346 research outputs found

    Intelligent Sensor Networks

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    In the last decade, wireless or wired sensor networks have attracted much attention. However, most designs target general sensor network issues including protocol stack (routing, MAC, etc.) and security issues. This book focuses on the close integration of sensing, networking, and smart signal processing via machine learning. Based on their world-class research, the authors present the fundamentals of intelligent sensor networks. They cover sensing and sampling, distributed signal processing, and intelligent signal learning. In addition, they present cutting-edge research results from leading experts

    From geographically dispersed data centers towards hierarchical edge computing

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    Internet scale data centers are generally dispersed in different geographical regions. While the main goal of deploying the geographically dispersed data centers is to provide redundancy, scalability and high availability, the geographic dispersity provides another opportunity for efficient employment of global resources, e.g., utilizing price-diversity in electricity markets or utilizing locational diversity in renewable power generation. In other words, an efficient approach for geographical load balancing (GLB) across geo-dispersed data centers not only can maximize the utilization of green energy but also can minimize the cost of electricity. However, due to the different costs and disparate environmental impacts of the renewable energy and brown energy, such a GLB approach should tap on the merits of the separation of green energy utilization maximization and brown energy cost minimization problems. To this end, the notion of green workload and green service rate, versus brown workload and brown service rate, respectively, to facilitate the separation of green energy utilization maximization and brown energy cost minimization problems is proposed. In particular, a new optimization framework to maximize the profit of running geographically dispersed data centers based on the accuracy of the G/D/1 queueing model, and taking into consideration of multiple classes of service with individual service level agreement deadline for each type of service is developed. A new information flow graph based model for geo-dispersed data centers is also developed, and based on the developed model, the achievable tradeoff between total and brown power consumption is characterized. Recently, the paradigm of edge computing has been introduced to push the computing resources away from the data centers to the edge of the network, thereby reducing the communication bandwidth requirement between the sources of data and the data centers. However, it is still desirable to investigate how and where at the edge of the network the computation resources should be provisioned. To this end, a hierarchical Mobile Edge Computing (MEC) architecture in accordance with the principles of LTE Advanced backhaul network is proposed and an auction-based profit maximization approach which effectively facilitates the resource allocation to the subscribers of the MEC network is designed. A hierarchical capacity provisioning framework for MEC that optimally budgets computing capacities at different hierarchical edge computing levels is also designed. The proposed scheme can efficiently handle the peak loads at the access point locations while coping with the resource poverty at the edge. Moreover, the code partitioning problem is extended to a scheduling problem over time and the hierarchical mobile edge network, and accordingly, a new technique that leads to the optimal code partitioning in a reasonable time even for large-sized call trees is proposed. Finally, a novel NOMA augmented edge computing model that captures the gains of uplink NOMA in MEC users\u27 energy consumption is proposed

    A modelling and networking architecture for distributed virtual environments with multiple servers.

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    Virtual Environments (VEs) attempt to give people the illusion of immersion that they are in a computer generated world. VEs allow people to actively participate in a synthetic environment. They range from a single-person running on a single computer, to multiple-people running on several computers connected through a network. When VEs are distributed on multiple computers across a network, we call this a Distributed Virtual Environment (DVE). Virtual Environments can benefit greatly from distributed strategies.A networked VE system based on the Client-Server model is the most commonly used paradigm in constructing DVE systems. In a Client-Server model, data can be distributed on several server computers. The server computers provide services to their own clients via networks. In some client-server models, however, a powerful server is required, or it will become a bottleneck. To reduce the amount of data and traffic maintained by a single server, the servers themselves can be distributed, and the virtual environment can be divided over a network of servers.The system described in this thesis, therefore, is based on the client-server model with multiple servers. This grouping is called a Distributed Virtual Environment System with Multiple- Servers (DVM). A DVM system shows a new paradigm of distributed virtual environments based on shared 3D synthetic environments. A variety of network elements are required to support large scale DVM systems. The network is currently the most constrained resource of the DVM system. Development of networking architectures is the key to solving the DVM challenge. Therefore, a networking architecture for implementing a DVM model is proposed. Finally, a DVM prototype system is described to demonstrate the validity of the modelling and network architecture of a DVM model

    High performance simulation and modelling of wireless vehicular ad hoc networks

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    Vehicular communications occur when two or more vehicles come into range of one another, to share data over wireless media. The applications of this communication are far-reaching, from toll collection to collision avoidance. Due to the proliferation of wireless devices and their ubiquitous nature it is now possible to operate in an ad hoc manner between transmitting stations. Vehicular ad hoc networks (VANET) are a special kind of network, that experience short link times and high levels of interference, but have the ability to present many driver information and safety solutions for the worlds roads. Computer simulation of VANET enables rapid-prototyping and intensive exploration of systems and protocol, using highly complex and computationally expensive models and programs. Experimentation with real vehicles would be time consuming and expensive, limiting the range of study that could be achieved and therefore reducing the accuracy of analytical solutions exposed through experimentation. An extensive corpus of work on networking, traffic modelling and parallel processing algorithm has been reviewed as part of this thesis, to isolate the current state-of-the-art and examine areas for novel research. In this thesis the value and importance of computer simulation for VANET is proposed, which explores the applications of a high-fidelity system when applied to real-world scenarios. The work is grounded on two main contributions: 1) that by using intervehicle communication and an advanced lane changing/merging algorithm the congestion that builds up around an obstruction on a highway can be alleviated and reduced more effectively than simple line-of-sight, even when only a proportion of the vehicles are radio equipped. 2) that the available parameter space, as large as it is, can be efficiently explored using a parallel algorithm with the NS-3 network simulation system. The large-scale simulation of VANET in highway scenarios can be used to discover universal trends and behaviours in the successful and timely delivery of data packets. The application of VANET research has a broad scope for use in modern vehicles and the optimisation of the transmission of data is highly relevant; a large number of parameters can be tuned in a networking device, but knowing which to tune and by how much is paramount to the operation of intelligent transport systems

