Graduate School and Research Center in Digital Sciences

Seminar: Indoor Radio-based Localization: research overview and future work

Islam Alyafawi - PhD Student - University of Bern

Communication systems

Date: December 17, 2014

Localization, tracking and activity detection based on radio signals are of great interest in many application fields, such as health care, emergency systems or smart homes. The global positioning system (GPS) offers an adequate technology for outdoor localization. However, its use is limited to areas maintaining a line-of-sight (LOS) connection with satellites, rendering its use difficult in dense urban areas and indoors. Depending on the participation of the tracked device, two types of localization systems can be distinguished. In active systems the mobile device (MD) communicates with several anchor nodes (ANs) and the localization process is a collaborative effort. Examples of such systems are the use of WiFi access points or GSM base stations as anchor nodes. On the contrary, in a passive system the ANs are hidden for the target and only overhear the target?s radio transmissions. While passive systems offer invisibility to the GSM network operator and end users, they set several challenges to signal capturing. Concerning the radio signal, metrics often used in radio-based localization are received signal strength (RSS), time of arrival (TOA), time difference of arrival (TDOA) and angle of arrival (AOA). Indoor radio propagation is subject to a number of factors such as multipath interference, non-line-of-sight (NLOS) reception, and any abnormal signals caused by incorrect hardware calibration. This generates contaminated signals, which behave in unpredictable ways and subsequently introduce localization errors. This talk begins with a discussion of challenges in indoor localization, followed by some experimental results and proposed ideas to overcome these challenges, and finally future work.

Indoor Radio-based Localization: research overview and future work