ChirpCom: A CSS based Underwater Acoustic Communication for Smart Devices

Acoustic communication is a promising technique for underwater communication. However, most of the existing acoustic communication technologies usually require custom acoustic modem hardware and custom amplifiers, leading to high hardware costs and a lack of portability. The recent method leverages microphones and speakers on commodity mobile devices to achieve OFDM modulation and demodulation. However, OFDM modulation in underwater acoustic communication is extremely susceptible to narrow-band interferers and frequency selective fading. In this paper, we propose ChirpCom, a CSS-based underwater acoustic communication for smart devices. We derive the theoretical channel model to guide the CSS-based underwater acoustic communication. To cope with the frequency selectivity and time-varying of underwater acoustic channels, We design a link quality estimation method as well as an adaptation algorithm to reliably decode the symbols. We implement a prototype of ChirpCom with a commercial smartphone. The experiments demonstrate that ChirpCom can achieve a communication range of 20m with a throughput up to 230bps.