Orientador: Varese Salvador Timóteo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia / Made available in DSpace on 2018-08-19T02:14:36Z (GMT). No. of bitstreams: 1 Pinotti_FernandoLuiz_M.pdf: 996964 bytes, checksum: a6ab776d59d9b99c17725660a37049c1 (MD5) Previous issue date: 2011 / Resumo: Esta dissertação apresenta dois estudos, o primeiro trata de uma substituição do socket pela pilha TCP/IP uIP de um gerador de trafego multimídia sobre IP com o objetivo de manipularmos os campos dos cabeçalhos IP (Ipv4 Type of Service, e Ipv6 Traffic Class), que serão utilizados para a identificação dos serviços multimídia. O gerador gera diferentes tráfegos multimídia simultâneos seguindo funções de distribuições conhecidas utilizando o conceito de thread. O segundo estudo trata de modelos de simulações utilizando o simulador de eventos discretos ARENA. Propomos três diferentes modelos de simulação que simulam ambientes multimídia, onde serviços stream e elástico são requisitados simultaneamente pelos usuários. No modelo 1 foram realizados simulações propondo um estudo de demanda de requisições dos usuários. Onde, três cenários foram estudados. O primeiro, quando ocorre um aumento repentino de usuários, com isso aumentando o intervalo de requisições dos serviços. O segundo cenário, quando a duração dos serviços aumentam ocorrendo bloqueios de novos serviços por falta de recursos. E o terceiro cenário e com relação ao Controle de Admissão de Chamada (CAC) do sistema. Os modelos 2 e 3 são ambientes VPN, onde e estudado o Sojourn, tempo que o pacote leva para chegar ao host de destino. A principal diferença entre os dois modelos e que o modelo 2 não apresenta a implementação de atributos como jitter e latência. O jitter e latência influenciam no tempo que leva para o quadro ser entregue ao seu destino, podendo causar diversos problemas nos serviços stream, como degradação da qualidade do serviço ou bloqueio do serviço. O estudo de modelos de simulações e de grande importância para a validação dos resultados obtidos na emulação do gerador de tráfegos multimídia, tendo em conta que na simulação os pacotes não são transmitidos através de um meio físico, e no emulador são transmitidos de um host a outro utilizando Ethernet / Abstract: This dissertation presents two studies, the first is a replacement of a socket for a TCP/IP stack uIP of a multimedia traffic generator over IP in order to manipulate the fields of IP headers (IPv4 Type of Service and IPv6 Traffic Class), which will be used for the multimedia services identification. The multimedia traffic generator generates simultaneous multimedia services following different well known distributions functions using the concept of thread. A second study of simulation models is propose using the discrete event simulator ARENA, we propose three different simulation model witch simulates multimedia environments, where stream and elastics services are required simultaneous by users. The model 1 were performed simulations proposing a request demand study from the users. Where three scenarios were studied. The first when occurs a sudden increase of users, thereby increasing the range of requests of services. The second scenario when the length of services increases, occurring blockages of new services due the lack of resources, for example, trunks in a telephony exchange. The third scenario is related to Call Admission Control (CAC) system. Models 2 and 3 are VPN environments, where is studied the sojourn, time that the packet takes to reach the destination. The main differences between the two models is that the model 2 does not preset the attributes implementation jitter and latency. The jitter and latency affects the time it takes the frame to be delivered to its destination, may cause various problems in streaming services, such as quality of service degradation or blocking the service. The study of simulation models are of great importance for the emulation's results validations of the multimedia traffic generator, taking into account that the simulation packets are not transmitted over a physical structure, and the emulation are transmitted from one host to another using Ethernet LAN / Mestrado / Tecnologia e Inovação / Mestre em Tecnologia

[pt] Este trabalho descreve o projeto de um Sistema Remoto de Entrada e Saída de Dados (Remote Job Entry-RJE). O sistema desenvolvido emula a estação IBM/2780 do RJE. A emulação é obtida por software de microcomputador (MCPUC-80, INTEL 8080). A abordagem teórica inclui, em detalhes, Sistemas de Comunicação de Dados e Protocolos de Comunicação, e em particular, o protocolo BSC (Binary Synchronours Communication) que foi implementado neste projeto. A implementação é descrita em termos de requisitos, adaptações e métodos empregados no processo de emulação do IBM/2780 por sistema de microcomputador. / [en] This paper discribes de development of a Remote Job Entry System. The system developed is an emulation version of do IBM/2780, RJE station. the emulation process is by microcomputer software and hardware (MCPUC-80, INTEL 8080). The paper includes theoretical aspects of Data Communications Systems and Protocols, specialy of the Bunary Synchronous Communications protocol, which was used in this work. The implementation also describes the requirements, methods and adaptations that were necessary in the emulation process.

