Indoor/Outdoor Location of Cellular Handsets Based on Received Signal Strength Jian Zhu 123 pages Directed by Dr. Gregory D. Durgin Accurate geo-location is an important emerging technology for public safety, commercial use, and military application. Especially, in the United States, the wireless Enhanced 911 (E911) rules by the Federal Communication Commission (FCC) seek to provide 911 dispatchers with additional information on wireless 911 calls. This dissertation presents a novel technique for indoor/outdoor location of cellular handsets based on received signal strength (RSS) measurements taken by a cellular handset of the surrounding base stations. RSS location accuracy for different environments is studied as a function of base station separation distance, cell sector density, measurement density, radio propagation environment, and accuracy of measurement. The analytical and experimental results in this thesis serve as a guideline for the accuracy of RSS signature location technology under different conditions. Accurate outdoor to indoor penetration models are proposed and validated for dense urban areas by introducing pseudo-transmitters to simulate the wave-guiding effects in urban canyon environments. A set of location algorithms is developed to improve location accuracy. Furthermore, an algorithm to discriminate between indoor and outdoor users is proposed and validated. The research results demonstrate the feasibility of RSS location techniques to meet the FCCs requirements for E911 accuracy in urban and semi-urban environments. The techniques remain accurate for indoor handsets. The results also suggest that a hybridization of the handset-based GPS method and the RSS signature method may prove to be the most effective solution for locating handsets across a range of environments; including rural, suburban, dense urban, and indoor.

The area of deterministic noise cancellation in mobile radio communication systems is investigated and analyzed. Several interoperation problems in the mobile wireless radio space are identified and interference concerns for the Bluetooth - WLAN networks are characterized and quantified in the physical layer. A mathematical framework has been created for describing interference in the 2.4 GHz band. An adaptive noise suppression system has been developed that is able to alleviate the encroachment of the aggressor signal on the victim without sacrificing any of the original signal. This system is demonstrated to improve the victim SNR in a spread spectrum communication scenario. The research is extended to construct an interference canceller that is easy to assimilate into existing RF front-ends. A low-power small form-factor analog active canceller has been designed in 0.18-ìm Si-CMOS IC technology that delivers adequate noise suppression performance while operating in the RF domain. This includes novel implementations of phase rotator circuits based on delay interpolation and an integrated low-current quadrature modulator-based continuously variable analog phase shifter. This canceller is capable of up to 30 dB of in-band cancellation for the Bluetooth - WLAN problem. Other versions of the canceller are configured to protect GPS and DVB-H receivers from unintentional radiators transmitting in the vicinity. These demonstrate noise mitigation of at least 15 dB in their respective bands while generating very low broadband noise at the output. A simple low-power mixed-signal automatic control mechanism is also developed to operate the canceller adaptively. The work described in this dissertation advances the state-of-the-art in the area of mobile wireless radio coexistence.

This dissertation studies the design of an efficient adaptive digital baseband predistorter for modern cellular handsets that combines low power consumption, low implementation complexity, and high performance. The proposed enhancements are optimized for hardware implementation. We first present a thorough study of the optimal spacing of linearly-interpolated lookup table predistorters supported by theoretical calculations and extensive simulations. A constant-SNR compander that increases the predistorter's supported input dynamic range is derived. A corresponding low-complexity approximation that lends itself to efficient hardware design is also implemented in VHDL and synthesized with the Synopsys Design Compiler. This dissertation also proposes an LMS-based predistorter adaptation that is optimized for hardware implementation and compares the effectiveness of the direct and indirect learning architectures. A novel predistorter design with quadrature imbalance correction capability is developed and a corresponding adaptation scheme is proposed. This robust predistorter configuration is designed by combining linearization and I/Q imbalance correction into a single function with the same computational complexity as the widespread complex-gain predistorter.

<p>This thesis investigates the use of mobile phones as service-delivery devices in a sign language machine translation system. Four sign language visualization methods were evaluated on mobile phones. Three of the methods were synthetic sign language visualization methods. Three factors were considered: the intelligibility of sign language, as rendered by the method / the power consumption / and the bandwidth usage associated with each method. The average intelligibility rate was 65%, with some methods achieving intelligibility rates of up to 92%. The average le size was 162 KB and, on average, the power consumption increased to 180% of the idle state, across all methods. This research forms part of the Integration of Signed and Verbal Communication: South African Sign Language Recognition and Animation (SASL) project at the University of the Western Cape and serves as an integration platform for the group's research. In order to perform this research a machine translation system that uses mobile phones as service-delivery devices was developed as well as a 3D Avatar for mobile phones. It was concluded that mobile phones are suitable service-delivery platforms for sign language machine translation systems.</p>

Traditionally, real-time communication, such as voice calls, has run on separate, closed networks. Of all the limitations that these networks had, the ability of malicious attacks to cripple communication was not a crucial one. This situation has changed radically now that real-time communication and data have merged to share the same network. The objective of this project is to investigate the securing of softswitches with functionality similar to Private Branch Exchanges (PBX) from malicious attacks. The focus of the project will be a practical investigation of how to secure ILANGA, an ASTERISK-based system under development at Rhodes University. The practical investigation that focuses on ILANGA is based on performing six varied experiments on the different components of ILANGA. Before the six experiments are performed, basic preliminary security measures and the restrictions placed on the access to the database are discussed. The outcomes of these experiments are discussed and the precise reasons why these attacks were either successful or unsuccessful are given. Suggestions of a theoretical nature on how to defend against the successful attacks are also presented.

