Dissertations / Theses on the topic 'Hybrid communicating systems'

Les infrastructures industrielles critiques seront dotées de plusieurs équipements embarqués intelligents. Elles exploitent des systèmes complexes, embarqués, intelligents et sémantiques pour leurs fonctionnements, en local et à distance, dans un contexte de développement, de villes intelligentes et du web des objets. Elles emploient, de plus en plus de systèmes «contrôle/commande», pour la surveillance des plateformes industrielles critiques, en temps réel. Les infrastructures critiques seront de plus en plus communicantes dans le cadre des échanges des alarmes et la mise en place de marchés euro-méditerranéens de l’électricité et davantage plus vulnérables. La cybernétique des plateformes critiques se développe, de jour en jour, essentiellement avec l’usage de systèmes complexes embarqués intelligents sémantiques, des services web, des ontologies,..etc. Ils sont tous embarqués sur les instruments intelligents, composant les systèmes sémantiques. Des réseaux de télécommunication intelligents, filaire et sans fil, dit hybrides, se développent. Ils représentent un grand challenge, pour la sécurité des systèmes communicants futurs. Dans un contexte de développement du web, des objets et des villes intelligentes, nos travaux de recherche visent à renforcer les bases de la sécurité et de la cybernétique sémantique, pour les systèmes communicants. Dans notre solution globale, en matière de sécurité sémantique, des infrastructures critiques, nous avons proposé plusieurs sous-solutions, tels que des méta-modèles et des modèles, ainsi qu’une stratégie de sécurité de bout en bout, avec un fonctionnement sur un réseau Cloud global, hybride et sécurisé
Critical, modern, current, and even future industrial infrastructures will be equipped with several intelligent embedded equipment. They exploit complex, embedded, intelligent and semantic systems for their operations, locally and remotely, in a context of development, smart cities and the web of things. They are using more and more SCADA and DCS control systems to monitor critical industrial platforms in real time. Critical infrastructures will be more and more communicating in the framework of the exchanges of allarmes and the establishment of Euro-Mediterranean markets of the életcricité and also more and more vulnerable, to classic and even semantic attacks, to viruses, to Trojan horses. The cybernetics of critical platforms is growing, day by day, mainly with the use of complex embedded intelligent semantic systems, web services, ontologies, and format files (XML, OWL, RDF, etc.). They are all embedded in intelligent instruments, making up semantic SCADA systems. Intelligent telecommunication networks, wired and wireless, called hybrids, are developing. They represent a great challenge for the security of future communicating systems. In a context of development of the web of things and smart cities, our research aims to strengthen the bases of security and semantic cybernetics, for communicating systems. In our global solution for semantic security, critical infrastructures, we have proposed several sub-solutions, such as metamodels and models, as well as an end-to-end security strategy, with operation on a global cloud network, hybrid and secure

As a benefit of achieving a diversity gain and/or a multiplexing gain, MIMO techniques are capable of significantly increasing the achievable throughput and/or the network coverage without additional bandwidth or transmit power. For the sake of striking an attractive trade-off between the attainable diversity gain and/or multiplexing gain, in this thesis the novel Space-Time-Frequency Shift Keying (STFSK) concept is proposed for the family of MIMO systems. More specifically, in order to generate space-time-frequency domain codewords, the STFSK encoding schemes activate one out of Q dispersion matrices, and the associated address bits are then combined with a classic time-domain and frequency-domain modulation scheme. The resultant arrangements impose no inter-symbol interference and are capable of eliminating the inter-antenna interference, hence offering a range of benefits over other classic MIMO arrangements. Additionally, a soft-output STFSK demodulator is designed for iterative detection and the complexity of both the hard- as well as soft-decision demodulators is quantified. Furthermore, the STFSK performance is studied in both the single-user and the multipleuser multi-cell environment in order to investigate the effects of these techniques on the performance of the holistically optimized systems. Furthermore, we studied the H-ARQ systems advocated in the context of cooperation-aided wireless networks, where the MIMO elements are constituted by the individual elements of separate network nodes. Both perfect and imperfect coherent detection as well as non-coherent detection aided cooperative H-ARQ schemes are considered. In the perfect coherent detection based pilot symbol assisted scheme, a novel relay-switching aided H-ARQ scheme is proposed for mitigating the effects of correlation in fading wireless channels, followed by a H-ARQ scheme employing systematic Luby transform codes. In contrast to the unrealistic perfect coherent detection, realistic imperfect coherent schemes are studied, where the channel impulse responses are imperfectly estimated. Furthermore, non-coherent differential detection aided cooperative H-ARQ schemes are proposed and compared to their coherent detection assisted counterparts. Finally, a novel cooperative H-ARQ arrangement based on distributed space-time codes is proposed for the sake of improving the attainable system throughput, while reducing the system’s complexity.

Un rôle important des C-ITS est d'élargir la perception des usagers de la route afin d'éviter les accidents de la route. Une telle perception étendue est construite par l'échange d'informations entre les véhicules, les piétons et l'infrastructures à l'aide de différents types de messages, notamment le message CAM et le message de perception collective (CPM). Bien que les données transportées par ces messages soient critiques, elles consomment beaucoup de ressources. Actuellement, les CAM et les CPM sont diffusés périodiquement avec une fréquence minimale de 1 Hz. De plus, leurs fréquences peuvent être adaptées en fonction de la dynamique du véhicule (vitesse, accélération,...) et en outre avec l'état du canal sans fil lorsqu'une fonctionnalité de contrôle de congestion distribué (DCC) est activée. Cependant, il peut être vital pour un véhicule de transmettre ses informations à un débit élevé dans les zones critiques, telles que les intersections, même si cela peut entraîner un taux d'occupation de canal (CBR) plus élevé. Au contraire, les véhicules à faible risque de collision peuvent réduire leur fréquence de transmission pour éviter une charge inutile sur le canal. Par conséquent, la diffusion de tels messages doit être effectuée de manière efficace afin que les exigences d'application de la sécurité routière soient garanties et que l'utilisation des ressources soit optimisée.Cela nécessite que la communication soit contextuelle, capable de contrôler les paramètres de communication en tenant compte des exigences de l'application, de la disponibilité des technologies de communication et des ressources radio ainsi que des conditions environnementales (configuration des routes, densité du trafic, présence d'infrastructures en bordure de route, etc.) . Par conséquent, établir des contextes qui caractérisent les informations collectées environnementales et non environnementales est un défi majeur pour la communication contextuelle.La thèse vise à étudier et à développer une communication contextuelle pour les applications de sécurité routière. L'objectif principal est de concevoir des algorithmes capables d'optimiser la communication V2X sur la base d'une reconnaissance des contextes, notamment la disponibilité des ressources radio, les conditions environnementales et les exigences de l'application. Le travail comprend deux phases. Dans la première phase, nous présentons une architecture de communication contextuelle et nous modélisons des contextes en termes d'exigences applicatives (contexte1) et de contexte environnemental (contexte2). Le premier contexte vise à définir les exigences de l'application et à évaluer les performances des stratégies de diffusion des messages CAM par rapport aux exigences. Le contexte environnemental particulièrement la disponibilité de l'infrastructure permettant une communication I2V qui peut remplacer la communication V2V dans cette zone locale, ce qui améliore la perception collective et réduit la charge du canal grâce à sa plus grande couverture de communication et son plus large champ de vision de capteurs. La deuxième phase vise à concevoir et développer des algorithmes qui contrôlent le contenu des messages en tenant compte des contextes préalablement modélisés tout en assurant un haut niveau de perception/conscience collective
An important role of C-ITS is to extend perception of individual road users so that traffic accidents are avoided. Such an extended perception is built by information exchange among vehicles, pedestrians, and infrastructure using different types of messages including cooperative awareness message (CAM) and Collective Perception Message (CPM). While data carried by these messages are critical, they are resource-consuming. Currently, CAMs and CPMs are broadcasted periodically with a minimum frequency of 1Hz. In addition, their frequencies can be adapted based on vehicle dynamics (speed, acceleration,...) and further with wireless channel condition when a distributed congestion control (DCC) functionality is enabled. However, it might be vital for a vehicle to transmit its beacons at a high rate in critical areas, such as intersections, even if this may result in higher channel busy ratio (CBR). On the contrary, vehicles with a low risk of collision may reduce their transmission frequency to avoid unnecessary load on the channel. Hence, dissemination of such messages must be made in an efficient way so that road safety application requirement is ensured and resource utilization is optimized.This requires the communication be context-aware, being able to control communication parameters by taking into account application requirements, availability of communication technologies and radio resources as well as environmental condition (road layout, traffic density, presence of roadside infrastructure, and etc.). Hence, establishing contexts that characterize environmental and non-environmental collected information is a key challenge for context-aware communication.The thesis targets at studying and developing context aware communication for road safety applications. The main goal is to design algorithms that are able to optimize V2X communication based on a recognition of the contexts particularly radio resource availability, environmental condition and application requirements. The work consists of two phases. In the first phase, we present context aware communication architecture and study/model contexts in terms of application requirement (context1) and environmental context (context2). The first context aims to define application requirement and evaluate performances of Cooperative Awareness Service strategies against requirements. Environmental context consists on infrastructure availability allowing I2V communication that may replace V2V communication in that local area resulting in improved collective perception and reduced channel load thanks to its larger communication coverage and sensor field of view. The second phase intends to design and develop algorithms that control/select message data contents taking into account contexts previously modeled while ensuring a high level of collective perception/awareness

