ABSTRACT
In this chapter, the authors propose an indoor localization system called "Guoguo," and further improve its performance in terms of coverage, accuracy, update rate, and sound pollution. The authors make its acoustic beacons imperceptible to humans and improve detection sensitivity for better location coverage. Rather than simply using "Beep" signals to enable passive sensing for multiple smartphone users, the authors design transmission waveform, wide-band modulation, and one-way synchronization and ranging schemes. To meet the localization accuracy, time-of-arrival (TOA) based ranging is more appropriate. Limited by the smartphone, using acoustic signal for TOA-based ranging is an appropriate solution. However, making the acoustic signal for ranging and localization in real situations has a lot of challenges. Significant improvements were achieved in terms of accuracy, cost, and scalability, compared with other existing approaches. Guoguo represents a leap of progress in smartphone-based indoor localization, opening enormous new opportunities for indoor location-based services, positioning and navigation systems, and other commercial, educational, or entertainment applications.
