Among the low-power wireless technologies that have emerged in recent years, ultra-wideband (UWB) has successfully established itself as the reference for accurate ranging and localization, both outdoors and indoors. Due to its unprecedented performance, paired with relatively low energy consumption, UWB is going to play a central role in the next wave of location-based applications. As the trend of integration in smartphones continues, UWB is also expected to reach ordinary users, revolutionizing our lives the same way GPS and similar technologies have done. But the impact of UWB may not be limited to ranging and localization. Because of its considerable data rate, and its robustness to obstacles and interference, UWB communication may hold untapped potential for sensing and control applications. Nevertheless, several research questions still need to be answered to assess whether UWB can be adopted widely in the communication and localization landscapes. On one hand, the rapid evolution of UWB radios and the release of ever more efficient chips is a clear indication of the growing market for this technology. However, for it to become pervasive, full-fledged communication and localization systems must be developed and evaluated, tackling the shortcomings affecting current prototypes. UWB systems are typically single-hop networks designed for small areas, making them impractical for large-scale coverage. This limitation is found in communication and localization systems alike. Specifically for communication systems, energy-efficient multi-hop protocols are hitherto unexplored. As for localization systems, they rely on mains-powered anchors to circumvent the issue of energy consumption, in addition to only supporting small areas. Very few options are available for light, easy to deploy infrastructures using battery-powered anchors. Nonetheless, large-scale systems are required in common settings like industrial facilities and agricultural fields, but also office spaces and museums. The general goal of enabling UWB in spaces like these entails a number of issues. Large multi-hop infrastructures exacerbate the known limitations of small, single-hop, networks; notably, reliability and latency requirements clash with the need to reduce energy consumption. Finally, when device mobility is a factor, continuity of operations across the covered area is a challenge in itself. In this thesis, we design energy-efficient UWB systems for large-scale areas, supporting device mobility across multi-hop infrastructures. As our opening contribution, we study the unique interference rejection properties of the radio to inform our design. This analysis yields a number of findings on the impact of interference in communication and distance estimation, that are directly usable by developers to improve UWB solutions. These findings also suggest that concurrent transmissions in the same frequency channel are a practical option in UWB. While the overlapping of frames is typically avoided to prevent collisions, concurrent transmissions have counter-intuitively been used to provide highly reliable communication primitives for a variety of traffic patterns in narrowband radios. In our first effort to use concurrent transmissions in a full system, we introduce the UWB version of Glossy, a renowned protocol for efficient network-wide synchronization and data dissemination. Inspired by the success of concurrency-based protocols in narrowband, we then apply the same principles to define a novel data collection protocol, Weaver. Instead of relying on independent Glossy floods like state-of-the-art systems, we weave multiple data flows together to make our collection engine faster, more reliable and more energy-efficient. With Glossy and Weaver supporting the communication aspect in large-scale networks, we then propose techniques for large-scale localization systems. We introduce TALLA, a TDoA solution for continuous position estimation based on wireless synchronization. We evaluate TALLA in an UWB testbed and in simulations, for which we replicate accurately the behavior of the clocks in our real-world platforms. We then offer a glimpse of what TALLA can be employed for, deploying an infrastructure in a science museum to track visitors. The collected movement traces allow us to analyze fine-grained stop-move mobility patterns and infer the sequence of visited exhibits, which is only possible because of the high spatio-temporal granularity offered by TALLA. Finally, with SONAR, we tackle the issue of large-scale ranging and localization when the infrastructure cannot be mains-powered. By blending synchronization and scheduling operations into neighbor discovery and ranging, we drastically reduce energy consumption and ensure years-long system lifetime. Overall, this thesis enhances UWB applicability in scenarios that were previously precluded to the technology, by providing the missing communication and localization support for large areas and battery-powered devices. Throughout the thesis, we follow an experiment-driven approach to validate our protocol models and simulations. Based on the evidence collected during this research endeavor, we develop full systems that operate in a large testbed at our premises, showing that our solutions are immediately applicable in real settings.