Signals in chaotic communication systems can be used in secure communications because they are unstable and aperiodic making them difficult to detect or predict. Receivers for conventional chaotic communication systems are complex as chaotic signals are sensitive initial condition and difficult to synchronize. This research developed a method to create a Generalized Multilevel-Hybrid Chaotic Oscillator and derived its generalized fixed basis function leading to the implementation of a simple matched filter receiver that can be synchronized. The proposed system is not sensitive initial condition and can be used effectively for multi-level and multi-access communication systems.

Success of Wireless Sensor Networks (WSN) largely depends on whether the deployed network can provide desired area coverage with acceptable network lifetime. In hostile or harsh environments such as enemy territories in battlefields, fire or chemical spills, it is impossible to deploy the sensor nodes in a predeter- mined regular topology to guarantee adequate coverage. Random deployment is thus more practical and feasible for large target areas. On the other hand, random deployment of sensors is highly susceptible to the occurrence of coverage holes in the target area. A potential solution for enhancing the existing coverage achieved by random deployments involves the use of mobility capable sensors that would help fill the coverage holes. This thesis seeks to address the problem of determining the current coverage achieved by the non-deterministic deployment of static sensor nodes and subsequently enhancing the coverage using mobile sensors. The main contributions of this dissertation are the design and evaluation of MAPC (Mobility Assisted Probabilistic Coverage), a distributed protocol for ensuring area coverage in hybrid wireless sensor networks. The primary contribution is a pragmatic approach to sensor coverage and maintenance that we hope would lower the technical barriers to its field deployment. Most of the assumptions made in the MAPC protocol are realistic and implementable in real-life applications e.g., practical boundary estimation, coverage calculations based on a realistic sensing model, and use of movement triggering thresholds based on real radio characteristics etc. The MAPC is a comprehensive three phase protocol. In the first phase, the static sensors calculate the area coverage using the Probabilistic Coverage Algorithm (PCA). This is a deviation from the idealistic assumption used in the binary detection model, wherein a sensor can sense accurately within a well defined (usually circular) region. Static sensors execute the PCA algorithm, in a distributed way, to identify any holes in the coverage. In the second phase, MAPC scheme moves the mobile nodes in an optimal manner to fill these uncovered locations. For different types of initial deployments, the proposed movement algorithms consume only 30-40% of the energy consumed by the basic virtual force algorithm. In addition, this thesis addresses the problem of coverage loss due to damaged and energy depleted nodes. The problem has been formulated as an Integer Linear Program and implementable heuristics are developed that perform close to optimal solutions. By replacing in-operational nodes in phase three, MAPC scheme ensures the continuous operation of the WSN. Experiments with real mote hardware were conducted to validate the boundary and coverage estimation part of the MAPC protocol. Extensive discrete event simulations (using NS2) were also performed for the complete MAPC protocol and the results demonstrate that MAPC can enhance and maintain the area coverage by efficiently moving mobile sensor nodes to strategic positions in the uncovered area.

The increasing number of network security related incidents has made it necessary for the organizations to actively protect their sensitive data with network intrusion detection systems (IDSs). Detecting intrusion in a distributed network from outside network segment as well as from inside is a difficult problem. IDSs are expected to analyze a large volume of data while not placing a significant added load on the monitoring systems and networks. This requires good data mining strategies which take less time and give accurate results. In this study, a novel hybrid layered multiagent-based intrusion detection system is created, particularly with the support of a multi-class supervised classification technique. In agent-based IDS, there is no central control and therefore no central point of failure. Agents can detect and take predefined actions against malicious activities, which can be detected with the help of data mining techniques. The proposed IDS shows superior performance compared to central sniffing IDS techniques, and saves network resources compared to other distributed IDSs with mobile agents that activate too many sniffers causing bottlenecks in the network. This is one of the major motivations to use a distributed model based on a multiagent platform along with a supervised classification technique. Applying multiagent technology to the management of network security is a challenging task since it requires the management on different time instances and has many interactions. To facilitate information exchange between different agents in the proposed hybrid layered multiagent architecture, a low cost and low response time agent communication protocol is developed to tackle the issues typically associated with a distributed multiagent system, such as poor system performance, excessive processing power requirement, and long delays. The bandwidth and response time performance of the proposed end-to-end system is investigated through the simulation of the proposed agent communication protocol on our private LAN testbed called Hierarchical Agent Network for Intrusion Detection Systems (HAN-IDS). The simulation results show that this system is efficient and extensible since it consumes negligible bandwidth with low cost and low response time on the network.

The HF band of radio frequencies, from 3-30 MHz, is unique in its property that it is refracted by the ionosphere. This property allows long distance radio telecommunications around the world without requiring infrastructure. High frequency (HF) communication has been largely superseded by satellite and cellular technologies for day-to-day communications, due to the tight bandwidth constraints and technical difficulties inherent in using it. However there is still a need for HF communications devices where existing infrastructure is not available, such as in remote or polar locations, or in emergency situations due to natural disasters. This research is aimed at the development of an asymmetric HF communications link, with a battery-powered remote unit that transmits a small amount of data to a mains-powered base station. New technologies are identified and evaluated for use in the link, with the aim of reducing the power requirements of the remote unit. Error correction techniques are investigated. Low-density parity check (LDPC) codes, which are powerful codes used for forward error correction, are suggested for use in the link. Quasi-cyclic LDPC codes allow the low-power transmitter unit to use a computationally simple encoder based on feedback shift registers for generating the LDPC block codes cheaply. Semi-blind LDPC turbo equalisation is a powerful technique that can be used at the base station which utilises the structure of the LDPC code to encode the data stream. This equalises a received signal with a minimal amount of training data required, reducing the duty cycle of the remote unit. Hybrid automatic repeat request (HARQ) techniques are also investigated, which increase the throughput of a link when data repeats are required. A novel HARQ techniquewas created and proven to increase throughput in links with noise. As the proposed system may be deployed in remote locations, or locations where it might be difficult or undesirable to erect a proper HF antenna, a selection of buried antennas are characterised. A design for a remote unit is suggested. This unit was manufactured and used to test the capability of inexpensive, low power hardware to implement the proposed remote unit algorithms.

The purpose of this qualitative macromarketing investigation is to explore the issue of the sustainability of marketing systems. Drawing on complex systems thinking, an alternative logic of marketing systems and a methodological basis for interpreting communicated meanings are developed. The alternative logic of marketing systems recognises the unity of a difference between a marketing system and its environment. This insight has become a cornerstone for synthesising the systeming methodology. Systeming comprises the philosophy, the model, and the method of interpreting communication-as-self-observation of marketing system agents. Data, communication by hybrid car manufacturers and consumers, were collected from netnographic sources such as corporate websites, reports posted online, weblogs, and consumer forums. The interpretation of these data was accomplished using systeming procedures, e.g. communication analysis, distinction identification, re-entry description, and logical level tracking. The systeming analysis of the hybrid car marketer and consumer communications illustrates that meaning-creation in the system is underpinned by purposeful human behaviour in reducing complexity of marketplace experience into a meaningful pattern, sustainability. Both manufacturers and consumers claim to become sustainable in reference to being unsustainable by creating self-referential differences, operating in different interaction contexts, and expanding meaning paradoxes. The interpretation shows that interactive meaning-creation in the system is inherently contradictory. Manufacturers expand (give a logical form to) contradictions through introducing hierarchical meaning structures, temporality, new functions, and communicative transvection. Consumers deal with the contradictions through enriching co-creation experiences and learning the proper continuation of specific hybrid car driving practices. The significant insight gained from this investigation is that the hybrid car marketing system is not a passive entity; it is the locus of purposefully expanding meanings. Two modes of sustainability with regard to the hybrid car marketing system can be distinguished: the content of communication that denotes enacted meanings of sustainability and the form of communication that indicates how sustainable these sustainability enactments are. The content/form distinction implies that the sustainability of the hybrid car marketing system is a matter of interactive meaning-creation between system agents. The sustainable development process, in at least a mobility domain, is driven by purposeful social interaction rather than static product attributes. This investigation is innovative because it a) offers a conceptualisation of a marketing system as a meaning flow; b) synthesises and compiles a methodology and method for interpreting communication in a marketing system; c) reveals systemic insights into the hybrid car marketing system; d) characterises the sustainability dimension of the hybrid car marketing system; e) explains a conceptual ground for reconciling the marketing system and society; f) provides a general macromarketing perspective to scrutinise recent conceptual developments in the marketing discipline; g) unifies marketing systems thinking with recent advancements in the marketing discipline, such as the service-dominant logic, and consumer culture theory; and, also, h) provides recommendations for a number of micro-managerial situations from a holistic perspective.

