A Robust Acoustic Signal for Smartphone-based Indoor Ranging and Positioning

The acoustic signal is an important medium in communication, damage and leakage detecting, etc. They are also used in the wireless sensor network positioning in recent years. With the development of mobile communication technology, smartphone-based indoor positioning by acoustic signals becomes possible. In the indoor environment, however, acoustic signals will be interfered with by environmental noise and multipath effect. Moreover, when multiple users are positioning simultaneously, acoustic signals will interfere with each other. In order to eliminate various forms of interference, we design a robust acoustic signal for smartphone-based indoor positioning in this paper. The signal is generated by using the pseudo-random codes, Gold sequences to modulate 6 kHz cosine wave. It is detected through its auto-correlation properties in the receiver. The designed acoustic signal can resist various noises with its excellent cross-correlation characteristic. We conduct experiments on real smartphones and the results show the signals can work well in the presence of forms of interference.