The proliferation of modern wireless networks increases demand for high capacity and throughput in order to provide faster, more robust, efficient and broadband services to end users. Mobile WiMAX and LTE are examples of such networks in which for some cases they have exposed limited connectivity due to harsh environment. Relay stations are preferred to overcome problems of weak or no access for such network devices, that are placed in specific positions to maintain high quality of data transfer at low cost and provide the required connectivity anywhere anytime. These stations should be equipped with an antenna system capable of establishing communication between base station (backhaul link) and end users (access link). This thesis focuses on the design and development of a new antenna system that is suitable for a relay-based wireless network. Planar geometries of microstrip patch antennas are utilized. The antenna system comprises two antenna modules: a new design of a single antenna for access link and a new design of an antenna array for backhaul link realization. Both antenna specifications are compatible with the IEEE802.16j protocol standard. Hence, relay station should be capable of pointing its radiation pattern to the base station antenna, thus to achieve the desired radiation pattern of the relay station, a new beam-forming module is proposed, designed and developed to generate the proper radiation pattern. The beam-forming module incorporating digital phase shifters and attenuator chips is fabricated and tested. The optimization process using the Least Mean Square (LMS) algorithm is considered in this study to assign the proper phase and amplitude that is necessary to each radiation element excitation current, to produce the desired steered radiation pattern. A comprehensive study on the coupling effects for several relative positions between two new backhaul and access link antenna elements is performed. Two new antenna configurations for coupling reduction are tested and the simulated and measured results in terms of antenna radiation performances were compared and commented.

No description available.

Approved for public release; distribution is unlimited / Handheld devices have evolved significantly from mere simple organizers to more powerful handheld computers that are capable of network connectivity, giving it the ability to send e-mail, browse the World Wide Web, and query remote databases. However, handheld devices, because of its design philosophy, are limited in terms of size, memory, and processing power compared to desktop computers. This thesis investigates the use of Data Flow Query Language (DFQL) in querying local and remote databases from a handheld device. Creating Standard Query Language (SQL) queries can be a complex undertaking; and trying to create one on a handheld device with a small screen only adds to its complexity. However, by using DFQL, the user can submit queries with an easy to use graphical user interface. Although handheld devices are currently more powerful than earlier PCs, they still require applications with a small footprint, which is a limiting factor for software developed. This thesis will also investigate the best division of labor between handheld device and remote servers. / Sergeant, United States Army

The proliferation of modern wireless networks increases demand for high capacity and throughput in order to provide faster, more robust, efficient and broadband services to end users. Mobile WiMAX and LTE are examples of such networks in which for some cases they have exposed limited connectivity due to harsh environment. Relay stations are preferred to overcome problems of weak or no access for such network devices, that are placed in specific positions to maintain high quality of data transfer at low cost and provide the required connectivity anywhere anytime. These stations should be equipped with an antenna system capable of establishing communication between base station (backhaul link) and end users (access link). This thesis focuses on the design and development of a new antenna system that is suitable for a relay-based wireless network. Planar geometries of microstrip patch antennas are utilized. The antenna system comprises two antenna modules: a new design of a single antenna for access link and a new design of an antenna array for backhaul link realization. Both antenna specifications are compatible with the IEEE802.16j protocol standard. Hence, relay station should be capable of pointing its radiation pattern to the base station antenna, thus to achieve the desired radiation pattern of the relay station, a new beam-forming module is proposed, designed and developed to generate the proper radiation pattern. The beam-forming module incorporating digital phase shifters and attenuator chips is fabricated and tested. The optimization process using the Least Mean Square (LMS) algorithm is considered in this study to assign the proper phase and amplitude that is necessary to each radiation element excitation current, to produce the desired steered radiation pattern. A comprehensive study on the coupling effects for several relative positions between two new backhaul and access link antenna elements is performed. Two new antenna configurations for coupling reduction are tested and the simulated and measured results in terms of antenna radiation performances were compared and commented.

