502 research outputs found

    Smart Vehicles, Technologies and Main Applications in Vehicular Ad hoc Networks

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    Vehicular Ad hoc NETworks (VANETs) belong to a subcategory of traditional Mobile Ad hoc NETworks (MANETs). The main feature of VANETs is that mobile nodes are vehicles endowed with sophisticated “on-board” equipments, traveling on constrained paths (i.e., roads and lanes), and communicating each other for message exchange via Vehicle-to-Vehicle (V2V) communication protocols, as well as between vehicles and fixed road-side Access Points (i.e., wireless and cellular network infrastructure), in case of Vehicle-to-Infrastructure (V2I) communications. In this chapter we will introduce the state-of-the-art of recent technologies used in vehicular networks, specifically for smart vehicles, which require novel functionalities such as data communications, accurate positioning, control and decision monitoring

    Scalable Streaming Multimedia Delivery using Peer-to-Peer Communication

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    Understanding the End-Users and Technical Requirements for Real-Time Streaming Data Analytics and Visualisation

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    Today's digital world deals with tremendous amounts of data with high complexity and velocity. The data being generated continuously from a variety of sources at very high speeds is considered as streaming data. The number of technologies to ingest, explore, analyze, and visualize the streaming data is growing rapidly across many industries. However, the use of real-time technologies in the Architecture, Engineering Construction (AEC) sector is still at its early stages of development and further research is needed to make the tools truly commercial. The AEC is a data-intensive, project-based industry that relies on real-time information to help projects stay on schedule and enable companies to cut costs. The technologies supporting real-time data capability in the AEC sector must satisfy several key functional and nonfunctional requirements. This paper aims to identify and prioritize both end-users and technical requirements for AEC businesses when adopting a real-time streaming data analytics and visualization technology in their production control rooms. To this aim, an expert questionnaire survey is conducted to investigate the requirements in four distinct areas, namely: (i) data collection and ingestion, (ii) stream processing, (iii) real-time analytics, and (iv) presentation and visualization. A five-level Likert scale is used in the questionnaire to allow respondents to indicate their perceptions on the importance of each of the identified requirements. The survey is distributed using Qualtrics online tool to over twenty organizations all over the world and the responses are analyzed using SPSS statistical software. The findings of the study reveal that 'interactivity' and 'user assistance' are the most important requirements from the end-users' perspective, whereas 'fast data processing', 'real-time reporting', 'scalable data processing', and 'dashboard connectivity' are the most important requirements from the technology developers' perspective. The findings of this research can help stakeholders and researchers get a better picture of the current challenges facing the AEC sector in terms of streaming data analytics and provide insight into the possible directions of future technological changes

    Conectividade definida por software em ambientes mĂłveis

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    Broadband Internet access on trains has become an expected service for passengers, and the rise in quality demand has been posing a challenge to service providers. There are solutions for Internet access on trains that lack the flexibility and redundancy needed for an improved QoS in the network. Thus, this dissertation studies two new load balancing solutions, one distributed and the other centralized. In an emulated train network, routers of each car communicate their network statistics to other nodes of the network, to be used in load balancing decisions. In the distributed solution, each router has the capacity to make load balancing decisions, while in the centralized solution, an onboard controller makes those decisions. The latter solution is based on load balancing in an SDN environment. In this system, a remote entity aggregates the passengers’ traffic and forwards it to an external network, or to the Internet. The systems must provide an improved quality of experience to the passengers on the train and the total avaliable bandwidth should be distributed evenly by all cars. Requirements were established for the systems, which were developed after an in-depth analysis of solutions for Internet access on board found in the literature. After obtaining the results of the performance tests, it was concluded that the systems improve the QoE of the passengers, as long as the network conditions are approximately constant for an extended period.O acesso à Internet de banda larga em comboios tornou-se num serviço esperado por parte dos passageiros e o aumento na exigência de qualidade tem constituído um desafio para os prestadores de serviços. Existem soluções de acesso à Internet em comboios que carecem da flexibilidade e redundância necessárias para uma melhor qualidade de serviço na rede. Assim, esta dissertação estuda duas novas soluções de balanceamento de carga, uma distribuída e outra centralizada. Numa rede de comboio emulada, routers de cada carruagem comunicam as suas estatísticas de rede para outros nós da rede, para posteriormente serem tomadas decisões de balanceamento de carga. Na solução distribuída, cada router tem capacidade de tomar decisões de balanceamento de carga, enquanto que na solução centralizada, um controlador dentro do comboio toma essas decisões. Esta última solução baseiase num balanceamento de carga em ambiente SDN. Neste sistema, uma entidade remota agrega o tráfego dos passageiros e encaminha-o para uma rede externa, ou para a Internet. Os sistemas devem proporcionar uma qualidade de experiência melhorada aos passageiros do comboio e a largura de banda total disponível deve ser distribuída mais uniformememente por todas as carruagens. Requisitos foram estabelecidos para os sistemas, que foram desenvolvidos após uma análise aprofundada das soluções de acesso à Internet em comboios encontradas na literatura. Após a obtenção dos resultados dos testes de desempenho, concluiu-se que as duas soluções melhoram o QoE dos passageiros, desde que as condições da rede sejam aproximadamente constantes durante um certo período.Mestrado em Engenharia de Computadores e Telemátic

