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Traditional Machine Learning (ML) methods usually rely on a central server to per-form ML tasks. However, these methods have problems like security risks, datastorage issues, and high computational demands. Federated Learning (FL), on theother hand, spreads out the ML process. It trains models on local devices and thencombines them centrally. While FL improves computing and customization, it stillfaces the same challenges as centralized ML in security and data storage. This thesis introduces a new approach combining Federated Learning and Decen-tralized Machine Learning (DML), which operates on an Ethereum Virtual Machine(EVM) compatible blockchain. The blockchain’s security and decentralized naturehelp improve transparency, trust, scalability, and efficiency. The main contributionsof this thesis include:1. Redesigning a semi-centralized system with enhanced privacy and the multi-KRUM algorithm, following the work of Shayan et al..2. Developing a new decentralized framework that supports both standard anddeep-learning FL, using the InterPlanetary File System (IPFS) and EthereumVirtual Machine (EVM)-compatible Smart Contracts.3. Assessing how well the system defends against common data poisoning attacks,using a version of Multi-KRUM that’s better at detecting outliers.4. Applying privacy methods to securely combine data from different sources.

This report explains the development of a telephone line multiplexer to be used with a computer based personal paging system. The large geographical area coverage made possible by computer processing results in many calls having to cross telephone tariff boundaries. Since system users cannot be expected to pay long distance charges, dedicated lines which cross tariff boundaries must be leased. Multiplexing applied to those leased lines reduces the cost of data transmission, and is, therefore, justified. The design of the multiplexer proceeds from a specification set which is derived from user response requirements. Fundamentally, the response consists in advising the user, within a reasonable time, that a "page" has been accepted by the system. The specification set is then partitioned into functional blocks which are modeled using flow charts and state diagrams. Logic design follows directly from the models. Production of the multiplexer is followed by field installation. The savings resulting from the multiplexing are considerable.

WiFi networks are susceptible to statistical traffic analysis attacks. Despite encryption, the metadata of encrypted traffic, such as packet inter-arrival time and size, remains visible. This visibility allows potential eavesdroppers to infer private information in the Internet of Things (IoT) environment. For example, it allows for the identification of sleep monitors and the inference of whether a user is awake or asleep. WiFi eavesdropping theoretically enables the identification of IoT devices without the need to join the victim's network. This attack scenario is more realistic and much harder to defend against, thus posing a real threat to user privacy. However, researchers have not thoroughly investigated this type of attack due to the noisy nature of wireless channels and the relatively low accuracy of WiFi sniffers. Furthermore, many countermeasures proposed in the literature are inefficient in addressing side-channel leakage in WiFi networks. They often burden internet traffic with high data overhead and disrupt the user experience by introducing deliberate delays in packet transmission. This dissertation investigates privacy leakage resulting from WiFi eavesdropping and proposes efficient defensive techniques. We begin by assessing the practical feasibility of IoT device identification in WiFi networks. We demonstrate how an eavesdropper can fingerprint IoT devices by passively monitoring the wireless channel without joining the network. After exploring this privacy attack, we introduce a traffic spoofing-based defense within the WiFi channel to protect against such threats. Additionally, we propose a more data-efficient obfuscation technique to counter traffic analytics based on packet size without adding unnecessary noise to the traffic.

The role of the South African National Defence Force (SANDF) has changed considerably in the last decade. The emphasis has moved from protecting the country's borders to peacekeeping duties in Central Africa and even further North. Communications between the peacekeeping missions and the military bases back in South Africa is vital to ensure the success of these missions. Currently use is made of satellite as well as High Frequency (HF) communications. There are drawbacks associated with these technologies (high cost and low data rates/interference respectively). Successful long distance ionospheric propagation in the low Very High Frequency (VHF) range will complement the existing infrastructure and enhance the success rate of these missions. This thesis presents a feasibility study to determine under what ionospheric conditions such low VHF communications will be possible. The International Reference Ionosphere (IRI) was used to generate ionospheric data for the reflection point(s) of the signal. The peak height of the ionospheric F2 layer (hmF2) was used to calculate the required antenna elevation angle. Once the elevation angle is known it is possible to calculate the required F2 layer critical frequency (foF2). The required foF2 value was calculated by assuming a Maximum Useable Frequency (MUF) of 20% higher than the planned operational frequency. It was determined that single hop propagation is possible during the daytime if the smoothed sunspot number (SSN) exceeds 15. The most challenging requirement for successful single hop propagation is the need of an antenna height of 23 m. For rapid deployment and semi-mobile operations within a jungle environment it may prove to be a formidable obstacle.

