ECO-UW IoT: Eco-friendly Reliable and Persistent Data Transmission in Underwater Internet of Things

Achieving reliable and persistent environmental field estimation in Underwater Internet of Things (UW IoT) is a challenging problem. Given the need for high-resolution spatio-temporal sensing in such environment, traditional digital sensors are not suitable due to their high cost, high power consumption, and non-biodegradable nature. Further, reliable communication techniques that avoid retransmissions are crucial for reconstructing the phenomenon in a timely manner at the fusion center such as a drone. To address the above challenges, we propose a novel architecture consisting of a substrate of densely deployed underwater all-analog biodegradable sensors that continuously transmit data to the surface digital buoys. The analog nodes are designed to be energy efficient by implementing Analog Joint Source Channel Coding (AJSCC), a low-complexity compression-communication technique, using biodegradable Field Effect Transistors (FETs). We then propose a correlation-aware Hybrid Automatic Repeat Request (HARQ) technique to transmit data from the surface buoys to the fusion center. Such HARQ technique leverages redundancy in the buoy data (arising from the correlation of the phenomenon at the analog nodes) to avoid retransmissions, thus saving energy and time. The performance of the proposed analog sensor design and of the correlation-aware HARQ communication technique has been evaluated via simulations and shown to achieve the desired behavior.