This thesis will begin with an investigation on the limitations associated with the predominate two-port stability analysis techniques with respect to multi-stage RF amplifier design. The primary focus will be to investigate and develop network analysis techniques that allow internal ports to be created within a RF circuit. This technique will facilitate the application of existing stability analysis techniques in ways that are not commonly known. Examples of situations where traditional network and stability analysis is insufficient will be presented, and the application of the newly developed techniques will be examined.

O CAN possui diversas características intrínsecas que o fazem mais apropriado para aplicações automotivas. Neste trabalho serão destacadas algumas dessas características aplicadas a sistemas que exigem um nível muito alto de confiabilidade, através de dois estudos de casos, um para analisar as características gerais do funcionamento da rede CAN, numa arquitetura eletrônica distribuída de um veículo em diversas configurações, cuja taxa de ocupação do barramento é alterado através da modificação do tempo de transmissão de algumas mensagens, e outro estudo para verificar o comportamento de um sistema de controle em malha fechada sobre a rede, focando no impacto do atraso temporal da rede. / The CAN has several inherent characteristics that are more appropriate for automotive applications. In this work will be highlighted some of those characteristics applied to systems that require a very high level of reliability. It is presented two case studies, one to analyze the general characteristics of operation of the CAN network in a electronic distributed architecture of a vehicle for various configurations, whose busload is amended by modifying the time of transmission of some messages, and another study to verify the behavior of a control system in closed loop on the network, focusing on the impact of the delay time in the network.

Esta tese propõe um algoritmo denominado ADAP_RSSF para manutenção de topologia de Redes de Sensores Sem Fio para Aplicações com Modelo de Entrega de Dados Híbrida, com o objetivo de garantir que eventos como falhas e inserção de novos nós não interfiram no funcionamento da rede. O algoritmo proposto utiliza uma Tabela de Decisão Adaptativa com algumas modificações, para realizar a reconstrução da topologia sempre que necessário. Além disso, é apresentada a formalização de grafos dinâmicos, baseada na definição de Dispositivos Adaptativos; eles são utilizados para mostrar graficamente as diversas mudanças que podem ocorrer na topologia da rede. A utilização de Tecnologia Adaptativa é importante para garantir que mudanças e eventos não previstos possam ser incorporados de maneira automática, sem que haja necessidade de interação com o usuário após a configuração inicial da tabela, pois nem sempre isto é possível em uma Rede de Sensores Sem Fio. Dessa forma, sempre que um ou mais eventos que possam causar mudanças na rede são detectados, é realizada uma busca na Tabela de Decisão Adaptativa e, caso não exista nenhuma regra que trate aquele evento específico, uma nova regra é criada usando a camada adaptativa da tabela. A solução proposta nesta tese mostra uma possibilidade de aplicação da Tecnologia Adaptativa em Redes de Sensores Sem Fio. Uma outra contribuição deste trabalho é a possibilidade de modificação no comportamento do algoritmo de forma que não somente os eventos e regras pré-estabelecidos sejam considerados na manutenção da topologia, de tal forma que a incorporação de novas informações sobre mudanças na topologia e funcionamento da rede seja possível sempre que necessário. Por fim, são apresentados o funcionamento do algoritmo, uma breve análise baseada em hop counts e considerações sobre uma possível simulação. Esta análise mostrou que o algoritmo apresenta um hop count inferior ou igual a algoritmos como o REMUDA e MULTI. / An algorithm named ADAP_RSSF is proposed to solve Wireless Sensor Network for Applications with Hybrid Data Delivery Model topology maintenance problems, guaranteeing that network operation will not be interfered by node faults or insertion of new nodes. The proposed algorithm uses a modified Adaptive Decision Table to rebuild network topology as needed. Besides, based on adaptive device definition, the description of dynamic graphs is also presented to use these devices to graphically represent a Wireless Sensor Network topology. The use of Adaptive Technology is important to guarantee that unforeseeable changes and events may be incorporated with no user interaction. Thus, every time an event that may change network topology is detected, a search on the Adaptive Table is executed and, if no results are found, the adaptive layer accounts for a new rule creation. The solution described here shows the applicability of Adaptive Technology in Wireless Sensor Networks. Another contribution is the algorithm behavior modification in such a way that not only are previous events and rules used in topology rebuilding, but new rules and criteria may be incorporated as needed. The algorithm operation, a brief analysis based on hop count and a possible simulation considerations are also presented. This analysis showed that the proposed algorithm presents a hop count less or equal other algorithms, such as, REMUDA and MULTI.