Orientador: Celso de Almeida / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-24T01:46:06Z (GMT). No. of bitstreams: 1 Mello_RodolphoContiGianiniFerreira_M.pdf: 1434278 bytes, checksum: c9d50dad0686c63ee7429ff495370ace (MD5) Previous issue date: 2013 / Resumo: Os fatores responsáveis pela vazão de dados em uma rede celular são o número de usuários alocados em uma célula e a taxa de dados de cada usuário. Desta forma, para alcançar melhores resultados em termos de vazão de dados, deve-se utilizar de técnicas que trabalhem com foco no produto destes dois parâmetros. Este trabalho consiste em uma análise comparativa entre diferentes sistemas CDMA sob a ótica da vazão de dados, tendo como foco sequências de espalhamento do tipo aleatórias e também de Walsh e detecção com filtro casado e com o detector multiusuário descorrelacionador (MUD-D - Multiuser Detector Decorrelator), além de considerar a presença de interferência interna e externa no sistema. O método utilizado para a análise e comparação consiste na modelagem matemática do enlace reverso de um sistema celular DS-CDMA em canal AWGN com controle perfeito de potência e com alguns parâmetros fixos, tais como, a taxa máxima de erro de bit ( ), a taxa mínima de dados por usuário (10 kbps, referente ao serviço de voz) e a potência máxima de transmissão de 0,5W por estação móvel. Este trabalho apresenta também uma análise comparativa entre um sistema DS-CDMA com filtro casado e outro com o detector MUD-D na presença de interferência externa. A análise comparativa do detector MUD-D com o filtro casado em ambiente com interferência externa e toda a análise da vazão de dados do sistema são contribuições do autor / Abstract: The factors responsible for the data throughput in a cellular network are the number of users allocated in a cell and the users' data rate. This way, to reach better results in terms of data throughput, one must use techniques that act with focus on the product of those two parameters. This work consists in a comparative analysis among different CDMA systems from the perspective of the data throughput, focusing on random and Walsh spreading sequences and detection method with matched filter and with the multi-user detector decorrelator (MUD-D), besides considering the presence of internal and external interference in the system. The analysis and comparison methods consist in the CDMA cellular system uplink mathematical modelling in an AWGN channel considering a perfect power control and some fixed parameters such as the maximum bit error rate ( ), minimum data rate per user (10 kbps, referring to the voice service) and maximum transmitting power of 0.5 W per mobile station. This work also presents a comparative analysis between a DS-CDMA system with matched filter and another with the MUD-D detector in the presence of external interference. The MUD-D and matched filter comparative analysis in a scenario with external interference and the whole system's data throughput analysis are the author's contribution / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

Masters of Science / This thesis investigates the use of mobile phones as service-delivery devices in a sign language machine translation system. Four sign language visualization methods were evaluated on mobile phones. Three of the methods were synthetic sign language visualization methods. Three factors were considered: the intelligibility of sign language, as rendered by the method; the power consumption; and the bandwidth usage associated with each method. The average intelligibility rate was 65%, with some methods achieving intelligibility rates of up to 92%. The average size was 162 KB and, on average, the power consumption increased to 180% of the idle state, across all methods. This research forms part of the Integration of Signed and Verbal Communication: South African Sign Language Recognition and Animation (SASL) project at the University of the Western Cape and serves as an integration platform for the group's research. In order to perform this research a machine translation system that uses mobile phones as service-delivery devices was developed as well as a 3D Avatar for mobile phones. It was concluded that mobile phones are suitable service-delivery platforms for sign language machine translation systems. / South Africa

Despite the inherent limitation of accessing information serially, voice applications are increasingly growing in popularity as computing technologies advance. This is a positive development, because voice communication offers a number of benefits over other forms of communication. For example, voice may be better for delivering services to users whose eyes and hands may be engaged in other activities (e.g. driving) or to semi-literate or illiterate users. This thesis proposes a knowledge based architecture for building voice applications to help reduce the limitations of serial access to information. The proposed architecture, called OVR (Ontologies, VoiceXML and Reasoners), uses a rich backend that represents knowledge via ontologies and utilises reasoning engines to reason with it, in order to generate intelligent behaviour. Ontologies were chosen over other knowledge representation formalisms because of their expressivity and executable format, and because current trends suggest a general shift towards the use of ontologies in many systems used for information storing and sharing. For the frontend, this architecture uses VoiceXML, the emerging, and de facto standard for voice automated applications. A functional prototype was built for an initial validation of the architecture. The system is a simple voice application to help locate information about service providers that offer HIV (Human Immunodeficiency Virus) testing. We called this implementation HTLS (HIV Testing Locator System). The functional prototype was implemented using a number of technologies. OWL API, a Java interface designed to facilitate manipulation of ontologies authored in OWL was used to build a customised query interface for HTLS. Pellet reasoner was used for supporting queries to the knowledge base and Drools (JBoss rule engine) was used for processing dialog rules. VXI was used as the VoiceXML browser and an experimental softswitch called iLanga as the bridge to the telephony system. (At the heart of iLanga is Asterisk, a well known PBX-in-a-box.) HTLS behaved properly under system testing, providing the sought initial validation of OVR. / LaTeX with hyperref package

