Spartacus: Spatially-Aware Interaction for Mobile Devices Through Energy-Efficient Audio Sensing.

ABSTRACTRecent developments in ubiquitous computing enable applications that leverage personal mobile devices, such as smartphones, as a means to interact with other devices in their close proximity. In this paper, we propose Spartacus, a mobile system that enables spatially-aware neighboring device interactions with zero prior configuration. Using built-in microphones and speakers on commodity mobile devices, Spartacus uses a novel acoustic technique based on the Doppler effect to enable users to accurately initiate an interaction with a neighboring device through a pointing gesture. To enable truly spontaneous interactions on energy-constrained mobile devices, Spartacus uses a continuous audio-based lower-power listening mechanism to trigger the gesture detection service. This eliminates the need for any manual action by the user. Experimental results show that Spartacus achieves an average 90% device selection accuracy within 3m for most interaction scenarios. Our energy consumption evaluations show that, Spartacus achieves about 4X lower energy consumption than WiFi Direct and 5.5X lower than the latest Bluetooth 4.0 protocols.