    Proceedings of the Fifth International Mobile Satellite Conference 1997

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    Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments

    Software architecture for modeling and distributing virtual environments

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    Advances in Robotics, Automation and Control

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    The book presents an excellent overview of the recent developments in the different areas of Robotics, Automation and Control. Through its 24 chapters, this book presents topics related to control and robot design; it also introduces new mathematical tools and techniques devoted to improve the system modeling and control. An important point is the use of rational agents and heuristic techniques to cope with the computational complexity required for controlling complex systems. Through this book, we also find navigation and vision algorithms, automatic handwritten comprehension and speech recognition systems that will be included in the next generation of productive systems developed by man

    Energy-Efficient Self-Organization Protocols for Sensor Networks

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    A Wireless Sensor Network (WSN, for short) consists of a large number of very small sensor devices deployed in an area of interest for gathering and delivery information. The fundamental goal of a WSN is to produce, over an extended period of time, global information from local data obtained by individual sensors. The WSN technology will have a significant impact on a wide array of applications on the efficiency of many civilian and military applications including combat field surveillance, intrusion detection, disaster management among many others. The basic management problem in the WSN is to balance the utility of the activity in the network against the cost incurred by the network resources to perform this activity. Since the sensors are battery powered and it is impossible to change or recharge batteries after the sensors are deployed, promoting system longevity becomes one of the most important design goals instead of QoS provisioning and bandwidth efficiency. On the other hand the self-organization ability is essential for the WSN due to the fact that the sensors are randomly deployed and they work unattended. We developed a self-organization protocol, which creates a multi-hop communication infrastructure capable of utilizing the limited resources of sensors in an adaptive and efficient way. The resulting general-purpose infrastructure is robust, easy to maintain and adapts well to various application needs. Important by-products of our infrastructure include: (1) Energy efficiency: in order to save energy and to extend the longevity of the WSN sensors, which are in sleep mode most of the time. (2) Adaptivity: the infrastructure is adaptive to network size, network topology, network density and application requirement. (3) Robustness: the degree to which the infrastructure is robust and resilient. Analytical results and simulation confirmed that our self-organization protocol has a number of desirable properties and compared favorably with the leading protocols in the literature

    System-on-chip architecture for secure sub-microsecond synchronization systems

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    213 p.En esta tesis, se pretende abordar los problemas que conlleva la protección cibernética del Precision Time Protocol (PTP). Éste es uno de los protocolos de comunicación más sensibles de entre los considerados por los organismos de estandarización para su aplicación en las futuras Smart Grids o redes eléctricas inteligentes. PTP tiene como misión distribuir una referencia de tiempo desde un dispositivo maestro al resto de dispositivos esclavos, situados dentro de una misma red, de forma muy precisa. El protocolo es altamente vulnerable, ya que introduciendo tan sólo un error de tiempo de un microsegundo, pueden causarse graves problemas en las funciones de protección del equipamiento eléctrico, o incluso detener su funcionamiento. Para ello, se propone una nueva arquitectura System-on-Chip basada en dispositivos reconfigurables, con el objetivo de integrar el protocolo PTP y el conocido estándar de seguridad MACsec para redes Ethernet. La flexibilidad que los modernos dispositivos reconfigurables proporcionan, ha sido aprovechada para el diseño de una arquitectura en la que coexisten procesamiento hardware y software. Los resultados experimentales avalan la viabilidad de utilizar MACsec para proteger la sincronización en entornos industriales, sin degradar la precisión del protocolo

    System-on-chip architecture for secure sub-microsecond synchronization systems

    Get PDF
    213 p.En esta tesis, se pretende abordar los problemas que conlleva la protección cibernética del Precision Time Protocol (PTP). Éste es uno de los protocolos de comunicación más sensibles de entre los considerados por los organismos de estandarización para su aplicación en las futuras Smart Grids o redes eléctricas inteligentes. PTP tiene como misión distribuir una referencia de tiempo desde un dispositivo maestro al resto de dispositivos esclavos, situados dentro de una misma red, de forma muy precisa. El protocolo es altamente vulnerable, ya que introduciendo tan sólo un error de tiempo de un microsegundo, pueden causarse graves problemas en las funciones de protección del equipamiento eléctrico, o incluso detener su funcionamiento. Para ello, se propone una nueva arquitectura System-on-Chip basada en dispositivos reconfigurables, con el objetivo de integrar el protocolo PTP y el conocido estándar de seguridad MACsec para redes Ethernet. La flexibilidad que los modernos dispositivos reconfigurables proporcionan, ha sido aprovechada para el diseño de una arquitectura en la que coexisten procesamiento hardware y software. Los resultados experimentales avalan la viabilidad de utilizar MACsec para proteger la sincronización en entornos industriales, sin degradar la precisión del protocolo
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