This thesis presents a feasibility study on unobtrusive localization of GSM en- abled cellphones using a Fake Base Station (FBS). An FBS is a radio transceiver that emulates the behaviour of a legitimate GSM Base Station (BS) to fool unal- tered cellphones to connect with it. This feasibility study investigates how an FBS can be utilized to estimate positions of connected cellphones in an area of interest. We present a proof of concept system that consists of a mobile FBS that measures the Time Of Arrival (TOA) and Received Signal Strength (RSS) to a cell- phone. The positions of the mobile FBS are determined with GPS. We employ calibration-free localization algorithms as we assume unknown environments and unknown hardware. Our experiments in an outdoor 180x100 m2 Line-Of- Sight (LOS) environment show that our calibration-free localization algorithms provide an average localization error less than 10 meters, which is sufficient for most applications of interest. In addition, our experiments show that RSS-based localization outperforms TOA-based localization when the average distance be- tween the FBS and cellphone is roughly 50 meters. Our experiments show that TOA-based localization outperforms RSS-based localization when the average dis- tance increases to roughly 75 meters. This research is part of the Smart Savannah project in which a wide range of different surveillance systems are developed to protect rhinos from poachers. We envision that our localization system can be used to detect and localize these poachers in an unobtrusive way. In addition, we envision that our localization sys- tem can be used in Search And Rescue (SAR) operations to estimate the positions of cellphones of missing persons. / Detta examensarbete undersöker möjligheten att lokalisera mobiltelefoner med GSM teknologi genom att använda en Falsk Basstation (FBS). En FBS är en radio transceiver som emulerar beteendet hos en legitim GSM basstation för att lura omodifierade mobiltelefoner att ansluta till den. Undersökningen tar reda på hur en FBS kan användas för att estimera positionerna av anslutna mobiltelefoner inom ett målområde. För att undersöka detta har ett Proof-Of-Concept-system ta- gits fram. Systemet består av en mobil FBS som som mäter propageringstid (TOA) och mottagen signalstyrka (RSS). FBS:ens positioner bestäms med GPS. Systemet använder kalibreringsfria algoritmer för lokalisering, då vi antar att miljön och mobiltelefonernas hårdvara är okänd. Tester av systemet har utförts utomhus i ett 180x100 m2 Line-Of-Sight-område. Dessa tester visar att lokaliseringsalgorit- merna ger ett genomsnittligt fel på mindre än 10 meter. Detta anses vara till- räckligt för de flesta tillämpningar av intresse. Utöver detta visar även testerna att RSS-baserad lokalisering ger bättre resultat än TOA-baserad lokalisering när medelavståndet mellan FBS och mobiltelefon är omkring 50 meter. TOA-baserad lokalisering ger däremot ett bättre resultat än RSS-baserad lokalisering när me- delavståndet ökar till omkring 75 meter. Denna undersökning är en del av Smart Savannah projektet som innefattar flera olika övervakningssystem, utvecklade för att skydda noshörningar från tjuv- skyttar. Målet med vårt lokaliseringssystem är att det ska kunna användas för att upptäcka och lokalisera tjuvskyttar utan deras vetskap. Vi tror även att lokalise- ringssystemet kan användas vid eftersökning- och räddnings-operationer för att lokalisera försvunna personers mobiltelefoner. / Project Ngulia

Web 2.0 tools, namely blogs, wikis, podcasts, and RSS were introduced to change teaching practices of in-service high school teachers to improve the collaboration of today's students in the English language classroom. Two high school teachers of English language and their classes participated. The teachers were interviewed about their current teaching practices and provided with training to develop teaching units that use Web 2.0 to engage students as active collaborators in their learning. They integrated blogs, podcasts, wikis, and RSS into their teaching. Additional interviews were conducted during and after the implementation stage. Implementation strategies, changes in teaching practices, challenges encountered, and the impact on student interaction and collaboration were closely examined. Students were surveyed at the conclusion. Teachers found that Web 2.0 tools made them more efficient in teaching. Blogging was the most powerful tool for journal writing and sharing ideas. Wikis were more difficult to use but were useful to facilitate group planning and collaborative construction of knowledge. Podcasts were useful for publishing audio recordings of interviews, speeches, and poetry recitals. RSS feeds made it easy for teachers and students to track updates on websites, posts on blogs, collaborations on wikis, and audio recordings on podcasts. Both teachers and students enjoyed the interactions and collaboration that took place in the English classroom using Web 2.0 tools.

