Ubiquity of Wi-Fi: Crowdsensing Properties for Urban Fingerprint Positioning

Positioning systems based on location fingerprinting have become an area of intense research, mainly with the aim of providing indoor localization. Many challenges arise when trying to deploy location fingerprinting to an outdoor environment. The main problem is achieving coverage of large outdoor spaces, which needs an intensive data gathering effort. This paper proposes the use of mobile crowdsensing in order to build a fingerprint database consisting of Wi-Fi networks received signal strength measurements. Mobile crowdsensing is represented by the usage of smart-phones equipped with GPS and Wi-Fi sensors for the collection of fingerprints. The primary objective of this work is to prove the feasibility of urban positioning using Wi-Fi crowdsensed data by showing that Wi-Fi networks are ubiquitous in urban areas. We then examine the gathered data and report our findings on challenges in building and maintaining a large-scale fingerprint database, the influence of the data collection method on the Wi-Fi data and the influence of fading on measurements. As Wi-Fi access-points are shown to exhibit mobility, we also propose and analyze methods for detecting and classification of mobile and static access-points.