Communication protocols based on SMS and e-email are simple and straightforward to implement yet they possess a significant communication overhead and delay. In a large sensor network this would increasingly lead to performance issues and decrease scalability of the overall system, since SMS and e-mail include a significant transmission delay and overhead. Additionally, a communication architecture, where clients communicate directly to the central server requires these to be online all the time, thus decreasing battery time. We replaced the initial SMS and e-mail based communication protocol with a TCP based protocol. Furthermore, we selected a new architecture where sensor groups could communicate to a master node in that group, which in turn communicates to the central server. These changes were implemented in an emulator, since the real sensors could not be reconfigured. We evaluated the improvements and could show that we can reduce the communication overhead and transmission delay as well as that the average battery time for all sensors in a group is increased. / Emulator for complex sensor-based IT system

Wireless Sensor Networks (WSNs) have attracted growing interest from both realcustomers and the scientific community in the recent years due to their powerfulcapabilities and varied applications. Each wireless sensor node relays data to thebase station (BS) directly in the direct communication protocol. However, there aresome applications that require some of the nodes to be placed at vast distances fromthe BS, which leads to rapid reduction in the total energy of all nodes. Since energyconsumption in sensor networks is critical, many new protocols have beendeveloped to reduce losses. The Low-energy adaptive clustering hierarchy(LEACH) is one of the most popular protocols that increase network lifetime byreducing losses. In this report, I survey and compare some algorithms and propose a new enhancedalgorithm for the LEACH protocol, thus saving energy and prolonging the networklifespan. MATLAB is used for simulation.

Networking protocols have been developed throughout time following layered architectures such as the Open Systems Interconnection model and the Internet model. These protocols are grouped in the Internet protocol suite. Most developers do not deal with low-level protocols, instead they design application-level protocols on top of the low-level protocol. Although each application-level protocol is different, there is commonality among them and developers can apply lessons learned from one protocol to the design of new ones. Design patterns can help by gathering and sharing proven and reusable solution to common, reoccurring design problems. The Application-level Communication Protocols Design Patterns language captures this knowledge about application-level protocol design, so developers can create better, more fitting protocols base on these common and well proven solutions. Another aspect of contemporary development technics is the need of distribution of software artifacts. Most of the development companies have started using Cloud Computing services to overcome this need; either public or private clouds are widely used. Future developers need to manage this technology infrastructure, software, and platform as services. These two aspects, communication protocols design and cloud computing represent an opportunity to contribute to the software development community and to the software engineering education curriculum. The Application-level Communication Protocols Design Patterns language aims to help solve communication software design. The use of cloud computing in programming assignments targets on a positive influence on improving the Analysis to Reuse skills of students of computer science careers.

Since artificial intelligence (AI) is growing more prominent it is interesting to look at the methods used to train AI. One such method is reinforcement learning in simulation, where AI can train safely in the confines of a simulation. For this a simulation environment is needed which in turn needs to communicate with a reinforcement learning system. It is therefore interesting to look at how this communication may affect the performance of the system. This study is made to look at this question.  A few different communication protocols are evaluated in a test program using data of the same kind used in reinforcement learning systems, floating point numbers and images. These protocols are sockets, Socket.IO, gRPC, and ZeroMQ. Of the protocols sockets and ZeroMQ are shown to be similar for sending floats, with ZeroMQ being better performing at sending images. For larger amounts of data sockets are however better. ZeroMQ is considered the best choice for an application dealing with floats and images, due to the performance and more built in ease of use functionality compared to sockets.  ZeroMQ is adapted into a working example for reinforcement learning training in simulation using Unreal Engine as a simulation environment, AGX Dynamics for physics simulation, and Stable Baselines3 for reinforcement learning. Performance in the simulation is similar but slower than in the test program. In the small example used the reinforcement learning process is the slowest part of the system, the simulation is the next slowest at a third of the time of the reinforcement learning, communication back and forth stands for half of the simulation time. As the system grows more complexreinforcement learning time and simulation time are expected to grow at a much faster speed than thecommunication. Therefore if optimization is to be made it is likely better to focus at the other part first.