Chaos-based communication piqued interest of several researchers due to the aperiodic and low cross-correlated waveforms used for modulation at the transmitter. Because of their wideband nature, they were first used as spreading sequences in traditional spread-spectrum communication systems. Later, these techniques were followed by coherent and noncoherent schemes. Noncoherent schemes unlike coherent schemes do not require chaos synchronization.

Through the years, many methods have been proposed in this category. However, increasing data rates in these schemes posed a challenge. Therefore, multidimensional signaling schemes were proposed. Orthogonal chaotic vector shift keying is one such multidimensional signaling scheme proposed by Wren and Yang. However, the chaotic system which was used to generate signaling basis in their scheme was the Lorenz system. This system forms a weak signaling basis due to the pseudo-repetitive behavior of its chaotic waveforms. Hence, the bit error rate performance of this communication scheme deteriorates in higher dimensions. In this thesis, we design and implement a hybrid hyperchaotic sequence generator for improving the performance of the orthogonal chaotic vector shift keying for higher dimensions. The analysis in this thesis is performed through computer simulations.

Hybrid Digital/RF Envelope Predistortion Linearization for High Power Amplifiers in Wireless Communication Systems Wangmyong Woo 151 Pages Directed by Dr. J. Stevenson Kenney The objective of this research is to implement a hybrid digital/RF envelope predistortion linearization system for high-power amplifiers used in wireless communication systems. It is well known that RF PAs have AM/AM (amplitude modulation) and AM/PM (phase modulation) nonlinear characteristics. Moreover, the distortion components generated by a PA are not constant, but vary as a function of many input conditions such as amplitude, signal bandwidth, self-heating, aging, etc. Memory effects in response to past inputs cause a hysteresis in the nonlinear transfer characteristics of a PA. This hysteresis, in turn, creates uncertainty in predictive linearization techniques. To cope with these nonlinear characteristics, distortion variability, and uncertainty in linearization, an adaptive digital predistortion technique, a hybrid digital/RF envelope predistortion technique, an analog-based RF envelope predistortion technique, and a combinational digital/analog predistortion technique have been developed. A digital adaptation technique based on the error vector minimization of received PA output waveforms was developed. Also, an adaptive baseband-to-baseband test system for the characterization of RF PAs and for the validation of linearization algorithms was implemented in conjunction with the adaptation technique. To overcome disadvantages such as limited correction bandwidth and the need for a baseband input signal in digital predistortion, an adaptive, wideband RF envelope predistortion system was developed that incorporates a memoryless predistortion algorithm. This system is digitally controlled by a look-up table (LUT). Compared with conventional baseband digital approaches, this predistortion architecture has a correction bandwidth that is from 20 percent to 33 percent wider at the same clock speeds for third to fifth order IMDs and does not need a digital baseband input signal. For more accurate predistortion linearization for PAs with memory effects, an RF envelope predistortion system has been developed that uses a combination of analog-based envelope predistortion (APD) working in conjunction with digital LUT-based adaptive envelope predistortion (DPD). The resulting combination considerably decreases the computational complexity of the digital system and significantly improves linearity and efficiency at high power levels.

Le LPWAN, ou Low Power Wide Area Network, est un type de réseau de communication sans fil à faible débit, de large couverture avec une consommation minimale d’énergie. La variante LoRaWAN, Long Range Wide Area Network permet de connecter un grand nombre d'appareils sur de vastes zones. Cependant, ces réseaux présentent des limites en termes de qualité de service (QoS). Ce travail propose des solutions d'optimisation susceptibles de permettre à ce réseau de répondre aux exigences de la connectivité des villes intelligentes. Nos recherches ont permis de détecter l’impact du facteur charge utile (Payload) sur les indicateurs clés de la QoS. Le facteur History Range (HR) lié au mécanisme d’auto-adaptation de débits de données (ADR), servant de base de changement dynamique du Data Rate (DR) du mécanisme ADR a également été étudié. Grâce à l’ajustement de ce paramètre, les simulations conduites sur NS3 ont permis d’obtenir un taux de PDR allant jusqu’à 88% par rapport au mécanisme ADR natif et ont réduit les pertes liées aux interférences de 20%. Partant des analyses citées, nous proposons le mécanisme d’optimisation LLNRM qui présente des résultats meilleurs que les autres approches d'optimisation de référence, avec une amélioration allant jusqu'à 40 % du PDR avec deux passerelles et de plus de 25 % avec cinq passerelles. Ces résultats mettent également en évidence la capacité de LLNRM à améliorer les performances du réseau dans des scénarios de type urbain.Sur le plan général, les contributions issues de cette thèse permettraient à LoRaWAN de répondre aux besoins des villes intelligentes, ce qui est un gage de l’atteinte des Objectifs de Développement Durable (ODD9)
LPWAN, or Low Power Wide Area Network, is a type of low-speed wireless communication network with wide coverage and minimal power consumption. The LoRaWAN variant, Long Range Wide Area Network, allows a large number of devices to be connected over large areas. However, these networks have limitations in terms of quality of service (QoS). This work proposes optimization solutions that could enable this network to meet the connectivity requirements of smart cities. Our research has detected the impact of payload factor on key QoS metrics. The History Range (HR) factor related to the data rate self-adaptation (ADR) mechanism, serving as a basis for dynamic change in the Data Rate (DR) of the ADR mechanism, was also studied. Thanks to the adjustment of this parameter, the simulations conducted on NS3 allowed to obtain a PDR rate of up to 88% compared to the native ADR mechanism and reduced the interference losses by 20%. Based on the above analyses, we propose the LLNRM optimization mechanism which presents better results than other reference optimization approaches, with an improvement of up to 40% of the PDR with two gateways and more than 25% with five gateways. These results also highlight LLNRM's ability to improve network performance in urban scenarios. In general, the contributions resulting from this thesis would allow LoRaWAN to meet the needs of smart cities, which is a guarantee of the achievement of the Sustainable Development Goals (SDG9)