Made available in DSpace on 2016-04-04T18:31:20Z (GMT). No. of bitstreams: 1 Edizon Eduardo Basseto Junior.pdf: 3122282 bytes, checksum: f4c584d20c71eb7d623b23f592a8a4c2 (MD5) Previous issue date: 2008-02-08 / The goal of this work is to propose a metric to analyze the quality of videos transmitted through wireless networks. A wireless network is a degenerative means to transmit data given its huge instability, which affects transmitted videos. The present proposal adds a technical network parameter, known as jitter, to clients opinion. For these studies a video was streamed through a RF emulation testbed, which can emulate the IEEE wireless networks (WLAN) 802.11b and 802.11g standards. The experiments were done by streaming a DVD, with known characteristics, from a server to a workstation, passing through the testbed. This is capable to concentrate, in a controlled way, the wireless signal into a coaxial cable. With the possibility to control the signal level of the carrier, twelve scenarios were developed and studied: video transmissions with maximum and minimum signal levels, and also with the signal level characterized as Rayleigh distribution, were done for each of the two IEEE standards measures. Under the same signal conditions, I analyzed the video streaming with UDP traffic sent together. The results confirm the action of jitter in the degeneration of the received video, which justifies the use of jitter in the proposed metric. The results also show that the 802.11g networks work a little better than 802.11b for video streaming, but none of them showed a good performance when the UDP traffic was sent together. A questionnaire has also been developed, with the purpose of analyzing the streaming subjectively. Those two factors (jitter and subjective analysis) result in an equation that can be applied to a MOS scale making it possible to numerically define the quality of the video transmission. / O objetivo deste trabalho ? propor uma m?trica de qualidade para v?deos transmitidos em redes sem fio. As redes sem fio s?o um meio de transmiss?o muito degenerativo devido ? sua instabilidade, o que afeta um v?deo transmitido. A presente proposta soma ? opini?o dos espectadores um par?metro t?cnico da rede, conhecido por jitter, e a taxa de dados do v?deo transmitido. Para os estudos realizados, um v?deo foi transmitido atrav?s de uma bancada de emula??o de r?dio freq??ncia (RF) que simula a transmiss?o das redes sem fios (WLAN) padr?es IEEE 802.11b e 802.11g. Os experimentos foram realizados a partir do streaming de um DVD, com caracter?sticas conhecidas, de um servidor para uma esta??o, atrav?s da bancada que confina o sinal transmitido de maneira controlada em um cabo coaxial. Tendo-se essa possibilidade de controlar o n?vel do sinal da portadora, foram estudadas doze situa??es. Para cada um dos padr?es IEEE foram realizadas medidas com a transmiss?o de v?deo e um n?vel m?ximo de sinal, outra com o n?vel m?nimo e uma situa??o que tem o n?vel de sinal caracterizado por uma distribui??o de Rayleigh. Para essas mesmas condi??es de sinal foi estudada a transmiss?o do v?deo mais um tr?fego UDP concorrente. Os resultados confirmam a atua??o do jitter na degenera??o do v?deo recebido, justificando sua utiliza??o na m?trica proposta. Os resultados demonstram tamb?m que existe uma pequena vantagem das redes 802.11g na transmiss?o do streaming, por?m nenhuma das redes demonstrou um desempenho satisfat?rio na presen?a de tr?fego UDP transmitido concorrentemente. Na proposta tamb?m ? desenvolvido um question?rio com a finalidade de analisar subjetivamente o streaming, gerando uma equa??o que pode ser aplicada ? escala MOS, podendo assim definir numericamente a qualidade de v?deo transmitido.

