Speaker:Asc.-Prof. Dr. Guenther Retscher

Date: 10:00 Oct 28

Venue: C505 Haiyun Admin Building

Abstract:The development of indoor navigation systems has become a growing field of research interest in recent years as many applications nowadays require ubiquitous positioning in combined out-/indoor environments. There are still many unresolved challenges in such type of applications as satellite-based GNSS and GNSS-aided inertial navigation systems (INS) are capable methods for mainly outdoor navigation only. Indoor positioning can be defined as any system which attempts to provide an accurate positioning inside of a covered structure using radio waves, acoustic signals, or other sensory information collected by mobile devices. It is primarily used for real-time location of people or objects in large buildings and in closed areas/spaces. Several types of location-sensing systems exist which each have its own strengths as well as limitations. In general, localization technologies can be classified into three categories, i.e., designated technologies based on pre-deployed signal transmission infrastructure, technologies based on ‘signals-of-opportunity’ and technologies not based on signals. In the first categories fall systems using infrared or ultrasonic signals, magnetic fields, Ultra Wide Band (UWB), Radio Frequency Identification (RFID) or other RF-based systems. Signals-of-opportunity include RF signals not intended for positioning, for instance, Wi-Fi, digital television, mobile telephony, FM radio and others. Dead reckoning (DR) using inertial sensors (accelerometers and gyroscopes) as well as vision/camera systems belong to the third category.

This talk aims to provide an insight into the use of a prominent signal of opportunity, namely Wi-Fi. Two new approaches developed at the TU Wien–Vienna University of Technology, Austria are introduced. In the first one, localization fingerprinting is the employed positioning method. A so-called ‘intelligent check-point’ (iCP) concept has been developed to reduce the laborious work for the establishment of reference points and radio maps of Wi-Fi signal strength distributions located throughout the area of interest. The second approach is based on the well-known DGPS principle. We term it Differential Wi-Fi (DWi-Fi). From measurements to reference stations area correction parameters are derived and applied for positioning determination of a mobile user. Both technologies have been extensively tested in a multi-storey office building. The main findings are highlighted in this presentation. It is shown that the approaches are capable to located a user carrying a smartphone or other mobile device in complex buildings. Furthermore, the combination and integration with RFID is briefly elaborated.

BIOGRAPHICAL NOTES

Guenther Retscher is Associate Professor at the Department of Geodesy and Geoinformation of the TU Wien – Vienna University of Technolgy, Austria. He received his Venia Docendi in the field of Applied Geodesy from the same university in 2009 and his Ph.D. in 1995. His main research and teaching interests are in the fields of engineering geodesy, satellite positioning and navigation, indoor and pedestrian positioning as well as application of multi-sensor systems in geodesy and navigation.