Abstract
Aerial acoustic communication (AAC) has been developed for a variety of Internet-of-things (IoT) applications, thanks to the merit of embedding small amounts of data directly into audio contents and transmitting them through commercial off-the-shelf (COTS) devices without additional infrastructure. However, AAC has clear limitations due to ambient noise, severely frequency-selective acoustic channels, and high power consumption of COTS devices. We adopt chirp spread spectrum (CSS) modulation and design new quaternary symbols to overcome frequency selectivity of audio interfaces of COTS devices. We also develop a computation-efficient method to demodulate the proposed symbols, aiming to reduce the power consumption of COTS devices. We employ a frame combining technique without increasing computational complexity, to mitigate the effects of multipath fading and ambient noise in acoustic channels. To evaluate the proposed methods, we conduct extensive experiments with several smartphones in various environments. The experimental results and evaluation demonstrate that the proposed symbols and frame combining method contribute to improving the frame reception ratio by up to 59.8%p (267.9%) and 14%p (84.3%), respectively. The frame combining increases the possibility of receiving a frame within two attempts at extremely low SNR, by up to 107.9%, resulting in reduced excessive delay. The method to demodulate the proposed symbols lowers power consumption by tens to hundreds of milliwatts, depending on the device. Our proposal significantly helps to achieve high reliability and low power consumption of COTS devices in AAC.
Highlights
With the advent of the Internet-of-things (IoT), various wireless communication technologies have been considered to connect a wide range of objects
Aerial acoustic communication (AAC) is a major candidate to consider in the scenarios where small amounts of data are transmitted through commercial off-the-shelf (COTS) devices, such as sharing URLs, user authentication, The associate editor coordinating the review of this manuscript and approving it for publication was Ananya Sen Gupta
The proposed quaternary symbols, named cyclic time shift (CTS)-chirp, exploit the time shift property to cope with frequency selectivity of audio interfaces of COTS devices
Summary
With the advent of the Internet-of-things (IoT), various wireless communication technologies have been considered to connect a wide range of objects. B. POWER CONSUMPTION Various AAC systems for COTS devices have been proposed, and they exploit signal processing techniques with high computation complexity to demodulate acoustic signals [2]. POWER CONSUMPTION Various AAC systems for COTS devices have been proposed, and they exploit signal processing techniques with high computation complexity to demodulate acoustic signals [2] This issue is more important because many mobile applications using AAC run in the background and consume excessive power consistently without being perceived by users [3]. Inaudible acoustic signals use high-frequencies and should be transmitted with very low transmission power. D. POWER CONSUMPTION OF MOBILE DEVICES Recently, various AAC systems for COTS devices have been proposed, most of which exploit signal processing techniques with high computation complexity to demodulate acoustic signals, e.g., FFT. To achieve low power consumption in mobile devices, we develop a computation-efficient method for demodulating the proposed symbols
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