Practical Sliding Window Recoder: Design, Analysis, and Usecases

Network coding has been widely used as a technology to ensure efficient and reliable communication. The ability to recode packets at the intermediate nodes is a major benefit of network coding implementations. This allows the intermediate nodes to choose a different code rate and fine-tune the outgoing transmission to the channel conditions, decoupling the requirement for the source node to compensate for cumulative losses over a multi-hop network. Block network coding solutions already have practical recoders but an on-the-fly recoder for sliding window network coding has not been studied in detail. In this paper, we present the implementation details of a practical recoder for sliding window network coding for the first time along with a comprehensive performance analysis of a multi-hop network using the recoder. The sliding window recoder ensures that the network performs closest to its capacity and that each node can use its outgoing links efficiently

Localized Application for Video Capture for a Multimedia Sensor Node with Name-Based Segment Streaming

abstract: The Internet of Things (IoT) has become a more pervasive part of everyday life. IoT networks such as wireless sensor networks, depend greatly on the limiting unnecessary power consumption. As such, providing low-power, adaptable software can greatly improve network design. For streaming live video content, Wireless Video Sensor Network Platform compatible Dynamic Adaptive Streaming over HTTP (WVSNP-DASH) aims to revolutionize wireless segmented video streaming by providing a low-power, adaptable framework to compete with modern DASH players such as Moving Picture Experts Group (MPEG-DASH) and Apple’s Hypertext Transfer Protocol (HTTP) Live Streaming (HLS). Each segment is independently playable, and does not depend on a manifest file, resulting in greatly improved power performance. My work was to show that WVSNP-DASH is capable of further power savings at the level of the wireless sensor node itself if a native capture program is implemented at the camera sensor node. I created a native capture program in the C language that fulfills the name-based segmentation requirements of WVSNP-DASH. I present this program with intent to measure its power consumption on a hardware test-bed in future. To my knowledge, this is the first program to generate WVSNP-DASH playable video segments. The results show that our program could be utilized by WVSNP-DASH, but there are issues with the efficiency, so provided are an additional outline for further improvements.Dissertation/ThesisMasters Thesis Computer Engineering 201

Minimização de perdas em redes veiculares com multihoming

The growing interest in Vehicular Ad-hoc NETworks (VANETs) is encouraging its deployment in new environments, allowing the development of safety and entertainment applications. Vehicles can connect to other vehicles or to the infrastructure, providing an Internet connection. The communication equipment placed inside the vehicles may have multiple network interfaces of diverse technologies, such as IEEE 802.11p/WAVE, IEEE 802.11a/g/n (Wi- Fi) and cellular. This diversity enables the exploration of Multihoming (MH) and Network Coding (NC) mechanisms which can be used to provide higher bandwidth and reliability to these services, reducing packet losses due to poor wireless signal quality, therefore improving the final Quality-of-Service (QoS). This dissertation enhances the communication quality of a MH vehicular network by improving its mobility protocol and the NC mechanisms. Specifically, changes were performed to ensure the reliability of control mobility messages to help the infrastructure to react faster to the wireless communication conditions of a mobile node. On a different perspective, it has been provided a mechanism to enable NC through different technologies being used in MH, and making use of all technologies simultaneously to code and recover the packets. Both approaches were evaluated with real systems in a laboratory scenario. The obtained results on the reliability of the control messages show that the new approach is able to provide higher communication reliability, reducing the packet losses presented in case of an abrupt disconnection, and when in presence of other connections. For the multi-technology architecture proposed for the NC, the experimental tests evaluated its impact on the effective delivery ratio and the delay. The comparative results show that the multi-technology approach integrated with MH has a better delivery ratio when compared to the single-technology, despite the small impact on the packet delay.O interesse crescente em Redes Veiculares está a encorajar a sua implementação em novos ambientes, permitindo o desenvolvimento de aplicações de segurança e de entretenimento. Os veículos podem-se ligar a outros veículos ou à infraestrutura, tendo assim uma ligação à Internet. O equipamento de comunicação colocado nos veículos poderá ter múltiplas interfaces de rede de tecnologias diferentes, como por exemplo, IEEE 802.11p/WAVE, IEEE 802.11a/g/n (Wi-Fi) e celular. Esta diversidade permite a exploração e utilização de mecanismos de Multihoming e de Network Coding, os quais podem ser usados para oferecer maior largura de banda e maior fiabilidade a este tipo de aplicações, reduzindo as perdas de pacotes na presença de um sinal sem fios de fraca qualidade, melhorando assim a qualidade de serviço. Esta dissertação tem como objetivo melhorar a qualidade de comunicação de uma rede veicular que suporta Multihoming, assim como melhorar os seus mecanismos de Network Coding e do protocolo de mobilidade. Mais especificamente, foram feitas alterações a nível do processo de handover entre redes, para ajudar a infraestrutura a reagir mais rapidamente às condições de comunicação de um nó móvel na rede. Numa perspetiva diferente, foi desenvolvido um mecanismo que permite a aplicação de Network Coding através de diferentes tecnologias em Multihoming, o qual faz uso das diferentes tecnologias simultaneamente para codificar e recuperar os pacotes. Ambos os mecanismos foram avaliados em cenários de laboratório com sistemas reais. Os resultados obtidos relativos ao envio das mensagens de controlo mostram que esta nova abordagem é capaz de fornecer uma comunicação com maior fiabilidade, reduzindo as perdas de pacotes no caso de uma desconexão abrupta, e quando na presença de outras tecnologias e ligações. Quanto à proposta de muti-tecnologia para o Network Coding, os testes experimentais avaliaram o seu impacto na taxa de entrega de pacotes efetiva e no atraso de transmissão. Os resultados comparativos evidenciam que, apesar de ter um pequeno impacto no atraso dos pacotes em comparação com a abordagem que considera o Network Coding em cada tecnologia de forma independente, a abordagem de multi-tecnologia apresenta uma melhor taxa de entrega.CMUP-ERI/TIC/0010/2014Mestrado em Engenharia Eletrónica e Telecomunicaçõe

Design and Performance Analysis of Functional Split in Virtualized Access Networks

abstract: Emerging modular cable network architectures distribute some cable headend functions to remote nodes that are located close to the broadcast cable links reaching the cable modems (CMs) in the subscriber homes and businesses. In the Remote- PHY (R-PHY) architecture, a Remote PHY Device (RPD) conducts the physical layer processing for the analog cable transmissions, while the headend runs the DOCSIS medium access control (MAC) for the upstream transmissions of the distributed CMs over the shared cable link. In contrast, in the Remote MACPHY (R-MACPHY) ar- chitecture, a Remote MACPHY Device (RMD) conducts both the physical and MAC layer processing. The dissertation objective is to conduct a comprehensive perfor- mance comparison of the R-PHY and R-MACPHY architectures. Also, development of analytical delay models for the polling-based MAC with Gated bandwidth alloca- tion of Poisson traffic in the R-PHY and R-MACPHY architectures and conducting extensive simulations to assess the accuracy of the analytical model and to evaluate the delay-throughput performance of the R-PHY and R-MACPHY architectures for a wide range of deployment and operating scenarios. Performance evaluations ex- tend to the use of Ethernet Passive Optical Network (EPON) as transport network between remote nodes and headend. The results show that for long CIN distances above 100 miles, the R-MACPHY architecture achieves significantly shorter mean up- stream packet delays than the R-PHY architecture, especially for bursty traffic. The extensive comparative R-PHY and R-MACPHY comparative evaluation can serve as a basis for the planning of modular broadcast cable based access networks.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201