodecahedron, and Truncated Octahedron. These algorithms aim to optimize network connectivity and coverage by determining the spatial arrangement of underwater nodes. The SDN controller computes shortest paths, informs nodes of their routing decisions, and directs packet forwarding. Beyond a direct comparison of existing topologies, this study provides a unified SDN-based evaluation framework to analyze how 3D geometric node placement affects QoS performance, routing efficiency, and deployment cost in underwater IoUT environments. Key QoS metrics, including throughput, network lifetime, energy consumption, and delay, are evaluated and compared across these topologies to identify the most effective design for underwater networks. The results provide valuable insights into the trade-offs between topology structures and their impact on QoS, contributing to the development of more robust and energy-efficient SDN-enabled IoUT systems. The simulation results indicate that the RD method reduces the number of deployed nodes by approximately 63% while concurrently improving network lifetime by 25% and decreasing end-to-end delay by 16%.