Autonomous WLAN heading and position for smartphones

In recent years, indoor positioning systems have become important and WiFi positioning based on fingerprinting has been gaining a lot of attention in this field. However, surveying for the WiFi fingerprints in a specific area is a labor and time consuming process. In this work, an innovative method is proposed to automatically generate geo-referenced radio maps for Wireless Local Area Networks (WLAN). The Trusted Portable Navigator (T-PN) was used to provide an integrated navigation solution using inertial sensors and Global Navigation Satellite System (GNSS), when GNSS is available. The T-PN provided positions were used to automatically build a radio map when the solution was reliable. Building a radio map by using this method alleviates the cost of expensive surveys and does not require additional time or manual labor. After the radio map is built, it is used for typical fingerprinting-based WiFi positioning. The experimental results show that reasonable positioning accuracy can be obtained with this automatic fingerprint collection method in indoor environments. Nevertheless, the positions calculated in this manner are not accurate enough to calculate a useful heading of the user. In this paper, we propose another innovative method that estimates user heading based on WLAN signals. This estimation technique is based on the mathematical relationship between the rate of change of RSS for the different access points (APs) and the user velocities, and consequently the user heading.