AquaSaC: A Single Optical Waveform for Underwater Sensing and Communication

Underwater sensing and communication are fundamental enablers for marine applications, such as autonomous exploration, environmental monitoring, and infrastructure inspection. However, conventional underwater communication techniques suffer from fundamental limitations: (i) acoustic-based methods offer long-range coverage but with limited data rates and high latency; (ii) radio-frequency signals suffer from severe attenuation in water, failing to provide communication for most underwater tasks; (iii) while Optical Wireless Communication (OWC) has emerged as a promising alternative due to its high bandwidth and low latency, its highly directional characteristic requires strict alignment between transceivers, posing significant challenges for Unmanned Underwater Vehicle (UUV) systems. To address these limitations, in this paper, we propose AquaSaC, a novel system that enables simultaneous underwater optical sensing and communication through a newly designed unified waveform modulation scheme. AquaSaC is inspired by the observation that frequency-modulated optical sensing signals in water can also be detected by optical receivers such as photodetectors. Building on this insight, we design AquaSaC with three key components: (i) Integrated Optical SensCom (IOSC) Modulator/Demodulator, (ii) Information-rich Beacon Generator (IBG), and (iii) Adaptive Waveform Optimization (AWO) module, with the objective to achieve precise sensing and high-speed communication simultaneously in dynamic underwater environments. To evaluate AquaSaC in practice, we design and implement a prototype using commercial off-the-shelf components and conduct extensive real-world underwater experiments to evaluate its sensing and communication performance. Results demonstrate that AquaSaC can achieve high-accuracy sensing, with an average error of ±5 cm in distance and ±10 cm/s in velocity estimation, while enabling reliable optical communication at Mbps-level data rates. These results highlight AquaSaC’s potential as a practical and efficient underwater integrated sensing and communication solution.