Mestrado em Engenharia Eletrónica e Telecomunicações
Wireless communications are continuously evolving, and the demand for higher data rates, more capacity, a better quality of service and more coverage is rising. The next generation, 5G, is currently being developed and it is expected to be delivered by 2020. However, in order to fulfill the 5G requirements, such as a consistent user experience, peak bit rates of 10 to 50 Gbps, higher reliability and availability, changes in the cellular architecture are needed, using new technology. Millimeter waves are a promising carrier frequency for 5G cellular systems, due to their underutilized large bandwidth that can potentially provide high data rates for future wireless networks. Single-carrier frequency-division multiple access (SC-FDMA), a modified form of orthogonal frequency-division multiple access (OFDMA), is a promising solution technique for high data rate uplink communications in future cellular systems. When compared with OFDMA, SC-FDMA has similar throughput and essentially the same overall complexity. A principal advantage of SC-FDMA is the peak-to-average power ratio (PAPR), which is lower than that of OFDMA, being less sensitive to nonlinear distortion caused by the power amplifier (PA). It is well known that an efficient PA is critical for future millimeter wave based wireless systems. Conjugating mmWaves with massive MIMO will allow packing a higher number of antennas into the same volume, since mmWaves have a smaller wavelength than the currently used cellular systems. Consequently, millimeter wave communications and massive MIMO have been considered as two of the key enabling technologies needed to provide multi-Gbps for future wireless communications. In this Dissertation a hybrid analog-digital multi-user linear equalizer for broadband mmWave massive MIMO SC-FDMA systems is designed and evaluated. The digital part is computed on a per subcarrier basis and the analog part is constant over all subcarriers. The simulation results show that the proposed hybrid equalizer achieves an average BER close to the full-digital equalizer (gap of ∼ 1 dB), when the number of RF chains is twice the number of users. When the number of RF chains is smaller than twice the number of users, a compromise between complexity and performance is achieved.
As comunicações sem fio estão em constante evolução, e a necessidade por elevadas taxas de transmissão de dados, mais capacidade, melhor qualidade de serviço e mais cobertura, está a aumentar. A próxima geração, 5G, está neste momento a ser desenvolvida e espera-se que seja implementada em 2020. No entanto, de forma a cumprir os requisitos do 5G, tais como proporcionar uma melhoria na experiência do utilizador, taxas de transmissão máximas de 10 a 50 Gbps, maior fiabilidade e cobertura, são necessárias mudanças na arquitetura celular, utilizando para tal novas tecnologias. As ondas milimétricas constituem uma frequência portadora promissora para os sistemas celulares 5G, devido à sua grande largura de banda disponível, que potencialmente pode fornecer taxas de transmissão elevadas para os futuros sistemas sem fios. Single-carrier frequency-division multiple access (SC-FDMA), um método modificado de orthogonal frequency-division multiple access (OFDMA), é uma técnica promissora que poderá ser uma solução para comunicações com elevadas taxas de transmissão no sentido ascendente nos sistemas celulares futuros. Quando comparado com OFDMA, SC-FDMA possui um rendimento semelhante e apresenta essencialmente a mesma complexidade. A principal vantagem de SC-FDMA é o peak-to-average power ratio (PAPR), que é menor que no OFDMA, sendo menos sensível às distorções não-lineares causadas pelo amplificador de potência (AP). Sabe-se que a eficiência do AP é um problema crítico para os futuros sistemas sem fio baseados em ondas milimétricas. Conjugando ondas milimétricas com massive MIMO permitirá colocar um maior número de antenas no mesmo volume, uma vez que as ondas milimétricas têm um comprimento de onda menor do que os sistemas celulares usados atualmente. Consequentemente, as comunicações que usam ondas milimétricas e massive MIMO são consideradas duas das principais tecnologias que oferecem as condições necessárias para fornecer multi-Gbps para os futuros sistemas de comunicação. Nesta dissertação é projetado e avaliado um equalizador linear híbrido analógico-digital multi-user para sistemas massive MIMO SC-FDMA de banda larga usando ondas milimétricas. Assume-se que a parte analógica é constante para todas as subportadoras, enquanto que a parte digital é calculada por cada subportadora. Os resultados mostram que a arquitetura proposta atinge uma taxa média de erro próxima do equalizador digital (separação de ∼ 1 dB), quando o número de cadeias RF é o dobro que o número de utilizadores. Se o mesmo for inferior que o dobro dos utilizadores, um compromisso entre complexidade e desempenho é alcançado.

Thesis (M.S.)--West Virginia University, 2001.
Title from document title page. Document formatted into pages; contains xi, 113 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 110-112).

The Internet of Things (IoT) has the vision to interconnect everything of the physical world and the virtual world. Advanced automated and adaptive connectivity of objects, systems, and services is expected to be achieved under the IoT context, especially in the industrial environment. Industry 4.0 with the goal of intelligent and self-adaptable manufacturing is driven by the IoT. The Object Layer, where real-time and reliable information acquisition from the physical objects carried out, is the basic enabler in the 3-layer industrial IoT system. Such acquisition system features deterministic access, reliable communication with failure resistance mechanism, latency-aware real-time response, deployable structure/protocol, and adaptive performance on various QoS demands. This thesis proposes a reliable RFID communication system for acquisition in the industrial environment. A discrete gateway structure and a contention-free communication protocol are designed to fulfill the unique system requirements. Such gateway structure offers a flexible configuration of readers and RF technologies. It enables a full duplex communication between the objects and the gateway. The designed MF-TDMA protocol can enhance the failure resistance and emergency report mechanism thanks to the separation of control link and data link in the gateway. Specifically, an optional ARQ mechanism, an independent/uniform synchronization and control method, and a slot allocation optimization algorithm are designed besides time-division and frequency-division multiplexing. Protocol implementations for different industrial situations illustrate the system ability for supporting the demands of various QoS. Finally, a 2.4-GHz/UWB hybrid positioning platform is explored based on the introduced RFID system. Taking advantage of the UWB technology, the positioning platform can achieve positioning accuracy from meter level to centimeter level. Hybrid tag prototype and specific communication process based on the MF-TDMA protocol are designed. An SDR UWB reader network, capable of evaluating multiple algorithms, is built to realize accurate positioning with an improved algorithm proposed.

QC 20161109

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.

Native Multicast plays an important role in distributing and managing delivery of some of the most popular Internet applications, such as IPTV and media delivery. However, due to patchy support and the existence of multiple approaches for Native Multicast, the support for Native Multicast is fragmented into isolated areas termed Multicast Islands. This renders Native Multicast unfit to be used as an Internet wide application. Instead, Application Layer Multicast, which does not have such network requirements but is more expensive in terms of bandwidth and overhead, can be used to connect the native multicast islands. This thesis proposes Opportunistic Native Multicast (ONM) which employs Application LayerMulticast (ALM), on top of a DHT-based P2P overlay network, and Automatic Multicast Tunnelling (AMT) to connect these islands. ALM will be used for discovery and initiating the AMT tunnels. The tunnels will encapsulate the traffic going between islands' Primary Nodes (PNs). AMT was used for its added benefits such as security and being better at traffic shaping and Quality Of Service (QoS). While different approaches for connecting multicast islands exists, the system proposed in the thesis was designed with the following characteristics in mind: scalability, availability, interoperability, self-adaptation and efficiency. Importantly, by utilising AMT tunnels, this approach has unique properties that improve network security and management.

Vehicular Ad-hoc Network (VANET) is considered to be a viable technology for inter- vehicle communications for the purpose of improving road safety and efficiency. The En- hanced Distribution Channel Access (EDCA) mechanism and multichannel operations are introduced to ensure the Quality of Service (QoS). Therefore, it is necessary to create an accurate vehicular network simulator that guarantees the vehicular communications will work as described in the protocols. A comprehensive vehicular network simulator should consider the interaction between mobility models and network protocols. In this dissertation, a novel vehicular network simulation environment, VANET Toolbox, designed using discrete-event system (DES) is presented. The APP layer DES Module of the proposed simulator integrates vehicular mo- bility operations with message generation functions. The MAC layer DES module supports single channel and multichannel EDCA operations. The PHY layer DES module supports bit-level processing. Compared with packet-based simulator such as NS-3, the proposed PHY layer is more realistic and accurate. The EDCA scheme is evaluated and compared with the traditional Carrier-Sensing Mul- tiple Access (CSMA) scheme, with the simulations proving that data with different priorities can coexist in the same channel. The multichannel operation for the EDCA scheme is also analyzed in this dissertation. The multichannel switching operation and coordination may cause packet dropping or increased latency to the communication. The simulations show that with heavy network traffic, multichannel communication performs better than single channel communication. From the perspective of safety-related messages, the multichannel operation is able to isolate the interference from the non-safety messages in order to achieve a better packet delivery rate and latency. On the other hand, the non-safety messages can achieve high throughput with reasonable latency from multichannel communication under heavy load traffic scenario.

This thesis is about the researching for 5th generation (5G) communication system, which focus on the improvement of 3D beamforming technology in the antenna array using in the Full Dimension Multiple-Input Multiple-Output (FD-MIMO) system and Millimeter-wave (mm-wave) system. When the 3D beamforming technology has been used in 5G communication system, the beam needs a weighting matrix to direct the beam to cover the UEs, but some compromises should be considered. If the narrow beams are used to transmit signals, then more energy is focused in the desired direction, but this has a restricted coverage area to a single or few User Equipments (UEs). If the BS covers multiple UEs, then multiple beams need to be steered towards more groups of UEs, but there is more interference between these beams from their side lobes when they are transmitted at same time. These challenges are waiting to be solved, which are about interference between each beam when the 3D beamforming technology is used. Therefore, there needs to be one method to decrease the generated interference between each beam through directing the side lobe beams and nulls to minimize interference in the 3D beamforming system. Simultaneously, energy needs to be directed towards the desired direction. If it has been decided that one beam should covera cluster of UEs, then there will be a range of received Signal to Interference plus Noise Ratio (SINR) depending on the location of the UEs relative to the direction of the main beam. If the beam is directed towards a group of UEs then there needs be a clustering method to cluster the UEs. In order to cover multiple UEs, an improved K-means clustering algorithm is used to cluster the multiple UEs into different groups, which is based on the cosine distance. Itcan decrease the number of beams when multiple UEs need be covered by multiple beams at same time. Moreover, a new method has been developed to calculate the weighting matrix for beamforming. It can adjust the values of weighting matrix according to the UEs' location and direct the main beam in a desired direction whilst minimizing its side lobes in other undesired directions. Then the minimum side lobe beamforming system only needs to know the UEs' location and can be used to estimate the Channel State Information (CSI) of UEs. Therefore, the scheme also shows lower complexity when compared to the beamforming methods with pre-coding. In order to test the improved K-means clustering algorithm and the new weighting method that can enhance the performance for 3D beamforming system, the two simulation systems are simulated to show the results such as 3D beamforming LTE system and mm-wave system.

