People-Sensing Spatial Characteristics of RF Sensor Networks

An "RF sensor" network can monitor RSS values on links in the network and perform device-free localization, i.e., locating a person or object moving in the area in which the network is deployed. This paper provides a statistical model for the RSS variance as a function of the person's position w.r.t. the transmitter (TX) and receiver (RX). We show that the ensemble mean of the RSS variance has an approximately linear relationship with the expected total affected power (ETAP). We then use analysis to derive approximate expressions for the ETAP as a function of the person's position, for both scattering and reflection. Counterintuitively, we show that reflection, not scattering, causes the RSS variance contours to be shaped like Cassini ovals. Experimental tests reported here and in past literature are shown to validate the analysis

Survey and Systematization of Secure Device Pairing

Secure Device Pairing (SDP) schemes have been developed to facilitate secure communications among smart devices, both personal mobile devices and Internet of Things (IoT) devices. Comparison and assessment of SDP schemes is troublesome, because each scheme makes different assumptions about out-of-band channels and adversary models, and are driven by their particular use-cases. A conceptual model that facilitates meaningful comparison among SDP schemes is missing. We provide such a model. In this article, we survey and analyze a wide range of SDP schemes that are described in the literature, including a number that have been adopted as standards. A system model and consistent terminology for SDP schemes are built on the foundation of this survey, which are then used to classify existing SDP schemes into a taxonomy that, for the first time, enables their meaningful comparison and analysis.The existing SDP schemes are analyzed using this model, revealing common systemic security weaknesses among the surveyed SDP schemes that should become priority areas for future SDP research, such as improving the integration of privacy requirements into the design of SDP schemes. Our results allow SDP scheme designers to create schemes that are more easily comparable with one another, and to assist the prevention of persisting the weaknesses common to the current generation of SDP schemes.Comment: 34 pages, 5 figures, 3 tables, accepted at IEEE Communications Surveys & Tutorials 2017 (Volume: PP, Issue: 99

BMP : un protocole de communication basé sur la distance entre les objets de l'Internet des objets

La quatrième révolution technologique est en marche et stimule des avancées majeures dans les domaines de l’intelligence artificielle et de l’Internet des objets. Cette thèse s’intéresse aux communications entre les objets intelligents. Une revue de la littérature scientifique sur le sujet permet de constater que les protocoles créés pour ces communications s’appuient sur les méthodes de fonctionnement établies à l’époque de la communication entre postes informatiques fixes. Cette thèse propose un nouveau protocole de communication abandonnant ces idées pour plutôt s’appuyer sur la notion de position des objets. Le protocole se nomme BMP, pour Bounded Message Protocol. Les caractéristiques principales du protocole sont que tous les messages sont envoyés en mode diffusion et que la propagation s’arrête lorsqu’une distance du point d’émission est atteinte. Les messages de ce protocole présentent aussi une durée de vie au bout de laquelle chaque message doit être détruit. Ce protocole est conçu pour être léger avec un en-tête minimal à son fonctionnement. Deux implémentations sont réalisées. Une première est en C++ et est utilisée sur des microcontrôleurs de type Arduino. L’expérience réalisée avec cette implémentation permet de valider le bon fonctionnement des mécanismes de contrôle de BMP. Une deuxième implémentation est en Java et est utilisée sur des tablettes et téléphones Android. L’implémentation est utilisée pour un scénario imitant la vie réelle dans un appartement intelligent et confirme que BMP fonctionne dans ce type d’environnement. Parallèlement à BMP, cette thèse présente IPADL (pour Indoor Positioning for Activities of Daily Living), une méthode de positionnement d’objets devant permettre l’usage de BMP à l’intérieur des bâtiments. IPADL utilise des arbres de décision pour convertir un vecteur de puissances de signal issues d’antennes RFID en une position approximative. La méthode est améliorée par l’addition de mesures statistiques sur les puissances

Inferring Person-to-person Proximity Using WiFi Signals

Today's societies are enveloped in an ever-growing telecommunication infrastructure. This infrastructure offers important opportunities for sensing and recording a multitude of human behaviors. Human mobility patterns are a prominent example of such a behavior which has been studied based on cell phone towers, Bluetooth beacons, and WiFi networks as proxies for location. However, while mobility is an important aspect of human behavior, understanding complex social systems requires studying not only the movement of individuals, but also their interactions. Sensing social interactions on a large scale is a technical challenge and many commonly used approaches---including RFID badges or Bluetooth scanning---offer only limited scalability. Here we show that it is possible, in a scalable and robust way, to accurately infer person-to-person physical proximity from the lists of WiFi access points measured by smartphones carried by the two individuals. Based on a longitudinal dataset of approximately 800 participants with ground-truth interactions collected over a year, we show that our model performs better than the current state-of-the-art. Our results demonstrate the value of WiFi signals in social sensing as well as potential threats to privacy that they imply

Array signal processing for source localization and enhancement

“A common approach to the wide-band microphone array problem is to assume a certain array geometry and then design optimal weights (often in subbands) to meet a set of desired criteria. In addition to weights, we consider the geometry of the microphone arrangement to be part of the optimization problem. Our approach is to use particle swarm optimization (PSO) to search for the optimal geometry while using an optimal weight design to design the weights for each particle’s geometry. The resulting directivity indices (DI’s) and white noise SNR gains (WNG’s) form the basis of the PSO’s fitness function. Another important consideration in the optimal weight design are several regularization parameters. By including those parameters in the particles, we optimize their values as well in the operation of the PSO. The proposed method allows the user great flexibility in specifying desired DI’s and WNG’s over frequency by virtue of the PSO fitness function. Although the above method discusses beam and nulls steering for fixed locations, in real time scenarios, it requires us to estimate the source positions to steer the beam position adaptively. We also investigate source localization of sound and RF sources using machine learning techniques. As for the RF source localization, we consider radio frequency identification (RFID) antenna tags. Using a planar RFID antenna array with beam steering capability and using received signal strength indicator (RSSI) value captured for each beam position, the position of each RFID antenna tag is estimated. The proposed approach is also shown to perform well under various challenging scenarios”--Abstract, page iv