Today
Bookmark and Share    
Full Text
Peer Reviewed
See detailWi-Fi butterfly effect in indoor localization: The impact of imprecise ground truth and small-scale fading
Popleteev, Andrei UL

in 14th IEEE Workshop on Positioning, Navigation and Communications (WPNC-2017) (2017, October)

The increasing accuracy of indoor positioning systems makes their evaluation an increasingly challenging task. A number of factors are already known to affect performance of fingerprint-based systems ... [more ▼]

The increasing accuracy of indoor positioning systems makes their evaluation an increasingly challenging task. A number of factors are already known to affect performance of fingerprint-based systems: hardware diversity, device orientation, environment dynamics. This paper presents a new butterfly-like effect in localization experiments. The effect is caused by minor ground truth (GT) errors --- that is, small deviations between calibration and test positions. While such deviations are widely considered as purely additive and thus negligible, we demonstrate that even centimeter-scale GT errors are amplified by small-scale radio fading and lead to severe multi-meter Wi-Fi positioning errors. The results show that fingerprint-based localization accuracy quickly deteriorates as GT errors increase towards 0.4 wavelength (5 cm for 2.4 GHz). Beyond that threshold, system's accuracy saturates to about one-third of its original level achievable with precise GT. This effect challenges the impact of the already known accuracy-limiting factors (such as cross-user tests, receiver diversity, device orientation and temporal variations), as they can be partially explained by minor GT errors. Moreover, for smartphone-in-a-hand experiments, this effect directly associates the evaluation outcomes with experimenters' diligence. [less ▲]

Detailed reference viewed: 19 (0 UL)
Full Text
Peer Reviewed
See detailPlease Stand By: TV-based indoor localization
Popleteev, Andrei UL

in 28th IEEE Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC-2017) (2017, October)

Despite the decades of efforts, indoor positioning remains an open research challenge. While existing solutions already demonstrate high accuracy, their in-building infrastructure --- such as Wi-Fi access ... [more ▼]

Despite the decades of efforts, indoor positioning remains an open research challenge. While existing solutions already demonstrate high accuracy, their in-building infrastructure --- such as Wi-Fi access points or Bluetooth beacons --- provides only a limited coverage. This paper investigates feasibility of accurate indoor positioning using broadcast digital TV signals, readily available in populated areas worldwide. We experiment with the classic received signal strength (RSS) fingerprinting, and introduce a novel approach based on channel state information (CSI), which leverages frequency-selective multipath fading of wideband TV signals. The proposed methods are experimentally evaluated on an extensive dataset of DVB-T signals, systematically collected in two large buildings over the course of 8 months. The results show that the proposed approach consistently outperforms RSS fingerprinting and achieves 92--98% localization accuracy. While this study is based on the European DVB-T signals, the proposed method is directly generalizable to other TV standards (such as ATSC, ISDB, DTMB and DMB) and wide-area TV white space (TVWS) networks. [less ▲]

Detailed reference viewed: 21 (4 UL)
Full Text
Peer Reviewed
See detailAmbiLoc: A year-long dataset of FM, TV and GSM fingerprints for ambient indoor localization
Popleteev, Andrei UL

in 8th International Conference on Indoor Positioning and Indoor Navigation (IPIN-2017) (2017, September)

Ambient indoor localization - an approach that leverages ambient radio signals - has been previously shown to provide promising positioning performance using the globally available infrastructure of FM ... [more ▼]

Ambient indoor localization - an approach that leverages ambient radio signals - has been previously shown to provide promising positioning performance using the globally available infrastructure of FM, TV and cellular stations. However, the need for specialized equipment and laborious data collection constitute a high entry barrier for follow-up studies. This paper presents AmbiLoc - a dataset of radio signals for ambient indoor localization research. The dataset has been systematically collected in multiple testbeds, including large-scale and multi-floor buildings, over the course of one year. Due to the use of a software-defined radio receiver, raw signal samples in AmbiLoc allow extraction of arbitrary fingerprinting features. The first edition of AmbiLoc, introduced in this paper, includes received signals strength (RSS) fingerprints of FM, TV and GSM signals, along with the relevant metadata (such as weather conditions). The dataset is available online at AmbiLoc.org. As the first public dataset of ambient localization signals, AmbiLoc provides an easy entry and a common reference for researchers exploring novel indoor localization methods. [less ▲]

