An analytical framework for low-power underwater backscatter communications

Acoustic underwater backscatter enables ultra-low-power communication with applications in ocean exploration, monitoring, navigation, and aquaculture. Unlike traditional communication systems, acoustic backscatter does not require active signal generation. Instead, it communicates data by modulating existing acoustic signals, requiring few microwatts of power for operation. Backscatter communication enables ultra-low power sensors by switching between absorbing and reflecting acoustic waves transmitted from a central station. The energy burden is shifted to the transmitting station, and the acoustic power supplied by the station can power the sensor, allowing for battery-free operation. Initial demonstrations of underwater backscatter communication were encouraging; however, the theoretical and practical limits are still unknown. In this work, we develop a multiphysics analytical framework for the communication and power link budget of underwater backscatter. The framework calculates practical communication and power-up range, transmitter power budget, and signal-to-noise ratio, accounting for transducers’ characteristics and the underwater communication channel. The analytical predictions are validated for practical transducers using high-fidelity piezo-acoustic finite element simulations and experimental measurements. The framework will guide future backscatter systems design, identifying practical operation ranges and optimal frequencies for data transmission and batteryless operation.