"Precise Tracking of Things (PToT) using RF signals has posed a serious challenge in an indoor environment. The precision localization information is an enabler for better coordinated-tasks and is essential for a successful launch of many emerging applications. PToT relies on two principal components, a novel navigation (tracking) algorithm, and a hybrid 3D fingerprint database. In this dissertation, we begin by using the two widely known ranging techniques, Time Of Arrival (TOA) associated with Ultra-wideband (UWB) and Received Signal Strength (RSS) with WiFi signals. First, we use the theoretical models derived from empirical measurement of TOA and RSS to analyze the performance of hybrid (WiFi & UWB) cooperative localization accuracy in a multi-robot operation in a typical office environment. To measure the performance of this hybrid localization, we derive a mathematical formulation for the Crame ́r-Rao-Lower- Bound (CRLB). The hybrid method shows more accuracy over WiFi-only approach. In achieving more precision, we extend our work. Second, we introduce a novel approach, a Kernel Method Particle Filter (KMPF) for tracking and predicting the position by accessing the information created by hybrid 3D fingerprint database. We derive the mathematical and statistical framework for the Particle Filter based on the statistical assumptions about the behavior of channel models. We also describe the formation of one of the necessary PToT component, a 3D fingerprint database. We compare the performance of the KMPF against the CRLB using WiFi signal channel models."

A number of techniques for indoor and outdoor WiFi localization using received signal strength (RSS) signatures have been published. Little work has been performed to characterize the RSS signatures used by these WiFi localization techniques or to assess the accuracy of current channel models to represent the signatures. Without accurate characterization and models of the RSS signatures, a large amount of empirical data is needed to evaluate the performance of the WiFi localization techniques. The goal of this research is to characterize the RSS signatures, propose channel model improvements based on the characterization, and study the performance of channel models for use in WiFi localization simulations to eliminate the need for large amounts of empirical data measurements. In this thesis, we present our empirical database of RSS signatures measured on the Worcester Polytechnic Institute campus. We use the empirical database to characterize the RSS signatures used in WiFi localization, showing that they are composed of connective segments and influenced by the access point (AP) location within a building. From the characterization, we propose improving existing channel models by building partitioning the signal path-loss using site-specific information from Google Earth. We then evaluate the performance of the existing channel models and the building partitioned models against the empirical data. The results show that using site-specific information to building partition the signal path-loss a tighter fit to the empirical RSS signatures can be achieved.

This thesis presents and discusses research associated with locating wireless devices. Several algorithms have been developed to determine the physical location of the wireless device and a subset of these algorithms only rely on received signal strength (RSS). Two of the most promising RSS-based algorithms are the LC and dwMDS algorithms; however each algorithm has only been tested via computer simulations with different environmental parameters. To determine which algorithm performs better (i.e., produces estimates that are closer to the true location of the wireless device), a fair comparison needs to be made using the same set of data. The goal of this research is to compare the performance of these two algorithms using not only the same set of data, but data that is collected from the field. An extensive measurement campaign at different environments provided a vast amount of data as input to these algorithms. Both of these algorithms are evaluated in a onedimensional (straight line) and two-dimensional (grid) setting. In total, six environments were used to test these algorithms; three environments for each setting. The results show that on average, the LC algorithm outperforms dwMDS in most of the environments. Since the same data was inputted for each algorithm, a fair comparison can be made and doesn’t give any unfair advantage to any particular algorithm. In addition, since the data was taken directly from the field as opposed to computer simulations, this provides a better degree of confidence for a successful realworld implementation.