The growth of Asynchronous Transfer Mode (ATM) was considered to be the ideal carrier of the high bandwidth applications like video on demand and multimedia e-learning. ATM emerged commercially in the beginning of the 1990's. It was designed to provide a different quality of service at a speed up 100 Gbps for both real time and non real time application. The turn of the 90's saw a variety of technologies being developed. This project analyzes these technologies, compares them to the Asynchronous Transfer Mode and assesses the future of ATM.

This thesis seeks to identify and explain some technology in order to more fully understand modern communication. This study makes use of metaphoric cluster analysis to examine the technological rhetoric of Nicholas Negroponte.

Thesis (Elec.E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981. / Includes bibliographical references. / by Howard Paul Hayden. / Thesis (Elec.E.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.

The open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the presence of an eavesdropper. We investigate the performance of the wireless network at the physical layer that is subject to a variety of fading environments that may be modeled by the Rayleigh, Nakagami-m, and Generalized-K distributions, to mention a few. We use the secrecy outage probability (SOP) as the standard performance metrics to study the performance of the wireless networks. We propose two different approaches to compute the secrecy outage probability, and derive explicit expressions for the secrecy outage probability that allow us to characterize the performance of the wireless networks. Specifically, we use a direct integration approach as well as a Taylor series base approach to evaluate the secrecy outage probability. Finally, we use computer simulations, based on MATLAB, to confirm the analytical results. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2016. / FAU Electronic Theses and Dissertations Collection

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2018-05-10T12:55:18Z No. of bitstreams: 1 Denis Augusto Carneiro Lobo.pdf: 2377689 bytes, checksum: ec66c81fcf1d6584b5311171b0eae5c2 (MD5) / Made available in DSpace on 2018-05-10T12:55:18Z (GMT). No. of bitstreams: 1 Denis Augusto Carneiro Lobo.pdf: 2377689 bytes, checksum: ec66c81fcf1d6584b5311171b0eae5c2 (MD5) Previous issue date: 2018-04-09 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This master’s thesis analyses the constitution of the so-called Hate Speech in Digital Social Networks (DSNs), specifically, on Facebook. Starting from users’ text interactions in public Facebook pages of the 2014 presidential candidates Dilma Rousseff (Workers Party) and Aécio Neves (Brazilian Social Democracy Party) during the presidential run (August to October 2014), I’ve searched for the characterization of this phenomena within a political-party polarization scenario. Focusing in the political constitution of the referred phenomena, I’ve then evidenced the difference between the legal concept of Hate Speech and a more widespread phenomena, which worked in this scenario as a political component of the social interactions: the political hate. Furthermore, the debate gets centralized in the mediation process of social interactions in an Instant Communication Technology (ICTs) scenario, in search of a confluence with the Latin American studies about the process of technological and communicational mediation, its diferences and implications in an Interactional Sociology. Finally, having analysed such studies as a theorical and methodological background, I've presented a discussion about the importance of the new computational techniques such as "filter bubbles", "social bots" and User Experience (UX) in the daily life of today's liberal democracies, leading the debate to the establishment of "fear techniques", clearly an expression of the so-called "Fear Culture", to which many authors refeer today / Esta dissertação analisou a constituição do chamado Discurso de Ódio nas Redes Sociais Digitais (RSDs), mais especificamente no Facebook. Partindo das interações textuais dos usuários nas páginas públicas dos candidatos à Presidência da República no ano de 2014, Dilma Rousseff (PT) e Aécio Neves (PSDB), durante o pleito eleitoral (agosto a outubro de 2014), buscou-se a caracterização desse fenômeno dentro de um cenário de polarização político-partidária. Voltando o olhar para a constituição política do fenômeno em questão, buscou-se a diferenciação da figura jurídica do Discurso de Ódio de um fenômeno mais capilar, que funcionou como componente político das interações societárias nesse cenário: o ódio político. Além disso, centralizamos o debate nas interações sociais e na mediação das Tecnologias de Comunicação Instantânea (TCIs), buscando uma confluência com o pensamento latino-americano sobre os processos de mediação tecnológica e comunicacional e suas diferenciações e implicações em uma Sociologia Interacionista. Buscou-se também, a partir desse arcabouço teórico-metodológico, discutir os pesos das novas técnicas computacionais, como a “bolha de filtros”, os “social bots”, “fake news” e as técnicas de User Experience (UX) no cotidiano das democracias liberais atuais, direcionando o debate para o estabelecimento de “técnicas do medo”, visivelmente assentados na chamada “Cultura do Medo”, a qual muitos pesquisadores recorrem na atualidade