Dans cette thèse, nous nous adressons le problème du contrôle de systèmes multi-agents connectés via des modèles réalistes de systèmes de communication. Nous traitons principalement les systèmes de véhicules connectés et automatisés (CAVs) communiquant via des systèmes de communication 5G qui permettent deux types de communication : la communication directe entre les nœuds, connue sous le nom de communication véhicule-à-véhicule (V2V), et la communication à travers l'infrastructure réseau, qui est la manière traditionnelle de communiquer dans les réseaux cellulaires.La thèse traite de trois problèmes : premièrement, nous analysons les propriétés de stabilité et de convergence de l'algorithme du consensus pour agents d'intégrateurs du premier ordre en utilisant un schéma d'accès multiple par répartition temporelle (TDMA) pour partager les ressources du réseau d'un canal de communication partagé. La stabilité exponentielle du système considéré est démontrée, et une borne explicite dépendant des paramètres du système de communication est fournie pour estimer la vitesse de convergence. Ensuite, nous abordons le problème du contrôle de formation d'un groupe de véhicules connectés dans un contexte de communication 5G. Nous proposons un algorithme d'allocation de ressources pour sélectionner les utilisateurs émetteurs afin d'atteindre la formation souhaitée tout en respectant les contraintes imposées par le couche de communication. Enfin, nous étudions les propriétés de stabilité des filtres de Kalman pour les systèmes hybrides, précisément, des systèmes avec une dynamique en temps continu observée à travers des mesures en temps discret. La stabilité d'entrée-à-état (ISS) est démontrée pour de tels systèmes en utilisant une fonction de Lyapunov appropriée. Ce résultat peut être considéré comme une première étape dans l'analyse de la robustesse du système global, car il permet de prendre en compte les effets des erreurs de communication sur la stabilité du système contrôlé
In this thesis, we address the problem of control of multi-agent systems connected over realistic models of communication systems. We mainly focus on systems of connected and automated vehicles (CAVs) that communicate through a 5G communication system, which allows two types of communication: direct communication between nodes, known as Vehicle-to-Vehicle (V2V) communications, and communication through the network infrastructure, which is the traditional way of communication in cellular networks.The thesis discusses three problems: first, we analyze the stability and convergence properties of the consensus algorithm of first-order integrator agents using a time-division multiple access (TDMA) scheme to share the network resources of a broadcast shared communication channel. Exponential stability of the considered system is proved, and an explicit bound depending on the communication system parameters is provided to estimate the convergence rate. Second, we treat the problem of formation control of a float of connected vehicles in a 5G communication context. We propose a resource allocation algorithm to select the transmitting users to achieve the desired formation while satisfying the constraints imposed by the communication system. Finally, we study the stability properties of Kalman filters for hybrid systems, i.e., systems with continuous-time dynamics observed through discrete-time measurements. Input-to-state stability (ISS) is proved for such systems relying on an appropriate Lyapunov function. This result can be considered as a first step in the robustness analysis of the overall system since it allows to treat the effects of communication errors on the controlled system stability

The main topic of this thesis is integer quadratic programming with applications to problems arising in the areas of automatic control and communication. One of the most widespread modern control methods is Model Predictive Control (MPC). In each sampling time, MPC requires the solution of a Quadratic Programming (QP) problem. To be able to use MPC for large systems, and at high sampling rates, optimization routines tailored for MPC are used. In recent years, the range of application of MPC has been extended to so-called hybrid systems. Hybrid systems are systems where continuous dynamics interact with logic. When this extension is made, binary variables are introduced in the problem. As a consequence, the QP problem has to be replaced by a far more challenging Mixed Integer Quadratic Programming (MIQP) problem, which is known to have a computational complexity which grows exponentially in the number of binary optimization variables. In modern communication systems, multiple users share a so-called multi-access channel. To estimate the information originally sent, a maximum likelihood problem involving binary variables can be solved. The process of simultaneously estimating the information sent by multiple users is called Multiuser Detection (MUD). In this thesis, the problem to efficiently solve MIQP problems originating from MPC and MUD is addressed. Four different algorithms are presented. First, a polynomial complexity preprocessing algorithm for binary quadratic programming problems is presented. By using the algorithm, some, or all, binary variables can be computed efficiently already in the preprocessing phase. In numerical experiments, the algorithm is applied to unconstrained MPC problems with a mixture of real valued and binary valued control signals, and the result shows that the performance gain can be significant compared to solving the problem using branch and bound. The preprocessing algorithm has also been applied to the MUD problem, where simulations have shown that the bit error rate can be significantly reduced compared to using common suboptimal algorithms. Second, an MIQP algorithm tailored for MPC is presented. The algorithm uses a branch and bound method where the relaxed node problems are solved by a dual active set QP algorithm. In this QP algorithm, the KKT systems are solved using Riccati recursions in order to decrease the computational complexity. Simulation results show that both the proposed QP solver and MIQP solver have lower computational complexity compared to corresponding generic solvers. Third, the dual active set QP algorithm is enhanced using ideas from gradient projection methods. The performance of this enhanced algorithm is shown to be comparable with the existing commercial state-of-the-art QP solver \cplex for some random linear MPC problems. Fourth, an algorithm for efficient computation of the search directions in an SDP solver for a proposed alternative SDP relaxation applicable to MPC problems with binary control signals is presented. The SDP relaxation considered has the potential to give a tighter lower bound on the optimal objective function value compared to the QP relaxation that is traditionally used in branch and bound for these problems, and its computational performance is better than the ordinary SDP relaxation for the problem. Furthermore, the tightness of the different relaxations is investigated both theoretically and in numerical experiments.
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This research devises a unified method for the distribution of pseudonyms in hybrid ephemeral vehicular networks (VNs), which are often referred to as vehicular ad hoc networks (VANETs), for the purposes of refill, intra-regional, and inter-regional movement. This work addresses a significant impediment to the use of pseudonyms, which has been almost universally accepted (and is on the verge of being standardized by the Institute for Electrical and Electronic Engineers (IEEE) and the Society for Automotive Engineers (SAE) as the best means to balance attribution and privacy to maximize the value of infrastructure deployment and citizen acceptability (i.e. use). The results include a pseudonym distribution protocol that maximizes ease of use while not compromising the security or privacy pseudonyms afford. These results contribute to the solution, in a scalable, adaptive, and bandwidth efficient manner, one of the remaining impediments to the adoption of VANETs. The new method shows improved performance compared to a baseline pseudonym distribution method that does not take these factors into consideration.

Structured Light Illumination is a widely used 3D shape measurement technique in non-contact surface scanning. Multi-pattern based Structured Light Illumination methods reconstruct 3-D surface with high accuracy, but are sensitive to object motion during the pattern projection and the speed of scanning process is relatively long. To reduce this sensitivity, single pattern techniques are developed to achieve a high speed scanning process, such as Composite Pattern (CP) and Modified Composite Pattern (MCP) technique. However, most of single patter techniques have a significant banding artifact and sacrifice the accuracy. We focus on developing SLI techniques can achieve both high speed, high accuracy and have the tolerance to the relative motion. We first present a novel Two-Pattern Full Lateral Resolution (2PFLR) SLI method utilizing an MCP pattern for non-ambiguous phase followed by a single sinusoidal pattern for high accuracy. The surface phase modulates the single sinusoidal pattern which is demodulated using a Quadrature demodulation technique and then unwrapped by the MCP phase result. A single sinusoidal pattern reconstruction inherently has banding error. To effective de-band the surface, we propose Projector Space De-banding algorithm (PSDb). We use projector space because the band error is aligned with the projector coordinates allowing more accurate estimation of the banding error. 2PFLR system only allows the relative motion within the FOV of the scanner, to extend the application of the SLI, we present the research on Relative Motion 3-D scanner which utilize a single pattern technique. The pattern in RM3D system is designed based on MCP but has white space area to capture the surface texture, and a constellation correlation filter method is used to estimate the scanner's trajectory and then align the 3-D surface reconstructed by each frame to a point cloud of the whole object surface.