Sensor nodes are deployed over sensing fields for the purpose of monitoring certain phenomena of interest. The sensor nodes perform specific measurements, process the sensed data, and send the data to a base station over a wireless channel. The base station collects data from the sensor nodes, analyses this data, and reports it to the users. Wireless sensor networks are different from traditional networks, because of the following constraints. Typically, a large number of sensor nodes need to be randomly deployed and, in most cases, they are deployed in unreachable environments; however, the sensor nodes may fail, and they are subject to power constraints. Energy is one of the most important design constraints of wireless sensor networks. Energy consumption, in a sensor node, occurs due to many factors, such as: sensing the environment, transmitting and receiving data, processing data, and communication overheads. Since the sensor nodes behave as router nodes for data propagation, of the other sensor nodes to the base station, network connectivity decreases gradually. This may result in disconnected sub networks of sensor nodes. In order to prolong the network¿s lifetime, energy efficient protocols should be designed for the characteristics of the wireless sensor network. Sensor nodes in different regions of the sensing field can collaborate to aggregate the data that they gathered. Data aggregation is defined as the process of aggregating the data from sensor nodes to reduce redundant transmissions. It reduces a large amount of the data traffic on the network, it requires less energy, and it avoids information overheads by not sending all of the unprocessed data throughout the sensor network. Grouping sensor nodes into clusters is useful because it reduces the energy consumption. The clustering technique can be used to perform data aggregation. The clustering procedure involves the selection of cluster heads in each of the cluster, in order to coordinate the member nodes. The cluster head is responsible for: gathering the sensed data from its cluster¿s nodes, aggregating the data, and then sending the aggregated data to the base station. An adaptive clustering protocol was introduced to select the heads in the wireless sensor network. The proposed clustering protocol will dynamically change the cluster heads to obtain the best possible performance, based on the remaining energy level of sensor nodes and the average energy of clusters. The OMNET simulator will be used to present the design and implementation of the adaptive clustering protocol and then to evaluate it. This research has conducted extensive simulation experiments, in order to fully study and analyse the proposed energy efficient clustering protocol. It is necessary for all of the sensor nodes to remain alive for as long as possible, since network quality decreases as soon as a set of sensor nodes die. The goal of the energy efficient clustering protocol is to increase the lifetime and stability period of the sensor network. This research also introduces a new bidirectional data gathering protocol. This protocol aims to form a bidirectional ring structure among the sensor nodes, within the cluster, in order to reduce the overall energy consumption and enhance the network¿s lifetime. A bidirectional data gathering protocol uses a source node to transmit data to the base station, via one or more multiple intermediate cluster heads. It sends data through energy efficient paths to ensure the total energy, needed to route the data, is kept to a minimum. Performance results reveal that the proposed protocol is better in terms of: its network lifetime, energy dissipation, and communication overheads.

Quantum communication protocols require maximally entangled state of pair of qubits (spin-1/2 states in this context) to be shared between sender and the receiver. The entangled qubits lose entanglement because of random magnetic field disturbances. The dynamics in the form of joint density matrix of random pure entangled state provide the steady (joint) state and the associated timescales (time taken by the pair to reach the steady state) providing a scope in future to quantify the effective utilization of quantum communication protocols. / The dynamics of an identical pair of entangled spin-1/2 particles, both subjected to the identical, independent, correlated random magnetic fields is studied. The dynamics of the pure joint state of the pair is derived using stochastic calculus. In case of identical fields, an ensemble of such pure states are combined using the modified spin joint density matrix and the joint relaxation time is obtained for the pair of spin-1/2 particles. These dynamics can be interpreted as special kind of correlations involving the spatial components of the Bloch polarization vectors of the constituent entangled spin-1/2 particles. In case of independent random magnetic fields, the dynamics are obtained by considering a pure joint state of entangled spin-1/2 particles. The disentanglement time defined as the time taken for the particles to become disentangled, is obtained. In case of correlated random magnetic fields, the dynamics of a maximally entangled pair of spin-1/2 particles are derived in terms of the joint density matrix of the entangled pair from which the steady state density matrix and the associated timescale for it to be reached are obtained. The asymptotic density matrix in this case represents a state of (partial) disentanglement. In other words, there is a persistent entanglement in case of correlated field disturbances. / Thesis / Doctor of Philosophy (PhD) / Maximally entangled pair of quantum bits (in the form of spin-1/2 states) lose entanglement either partially or completely depending upon the nature of random magnetic field disturbances around them (correlated/independent/identical fields). The dynamics of entangled states (in the form of density matrix of a random pure state) in the presence of random magnetic fields are obtained using the ideas of stochastic calculus to understand the steady state of the pair and the associated timescales to be reached.

