We present the design, implementation, and evaluation of π2π΅, a technology that enables scalable ad ultra-low power ocean IoT. At the core of π2π΅βs design is a novel metamaterial inspired transducer for underwater backscatter, and algorithms that enable self-interference cancellation and FDMA-based medium access control.
The design for U2B nodes alternates between active (piezoelectric) and passive (polymer) layers and it uses the resonance of each individual layer and the resonance from their coupling to demonstrate wideband behavior. Not only does this new design allow us to extend our communication range and to decode backscatter signals in the presence of strong self-interference, but it also enables us to scale underwater backscatter to multiple nodes.
We fabricated π2π΅ nodes and tested them in a river across different weather conditions, including snow and rain. Our empirical evaluation demonstrates that π2π΅ can achieve throughputs up to 20 kbps, an operational range up to 62 m, and can scale to networks with more than 10 nodes. In comparison to the state-of-the-art system for underwater backscatter, our design achieves 5Γ more throughput and 6Γ more communication range.
The design bridges recent advances in metamaterials to underwater backscatter, and demonstrates significant improvements over state-of-the-art proposals. As the research evolves, we hope that these techniques would enable truly ubiquitous subsea IoT systems that can be used for climate change monitoring, marine life sensing, and ocean exploration.
If you are interested in this, check out our other ocean research projects: