WLAN indoor positioning: a look at the environment

Abstract

Positioning means to gain awareness, within a certain accuracy, of a mobile device location. It is not a stand alone application, but rather a service that is ground to several applications. Hundreds of research groups worldwide have been developing automated location systems for several decades, for both civilian and military purposes. To date the standard solution to outdoors positioning is provided by the Global Navigation Datellite System (GNSS),that is the GPS and the forthcoming Galileo. Challenges are different indoors and require micro-detailed geo-referencing to satisfy users’ growing needs. To geo referentiate a building is not enough if the position of users inside the building is also relevant to the application. Objects are used as landmarks, and relationships among the objects are crucial for symbolic representation of the whole system. The applications to this scenario are manifold and range from logistics to routing, from personal safety to emergency response. Unluckily, GNSS do not work properly indoors for the absence of Line Of Sight (LOS) propagation between the satellites and the mobile, such that deep multipath effects randomize the times of arrival of the signals. The impossibility of using satellite systems was already clear in the mid ‘90s and has driven toward the exploitation of local technologies; consequently, a plethora of choices has been explored. None of them has shown optimal or even sufficient performances in all settings, so the research in this field keeps on gathering much interest inside the Navigation Community. The main interest has been drawn to ‘local technologies’, that are non invasive, cheap and under the full control of the provider; in particular, the reuse of technologies already deployed for wireless communication purposes yields a great opportunity. Our choice falls on the Wireless Local Area Network (WLAN) and we adopt, as the relevant parameter to measure, the power propagated between transmitter and receiver; concerning the architecture and the experimental results described in the thesis, we rely on WLAN main example: the standard IEEE 802.11 also named WiFi… [edited by author]