Made available in DSpace on 2016-04-04T18:31:27Z (GMT). No. of bitstreams: 1 Manoel Peluso de Carvalho Filho.pdf: 1548469 bytes, checksum: 813f063c4ea17788aa795465c9e6e6f5 (MD5) Previous issue date: 2008-11-24 / Nowadays, the use of the wireless network technology has grown mainly motivated by the price of equipments, ease of installation, network maintenance and expansion of technical safety. The more you use the wireless network resource, the better should be the treatment related to its safety aspect. As the security level increases, the amount of information transmitted between the equipment decreases. This thesis aims to analyze the performance of WLAN network with the implementation of WEP and WPA / TKIP security protocols in an environment that uses applications whose characteristic is to generate small packets on the network. The LanTraffic TM software is used to generate traffic and also to capture the transmission rate in Kbps that flows through the stations. Three scenarios are simulated varying in the distance between the equipments. For each scenario, a comparative study was made and the WLAN behavior without the security resource analyzed, then it was analyzed with the WEP fitted and finally with the WPA/TKIP configured. To develop the experiments it was used a WLAN network in a controlled environment in the Laboratory Research on Radio System in PUC Campinas. Therefore, there is not external interference in the signal transmitted by equipments. / A utiliza??o da tecnologia de rede sem fio tem crescido ultimamente motivado principalmente pelo pre?o dos equipamentos, facilidade de instala??o, manuten??o da rede e amplia??o das t?cnicas de seguran?a. Quanto mais se utiliza o recurso de rede sem fio maior tem de ser o tratamento em rela??o ao aspecto de seguran?a. A medida que aumenta o n?vel de seguran?a, decresce a quantidade de informa??o transmitida entre os equipamentos. Esse trabalho visa analisar o desempenho de rede WLAN(Wireless Local ?rea Network) com a implementa??o dos protocolos de seguran?a WEP(Wired Equivalent Privacy) e WPA/TKIP(WI-FI Protected Access / Temporal Key Integrity Protocol). ? utilizado o software LanTrafficTM para gerar tr?fego na rede e tamb?m para capturar a taxa de transmiss?o em Kbps trafegados entre as STAs. S?o emulados tr?s cen?rios variando a dist?ncia entre os equipamentos. Para cada cen?rio foi confeccionado um comparativo e analisado o comportamento da WLAN configurado sem seguran?a, com o WEP habilitado e finalmente com o WPA/TKIP configurado. Para executar os experimentos utilizou-se uma rede WLAN no laborat?rio de pesquisa em sistema de r?dio (LP-SiRa) da PUC Campinas em um ambiente controlado. Com isso n?o h? interfer?ncias na transmiss?o dos sinais emitidos pelos equipamentos Ou seja, sem interfer?ncia externa no sinal transmitido entre os equipamentos.

De nos jours, l’expérience de l'utilisateur appelé en anglais « User Experience » est devenue l’un des indicateurs les plus pertinents pour les fournisseurs de services ainsi que pour les opérateurs de télécommunication pour analyser le fonctionnement de bout en bout de leurs systèmes (du terminal client, en passant par le réseaux jusqu’à l’infrastructure des services etc.). De plus, afin d’entretenir leur part de marché et rester compétitif, les différents opérateurs de télécommunication et les fournisseurs de services doivent constamment conserver et accroître le nombre de souscription des clients. Pour répondre à ces exigences, ils doivent disposer de solutions efficaces de monitoring et d’estimation de la qualité d'expérience (QoE) afin d’évaluer la satisfaction de leur clients. Cependant, la QoE est une mesure qui reste subjective et son évaluation est coûteuse et fastidieuse car elle nécessite une forte participation humaine (appelé panel de d’évaluation). Par conséquent, la conception d’un outil qui peut mesurer objectivement cette qualité d'expérience avec une précision raisonnable et en temps réel est devenue un besoin primordial qui constitue un challenge intéressant à résoudre. Comme une première contribution, nous avons analysé l'impact du comportement d’un réseau sur la qualité des services de vidéo à la demande (VOD). Nous avons également proposé un outil d'estimation objective de la QoE qui utilise le système expert basé sur la logique floue pour évaluer la QoE à partir des paramètres de qualité de service de la couche réseau. Dans une deuxième contribution, nous avons analysé l'impact des paramètres QoS de couche MAC sur les services de VoD dans le cadre des réseaux sans fil IEEE 802.11n. Nous avons également proposé un outil d'estimation objective de la QoE qui utilise le réseau aléatoire de neurones pour estimer la QoE dans la perspective de la couche MAC. Pour notre troisième contribution, nous avons analysé l'effet de différents scénarios d'adaptation sur la QoE dans le cadre du streaming adaptatif au débit. Nous avons également développé une plate-Forme Web de test subjectif qui peut être facilement intégré dans une plate-Forme de crowd-Sourcing pour effectuer des tests subjectifs. Finalement, pour notre quatrième contribution, nous avons analysé l'impact des différents paramètres de qualité de service Web sur leur QoE. Nous avons également proposé un algorithme d'apprentissage automatique i.e. un système expert hybride rugueux basé sur la logique floue pour estimer objectivement la QoE des Web services / Today user experience is becoming a reliable indicator for service providers and telecommunication operators to convey overall end to end system functioning. Moreover, to compete for a prominent market share, different network operators and service providers should retain and increase the customers’ subscription. To fulfil these requirements they require an efficient Quality of Experience (QoE) monitoring and estimation. However, QoE is a subjective metric and its evaluation is expensive and time consuming since it requires human participation. Therefore, there is a need for an objective tool that can measure the QoE objectively with reasonable accuracy in real-Time. As a first contribution, we analyzed the impact of network conditions on Video on Demand (VoD) services. We also proposed an objective QoE estimation tool that uses fuzzy expert system to estimate QoE from network layer QoS parameters. As a second contribution, we analyzed the impact of MAC layer QoS parameters on VoD services over IEEE 802.11n wireless networks. We also proposed an objective QoE estimation tool that uses random neural network to estimate QoE from the MAC layer perspective. As our third contribution, we analyzed the effect of different adaption scenarios on QoE of adaptive bit rate streaming. We also developed a web based subjective test platform that can be easily integrated in a crowdsourcing platform for performing subjective tests. As our fourth contribution, we analyzed the impact of different web QoS parameters on web service QoE. We also proposed a novel machine learning algorithm i.e. fuzzy rough hybrid expert system for estimating web service QoE objectively

