Scalable adaptive networking for the Internet of Underwater Things

Internet of Underwater Things (IoUT) systems comprising tens or hundreds of underwater acoustic communication nodes will become feasible in the near future. The development of scalable networking protocols is a key enabling technology for such IoUT systems, but this task is challenging due to the fundamental limitations of the underwater acoustic communication channel: extremely slow propagation and limited bandwidth. The aim of this paper is to propose the JOIN protocol to enable the integration of new nodes into an existing IoUT network without the control overhead of typical state-of-the-art solutions. The proposed solution is based on the capability of a joining node to incorporate local topology and schedule information into a probabilistic model that allows it to choose when to join the network to minimize the expected number of collisions. The proposed approach is tested in numerical simulations and validated in two sea trials. The simulations show that the JOIN protocol achieves fast convergence to a collision-free solution, fast network adaptation to new nodes, and negligible network disruption due to collisions caused by a joining node. The sea trials demonstrate the practical feasibility of this protocol in real UAN deployments and provide valuable insight for future work on the trade-off between control overhead and reliability of the JOIN protocol in a harsh acoustic communication environment

Target Detection Using Underwater Acoustic Networking

This paper presents a feasibility study for simultaneous underwater acoustic communication (UAC) and target detection using a network of underwater nodes. It can be achieved via anomaly detection in the estimated channel impulse response (CIR) of regular packet transmissions in the network. Such a network could serve as the first step in detecting and localising possible targets, which could then be followed up by the deployment of a sonar-equipped AUV to scan the identified area in more detail. The MAC layer based on Spatial Reuse TDMA (STDMA) fits the traffic requirements of such a network significantly better than contention-based MAC protocols. An enhancement of STDMA packet scheduling that utilises interference cancellation (IC) capabilities at the receivers can further increase the network throughput and, thus, the target detection performance. The simulation study shows that such an approach is feasible from the point of view of network throughput and the probability of the target ``crossing" an active acoustic path. Further work includes the integration of a more detailed acoustic environment model, and the development of a Network and Application Layer to deliver the detection information through the network and to enable target tracking