Acoustic ranging and communication via microphone channel

Absolute GPS-coordinates are typically inaccessible indoor. Pervasive smartphones offer new opportunities for relative indoor localization. The low-complexity and high-accuracy ranging under the communication-link is a crucial requirement for enabling location sensing in indoor environments. In this paper, we propose a Time-of-Arrival (TOA) estimation and communication scheme utilizing the ubiquitous speaker/microphone pair to achieve accurate ranging. To compensate for the performance loss caused by this simple device, an optimized TOA estimation method is proposed for enhanced ranging reliability and accuracy. To overcome the strong channel fading in acoustic communication, a dynamic demodulation method that jointly uses frequency and amplitude information has been proposed. Experimental results show that our proposed scheme can achieve near 8cm TOA ranging accuracy and 0.55% communication bit-error-rate (BER) with 70% probability.