Cooperative relay communication is a promising means of wireless communication in which cooperation is used to create a virtual transmit array between the source and the destination, thereby providing spatial diversity for combating the fading channel. In this thesis we develop cooperative communication protocols namely the orthogonal amplify-and-forward (OAF), non-orthogonal and orthogonal selection decode-and-forward (NSDF and OSDF) protocols. The diversity-multiplexing gain tradeoff (DMT) of the three protocols is determined and DMT-optimal distributed space-time code constructions are provided. The code construction is based on Cyclic Division Algebras. The codes constructed are sphere decodable and in some instances incur minimum possible delay. Included in our results is the perhaps surprising finding that the OAF and NAF protocols have identical DMT when the time durations of the broadcast and cooperative phases are optimally chosen to suit the respective protocol. Two variants of the NSDF protocol are considered: fixed-NSDF and variable-NSDF protocol. In the variable-NSDF protocol, the fraction of time occupied by the broadcast phase is allowed to vary with multiplexing gain. In the two-relay case, the variable-NSDF protocol is shown to improve on the DMT of the best previously-known static protocol for higher values of multiplexing gain. Our results also establish that the fixed-NSDF protocol has a better DMT than the NAF protocol for any number of relays.

Protocolos de comunicação seguros são essenciais em ambientes de automação industrial, onde falhas não detectadas na comunicação de dispositivos podem provocar danos irreparáveis à vida ou ao meio-ambiente. Esses protocolos seguros devem ser desenvolvidos de acordo com alguma norma de segurança, como a IEC 61508. Segundo ela, faz parte do processo de implementação destes protocolos, a escolha de técnicas adequadas de validação, entre elas a injeção de falhas, a qual deve considerar um modelo de falhas apropriado ao ambiente de operação do protocolo. Geralmente, esses ambientes são caracterizados pela existência de diversas formas de interferência elétrica e eletromagnética, as quais podem causar falhas nos sistemas eletrônicos existentes. Nos sistemas de comunicação de dados, isto pode levar a destruição do sinal de dados e causar estados de operação equivocados nos dispositivos. Assim, é preciso utilizar uma técnica de injeção de falhas que permita simular os tipos de erros de comunicação que podem ocorrer nos ambientes industriais. Dessa forma, será possível verificar o comportamento dos mecanismos de tolerância falhas na presença de falhas e assegurar o seu correto funcionamento. Para esta finalidade, este trabalho apresenta o desenvolvimento do injetor de falhas FITT para validação de protocolos de comunicação seguros. Esta ferramenta foi desenvolvida para ser utilizada com o sistema operacional Linux. O injetor faz uso do PF_RING, um módulo para o Kernel do Linux, que é responsável por realizar a comunicação direta entre as interfaces de rede e o injetor de falhas. Assim os pacotes não precisam passar pelas estruturas do Kernel do Linux, evitando que atrasos adicionais sejam inseridos no processo de recebimento e envio de mensagens. As funções de falhas desenvolvidas seguem o modelo de falhas de comunicação descrito na norma IEC 61508. Esse modelo é composto pelos erros de repetição, perda, inserção, sequência incorreta, endereçamento, corrupção de dados, atraso, mascaramento e falhas de memória em switches. / Safe communication protocols are essential in industrial automation environments, where undetected failures in the communication of devices can cause irreparable damage to life or to the environment. These safe protocols must be developed according to some safety standard, like IEC 61508. According to it, part of the process of implementing these protocols is to select appropriate techniques for validation, including the fault injection, which should consider an appropriate fault model for the operating environment of the protocol. Generally, these environments are characterized by the existence of various forms of electric and electromagnetic interference, which can cause failures in existing electronic systems. In data communication systems, this can lead to the destruction of the data signal and cause erroneous operation states in the devices. Thus, it is necessary to use a fault injection technique that allows simulating the types of communication errors that may occur in industrial environments. So, it will be possible to verify the behavior of the fault tolerance mechanisms in the presence of failures and ensure its correct functioning. For this purpose, this work presents the development of FITT fault injector for validation of safety communication protocols. This tool was developed to be used with Linux operating system. The fault injector makes use of PF_RING, a module for the Linux Kernel and that is responsible to perform the direct communication between the network interfaces and the fault injector. Thus the packages do not need to go through the Linux Kernel structures, avoiding additional delays to be inserted into the process of receiving and sending messages. The developed fault injection functions follow the communication fault model described in the IEC61508 standard, composed by the errors of repetition, loss, insertion, incorrect sequence, addressing, data corruption, delay, masking and memory failures within switches. The fault injection tests applied with this model allow to properly validate the fault tolerance mechanisms of safety protocols.