The acoustic capabilities (i.e. microphone) and the fast processors of modern smartphones allow for the transmission of data to groups of such devices through the audio channel. We discuss an acoustic data transmission system for broadcast communication to a multitude of smartphones without the need of a radio access point. Acoustic data transmission is particularly attractive in scenarios that involve sound systems (e.g., movie theaters or open-air film festivals). We discuss different techniques to hide data in sound tracks and how to form a microphone array from a collection of smartphones in the same location. Collaborating smartphones share (using their radio interfaces to form an ad hoc network) the received data streams to jointly correct errors. With a testbed of up to four smartphones, we demonstrate how the robustness and reliability of a downlink broadcast via an acoustic communication system can be improved by collaboration between spatially distributed devices. With field tests in different scenarios, we investigate the potential gain of the collaboration in a real environment.
The documents contained in these directories are included by the contributing authors as a means to ensure timely dissemination of scholarly and technical work on a non-commercial basis. Copyright and all rights therein are maintained by the authors or by other copyright holders, notwithstanding that they have offered their works here electronically. It is understood that all persons copying this information will adhere to the terms and constraints invoked by each author’s copyright. These works may not be reposted without the explicit permission of the copyright holder.