Location Estimation Methods for Open, Privacy Preserving Mobile Positioning

The future is mobile and location aware. More and more of our gadgets are portable and have an online presence. For our location-aware mobile future to be safe, we need to demand that our privacy and anonymity be protected. Currently, each and every location aware-system or feature requires us to give new people, corporations and entities access to one of our most intimate attributes, our location. The main solutions to ameliorate this have been by cloaking or hiding users from service providers or by moving trust to other "more trustable" parties. We want to minimize the need for trust. Your location is your own, and you should not have to pay with your privacy to determine it. Our focus lies on location estimation services - services that calculate your location based on measurements done on your network equipment - as they are the main drive behind the location-aware future. You can freely choose, discriminate against, and cloak yourself from services asking for your location, whereas removing the ability to determine your own location effectively impedes location awareness. We are interested in producing a freely available, open source, privacy preserving, community sourced, and safe location estimation service that minimizes the need for trust. In this thesis we focus on three things: Designing such a system, testing different ways of estimating locations, and determining the best way of estimating locations for the designed system

Fingerprint location methods using ray-tracing

Mobile location methods that employ signal fingerprints are becoming increasingly popular in a number of wireless positioning solutions. A fingerprint is a spatial database, created either by recorded measurement or simulation, of the radio environment. It is used to assign signal characteristics such as received signal strength or power delay profiles to an actual location. Measurements made by either the handset or the network, are then matched to those in the fingerprint in order to determine a location. Creation of the fingerprint by an a priori measurement stage is costly and time consuming. Virtual fingerprints, those created by a ray-tracing radio propagation prediction tool, normally require a lengthy off-line simulation mode that needs to be repeated each time changes are made to the network or built environment. An open research question exists of whether a virtual fingerprint could be created dynamically via a ray-trace model embedded on a mobile handset for positioning purposes. The key aim of this thesis is to investigate the trade-off between complexity of the physics required for ray-tracing models and the accuracy of the virtual fingerprints they produce. The most demanding computational phase of a ray-trace simulation is the ray-path finding stage, whereby a distribution of rays cast from a source point, interacting with walls and edges by reflection and diffraction phenomena are traced to a set of receive points. Due to this, we specifically develop a new technique that decreases the computation of the ray-path finding stage. The new technique utilises a modified method of images rather than brute-force ray casting. It leads to the creation of virtual fingerprints requiring significantly less computation effort relative to ray casting techniques, with only small decreases in accuracy. Our new technique for virtual fingerprint creation was then applied to the development of a signal strength fingerprint for a 3G UMTS network covering the Sydney central business district. Our main goal was to determine whether on current mobile handsets, a sub-50m location accuracy could be achieved within a few seconds timescale using our system. The results show that this was in fact achievable. We also show how virtual fingerprinting can lead to more accurate solutions. Based on these results we claim user embedded fingerprinting is now a viable alternative to a priori measurement schemes

Resource Allocation for Next Generation Radio Access Networks

Driven by data hungry applications, the architecture of mobile networks is moving towards that of densely deployed cells where each cell may use a different access technology as well as a different frequency band. Next generation networks (NGNs) are essentially identified by their dramatically increased data rates and their sustainable deployment. Motivated by these requirements, in this thesis we focus on (i) capacity maximisation, (ii) energy efficient configuration of different classes of radio access networks (RANs). To fairly allocate the available resources, we consider proportional fair rate allocations. We first consider capacity maximisation in co-channel 4G (LTE) networks, then we proceed to capacity maximisation in mixed LTE (including licensed LTE small cells) and 802.11 (WiFi) networks. And finally we study energy efficient capacity maximisation of dense 3G/4G co-channel small cell networks. In each chapter we provide a network model and a scalable resource allocation approach which may be implemented in a centralised or distributed manner depending on the objective and network constraints

Multimedia

The nowadays ubiquitous and effortless digital data capture and processing capabilities offered by the majority of devices, lead to an unprecedented penetration of multimedia content in our everyday life. To make the most of this phenomenon, the rapidly increasing volume and usage of digitised content requires constant re-evaluation and adaptation of multimedia methodologies, in order to meet the relentless change of requirements from both the user and system perspectives. Advances in Multimedia provides readers with an overview of the ever-growing field of multimedia by bringing together various research studies and surveys from different subfields that point out such important aspects. Some of the main topics that this book deals with include: multimedia management in peer-to-peer structures & wireless networks, security characteristics in multimedia, semantic gap bridging for multimedia content and novel multimedia applications