<p>The objective of the thesis research is to design such vertical handoff decision algorithms in order for mobile field workers and other mobile users equipped with contemporary multimode mobile devices to communicate seamlessly in the NGWN. In order to tackle this research objective, we used fuzzy logic and fuzzy inference systems to design a suitable handoff initiation algorithm that can handle imprecision and uncertainties in data and process multiple vertical handoff initiation parameters (criteria) / used the fuzzy multiple attributes decision making method and context awareness to design a suitable access network selection function that can handle a tradeoff among many handoff metrics including quality of service requirements (such as network conditions and system performance), mobile terminal conditions, power requirements, application types, user preferences, and a price model / used genetic algorithms and simulated annealing to optimise the access network selection function in order to dynamically select the optimal available access network for handoff / and we focused in particular on an interesting use case: vertical handoff decision between mobile WiMAX and UMTS access networks. The implementation of our handoff decision algorithm will provide a network selection mechanism to help mobile users select the best wireless access network among all available wireless access networks, that is, one that provides always best connected services to users.</p>

Wireless Sensor Networks (WSNs) are composed of a large number of battery-powered sensor nodes that have the ability to sense the physical environment, compute the obtained information and communicate using the radio interfaces. Because sensor nodes are generally deployed on a large and wild area, they are powered by embedded battery. And it is difficult to change or recharge the battery, thus to reduce the energy consumption when sensors and protocols are designed is very important and can extend the lifetime of WSNs. So sensor nodes transmit packets with a lower transmission power (e.g. OdBm). With this transmission power, a packet can only be transmitted dozens of meters away. Therefore, when a sensor detects an event, a packet is sent in a multi-hop, ad-hoc manner (without fixed infrastructure and each sensor is able to relay the packet) to the sink (specific node which gathers information and reacts to the network situation). In this thesis, we first give an elaborate state of the art of WSNs. Then the impacts of duty-cycle and unreliable links or the performances of routing layer are analyzed. Based on the analytical results, we then propose three new simple yet effective methods to construct virtual coordinates under unreliable links in WSNs. By further taking the duty-cycle and real-time constraints into consideration we propose two cross-layer forwarding protocols which can have a greater delivery ratio and satisfy the deadline requirements. In order to have protocols for the WSNs that have dynamic topology, we then propose a robust forwarding protocol which can adapt its parameters when the topology changes. At last, we conclude this thesis and give some perspectives.