Techniques to Leverage RF Signals for Context Sensing

RF signals and devices have been used for wireless communication to improve the mobility and ubiquity of mobile devices. In this dissertation, we show that these RF signals can also be used for context sensing applications. Specifically, we present cyber-physical systems and algorithms to sense human vital signals, object vibrations and movements, and object’s location to deliver new sensing capabilities for a variety of new applications including health-care monitoring, privacy protection, and indoor localization. We deliver three fundamental contributions. First, we develop an RF-based system to “sense” human breathing volume continuously in fine-grained from afar. Second, we develop a technique to “sense” the wireless signals emitted from drones/fly-cams to detect them and alert users for privacy protection. Last, we present our preliminary study on building a system to enable the mobile device to “sense” their global locations at the indoor environment. To deliver these contributions, we exploit the properties of physical characteristics of RF signals, analyze and understand targeted subjects behaviors (i.e., human, drones), work across different limitations and hardware-software barriers, and introduce novel systems and new algorithms to overcome the challenges. We implement and evaluate the system on real users/patients, test the systems across different environments, and demonstrate how they can enable many other real-world applications

Indoor positioning with GPS and GLONASS-like signals use of new codes and a repealite-based infrastructure in a typical museum building

International audienceIn order to propose a solution for the indoor positioning question, several tests with the repealite-based (similar to Pseudolites and repeaters) system have been carried out. This system uses a single Global Navigation Satellite System signal transmitted by all the indoor antennas. These signals may interfere with the satellite ones outdoors. Hence, the noise level at the outdoor receiver will be higher and the error range larger. To avoid these effects, new codes called Indoor-Modified Binary Offset Carrier codes that are capable of reducing interference with outdoor signals are generated. To analyse the performance of these codes, we carry out a theoretical expression of cross-correlation functions. Then the deployment of the repealite based system in a typical building is simulated. The goal of this step is to compare the interference performance of the new code with the one already used (Gold codes for GPS band and maximal sequence for Glonass one). A specific interest is given to the spectral interference when adding the new signal's spectrum in the considered frequency ban