<p>RSS is a format for easy information sharing between computers. A RSS-file, also known as a feed or a channel, consist of a list of items. The items are structured with XML-tags and have to be processed in some way before it can be read. RSS¬readers, web-browsers with RSS support and e-mail-clients with RSS support can be used to display the feed.</p><p>This thesis is focused to investigate if RSS can be used within an enterprise for internal communication. We look at different computer based communication tools that are available today and compare them with RSS. All the different tools has there advantages as well as disadvantages, we have tried to find out if there is room for one more information channel within an enterprise.</p><p>Our study shows that RSS is not suitable as a stand alone solution for internal combination. RSS main strengths lies in mass information that has to be pushed out in one direction.</p>

RF fingerprinting can solve the indoor positioning problem with satisfactory accuracy, but the methodology depends on the so-called radio map calibrated in the offline phase via manual site-survey, which is costly, time-consuming and somewhat error-prone. It also assumes the RF fingerprint’s signal-spatial correlations to remain static throughout the online positioning phase, which generally does not hold in practice. This is because indoor environments constantly experience dynamic changes, causing the radio signal strengths to fluctuate over time, which weakens the signal-spatial correlations of the RF fingerprints. State-of-the-arts have proposed adaptive RF fingerprint methodology capable of calibrating the radio map in real-time and on-demand to address these drawbacks. However, existing implementations are highly server-centric, which is less robust, does not scale well, and not privacy-friendly. This thesis aims to address these drawbacks by exploring the feasibility of implementing an adaptive RF fingerprint indoor positioning system in a distributed and client-centric architecture using only commodity Wi-Fi hardware, so it can seamlessly integrate with existing Wi-Fi network and allow it to offer both networking and positioning services. Such approach has not been explored in previous works, which forms the basis of this thesis’ main contribution. The proposed methodology utilizes a network of distributed location beacons as its reference infrastructure; hence the system is more robust since it does not have any single point-of-failure. Each location beacon periodically broadcasts its coordinate to announce its presence in the area, plus coefficients that model its real-time RSS distribution around the transmitting antenna. These coefficients are constantly self-calibrated by the location beacon using empirical RSS measurements obtained from neighbouring location beacons in a collaborative fashion, and fitting the values using path loss with log-normal shadowing model as a function of inter-beacon distances while minimizing the error in a least-squared sense. By self-modelling its RSS distribution in real-time, the location beacon becomes aware of its dynamically fluctuating signal levels caused by physical, environmental and temporal characteristics of the indoor environment. The implementation of this self-modelling feature on commodity Wi-Fi hardware is another original contribution of this thesis. Location discovery is managed locally by the clients, which means the proposed system can support unlimited number of client devices simultaneously while also protect user’s privacy because no information is shared with external parties. It starts by listening for beacon frames broadcasted by nearby location beacons and measuring their RSS values to establish the RF fingerprint of the unknown point. Next, it simulates the reference RF fingerprints of predetermined points inside the target area, effectively calibrating the site’s radio map, by computing the RSS values of all detected location beacons using their respective coordinates and path loss coefficients embedded inside the received beacon frames. Note that the coefficients model the real-time RSS distribution of each location beacon around its transmitting antenna; hence, the radio map is able to adapt itself to the dynamic fluctuations of the radio signal to maintain its signal-spatial correlations. The final step is to search the radio map to find the reference RF fingerprint that most closely resembles the unknown sample, where its coordinate is returned as the location result. One positioning approach would be to first construct a full radio map by computing the RSS of all detected location beacons at all predetermined calibration points, then followed by an exhaustive search over all reference RF fingerprints to find the best match. Generally, RF fingerprint algorithm performs better with higher number of calibration points per unit area since more locations can be classified, while extra RSS components can help to better distinguish between nearby calibration points. However, to calibrate and search many RF fingerprints will incur substantial computing costs, which is unsuitable for power and resource limited client devices. To address this