Esta tese propõe um algoritmo denominado ADAP_RSSF para manutenção de topologia de Redes de Sensores Sem Fio para Aplicações com Modelo de Entrega de Dados Híbrida, com o objetivo de garantir que eventos como falhas e inserção de novos nós não interfiram no funcionamento da rede. O algoritmo proposto utiliza uma Tabela de Decisão Adaptativa com algumas modificações, para realizar a reconstrução da topologia sempre que necessário. Além disso, é apresentada a formalização de grafos dinâmicos, baseada na definição de Dispositivos Adaptativos; eles são utilizados para mostrar graficamente as diversas mudanças que podem ocorrer na topologia da rede. A utilização de Tecnologia Adaptativa é importante para garantir que mudanças e eventos não previstos possam ser incorporados de maneira automática, sem que haja necessidade de interação com o usuário após a configuração inicial da tabela, pois nem sempre isto é possível em uma Rede de Sensores Sem Fio. Dessa forma, sempre que um ou mais eventos que possam causar mudanças na rede são detectados, é realizada uma busca na Tabela de Decisão Adaptativa e, caso não exista nenhuma regra que trate aquele evento específico, uma nova regra é criada usando a camada adaptativa da tabela. A solução proposta nesta tese mostra uma possibilidade de aplicação da Tecnologia Adaptativa em Redes de Sensores Sem Fio. Uma outra contribuição deste trabalho é a possibilidade de modificação no comportamento do algoritmo de forma que não somente os eventos e regras pré-estabelecidos sejam considerados na manutenção da topologia, de tal forma que a incorporação de novas informações sobre mudanças na topologia e funcionamento da rede seja possível sempre que necessário. Por fim, são apresentados o funcionamento do algoritmo, uma breve análise baseada em hop counts e considerações sobre uma possível simulação. Esta análise mostrou que o algoritmo apresenta um hop count inferior ou igual a algoritmos como o REMUDA e MULTI. / An algorithm named ADAP_RSSF is proposed to solve Wireless Sensor Network for Applications with Hybrid Data Delivery Model topology maintenance problems, guaranteeing that network operation will not be interfered by node faults or insertion of new nodes. The proposed algorithm uses a modified Adaptive Decision Table to rebuild network topology as needed. Besides, based on adaptive device definition, the description of dynamic graphs is also presented to use these devices to graphically represent a Wireless Sensor Network topology. The use of Adaptive Technology is important to guarantee that unforeseeable changes and events may be incorporated with no user interaction. Thus, every time an event that may change network topology is detected, a search on the Adaptive Table is executed and, if no results are found, the adaptive layer accounts for a new rule creation. The solution described here shows the applicability of Adaptive Technology in Wireless Sensor Networks. Another contribution is the algorithm behavior modification in such a way that not only are previous events and rules used in topology rebuilding, but new rules and criteria may be incorporated as needed. The algorithm operation, a brief analysis based on hop count and a possible simulation considerations are also presented. This analysis showed that the proposed algorithm presents a hop count less or equal other algorithms, such as, REMUDA and MULTI.

The use of communication networks in digital control systems introduces stability and reliability concerns. Standard reliability and safety assessment methods need further modification to accommodate the issue in the reliability assessment of networked control systems. In this thesis, it is demonstrated that the Dynamic Flowgraph Methodology (DFM) can be extended to model networked control systems. The modelling of the communication network influence on the performance of the control system is presented. The areas that can affect the reliability of the control system are identified using the methodology. The thesis also presents the application of the DFM to a nuclear-based thermochemical water splitting process for hydrogen production, the Copper-Chlorine (Cu-Cl) cycle. The architecture of a networked control system and configuration of instrumentation and control systems for the hydrogen production plant are proposed in the thesis. / UOIT

In this paper, the channel estimation problem for a two-way relay network (TWRN) based on two different wireless channel assumptions is considered. Previous works have proposed a training-based channel estimation method to obtain the channel state information (CSI). But in practice the channel change from one data block to another, which may cause the performance degradation due to the outdated CSI. To enhance the performance, the system has to insert more training signal. In order to improve the bandwidth efficiency, we propose a joint channel estimation and data detection method based on expectation-maximization (EM) algorithm. From the simulation results, the proposed method can combat the effect of fading channel and still the MSE results are very close to Cramer-Rao Lower Bound (CRLB) at the high signal-to-noise ratio (SNR) region. Additionally, as compare with the previous work, the proposed scheme also has a better detection performance for both time-varying and time-invariant channels.

