This dissertation is directed towards improving the performance of 5G Wireless Fronthaul Networks and Wireless Sensor Networks, as measured by reliability, fault recovery time, energy consumption, efficiency, and security of transmissions, beyond what is achievable with conventional error control technology. To achieve these ambitious goals, the research is focused on novel applications of networking techniques, such as Diversity Coding, where a feedforward network design uses forward error control across spatially diverse paths to enable reliable wireless networking with minimal delay, in a wide variety of application scenarios. These applications include Cloud-Radio Access Networks (C-RANs), which is an emerging 5G wireless network architecture, where Remote Radio Heads (RRHs) are connected to the centralized Baseband Unit (BBU) via fronthaul networks, to enable near-instantaneous recovery from link/node failures. In addition, the ability of Diversity Coding to recover from multiple simultaneous link failures is demonstrated in many network scenarios. Furthermore, the ability of Diversity Coding to enable significantly simpler and thus lower-cost routing than other types of restoration techniques is demonstrated. Achieving high throughput for broadcasting/multicasting applications, with the required level of reliability is critical for the efficient operation of 5G wireless infrastructure networks. To improve the performance of C-RAN networks, a novel technology, Diversity and Network Coding (DC-NC), which synergistically combines Diversity Coding and Network Coding, is introduced. Application of DC-NC to several 5G fronthaul networks, enables these networks to provide high throughput and near-instant recovery in the presence of link and node failures. Also, the application of DC-NC coding to enhance the performance of downlink Joint Transmission-Coordinated Multi Point (JT-CoMP) in 5G wireless fronthaul C-RANs is demonstrated. In all these scenarios, it is shown that DC-NC coding can provide efficient transmission and reduce the resource consumption in the network by about one-third for broadcasting/multicasting applications, while simultaneously enabling near-instantaneous latency in recovery from multiple link/node failures in fronthaul networks. In addition, it is shown by applying the DC-NC coding, the number of redundant links that uses to provide the required level of reliability, which is an important metric to evaluate any protection system, is reduced by about 30%-40% when compared to that of Diversity Coding. With the additional goal of further reducing of the recovery time from multiple link/node failures and maximizing the network reliability, DC-NC coding is further improved to be able to tolerate multiple, simultaneous link failures with less computational complexity and lower energy consumption. This is accomplished by modifying Triangular Network Coding (TNC) and synergistically combining TNC with Diversity Coding to create enhanced DC-NC (eDC-NC), that is applied to Fog computing-based Radio Access Networks (F-RAN) and Wireless Sensor Networks (WSN). Furthermore, it is demonstrated that the redundancy percentage for protecting against n link failures is inversely related to the number of source data streams, which illustrates the scalability of eDC-NC coding. Solutions to enable synchronized broadcasting are proposed for different situations. The ability of eDC-NC coding scheme to provide efficient and secure broadcasting for 5G wireless F-RAN fronthaul networks is also demonstrated. The security of the broadcasting data streams can be obtained more efficiently than standardized methods such as Secure Multicasting using Secret (Shared) Key Cryptography.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-05-11T12:40:43Z No. of bitstreams: 1 Felipe Rabuske Costa_.pdf: 3408830 bytes, checksum: 25a67ecb02629c811b5f305a1f2e3d27 (MD5) / Made available in DSpace on 2018-05-11T12:40:43Z (GMT). No. of bitstreams: 1 Felipe Rabuske Costa_.pdf: 3408830 bytes, checksum: 25a67ecb02629c811b5f305a1f2e3d27 (MD5) Previous issue date: 2018-02-28 / Nenhuma / Estima-se que até o ano de 2020, cerca de 50 bilhões de dispositivos móveis estarão conectados a redes sem fio e que 78% de todo o tráfego de dados gerado por esse tipo de dispositivos será conteúdo multimídia. Essas estimativas fomentam o desenvolvimento da quinta geração de redes móveis (5G). Uma das arquiteturas mais recentemente proposta, chamada de Fog Radio Access Networks (F-RAN), dá aos componentes localizados na borda da rede poder de processamento e armazenamento endereçados às atividades da rede. Um dos principais problemas dessa arquitetura é o intenso tráfego de dados no seu canal de comunicação centralizado chamado fronthaul, utilizado para conectar as antenas (F-APs) à rede externa. Dado esse contexto, esse trabalho apresenta o Nuoxus, um modelo de caching de conteúdo multimídia voltado para F-RANs que visa amenizar esse problema. Ao armazenar esse tipo de conteúdo nos nós de rede mais próximos ao usuário, o número de acessos concorrentes ao fronthaul é reduzido, sendo esse um dos fatores agravantes na latência de comunicação na rede. O Nuoxus pode ser executado em qualquer nó da rede que possua capacidade de armazenamento e processamento, ficando responsável por gerenciar o caching de conteúdo desse nó. Sua política de substituição de conteúdo utiliza a similaridade de requisições entre os nós filhos e o restante da rede como um fator para definir a relevância de armazenar o conteúdo requisitado em cache. Além disso, utilizando esse mesmo processo, o Nuoxus sugere, de forma proativa, aos demais nós filhos que apresentam um alto grau de similaridade que façam o caching desse conteúdo, visando um possível futuro acesso. A análise do estado da arte demonstra que até o momento não existe nenhum outro trabalho que explore o histórico de requisições para fazer caching de conteúdo em arquiteturas multicamadas para redes sem fio de forma proativa e sem utilizar algum componente centralizado para fazer coordenação e predição de caching. A fim de comprovar a eficiência do modelo, foi desenvolvido um protótipo utilizando o simulador ns-3. Os resultados obtidos demostram que a utilização do Nuoxus foi capaz de reduzir a latência de rede em cerca de 29.75%. Além disso, quando comparado com outras estratégias de caching, o número de acesso à cache dos componentes de rede aumentou em 53.16% em relação à estratégia que obteve o segundo melhor resultado. / It is estimated that by the year 2020, about 50 billion mobile devices will be connected to wireless networks and 78% of the data traffic of this kind of device will be multimedia content. These estimates foster the development of the 5th generation of mobile networks (5G). One of the most recently proposed architectures, named Fog Radio Access Networks or F-RAN, gives the components located at the edge of the network the processing power and storage capacity to address network activities. One of the main problems of this architecture is the intense data traffic in its centralized component named fronthaul, which is used to connect the antennas (FAPs) to the external network. Given this context, we propose Nuoxus, a multimedia content caching model for F-RANs that aims to mitigate this problem. By storing the content in the nodes closest to the user, the number of concurrent accesses to the fronthaul is reduced, which decreases the communication latency of the network. Nuoxus can run on any network node that has storage and processing capacity, becoming the responsible for managing the cache of that node. Its content replacement policy uses the similarity of requests between the child nodes and the rest of the network as a factor to decide the relevance of storing the requested content in the cache. Furthermore, by using this same process, Nuoxus proactively suggests to the child nodes whose degree of similarity is high to perform the caching of the content, assuming they will access the content at a future time. The State-of-the-art analysis shows that there is no other work that explores the history of requests to cache content in multi-layer architectures for wireless networks in a proactive manner, without using some centralized component to do coordination and prediction of caching. To demonstrate the efficiency of the model, a prototype was developed using the ns 3 simulator. The results obtained demonstrate that the use of Nuoxus reduced network latency in 29.75%. In addition, when compared to other caching strategies, the cache hit increased by 53.16% when compared to the strategy that obtained the second-best result.