challenge, this thesis introduces a novel algorithm suitable for client-centric positioning as another contribution. Given an unknown RF fingerprint to solve for location, the proposed algorithm first sorts the RSS in descending order. It then iterates over this list, first selecting the location beacon with the strongest RSS because this implies the unknown location is closest to the said location beacon. Next, it computes the beacon’s RSS using its path loss coefficients and coordinate information one calibration point at a time while simultaneously compares the result with the measured value. If they are similar, the algorithm keeps this location for subsequent processing; else it is removed because distant points relative to the unknown location would exhibit vastly different RSS values due to the different site-specific obstructions encountered by the radio signal propagation. The algorithm repeats the process by selecting the next strongest location beacon, but this time it only computes its RSS for those points identified in the previous iteration. After the last iteration completes, the average coordinate of remaining calibration points is returned as the location result. Matlab simulation shows the proposed algorithm only takes about half of the time to produce a location estimate with similar positioning accuracy compared to conventional algorithm that does a full radio map calibration and exhaustive RF fingerprint search. As part of the thesis’ contribution, a prototype of the proposed indoor positioning system is developed using only commodity Wi-Fi hardware and open-source software to evaluate its usability in real-world settings and to demonstrate possible implementation on existing Wi-Fi installations. Experimental results verify the proposed system yields consistent positioning accuracy, even in highly dynamic indoor environments and changing location beacon topologies.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Economia, Administração, Contabilidade e Ciência da Informação e Documentação, Departamento de Ciência da Informação e Documentação, 2008. / Submitted by Debora Freitas de Sousa (deborahera@gmail.com) on 2009-07-24T15:50:35Z No. of bitstreams: 1 Dissertação_Robson_Lopes_Almeida.pdf: 1261488 bytes, checksum: 88bd637180e3b5b1a275b1d8977bcd63 (MD5) / Approved for entry into archive by Tania Milca Carvalho Malheiros(tania@bce.unb.br) on 2009-07-27T15:13:51Z (GMT) No. of bitstreams: 1 Dissertação_Robson_Lopes_Almeida.pdf: 1261488 bytes, checksum: 88bd637180e3b5b1a275b1d8977bcd63 (MD5) / Made available in DSpace on 2009-07-27T15:13:51Z (GMT). No. of bitstreams: 1 Dissertação_Robson_Lopes_Almeida.pdf: 1261488 bytes, checksum: 88bd637180e3b5b1a275b1d8977bcd63 (MD5) Previous issue date: 2008-02-29 / Os efeitos da sobrecarga de informação verificada após o surgimento da Web, nos anos 90, vêm sendo motivo de preocupação de pesquisadores quanto à capacidade dos usuários na absorção e aproveitamento de conteúdos relevantes e úteis. A comunicação científica, tanto no seu aspecto informal quanto no formal, representado principalmente pelos periódicos científicos, enfrenta o mesmo problema, pois também sofre a influência dos avanços promovidos pelas tecnologias de informação e comunicação. Notadamente, verifica-se um crescimento nos títulos de periódicos científicos eletrônicos, conseqüência da agilidade no processo de publicação em meio eletrônico, que induz ao aumento da produção bibliográfica. Desse modo, se faz cada vez mais necessária a utilização de filtros, permitindo uma disseminação seletiva de conteúdos para usuários especializados, conforme suas reais necessidades. É nesse contexto que se insere a presente pesquisa, focada no estudo do potencial de uma tecnologia emergente, o RSS (Rich Site Summary, RDF Site Summary ou, ainda, Really Simple Syndication), voltada para a agregação e distribuição de conteúdos digitais. Como um estudo exploratório, o objetivo principal foi perceber as possíveis aplicações deste recurso no âmbito da comunicação científica, especialmente quanto ao aspecto da disseminação. Adicionalmente, comenta-se as vantagens e barreiras da tecnologia, além dos modos pelos quais os formatos RSS vêm sendo empregados no meio acadêmico. Além da análise da literatura pertinente, foi realizado um estudo de comportamento informacional junto a um grupo de pesquisadores da área da Ciência da Informação envolvidos com o processo de comunicação científica a fim de testar a viabilidade na adoção da tecnologia proposta. Complementando a pesquisa, descreve-se a criação de um protótipo de um serviço de agregação de conteúdo temático para ilustrar as funcionalidades da tecnologia. Os resultados obtidos indicam um terreno fértil e propício para implantação do RSS no contexto estudado, sugerindo ampliação da visibilidade da informação científica, além de integração com outros recursos tecnológicos, tais como bases de dados, bibliotecas e repositórios digitais. _______________________________________________________________________________________ ABSTRACT / The effect of the information overload verified after the advent of the Web, in the 90s, has become a concern for researchers as to the capability