A major consideration for mobile WiMAX is seamless handoff. The British English term for transferring a cellular call is handover whereas the Americans prefer to call it handoff. Cellular-based standards have the advantage of many years experience in handover for voice calls, while for broadband mobility in itself is no mean feat, and handover is still a challenge. Mobile IP, with "slow" handover, will be fine for web-browsing but not good enough for decent voice quality. Many services require the appearance of seamless connections (VoIP, VPNs, etc). Much of the complexity (and latency) in the cellular network is from maintaining these connections across cell boundaries. Handovers in wireless technologies have always been a challenging topic of discussion. According to the mobility framework of IEEE 802.16e, a Mobile Station (MSS) should scan the neighbouring Base Stations (BSs) for selecting the best BS for a potential handover. However, the standard does not specify the number of BSs to be scanned leaving room for unnecessary scanning. Moreover, prolonged scanning also interrupts data transmissions thus degrading the QoS of an ongoing connection. Reducing unnecessary scanning is an important issue. This thesis proposes a scheme to reduce the number of BSs to scan, thus improving the overall handover performance. Simulation results show that the proposed hybrid predictive BS selection scheme for potential scanning activities is more effective than the conventional IEEE 802.16e handover scheme in terms of handover delay and resource wastage. Before the actual handover process, there is scope of reducing the total number of iterations of message exchanges occurring between the mobile MSS, the SBS and the neighbouring BSs which are potential targets for handover. Simulations prove that it takes upto 700 ms to decide the target BS before initiating the handover process with it. There are multiple message exchanges to choose a set of potential target BSs from all the neighbouring BSs. A few more messages flow between the MSS, SBS and potential target BSs to choose the best candidate BS for handover. The many stages and messages waste time and could be reduced. This thesis discusses some ways to reduce them and backs it up with simulation results.

Opinion leaders are important political players who bridge the gap between the political elite and the general public. Traditionally opinion leaders use social pressure and social support via interpersonal communication to personally influence the opinions, attitudes and behaviours of their everyday associates (who make up the general public). However, in a hybrid media system opinion leaders have access to added channels which mean they can communicate with audiences beyond their everyday associates and/or engage in non-interpersonal interactions, potentially setting the stage for opinion leaders to become more influential since they can access more members of the general public. Conversely, since the ability of opinion leaders to influence others traditionally relies on strong social bonds, even if audiences are accessible for information transfer, the lack of social connection could mean influence does not flow. As such, opinion leaders' channel choice in a hybrid media system is potentially very important. To investigate the patterns of channel use as well as motivations for, and impacts of, channel choices by opinion leaders, a two phase mixed-methods study is employed. Phase one includes online social network analysis of the #CDNpoli (Canadian politics) hashtag on Twitter and an online survey. Phase two investigates the communication practices of 21 specific digitally enabled opinion leaders drawn from the #CDNpoli network. Two hour in-depth interviews are paired with visualizations of the participants trace data. Telephone interviews with associates (alters) of the primary interviewee were conducted (N=27). This design is therefore responsive to the multi-channel reality of a hybrid media system and improves upon large scale and single channel studies which are most common in this line of research. Now strategic and, at times, impersonal, a fundamental shift in how influence is derived challenges theories of social influence and information dissemination. Two types of strategic opinion leaders emerge: enthusiasts and champions. Their strategies contribute to a wider trend - a "just-in-time" informed citizenry - where those who do not opt in to receiving messages from the political elite only get information at the last possible minute, such as during a scandal or an election. Future research and communication strategy must be sensitive to the varied aims and tactics of digitally enabled opinion leaders as well as the subsequent inconsistent relationship between the uninformed and their political system.

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Esta dissertação tem como objetivo discutir as comunicações cooperativas híbrida e não híbrida aplicadas a sistemas de comunicação de dados em banda larga e em ambientes residenciais. Nesse sentido, o modelo de canal com retransmissor único em dois estágios é investigado para sistemas de comunicação em banda larga através da rede de energia elétrica. Este modelo de canal cooperativo é formado pela concatenação de dois canais com retransmissor único, cobrindo enlaces de comunicação de dados com até dois saltos. Além disso, um modelo de canal híbrido com retransmissor único, utilizando rede elétrica e ar, é analisado para sistemas de comunicação de dados em banda larga em que enlaces de até um salto são considerados. Expressões de taxas de dados alcançáveis ergódicas são derivadas para os modelos de canais cooperativos híbridos e não híbridos, a fim de compará-los. Devido às características de canais e ruído das redes de energia elétrica, os resultados numéricos são baseados em um conjunto de dados constituído por estimativas de canais e medições de ruído cobrindo a faixa de frequência de 1, 7 a 100 MHz e diferentes posições do nó retransmissor. Para os canais sem fio, o modelo HIPERLAN/2 com a mesma largura de banda é utilizado, considerando uma freqüência central de 5 GHz, enquanto o ruído aditivo é considerado branco gaussiano. Com relação aos sistemas de comunicação através da rede energia elétrica, mostra-se que o modelo de canal com retransmissor único em dois estágios é a melhor opção quando o enlace da fonte ao destino encontra-se severamente degradado (por exemplo, alta atenuação de sinal devido à longa distância entre nós fonte e destino e/ou presença de ruído de alta potência). Quando a degradação do canal não é acentuada, o modelo de canal de dois saltos é mais apropriado. Acerca dos sistemas híbridos, constata-se que, quando o retransmissor está no meio do caminho entre fonte e destino, o modelo de canal híbrido com retransmissor único apresenta o melhor desempenho em termos de taxa de dados alcançável ergódica, enquanto o modelo de canal híbrido de um salto oferece os melhores resultados para outros casos.
This dissertation aims to discuss hybrid and non-hybrid cooperative communications applied to in-home broadband data communication systems. In this sense, the two-stage single-relay channel model is investigated for in-home broadband power line communication systems. This cooperative channel model consists of the concatenation of two single-relay channels, covering data communication links with up to two hops. Moreover, a hybrid power line/wireless single-relay channel model is analyzed for broadband data communication systems, considering one-hop links. Ergodic achievable data rate expressions are derived for both hybrid and non-hybrid cooperative channel models in order to compare them. Due to channel and noise characteristics of electric power grids, numerical results are based on a data set constituted by power line channel estimates and additive noise measurements covering the frequency band from 1.7 up to 100 MHz and different relay positions. For wireless channels, the HIPERLAN/2 model with the same bandwidth is used, but at a central frequency of 5 GHz, while the additive noise is considered to be Gaussian white. Regarding only power line communication systems, it is shown that the two-stage single-relay channel model is the best option when the source-to-destination link is severely degraded (e.g., high signal attenuation due to the long distance between source and destination nodes and/or high-power noise presence). When the channel degradation is not severe, the two-hop channel model is more appropriate. Concerning hybrid systems, it is observed that, when the relay is halfway between source and destination nodes, the hybrid single-relay channel model presents the best performance in terms of ergodic achievable data rate, while the hybrid one-hop channel model yields the best results for other cases.

A body of research has established the political relevance of Social Media (SM) platforms for populist parties, claiming that populist politicians utilize a ‘bypassing-strategy’. However, the rather reluctant employment of Facebook and Twitter by German citizens other than, for example, media professionals and politicians, raises questions of the utilization intention for public actors. Even though multiple scholars already indicated the necessity of research on the ‘embeddedness of digital tools’ in journalists’ routines (Jungherr, 2016: 374) such studies remain scarce. Therefore this study aims to shed light on how power is exercised by political actors through the use of SM within Chadwick’s (2017) hybrid media system. In order to do so it firstly examines the existence of references to the Twitter and Facebook pages of politicians of the German right-wing populist party AfD within the coverage of four German newspapers about the party during the final phase of the 2017 General Federal Election campaign. Secondly, by employing issue competition theory, issues and topics that three AfD politicians communicated about on their SM pages are compared with those that the party has been covered in relation to in newspaper articles. The findings of the quantitative content analysis on the newspaper articles showed only few cases in which AfD politicians’ SM statements were quoted. In regard to issue competition theory, the quantitative mapping of issues and topics in newspaper coverage about the AfD as well its politicians’ SM statements however, demonstrate prevailing similarities between the issues and topics that dominated the newspaper coverage about the party as well as its politicians SM pages. A thematic analysis on the latter found three themes that suggest a possible explanation for the few cases in which newspaper articles referenced SM statements: All three politicians used SM differently to promote, circulate and comment on issues and topics which influenced whether statements originated from the platform or from other contexts, such as rally events, tv debates, media article etc. These different types of content distributed and published on the politicians’ SM pages could be a possible explanation for the limited instances in which SM statements were quoted by newspaper articles. These findings suggest that the AfD did indeed pursued a bypassing strategy and employed SM platforms to directly communicate with its supporters. However, future studies should continue research on the embeddedness of SM statements in contexts other than campaigning times. Furthermore insights from qualitative interviews with politicians about their utilization strategies and journalists regarding their possible hesitance to quote politicians’ SM Statements, that may be grounded in professional standards, are necessary in order to obtain a more complete assessment of the role of SM for political actors in navigating the hybrid media system.

