A robust acoustic signal for smartphone-based indoor ranging and positioning

The acoustic signal is an important medium in communication, damage and leakage detection, etc., and, in recent years, for use in wireless sensor network positioning. With the development of mobile communication technology, smartphone-based indoor positioning by acoustic signals becomes possible. In an indoor environment, however, acoustic signals are interfered with by environmental noise and multipath eects. Moreover, when multiple users position simultaneously, acoustic signals interfere with each other. In order to eliminate various forms of interference, in this paper, we design a robust acoustic signal for smartphone-based indoor positioning. The signal is generated using pseudorandom codes; gold sequences, to modulate a 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 that the signals can work well in the presence of forms of interference.