Using topography to aid smart phones geolocation

Global positioning system (GPS) on smart phones is often either unavailable or inaccurate in urban and natural canyons, indoors, and in forests. Hence it is augmented by use of other available radio frequency (RF) signals, such as WiFi with radio frequency identification and cellular, using their received signal strength, time difference of arrival and even angle of arrival. A novel methodology developed by our group has shown that using local magnetic field intensity mapping based on interval analysis performs better at geolocation than RF based augmentation where GPS is not accessible. In this article, we have extended the algorithms and developed using topographical maps-maps of local gravitational inclination vector to augment geolocation. Sensor measurements on the smart phones are used to construct the topographic maps and aid smart phone’s geolocation through our novel algorithms. Experimental results show the potential of our algorithms on uneven outdoors terrain.