Ultra-Wideband Underwater Backscatter via Piezoelectric Metamaterials

We present the design, implementation, and evaluation of 𝑈 2 𝐵, a technology that enables ultra-wideband backscatter in underwater environments. At the core of 𝑈 2 𝐵's design is a novel metamaterialinspired transducer for underwater backscatter, and algorithms that enable self-interference cancellation and FDMA-based medium access control.

We fabricated 𝑈 2 𝐵 nodes and tested them in a river across different weather conditions, including snow and rain. Our empirical evaluation demonstrates that 𝑈 2 𝐵 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 5× more throughput and 6× more communication range. Moreover, our evaluation represents the first experimental validation of underwater backscatter in the wild.