A Passive and Asynchronous Wake-up Receiver for Acoustic Underwater Communication

TL;DR

This paper introduces a passive, asynchronous wake-up receiver for underwater acoustic communication that achieves zero-power listening, significantly reducing energy consumption for long-term sensor deployments.

Contribution

It presents a novel passive wake-up receiver that extracts energy from acoustic signals, enabling zero-power always-on listening in underwater sensors.

Findings

Requires only 63 μW to operate

Detects and compares 8-bit UUID at 200 bps up to 5 meters

Energy is directly extracted from acoustic signals

Abstract

Establishing reliable data exchange in an underwater domain using energy and power-efficient communication methods is crucial and challenging. Radio frequencies are absorbed by the salty and mineral-rich water and optical signals are obstructed and scattered after short distances. In contrast, acoustic communication benefits from low absorption and enables communication over long distances. Underwater communication must match low power and energy requirements as underwater sensor systems must have a long battery lifetime and need to work reliably due to their deployment and maintenance cost. For long-term deployments, the sensors' overall power consumption is determined by the power consumption during idle state. It can be reduced by integrating asynchronous always-on wake-up circuits with nano-watt power consumption. However, this approach does reduce but not eliminate idle power consumption, leaving a margin for improvement. This paper presents a passive and asynchronous wake-up receiver for acoustic underwater communication enabling zero-power always-on listening. Zero-power listening is achieved by combining energy and information transmission using a low-power wake-up receiver that extracts energy out of the acoustic signal and eliminates radio frontend idle consumption. In-field evaluations demonstrate that the wake-up circuit requires only 63 uW to detect and compare an 8-bit UUID at a data rate of 200 bps up to a distance of 5 m and that the needed energy can directly be extracted from the acoustic signal.