Abstract

Underwater Wireless Sensor Networks (UWSNs) are one of the critical technologies that play a key role in environmental monitoring, ocean exploration, and marine security. UWSNs are deployed in harsh environments face aggressive conditions, limited energy, and bound communication bandwidth; maintenance is very expensive since ship missions are required to recover to deployed nodes. However, it reduces efficiency, reliability, and lifetime. This thesis presents the issues of reliability and lifetime issues of UWSNs by proposing an integrated method using fault-tree analysis (FTA), mean time between failures (MTBF), Failure Mode and Effects Analysis (FMEA), and reliability metrics. The proposed framework analyzes and compares the reliability and lifetime of existing UWSNs.
Furthermore, the thesis delves into the critical aspect of reliability analysis for low-cost underwater sensor nodes, which are becoming increasingly prevalent due to their affordability. A model is proposed for estimating the reliability of such nodes from individual component reliabilities. Case studies on existing low-cost underwater sensor node designs are used to validate this model.
The thesis integrates these methods to devise a framework that achieves substantial enhancement in reliability and lifetime, especially for cost-effective node-based UWSNs. That is to say, this will go a long way in establishing Underwater Sensor Networks as much more reliable and efficient in their operations for different applications. Moreover, the improvement in circuit reliability helped come up with a better design that improved upon its reliability and extended its lifetime.