Detailed reference viewed: 31 (0 UL)
Full Text
Peer Reviewed
See detailIndoor localization using ambient FM radio RSS fingerprinting: A 9-month study
Popleteev, Andrei UL

in 17th IEEE International Conference on Computer and Information Technology (CIT-2017) (2017, August)

While indoor positioning systems aspire for higher accuracy, their coverage is typically limited to buildings with dedicated hardware. A possible alternative is offered by infrastructure-free positioning ... [more ▼]

While indoor positioning systems aspire for higher accuracy, their coverage is typically limited to buildings with dedicated hardware. A possible alternative is offered by infrastructure-free positioning methods. In particular, several studies have demonstrated feasibility of indoor positioning using broadcast FM radio signals, which are available in most populated areas worldwide. However, previous work provides little information about long-term performance of FM-based indoor localization. This paper presents a longitudinal study of FM indoor positioning based on received signal strength (RSS) fingerprinting. We evaluate system's performance on a large dataset of real-world FM signals, systematically collected in several large-scale multi-floor testbeds over the course of 9 months. We also investigate the impact of different classifiers, training schedules and fingerprint sizes on localization accuracy. The results demonstrate that well-trained FM-based system can provide reliable indoor positioning even several months after deployment. [less ▲]

Detailed reference viewed: 6 (0 UL)
Full Text
See detailObservation and Control of Anaerobic Digestion Processes for Improved Biogas Production
Chaib Draa, Khadidja UL

Doctoral thesis (2017)

In this thesis, we propose a formal modelling framework for the anaerobic digestion process, where we add more degrees of freedom in the control of biogas production. Indeed, we add two additional control ... [more ▼]

In this thesis, we propose a formal modelling framework for the anaerobic digestion process, where we add more degrees of freedom in the control of biogas production. Indeed, we add two additional control inputs to the standardized AM2 (Acidogenesis Methanogenesis, 2 steps) model, re ecting addition of stimulating substrates which enhance the biogas quality and quantity. Then, we describe how the parameters of the resulted nonlinear model can be identi ed, and we analyse the positiveness and boundedness of its state variables. Based on the derived mathematical model and the analysis results, we design di erent software sensors to overcome the lack of reliable and cheap sensors. Indeed, we present a general class of systems to which the considered process model belongs. Then, we design an LMI-based invariant like observer as well as an LMI-based nonlinear observer of the same form as the generalized Arcak's observer. Furthermore, with the aim to render the observer design more robust to disturbances, we include the H1 criterion in its synthesis. Also, to promote the use of the proposed observers in real applications, we extend the methodology to the discrete time case and to the case of nonlinear systems with nonlinear outputs. For the di erent observers design, we use the di erential mean value theorem which allows the transformation of the nonlinear estimation error to a linear parameter varying system. Then, we use the Lipschitz conditions and the Lyapunov standard function to synthesize the stability conditions in the form of linear matrix inequalities. Finally, we enhance the feasibility of the later conditions by using a judicious reformulation of the Young's inequality. In the thesis, we also deal with the process control where we propose a control strategy to track an admissible reference trajectory planned by the plant operator. Moreover, to account for the partial availability of the state vector measurements, we include an exponential nonlinear observer in the control synthesis. Thus, we design an observer based tracking control scheme. To perform the stability analysis of the closed loop system, composed of the system, the observer and the controller, we use the Barbalat's lemma conjointly with the techniques already mentioned for the observers design. Finally, we propose two different methods to compute the controller and the observer parameters. In the first one, we propose to compute them separately. While, in the second one we compute the parameters simultaneously. [less ▲]