Multiplexed single molecule observation and manipulation of engineered biomolecules

Molecular processes in organisms are often enabled by structural elements resilient to mechanical forces. For instance, the microbial and hierarchical cellulosome protein system comprises enzymes and the receptor-ligand complexes Cohesin-Dockerin (Coh-Doc), that act in concert for the efficient hydrolysis of plant polysaccharides. The Coh-Doc complexes can withstand remarkably high forces to keep host cells and enzymes bound to their substrates in the extreme environmental conditions the microorganisms frequently live in. This work focuses on the investigation of mechanical stability of such biomolecules on the single-molecule level. The highly symmetric binding interface of the Coh-Doc type I complex from Clostridium thermocellum, enables two different binding conformations withcomparable affinity and similar strength. I was able to show that both conformations exist in the wild-type molecules and are occupied under native conditions. I further characterized one of the strongest non-covalent protein complexes known, Coh-Doc type III from Ruminococcus flavefaciens by elucidating the pivotal role of the adjacent xModule domain for the mechanical stabilization of the whole complex and the role of the bimodal rupture force distribution. Such large forces impair accuracy of measured contour length increments in unfolding studies by inducing conformational changes in poly-ethylene glycol (PEG) linkers in aqueous buffer systems. This problemwas solved by introducing elastin-like polypeptides (ELP) as surface tethers. Having a peptide backbone similar to that of unfolded proteins, ELP linkers do not alter accuracy of the single-molecule force spectroscopy (SMFS) assay. To provide high throughput and precise comparability, I worked on a microfluidic platform for the in vitro protein synthesis and immobilization. The Coh-Doc system was hereby integrated as a binding handle for multiplexed measurements of mechanostability. Employing a single AFM probe to measure multiple different molecules facilitates force precision required to shed light onto molecular mechanisms down to the level of single amino acids. I also applied the Coh-Doc complex to a purely protein based single-molecule cut and paste assay for the bottom-up assembly of molecular systems for quick phenotyping of spatial arrangements. With this system, interactions in enzymatic synergies can be studied by defined positioning patterns on the single molecule level. To understand and design force responses of complex systems, I complemented the investigation of protein systems with SMFS studies on DNA Origami structures. The results of SMFS on DNA were compared to a simulation framework. Despite their difference in force loading rates, both methods agree well within their results, enabling better fundamental understanding of complex molecular superstructures.Molekulare Prozesse in Organismenwerden oft von Strukturelementen ermöglicht, die mechanischen Kräften standhalten können. Ein Beispiel hierfür ist das mikrobielle und hierarchisch aufgebaute Proteinsystem des Zellulosoms. Enzyme und die Rezeptor-Liganden Komplexe Cohesin-Dockerin (Coh-Doc) arbeiten hierbei für die effiziente Hydrolyse von pflanzlichen Polysacchariden zusammen. Die Coh-Doc Komplexe können bemerkenswerten Kräften standhalten, um in den extremen Umweltbedingungen, in denen die Mikroorganismen teilweise leben, die Wirtszellen und Enzyme an ihre Substrate binden zu können. Die vorliegende Arbeit untersucht den Einfluss von mechanischer Kraft auf solche Biomoleküle mittels Einzelmolekülmessungen. Die hohe Symmetrie des Bindeinterfaces des Coh-Doc Typ I Komplexes aus Clostridium thermocellum ermöglicht zwei verschiedene Konformationen, die vergleichbare Affinität und Stärke aufweisen. Im Rahmen dieser Arbeit konnte ich beide in denWildtyp-Molekülen und unter nativen Bedingungen nachweisen. Eines der stärksten bekannten nicht-kovalenten Rezeptor-Liganden Systeme, Coh- Doc Typ III aus Ruminococcus flavefaciens wurde charakterisiert, und die Kernrolle des benachbarten xModuls für die Stabilität des gesamten Komplexes sowie die Rolle der bimodalen Kraftverteilung untersucht. Solch hohe Kräfte vermindern die Genauigkeit der gemessenenKonturlängeninkremente von Proteinentfaltungen, indem sie Konformationsänderungen der Poly- Ethylenglykol (PEG) Oberflächenanker in wässrigen Puffersystemen verursachen. Mit Elastin-ähnlichen Polypeptiden (ELP) als Anker wurde dieses Problem gelöst: durch die Ähnlichkeit des Peptid-Rückgrates von ELPs mit dem entfaltener Proteine beeinflussen diese die Genauigkeit des Experiments nicht. Für die Optimierung von Messdurchsatz und Vergleichbarkeit entwickelte ich an einer Mikrofluidik-Plattform zur in vitro Proteinsynthese und -immobilisierung. Das Coh-Doc System wurde hierbei als Binde-Molekül für gemultiplexte Messungen integriert. Die dadurch ermöglichte Nutzung einer einzigen AFM Messsonde für die Messung verschiedener Moleküle erlaubt die nötige Kraftpräzision, um molekulare Mechanismen bis auf die Ebene einzelner Aminosäuren aufzuklären. Des weiteren habe ich den Coh-Doc Komplex in einem rein auf Proteininteraktionen basierten ’Cut and Paste’ Assay für den modularen Aufbau molekularer Systeme implementiert. Dieses ermöglicht schnelle Phänotypisierung geometrischer Anordnunungen und die Untersuchung von Wechselwirkung zwischen Enzymen mittels definierter Positionierung auf Einzelmolekülebene. Um die Kraftantwort komplexer Systeme besser verstehen und letztendlich gestalten zu können, ergänzte ich die Untersuchung von Proteinsystemen mit derer von DNA-Origami Strukturen. Die Ergebnisse der Kraftspektroskopie an DNA wurden mit Computersimulationen verglichen, und trotz des großen Unterschieds ihrer Ladungsraten stimmen beide Methoden gut überein. Dadruch legen sie die Grundlagen für ein besseres Verständnis komplexer molekularer Superstrukturen