This thesis proposes resource allocation algorithms for multi-input multi-output (MIMO) relay and Scalable H.264/AVC video transmission over cooperative communication networks. For MIMO relay, we explore the reception diversity with maximal ratio combining (MRC) and transmission diversity with space-time block codes (STBC) respectively. Then, a condition is proposed to maximize the overall output signal-to-noise ratio (SNR). In this condition, the ineffective relays will be excluded in sequence from the cooperation. Simulation results indicate that the effect of bit error rate (BER) through the relay selection is similar to the scheme which applies all relays, but the amounts of used relay decreased. For Scalable H.264/AVC video, by introducing frame significance analysis, the video quality dependency between coding frame and its references is investigated for temporal layers and quality layers. The proposed algorithm allocates the relay and sub-band to each layer based on channel conditions and the priority of classified video packets. Experimental results indicate that the proposed algorithm is superior to the temporal-based allocation and quality-based allocation cooperative schemes.

Power quality has a great effect on the operation of system loads. To analyze its effects and the possible economic losses due to system disturbances, there is an immediate need of a power quality monitoring system. With an effective communication system, network disturbance data can be gathered and analyzed efficiently such that outage duration and its consequent losses can be reduced. This thesis presents communication network performance simulation results of different types of communication schemes used in a power quality monitoring system. Discrete event simulation method is used to study the end-to-end delay times of different communication architectures. Based on these simulation results, system designers can choose the best option to meet their data communication requirements in power quality monitoring.

Mobile Delay Tolerant Networks (MDTNs) are wireless mobile networks in which a complete routing path between two nodes that wish to communicate cannot be guaranteed. A number of networking scenarios have been categorized as MDTNs, such as vehicular ad hoc networks, pocket switched networks, etc. The network asynchrony, coupled with the limited resources of mobile devices make message dissemination (also called routing) one of the fundamental challenges in MDTNs. In the literature, a large body of work has been done to deal with routing in MDTNs. However, most of the existing routing protocols are based on at least one of the following three assumptions: (1) all messages can be routed by relying on a single mobility property; (2) all messages can be routed using a single message allocation strategy; (3) users are willing to disclose their mobility information and relationships to others in order to improve the quality of the routing. We argue that the above three assumptions are not realistic because: (1) users can exhibit various social behaviors and consequently various mobility properties (e.g., they can have regular movements during week-days and exhibit non-predictable movements during week-ends); (2) some messages might need more or less copies to be delivered according to the localization of the source and the destination and to the urgency of the message; and (3) users mobility data can disclose sensitive information about the users. In this thesis, we relieve MDTN routing from the above three restrictive assumptions. Firstly, we propose an adaptive routing protocol for mobile delay tolerant networks. The proposed protocol can dynamically learn the social properties of nodes based on their mobility patterns, and exploit the most appropriate routing strategy each time an intermediate node is encountered. Simulations performed on real mobility traces show that our protocol achieves a better delivery ratio than existing state-of-the-art routing protocols that rely on a single mobility property. Secondly, we present a delay and cost balancing protocol for efficient routing in mobile delay tolerant networks. The presented protocol reasons on the remaining time-to-live of a message to dynamically allocate the minimum number of copies that are necessary to achieve a given delivery probability. Evaluation results show that the protocol can achieve a good balance between message delivery delay and delivery cost, compared with most of the existing routing protocols in the literature. Lastly, we propose an efficient privacy preserving prediction-based routing protocol for mobile delay tolerant networks. This protocol preserves the mobility patterns of a node from being disclosed by exploiting the mobility pattern of communities that node belongs to. Evaluation results demonstrate that this protocol can obtain comparable routing performance to prediction-based protocols while preserving the mobility pattern of nodes.

O CAN possui diversas características intrínsecas que o fazem mais apropriado para aplicações automotivas. Neste trabalho serão destacadas algumas dessas características aplicadas a sistemas que exigem um nível muito alto de confiabilidade, através de dois estudos de casos, um para analisar as características gerais do funcionamento da rede CAN, numa arquitetura eletrônica distribuída de um veículo em diversas configurações, cuja taxa de ocupação do barramento é alterado através da modificação do tempo de transmissão de algumas mensagens, e outro estudo para verificar o comportamento de um sistema de controle em malha fechada sobre a rede, focando no impacto do atraso temporal da rede. / The CAN has several inherent characteristics that are more appropriate for automotive applications. In this work will be highlighted some of those characteristics applied to systems that require a very high level of reliability. It is presented two case studies, one to analyze the general characteristics of operation of the CAN network in a electronic distributed architecture of a vehicle for various configurations, whose busload is amended by modifying the time of transmission of some messages, and another study to verify the behavior of a control system in closed loop on the network, focusing on the impact of the delay time in the network.