Orientador: Celso de Almeida / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-26T13:51:01Z (GMT). No. of bitstreams: 1 OrozcoGarzon_NathalyVeronica_M.pdf: 2420238 bytes, checksum: 44b2e62e1f4262ea3a2a169999209c79 (MD5) Previous issue date: 2014 / Resumo: A principal contribuição desta tese é a proposta de um mecanismo com transmissão oportunista. Este método de transmissão é realizado apenas quando o desvanecimento no receptor estiver acima de um certo limiar. Neste sistema oportunista o transmissor e o receptor estão em constante comunicação através de um canal de realimentação e o receptor indica ao transmissor quando ele deve transmitir. Para a análise de desempenho do sistema oportunista vamos considerar um canal com ruído e desvanecimento plano e lento Rayleigh e também interferência de co-canal (CCI) vamos também considerar diferentes esquemas de modulação (BPSK, QPSK, 4-QAM, 16-QAM e 64-QAM). A análise de desempenho do sistema proposto baseia-se na probabilidade de erro de bit média (BER), para a qual expressões analíticas foram obtidas. Estas expressões foram verificadas usando o método de simulação de Monte Carlo, com excelente concordância entre os dois resultados. Além disso, foram consideradas a eficiência espectral e a potência de transmissão do sistema. Os resultados obtidos mostram que a transmissão oportunista pode combater o desvanecimento de forma eficiente, pois o sistema oportunista elimina os efeitos do desvanecimento quase em sua totalidade. Foi feita também uma comparação entre o sistema oportunista e um sistema ordinário para a comparação de desempenho. Além disso, a transmissão oportunista é menos sensível à interferência de co-canal. Várias curvas são apresentadas ilustrando a eficiência do mecanismo oportunista proposto em termos da probabilidade de erro de bit média / Abstract: This thesis proposes, as the main contribution, a new mechanism with an opportunistic transmission. This transmission method is realized just when the fading at receiver is above a threshold value. In this opportunistic system the transmitter and the receiver are in constant communication through a feedback link and the receiver indicates when the transmitter should transmit. To analyze the performance of the opportunistic system we consider a noise channel and a flat and slow Rayleigh fading channel in the presence of co-channel interference (ICC). We also consider different modulation schemes (BPSK, QPSK, 4-QAM, 16-QAM e 64-QAM). The performance analysis of the proposed system is based on the mean bit error probability (BER), for which analytical expressions are established. These expressions are verified using Monte-Carlo simulation method with excellent agreement between both results. Furthermore, we consider the spectral efficiency and the power transmission of this system. The opportunistic transmission can combat the fading efficiently. That is, once it eliminates the fading effects almost entirely. Moreover, it is made a comparison between the opportunistic system and the ordinary system performance. Furthermore, the opportunistic transmission is less sensitive to co-channel interference. Several figures are presented illustrating the efficiency of the proposed mechanism in terms of mean bit error probability / Mestrado / Telecomunicações e Telemática / Mestra em Engenharia Elétrica

Magister Scientiae - MSc / Text communication is often perceived as lacking some components of communication that are essential in sustaining interaction or conversation. This interaction incoherency tends to make text communication plastic. It is traditionally devoid of intonation, pitch, gesture, facial expression and visual or auditory cues. Nevertheless, Instant Messaging (IM), a form of text communication is on the upward uptake both on PCs and on mobile handhelds. There is a need to rubberise this plastic text messaging to improve co-presence for text communications thereby improving synchronous textual discussion, especially on handheld devices. One element of interaction is gesture, seen as a natural way of conversing. Attaining some level of interaction naturalism requires improving synchronous communication spontaneity, partly achieved by enhancing input mechanisms. To enhance input mechanisms for interactive text-based chat on mobile devices, there is a need to facilitate gesture input. Enhancement is achievable in a number of ways, such as input mechanism redesigning and input offering adaptation. This thesis explores affective gesture mode on interface redesign as an input offering adaptation. This is done without a major physical reconstruction of handheld devices. This thesis presents a text only IM system built on Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE). It was developed with a novel user-defined hotkey implemented as a one-click context menu to "fast-track" text-gestures and emoticons. A hybrid quantitative and qualitative approach was taken to enable data triangulation. Results from experimental trials show that an Affective Gesture (AG) approach improved IM chat spontaneity/response. Feedback from the user trials affirms that AG hotkey improves chat responsiveness, thus enhancing chat spontaneity.