Sistemas de posicionamento baseados em comunicação por luz para ambientes interiores

The demand for highly precise indoor positioning systems (IPSs) is growing rapidly due to its potential in the increasingly popular techniques of the Internet of Things, smart mobile devices, and artificial intelligence. IPS becomes a promising research domain that is getting wide attention due to its benefits in several working scenarios, such as, industries, indoor public locations, and autonomous navigation. Moreover, IPS has a prominent contribution in day-to-day activities in organizations such as health care centers, airports, shopping malls, manufacturing, underground locations, etc., for safe operating environments. In indoor environments, both radio frequency (RF) and optical wireless communication (OWC) based technologies could be adopted for localization. Although the RF-based global positioning system, such as, Global positioning system offers higher penetration rates with reduced accuracy (i.e., in the range of a few meters), it does not work well in indoor environments (and not at all in certain cases such as tunnels, mines, etc.) due to the very weak signal and no direct access to the satellites. On the other hand, the light-based system known as a visible light positioning (VLP) system, as part of the OWC systems, uses the pre-existing light-emitting diodes (LEDs)-based lighting infrastructure, could be used at low cost and high accuracy compared with the RF-based systems. VLP is an emerging technology promising high accuracy, high security, low deployment cost, shorter time response, and low relative complexity when compared with RFbased positioning. However, in indoor VLP systems, there are some concerns such as, multipath reflection, transmitter tilting, transmitter’s position, and orientation uncertainty, human shadowing/blocking, and noise causing the increase in the positioning error, thereby reducing the positioning accuracy of the system. Therefore, it is imperative to capture the characteristics of different VLP channel and properly model them for the dual purpose of illumination and localization. In this thesis, firstly, the impact of transmitter tilting angles and multipath reflections are studied and for the first time, it is demonstrated that tilting the transmitter can be beneficial in VLP systems considering both line of sight (LOS) and non-line of sight transmission paths. With the transmitters oriented towards the center of the receiving plane, the received power level is maximized due to the LOS components. It is also shown that the proposed scheme offers a significant accuracy improvement of up to ~66% compared with a typical non-tilted transmitter VLP. The effect of tilting the transmitter on the lighting uniformity is also investigated and results proved that the uniformity achieved complies with the European Standard EN 12464-1. After that, the impact of transmitter position and orientation uncertainty on the accuracy of the VLP system based on the received signal strength (RSS) is investigated. Simulation results show that the transmitter uncertainties have a severe impact on the positioning error, which can be leveraged through the usage of more transmitters. Concerning a smaller transmitter’s position epochs, and the size of the training set. It is shown that, the ANN with Bayesian regularization outperforms the traditional RSS technique using the non-linear least square estimation for all values of signal to noise ratio. Furthermore, a novel indoor VLP system is proposed based on support vector machines and polynomial regression considering two different multipath environments of an empty room and a furnished room. The results show that, in an empty room, the positioning accuracy improvement for the positioning error of 2.5 cm are 36.1, 58.3, and 72.2 % for three different scenarios according to the regions’ distribution in the room. For the furnished room, a positioning relative accuracy improvement of 214, 170, and 100 % is observed for positioning error of 0.1, 0.2, and 0.3 m, respectively. Ultimately, an indoor VLP system based on convolutional neural networks (CNN) is proposed and demonstrated experimentally in which LEDs are used as transmitters and a rolling shutter camera is used as receiver. A detection algorithm named single shot detector (SSD) is used which relies on CNN (i.e., MobileNet or ResNet) for classification as well as position estimation of each LED in the image. The system is validated using a real-world size test setup containing eight LED luminaries. The obtained results show that the maximum average root mean square positioning error achieved is 4.67 and 5.27 cm with SSD MobileNet and SSD ResNet models, respectively. The validation results show that the system can process 67 images per second, allowing real-time positioning.A procura por sistemas de posicionamento interior (IPSs) de alta precisão tem crescido rapidamente devido ao seu interesse nas técnicas cada vez mais populares da Internet das Coisas, dispositivos móveis inteligentes e inteligência artificial. O IPS tornou-se um domínio de pesquisa promissor que tem atraído grande atenção devido aos seus benefícios em vários cenários de trabalho, como indústrias, locais públicos e navegação autónoma. Além disso, o IPS tem uma contribuição destacada no dia a dia de organizações, como, centros