of the users in the process of acquisition and utilization of relevant and useful contents. Scientific communication, in its informal as well as in its formal aspect, represented mainly by scientific periodicals, faces the same problem, since it also suffers with the influence of the advancements caused by the information and communication technologies. Distinctively, a growth in the scientific electronic periodical headings is verified, as a consequence of the agility in the electronic publication process, what leads to the increase of the bibliographical production. This way, the use of filters is becoming more and more required, what allows a selective dissemination of contents for specialized users, according to their real needs. Inserted in this context, the present research focusses on the study of the potential of an emergent technology: the RSS (Rich Site Summary, RDF Site Summary or even Really Simple Syndication), intended to the aggregation and distribution of digital contents. As an inquisitive study, the main objective was to perceive the possible applications of this resource in the scope of scientific communication, especially as to the aspect of dissemination. Additionally, a comment about the advantages and barriers of the technology is made, as well as the ways by which formats RSS have been employed in the academic field. Besides the analysis of pertinent literature, a study of informational behavior of a group of Information Science researchers involved with the process of scientific communication in order to test the viability of the proposal technology. Complementing the research, the creation of a prototype of an aggregation of thematic contents service is described as to illustrate the functionalities of the technology. The obtained results indicate a fertile and propitious field for implantation of the RSS in the studied context, suggesting an increase of the visibility of scientific information, besides the integration with other technological resources, such as databases, digital libraries and repositories.

Traditional satellite positioning systems have limited resolution and have proved inaccuratein areas such as urban canyons where signals are subject to bounce phenomena or indeed may be entirely unavailable. An alternative method of positioning is that of tri/multilateration, which uses known positions and distances from beacon points to locate a receiver. In this project, a software was developed which used DSRC Basic Safety Messages (containing locational information) in combination with Received Signal Strength metrics (translated to distance information) to carry out such positioning in static environments. Initial studies confirmed that a signal received on the Craton 2 hardware was subject to considerable signal strength spread approximating a Gaussian distribution. A software was developed to simulate BSMs, including a measure of perturbation, over TCP. Three different traffic scenarios were constructed. Furthermore, multilaterationsoftware was developed to receive the BSMs and calculate position using three separate algorithms. The performance of these algorithms in the three different traffic scenarios was then evaluated. Lastly, the multilateration software was further developed to allow for the capture and processing of real BSMs sent on the 5.9 GHzband. The multilateration software was capable of determining the location of the receiver to varying degrees of accuracy, depending on the geometrical distribution of surrounding vehicles and the algorithm used to multilaterate. The 3D Linear Least Squares method performed well in situations where beacons were well spaced in three dimensions. Other implemented multilateration algorithms, i.e., a 2D Linear Least Squares method and a 3D Gauss Newton method, performed better in typical traffic scenarios where vehicles tend to be coplanar.The software developed provides a useful starting point for further developmentof static, but also dynamic, multilateration algorithms.

The purpose of this research is to design a proof of concept system that is capable of locating a hidden radio transmitter and to investigate methods of multi-agent formation control with a specific interest in the effectiveness of these methods on the overall objective of locating this transmitter. A system is proposed and developed in which autonomous agents work together to locate this transmitter and their responsiveness is analyzed while using formations based both on a behavioral system and a system derived from centroidal Voronoi tessellations. Many software adaptations to the existing MASnet program are required, as well as some hardware adaptations, including development of a robust simulation platform that may be used in conjunction with the MASnet system, and exploration of a distributed formation system. While this work does not accomplish the overall goal of the MASnet platform -- to be able to locate and control a diffusion process -- it does further understanding of the way autonomous agents interact with their environment and develop tools that aid future research in the program, as well as introduce exciting new areas to which the platform can be applied.