P4 is a high-level language for programming the data plane of a network switch. These P4-programmable switches come with no pre-defined behavior or protocols, so it is entirely up to the loaded P4 program to define these. This allows the user to exclude any unwanted functionality and to create custom protocols. It also removes the dependence on the switch vendor in terms of both trust and addition of new features. This thesis looks at migration from traditional switches to P4-programmable ones. Since no behavior is included out-of-the-box in the P4 switches, a search is made for open-source P4 projects and the functionality they provide is evaluated. It is found that most link layer functionality can be achieved with them, with the exception being loop prevention by spanning tree protocols. Therefore, one of the projects is extended with an implementation of the Rapid Spanning Tree Protocol based on the IEEE 802.1D-2004 standard. Finally, partial migration of networks to P4 switches and to the Software Defined Networking (SDN) paradigm is studied based on a literature review. Four general approaches and specific architectures for these are found, and it is concluded that such a hybrid network can still benefit from P4 and having a centralized SDN controller.

[EN] The present PhD thesis, which is entitled "Design of new bio-gated nanodevices for advanced communication processes and targeted controlled release of therapeutic agents" is focused on the development of new functional hybrid organic-inorganic materials for applications in the field of the controlled delivery of target molecules. The first chapter of the present thesis gives an introduction to the organic-inorganic hybrid materials functionalized with "molecular gates" and its application in controlled release processes. The second chapter of this thesis is focused on the development of a new nanodevice able to deliver its cargo as a function of the glucose concentration. The nanodevice is based on mesoporous silica nanoparticles loaded with a suitable fluorophore and functionalized with propylbenzymidazole moieties on the pore outlets. The mesopores are then capped with an active cyclodextrin modified glucose oxidase enzyme (through the formation of an inclusion complex between the cyclodextrins and the propylbenzymidazole group anchored to the solid support). When glucose is added its enzymatic oxidation produced gluconic acid. This acid induced a decrease in the pH of the medium and the protonation of the benzymidazole group that might result in the inclusion complex dethreading and the subsequent cargo release. The third chapter of the thesis is focused on the development of a new redox-responsive material for the controlled delivery of cytotoxic drugs in cancer cells. The system is based on mesoporous silica nanoparticles loaded with a reporter (safranin O) and functionalized with two different sized polyethylene glycol chains in the pore outlets using a disulfide linkage. In presence of glutathione, the disulfide bonds are cleaved allowing the release of the entrapped cargo. Once confirmed the aperture protocol, the uptake of the gated nanoparticles and their ability to deliver the cargo (fluorophore or cytotoxic agent) in HeLa cells were tested. Moreover, cell viability assays were also performed. The fourth chapter of the thesis is focused on the preparation and the study of a nanodevice for the controlled delivery in senescent cells in a murine model of pulmonary fibrosis. The material is prepared using mesoporous silica nanoparticles (as an inorganic support) and galactoligosaccharide (molecular gate) moieties anchored on the external surface. In presence of senescent cells, which overexpress ß-galactosidase enzyme, the hydrolysis of the galactooligosaccharide capping molecules take place and the cargo release from the inner of the pores is produced (rhodamine B). After the in vitro studies, the ability of nanoparticles to accumulate and release their payload in tissues with abundance of senescent cells was evaluated in vivo. For that purpose, mice with induced pulmonary fibrosis, pathogenesis with associated increased alveolar senescence, were treated with the synthesized material and subsequently examined to assess its ability to accumulate and release its payload (fluorophore) in lung's damaged areas. In the fifth chapter of the thesis it has been explored the concept of cascade chemical communication using different types of nanodevices, each of them loaded with a certain messenger and externally functionalized with a gate-like entity that controls the release of the payload. When the enzyme able to hydrolyze the molecular gate that blocks the pores of the first type of nanoparticles (S1), is added to an aqueous suspension containing the three nanoparticles, the delivery of the chemical messenger 1 is produced. This messenger is able to open the second type of nanoparticles (S2) which delivers the messenger 2. Finally, the messenger 2 triggers the aperture of the third group of gated system (S3), which ultimately delivers its load (a dye) as a final response.
[ES] La presente tesis doctoral titulada "Diseño de nuevos nanodispositivos para procesos avanzados de comunicación y liberación controlada y dirigida de agentes terapéuticos" está centrada en el desarrollo de nuevos materiales híbridos orgánico-inorgánicos funcionales para aplicaciones en el campo de la liberación controlada de moléculas de interés. El primer capítulo de la tesis ofrece una introducción a los materiales híbridos orgánico-inorgánicos funcionalizados con "puertas moleculares" y su aplicación en procesos de liberación controlada. En el segundo capítulo de la tesis se aborda el desarrollo de un nanodispositivo capaz de responder y liberar su carga en función de la concentración de glucosa. Este nanodispositivo está basado en nanoparticulas de sílice mesoporosa funcionalizadas en su superficie externa con grupos benzimidazol y con los poros cargados con un fluoróforo. Los poros se cierran al añadir la enzima glucosa oxidasa funcionalizada con ciclodextrinas (por formación de un complejo de inclusión entre el benzimidazol y los oligosacáridos cíclicos). Al adicionar glucosa se produce su oxidación enzimática dando ácido glucónico. Este ácido induce una bajada del pH del medio con la consiguiente protonación de los benzimidazoles y la ruptura de los complejos de inclusión. Esta ruptura provoca la salida de la enzima de la superficie y la liberación del colorante atrapado en los poros. El tercer capítulo de la tesis se ha centrado en el desarrollo de un material para la liberación controlada de agentes citotóxicos en células cancerosas en respuesta a cambios en el potencial redox. De nuevo se emplean nanopartículas de sílice mesoporosa con los poros cargados con un colorante (safranina O) y la superficie externa funcionalizada con dos polietilenglicoles conteniendo enlaces disulfuro. En presencia de glutatión se produce la reducción del enlace disulfuro con la consiguiente liberación del colorante. Una vez confirmado el protocolo de apertura, se estudió la internalización y la liberación de un fluoróforo y de un agente citotóxico en el modelo celular HeLa, realizando además ensayos de viabilidad. En el cuarto capítulo de la tesis se ha preparado y ensayado un nanodispositivo para la liberación controlada en células senescentes en un modelo murino de fibrosis pulmonar. El material se prepara empleando nanopartículas de sílice mesoporosa y un galactooligosacárido anclado en la superficie externa. En presencia de células senescentes, que sobreexpresan la enzima ¿-galactosidasa, se produce la hidrólisis del oligosacárido con la consiguiente liberación de la carga atrapada en los poros del soporte (rodamina B). Tras los estudios in vitro, la capacidad del nanodispositivo de acumularse y liberar su carga en tejidos ricos en células senescentes se evaluó in vivo. Para ello, ratones con fibrosis pulmonar inducida, patología en la que se ha descrito la aparición de senescencia, se trataron con el material sintetizado y posteriormente fueron examinados para comprobar la capacidad de acumularse y liberar su carga (fluoróforo) en la zona pulmonar dañada. En el quinto capítulo se ha explorado el proceso de comunicación química en cascada empleando tres tipos de nanopartículas mesoporosas de sílice cargadas con diferentes mensajeros y funcionalizadas con tres puertas moleculares distintas. Cuando sobre una suspensión de las tres nanopartículas se añade la enzima capaz de hidrolizar la puerta molecular que bloquea los poros del primer tipo de nanopartículas (S1), se produce la liberación del mensajero 1. Este mensajero es capaz de inducir la apertura del segundo tipo de nanopartículas (S2), que a su vez liberan al medio el mensajero 2. Por último, el mensajero 2 es capaz de abrir la puerta molecular del tercer tipo de nanopartículas (S3), que liberan finalmente su carga (un colorante) como respuesta final.
[CAT] La present tesis doctoral titulada "Disseny de nous nanodispositius per a processos avançats de comunicació i lliberació controlada i dirigida d'agents terapèutics" està centrada en el desenvolupament de nous materials híbrids orgànic-inorgànic funcionals per a aplicacions en el camp de la lliberació controlada de molècules d'interès. El primer capítol de la tesis ofereix una introducció als materials híbrids orgànic-inorgànic funcionalitzats amb "portes moleculars" i la seua aplicació en processos de lliberació controlada. En el segon capítol de la tesis s'aborda el desenvolupament d'un nanodispositiu capaç de respondre i lliberar la seua càrrega en funció de la concentració de glucosa. Este nanodispositiu està basat en nanopartícules de sílice mesoporoses funcionalitzades a la seua superfície externa amb grups benzimidazol i amb els pors carregats amb un fluoròfor. Els pors queden bloquejats al afegir el enzim glucosa oxidasa funcionalitzada amb ciclodextrines (per formació d'un complex d'inclusió entre el benzimidazol i els oligosacàrids cíclics). Al afegir glucosa es produeix la seua oxidació enzimàtica donant lloc a àcid glucònic. Este àcid indueix una baixada del pH del medi amb la consegüent protonació dels benzimidazols i el trencament dels complexes d'inclusió. Este trencament provoca l'eixida del enzim de la superfície i la lliberació del colorant atrapat als pors. El tercer capítol de la tesis s'ha centrat en la preparació d'un material per a la lliberació controlada d'agents citotòxics en cèl¿lules canceroses en resposta a canvis en el potencia redox. De nou s'empren nanopartícules de sílice mesoporoses amb els pors carregats amb un colorant (safranina O) i la superfície externa funcionalitzada amb dos polietilenglicols (de diferent pes molecular) contenint enllaços disulfur. En presència de glutatió es produeix la reducció del enllaç disulfur amb la consegüent lliberació del colorant. Una volta confirmat el protocol d'obertura, es va estudiar la internalització i la lliberació d'un fluoròfor i d'un agent citotòxic en el model cel¿lular HeLa, realitzant ademés assajos de viabilitat. En el quart capítol de la tesis s'ha preparat i s'ha estudiat un nanodispositiu per a la lliberació controlada en cèl¿lules senescents, en un model murí de fibrosis pulmonar. El material es prepara emprant nanopartícules de sílice mesoporoses i un galactooligosacàrid anclat a la superfície externa del material. En presència de cèl¿lules senescents, que sobreexpresen el enzim ¿-galactosidasa, es produeix la hidròlisis del oligosacàrid amb el consegüent alliberament de la càrrega atrapada en els pors del suport (rodamina B). Després dels estudis in vitro, la capacitat del nanodispositiu d'acumular-se i lliberar la càrrega en teixits rics en cèl¿lules senecents es va evaluar in vivo. Amb este propòsit, ratolins amb fibrosis pulmonar induïda, patologia en la que s'ha descrit l'aparició de senescència en els teixits danyats, es van tractar amb el material sintetitzat i posteriorment van ser examinats per a comprovar la capacitat d'acumular-se i lliberar la seua càrrega (fluoròfor) en la zona dels pulmons afectada. En el quint capítol s'ha explorat el procés de comunicació química en cascada utilitzant tres tipus de nanopartícules mesoporoses de sílice carregades amb diferents missatgers i funcionalitzades amb tres portes moleculars diferents. Quan, sobre una suspensió de les tres nanopartícules, s'afegeix l'enzim capaç d'hidrolitzar la porta molecular que bloqueja els pors del primer tipus de nanopartícules (S1), es produeix la lliberació del missatger 1 des de S1. Este missatger és capaç d'induir l'obertura del segon tipus de nanopartícules (S2), les quals lliberen al medi el missatger 2. Per últim, el missatger 2 és capaç d'obrir la porta molecular del tercer tipus de nanopartícules (S3), que lliberen finalment la seua càrr
Giménez Morales, C. (2016). Design of new bio-gated nanodevices for advanced communication processes and targeted controlled release of therapeutic agents [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62822
TESIS