de saúde, aeroportos, supermercados, fábricas, locais subterrâneos, etc. As tecnologias baseadas em radiofrequência (RF) e comunicação óptica sem fio (OWC) podem ser adotadas para localização em ambientes interiores. Embora o sistema de posicionamento global (GPS) baseado em RF ofereça taxas de penetração mais altas com precisão reduzida (ou seja, na faixa de alguns metros), não funciona bem em ambientes interiores (e não funciona bem em certos casos como túneis, minas, etc.) devido ao sinal muito fraco e falta de acesso direto aos satélites. Por outro lado, o sistema baseado em luz conhecido como sistema de posicionamento de luz visível (VLP), como parte dos sistemas OWC, usa a infraestrutura de iluminação baseada em díodos emissores de luz (LEDs) pré-existentes, é um sistemas de baixo custo e alta precisão quando comprado com os sistemas baseados em RF. O VLP é uma tecnologia emergente que promete alta precisão, alta segurança, baixo custo de implantação, menor tempo de resposta e baixa complexidade relativa quando comparado ao posicionamento baseado em RF. No entanto, os sistemas VLP interiores, exibem algumas limitações, como, a reflexão multicaminho, inclinação do transmissor, posição do transmissor e incerteza de orientação, sombra/bloqueio humano e ruído, que têm como consequência o aumento do erro de posicionamento, e consequente redução da precisão do sistema. Portanto, é imperativo estudar as características dos diferentes canais VLP e modelá-los adequadamente para o duplo propósito de iluminação e localização. Esta tesa aborda, primeiramente, o impacto dos ângulos de inclinação do transmissor e reflexões multipercurso no desempenho do sistema de posicionamento. Demonstra-se que a inclinação do transmissor pode ser benéfica em sistemas VLP considerando tanto a linha de vista (LOS) como as reflexões. Com os transmissores orientados para o centro do plano recetor, o nível de potência recebido é maximizado devido aos componentes LOS. Também é mostrado que o esquema proposto oferece uma melhoria significativa de precisão de até ~66% em comparação com um sistema VLP de transmissor não inclinado típico. O efeito da inclinação do transmissor na uniformidade da iluminação também é investigado e os resultados comprovam que a uniformidade alcançada está de acordo com a Norma Europeia EN 12464-1. O impacto da posição do transmissor e incerteza de orientação na precisão do sistema VLP com base na intensidade do sinal recebido (RSS) foi também investigado. Os resultados da simulação mostram que as incertezas do transmissor têm um impacto severo no erro de posicionamento, que pode ser atenuado com o uso de mais transmissores. Para incertezas de posicionamento dos transmissores menores que 5 cm, os erros médios de posicionamento são 23.3, 15.1 e 13.2 cm para conjuntos de 4, 9 e 16 transmissores, respetivamente. Enquanto que, para a incerteza de orientação de um transmissor menor de 5°, os erros médios de posicionamento são 31.9, 20.6 e 17 cm para conjuntos de 4, 9 e 16 transmissores, respetivamente. O trabalho da tese abordou a investigação dos aspetos de projeto de um sistema VLP indoor no qual uma rede neuronal artificial (ANN) é utilizada para estimativa de posicionamento considerando um canal multipercurso. O estudo considerou a influência do ruído como indicador de desempenho para a comparação entre diferentes abordagens de projeto. Três algoritmos de treino de ANNs diferentes foram considerados, a saber, Levenberg-Marquardt, regularização Bayesiana e algoritmos de gradiente conjugado escalonado, para minimizar o erro de posicionamento no sistema VLP. O projeto da ANN foi otimizado com base no número de neurónios nas camadas ocultas, no número de épocas de treino e no tamanho do conjunto de treino. Mostrou-se que, a ANN com regularização Bayesiana superou a técnica RSS tradicional usando a estimação não linear dos mínimos quadrados para todos os valores da relação sinal-ruído. Foi proposto um novo sistema VLP indoor baseado em máquinas de vetores de suporte (SVM) e regressão polinomial considerando dois ambientes interiores diferentes: uma sala vazia e uma sala mobiliada. Os resultados mostraram que, numa sala vazia, a melhoria da precisão de posicionamento para o erro de posicionamento de 2.5 cm são 36.1, 58.3 e 72.2% para três cenários diferentes de acordo com a distribuição das regiões na sala. Para a sala mobiliada, uma melhoria de precisão relativa de posicionamento de 214, 170 e 100% é observada para erro de posicionamento de 0.1, 0.2 e 0.3 m, respetivamente. Finalmente, foi proposto um sistema VLP indoor baseado em redes neurais convolucionais (CNN). O sistema foi demonstrado experimentalmente usando luminárias LED como transmissores e uma camara com obturador rotativo como recetor. O algoritmo de detecção usou um detector de disparo único (SSD) baseado numa CNN pré configurada (ou seja, MobileNet ou ResNet) para classificação. O sistema foi validado usando uma configuração de teste de tamanho real contendo oito luminárias LED. Os resultados obtidos mostraram que o erro de posicionamento quadrático médio alcançado é de 4.67 e 5.27 cm com os modelos SSD MobileNet e SSD ResNet, respetivamente. Os resultados da validação mostram que o sistema pode processar 67 imagens por segundo, permitindo o posicionamento em tempo real.Programa Doutoral em Engenharia Eletrotécnic

