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G. Retscher:
"Urban and Indoor Wi-Fi Positioning for Routing of Public Transport Users";
Talk: 1st Symposium on Location Based Services, Xiamen, China (invited); 2019-05-03.

The ubiquity of Wi-Fi signals in urban environments has the high potential to employ them for numerous applications for user localization and guidance in cities. Especially in indoor environments Wi-Fi location fingerprinting has become a popular method. The outreach of Wi-Fi localization is extended in this study for urban wide applications and combined in-/outdoor transitional environments. Serval public transport routes from a residential neighbourhood to different University office buildings in the city centre of Vienna are selected as test trajectories. A short system training was performed in the beginning along these trajectories at the benchmarks and public transport stops where only a few samples of received signal strengths (RSS) have been collected. Furthermore, long-term repeatedly observations of the Wi-Fi RSS along the routes are used for continuous system updating and training. As a high number of Access Points of public and private Wi-Fi networks are visible in dense urban environments a meaningful selection of the RSS is a highly important necessity. For localization the most stable, consistent and reliable measurements need to be selected. Additionally, a different availability of the selected Access Points on different locations along the trajectories has to be guaranteed to facilitate positioning. Thus, a detailed analysis of all visible Access Points and their RSS behaviour over time is carried out. Vienna has installed Wi-Fi Access Points in some metro stations and even directly on some of the trams. In addition, to the RSS measurements to the surrounding Access Points an analysis of the stability of the mobile Access Points on the trams is performed. The particular feature of the tram route is that it runs on different levels partially underground and then above ground in the middle of a road.

Wi-Fi localization, fingerprinting, mobile Access Points, public transport, multi-modal transport routing