    Context-Aware Recommendation Systems in Mobile Environments

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    Nowadays, the huge amount of information available may easily overwhelm users when they need to take a decision that involves choosing among several options. As a solution to this problem, Recommendation Systems (RS) have emerged to offer relevant items to users. The main goal of these systems is to recommend certain items based on user preferences. Unfortunately, traditional recommendation systems do not consider the user’s context as an important dimension to ensure high-quality recommendations. Motivated by the need to incorporate contextual information during the recommendation process, Context-Aware Recommendation Systems (CARS) have emerged. However, these recent recommendation systems are not designed with mobile users in mind, where the context and the movements of the users and items may be important factors to consider when deciding which items should be recommended. Therefore, context-aware recommendation models should be able to effectively and efficiently exploit the dynamic context of the mobile user in order to offer her/him suitable recommendations and keep them up-to-date.The research area of this thesis belongs to the fields of context-aware recommendation systems and mobile computing. We focus on the following scientific problem: how could we facilitate the development of context-aware recommendation systems in mobile environments to provide users with relevant recommendations? This work is motivated by the lack of generic and flexible context-aware recommendation frameworks that consider aspects related to mobile users and mobile computing. In order to solve the identified problem, we pursue the following general goal: the design and implementation of a context-aware recommendation framework for mobile computing environments that facilitates the development of context-aware recommendation applications for mobile users. In the thesis, we contribute to bridge the gap not only between recommendation systems and context-aware computing, but also between CARS and mobile computing.<br /

    High speed 802.11ad wireless video streaming

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    The aim of this thesis is to investigate, both theoretically and experimentally, the capability of the IEEE 802.11ad device, the Wireless Gigabit Alliance known as WiGig operating in the 60 GHz band to handle rise in data traffic ubiquitous to high speed data transmission such as bulk data transfer, and wireless video streaming. According to Cisco and others, it is estimated that in 2020, internet video traffic will account for 82 % of all consumer internet traffic. This research evalu- ated the feasibility of the 60 GHz to provide minimum data rate of about 970 Mbps from the Ethernet link limited or clamped to 1 Gbps. This translated to 97 % effi- ciency with respect to the IEEE 802.11ad system performance. For the first time, the author proposed the enhancement of millimetre wave propagation through the use of specular reflection in non-line-of-sight environment, providing at least 94 % bandwidth utilization. Additional investigations result of the IEEE 802.11ad device in real live streaming of 4k ultra-high definition (UHD) video shows the feasibility of aggressive frequency reuse in the absence of co-channel interference. Moreover, using heuristic approach, this work compared materials absorption and signal reception at 60 GHz and the results gives better performance in contrast to the theoretical values. Finally, this thesis proposes a framework for the 802.11ad wireless H.264 video streaming over 60 GHz band. The work describes the potential and efficiency of WiGig device in streaming high definition (HD) video with high temporal index (TI) and 4k UHD video with no retransmission. Caching point established at the re-transmitter increase coverage and cache multimedia data. The results in this thesis shows the growing potential of millimeter wave technology, the WiGig for very high speed bulk data transfer, and live streaming video transmission

    Digital Twins and Blockchain for IoT Management

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    We live in a data-driven world powered by sensors getting data from anywhere at any time. This advancement is possible thanks to the Internet of Things (IoT). IoT embeds common physical objects with heterogeneous sensing, actuating, and communication capabilities to collect data from the environment and people. These objects are generally known as things and exchange data with other things, entities, computational processes, and systems over the internet. Consequently, a web of devices and computational processes emerges involving billions of entities collecting, processing, and sharing data. As a result, we now have an internet of entities/things that process and produce data, an ever-growing volume that can easily exceed petabytes. Therefore, there is a need for novel management approaches to handle the previously unheard number of IoT devices, processes, and data streams. This dissertation focuses on solutions for IoT management using decentralized technologies. A massive number of IoT devices interact with software and hardware components and are owned by different people. Therefore, there is a need for decentralized management. Blockchain is a capable and promising distributed ledger technology with features to support decentralized systems with large numbers of devices. People should not have to interact with these devices or data streams directly. Therefore, there is a need to abstract access to these components. Digital twins are software artifacts that can abstract an object, a process, or a system to enable communication between the physical and digital worlds. Fog/edge computing is the alternative to the cloud to provide services with less latency. This research uses blockchain technology, digital twins, and fog/edge computing for IoT management. The systems developed in this dissertation enable configuration, self-management, zero-trust management, and data streaming view provisioning from a fog/edge layer. In this way, this massive number of things and the data they produce are managed through services distributed across nodes close to them, providing access and configuration security and privacy protection
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