Computer Science & Technology Series : XIX Argentine Congress of Computer Science. Selected papers

CACIC’13 was the nineteenth Congress in the CACIC series. It was organized by the Department of Computer Systems at the CAECE University in Mar del Plata. The Congress included 13 Workshops with 165 accepted papers, 5 Conferences, 3 invited tutorials, different meetings related with Computer Science Education (Professors, PhD students, Curricula) and an International School with 5 courses. CACIC 2013 was organized following the traditional Congress format, with 13 Workshops covering a diversity of dimensions of Computer Science Research. Each topic was supervised by a committee of 3-5 chairs of different Universities. The call for papers attracted a total of 247 submissions. An average of 2.5 review reports were collected for each paper, for a grand total of 676 review reports that involved about 210 different reviewers. A total of 165 full papers, involving 489 authors and 80 Universities, were accepted and 25 of them were selected for this book.Red de Universidades con Carreras en Informática (RedUNCI

Controlling the propagation of light in disordered scattering media

This thesis describes experimental work on the use of wavefront shaping to steer light through strongly scattering materials. We find that scattering does not irreversibly scramble the incident wave. By shaping the incident wavefront, we make opaque objects focus light as sharply as aberration free lenses. We use feedback from a target behind, or in, an opaque object to shape the incident wave. This way, light is focused through, or inside, opaque objects for the first time ever.Comment: PhD thesis by I.M. Vellekoop. Thesis supervisors: A. Lagendijk and A. P. Mosk. This work was performed at the Complex Photonic Systems (COPS) group, Faculty of Science and Technology and MESA+ institute for Nanotechnology, Univeristy of Twente. P.O. Box 217, 7500 AE Enschede, The Netherlands. This work contains contributions by E. G. van Putte