The mode-locked laser diode (MLLD) finds a lot of use in applications such as ultra high-speed data processing and sampling, large-capacity optical fiber communications based on optical time-division multiplexing (OTDM) systems. Integrating mode-locked lasers on silicon makes way for highly integrated silicon based photonic communication devices. The mode-locked laser being used in this thesis was built with Hybrid Silicon technology. This technology, developed by UC Santa Barbara in 2006, introduced the idea of wafer bonding a crystalline III- V layer to a Silicon-on-insulator (SOI) substrate, making integrated lasers in silicon chips possible. Furthermore, all mode-locked lasers produce phase noise, which can be a limiting factor in the performance of optical communication systems, specifically at higher bit rates. In this thesis, we design and discuss an impedance matching solution for a hybrid silicon mode-locked laser diode to lower phase noise and reduce the drive power requirements of the device. In order to develop an impedance matching solution, a thorough measurement and analysis of the impedance of the MLLD is necessary and was carried out. Then, a narrowband solution of two 0.1 pF chip capacitors in parallel is considered and examined as an impedance matching network for an operating frequency of 20 GHz. The hybrid silicon laser was packaged together in a module including the impedance- matching circuit for efficient RF injection. In conclusion, a 6 dB reduction of power required to drive the laser diode, as well as approximately a 10 dB phase noise improvement, was measured with the narrow-band solution. Also, looking ahead to possible future work, we discuss a step recovery diode (SRD) driven impulse generator, which wave-shapes the RF drive to achieve efficient injection. This novel technique takes into account the time varying impedance of the absorber as the optical pulse passes through it, to provide optimum pulse shaping.

Dans cette thèse de doctorat, nous étudions des algorithmes et des implémentations pour accélérer la résolution de systèmes linéaires denses en utilisant des architectures composées de processeurs multicœurs et d'accélérateurs. Nous nous concentrons sur des méthodes basées sur la factorisation LU. Le développement de notre code s'est fait dans le contexte de la bibliothèque MAGMA. Tout d'abord nous étudions différents solveurs CPU/GPU hybrides basés sur la factorisation LU. Ceux-ci visent à réduire le surcoût de communication dû au pivotage. Le premier est basé sur une stratégie de pivotage dite "communication avoiding" (CALU) alors que le deuxième utilise un préconditionnement aléatoire du système original pour éviter de pivoter (RBT). Nous montrons que ces deux méthodes surpassent le solveur utilisant la factorisation LU avec pivotage partiel quand elles sont utilisées sur des architectures hybrides multicœurs/GPUs. Ensuite nous développons des solveurs utilisant des techniques de randomisation appliquées sur des architectures hybrides utilisant des GPU Nvidia ou des coprocesseurs Intel Xeon Phi. Avec cette méthode, nous pouvons éviter l'important surcoût du pivotage tout en restant stable numériquement dans la plupart des cas. L'architecture hautement parallèle de ces accélérateurs nous permet d'effectuer la randomisation de notre système linéaire à un coût de calcul très faible par rapport à la durée de la factorisation. Finalement, nous étudions l'impact d'accès mémoire non uniformes (NUMA) sur la résolution de systèmes linéaires denses en utilisant un algorithme de factorisation LU. En particulier, nous illustrons comment un placement approprié des processus légers et des données sur une architecture NUMA peut améliorer les performances pour la factorisation du panel et accélérer de manière conséquente la factorisation LU globale. Nous montrons comment ces placements peuvent améliorer les performances quand ils sont appliqués à des solveurs hybrides multicœurs/GPU
In this PhD thesis, we study algorithms and implementations to accelerate the solution of dense linear systems by using hybrid architectures with multicore processors and accelerators. We focus on methods based on the LU factorization and our code development takes place in the context of the MAGMA library. We study different hybrid CPU/GPU solvers based on the LU factorization which aim at reducing the communication overhead due to pivoting. The first one is based on a communication avoiding strategy of pivoting (CALU) while the second uses a random preconditioning of the original system to avoid pivoting (RBT). We show that both of these methods outperform the solver using LU factorization with partial pivoting when implemented on hybrid multicore/GPUs architectures. We also present new solvers based on randomization for hybrid architectures for Nvidia GPU or Intel Xeon Phi coprocessor. With this method, we can avoid the high cost of pivoting while remaining numerically stable in most cases. The highly parallel architecture of these accelerators allow us to perform the randomization of our linear system at a very low computational cost compared to the time of the factorization. Finally we investigate the impact of non-uniform memory accesses (NUMA) on the solution of dense general linear systems using an LU factorization algorithm. In particular we illustrate how an appropriate placement of the threads and data on a NUMA architecture can improve the performance of the panel factorization and consequently accelerate the global LU factorization. We show how these placements can improve the performance when applied to hybrid multicore/GPU solvers