Detailed reference viewed: 54 (12 UL)
Full Text
Peer Reviewed
See detailPoster: Impact of ground truth errors on Wi-Fi localization accuracy
Popleteev, Andrei UL

Poster (2017, June)

This study investigates the impact of small ground truth (GT) errors on indoor positioning systems based on Wi-Fi fingerprinting. The results demonstrate that even centimeter-scale GT deviations cause ... [more ▼]

This study investigates the impact of small ground truth (GT) errors on indoor positioning systems based on Wi-Fi fingerprinting. The results demonstrate that even centimeter-scale GT deviations cause severe degradation of measured localization accuracy. [less ▲]

Detailed reference viewed: 7 (0 UL)
Full Text
See detailArbeiten unter Hitler. NS-Sozialpolitik und Herrschaftspraxis im besetzten Luxemburg 1940-1944
Schoentgen, Marc Mike Claude UL

Doctoral thesis (2017)

Die Arbeit untersucht Grundlagen, Konzeptionen und Auswirkungen der nationalsozialistischen Besatzungsherrschaft in Luxemburg (1940-1944) in den Bereichen der Wirtschafts- und Sozialpolitik ... [more ▼]

Die Arbeit untersucht Grundlagen, Konzeptionen und Auswirkungen der nationalsozialistischen Besatzungsherrschaft in Luxemburg (1940-1944) in den Bereichen der Wirtschafts- und Sozialpolitik. Berücksichtigung findet auch die NS-Volkstums- und Kulturpolitik. Staatliche Maßnahmen führten in der Besatzungszeit dazu, dass während einer relativ langen Phase die Auswirkungen des Krieges auf das Alltags- und Arbeitsleben wenig spürbar waren. Damit trug die Sozialpolitik zu einer politischen und psychologischen Stabilisierung des Regimes bei. Besonders betroffen von der Politik des nationalsozialistischen Gauleiters Gustav Simon waren die Luxemburger Gewerkschaften, die von den Machthabern instrumentalisiert und anschließend liquidiert wurden. An ihre Stelle trat die Deutsche Arbeitsfront, größte Massenorganisation des Regimes, die ihre vielfältigen Aktivitäten in den Bereichen der Sozial-, Wirtschafts-, Freizeit- und Kulturpolitik auch auf Luxemburg ausdehnte. Genauer untersucht wird die Institution des Stillhaltekommissars für das Organisationswesen, der die Gewerkschaften und andere Vereine liquidierte beziehungsweise nazifizierte. Damit wurden die Fundamente der Luxemburger Gesellschaft in Frage gestellt. Die Neuordnungspolitik des Regimes wird u.a. am Beispiel des Industriegebiets im Süden Luxemburgs dargestellt. Im Arbeitermilieu sahen die nationalsozialistischen Machthaber ein Experimentierfeld ihrer Politik. Krieg und Besatzung hatten letztlich auch Auswirkungen auf die großen Industriebetriebe. Gerade hier änderte sich ab der zweiten Hälfte des Krieges durch unterschiedliche Formen der Repression und Zwangsarbeit der Alltag der Menschen. Übergreifend befasst sich die Arbeit auch mit der Luxemburger Kriegsgesellschaft beziehungsweise den unterschiedlichen Reaktionen der Arbeiter und Angestellten auf Verlockung und Zwang. Kapitel: 1. Die NS-Sozialpolitik in Luxemburg 2. Die Luxemburger Gewerkschaften im Krieg. 3. Das Luxemburger Industriegebiet 4. Der Stillhaltekommissar für das Organisationswesen 5. Die Deutsche Arbeitsfront 6. Arbeiten im Krieg [less ▲]

Detailed reference viewed: 28 (9 UL)
Full Text
Peer Reviewed
See detailClosing or Persisting Gender Gap? A Cohort Analysis of Education and Wages in the United States and Europe
Chauvel, Louis UL; Hartung, Anne UL; Bar-Haim, Eyal UL

in Population Association of America - PAA Annual Meeting 2017 (2017)

Detailed reference viewed: 25 (0 UL)