896 resultados para mobile computing


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Commoditization and virtualization of wireless networks are changing the economics of mobile networks to help network providers (e.g., MNO, MVNO) move from proprietary and bespoke hardware and software platforms toward an open, cost-effective, and flexible cellular ecosystem. In addition, rich and innovative local services can be efficiently created through cloudification by leveraging the existing infrastructure. In this work, we present RANaaS, which is a cloudified radio access network delivered as a service. RANaaS provides the service life-cycle of an ondemand, elastic, and pay as you go 3GPP RAN instantiated on top of the cloud infrastructure. We demonstrate an example of realtime cloudified LTE network deployment using the OpenAirInterface LTE implementation and OpenStack running on commodity hardware as well as the flexibility and performance of the platform developed.

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In this paper, we present a revolutionary vision of 5G networks, in which SDN programs wireless network functions, and where Mobile Network Operators (MNO), Enterprises, and Over-The-Top (OTT) third parties are provided with NFV-ready Network Store. The proposed Network Store serves as a digital distribution platform of programmable Virtualized Network Functions (VNFs) that enable 5G application use-cases. Currently existing application stores, such as Apple's App Store for iOS applications, Google's Play Store for Android, or Ubuntu's Software Center, deliver applications to user specific software platforms. Our vision is to provide a digital marketplace, gathering 5G enabling Network Applications and Network Functions, written to run on top of commodity cloud infrastructures, connected to remote radio heads (RRH). The 5G Network Store will be the same to the cloud as the application store is currently to a software platform.

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Unattended Wireless Sensor Networks (UWSNs) operate in autonomous or disconnected mode: sensed data is collected periodically by an itinerant sink. Between successive sink visits, sensor-collected data is subject to some unique vulnerabilities. In particular, while the network is unattended, a mobile adversary (capable of subverting up to a fraction of sensors at a time) can migrate between compromised sets of sensors and inject fraudulent data. In this paper, we provide two collaborative authentication techniques that allow an UWSN to maintain integrity and authenticity of sensor data-in the presence of a mobile adversary-until the next sink visit. Proposed schemes use simple, standard, and inexpensive symmetric cryptographic primitives, coupled with key evolution and few message exchanges. We study their security and effectiveness, both analytically and via simulations. We also assess their robustness and show how to achieve the desired trade-off between performance and security.

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The Web of Data currently comprises ? 62 billion triples from more than 2,000 different datasets covering many fields of knowledge3. This volume of structured Linked Data can be seen as a particular case of Big Data, referred to as Big Semantic Data [4]. Obviously, powerful computational configurations are tradi- tionally required to deal with the scalability problems arising to Big Semantic Data. It is not surprising that this ?data revolution? has competed in parallel with the growth of mobile computing. Smartphones and tablets are massively used at the expense of traditional computers but, to date, mobile devices have more limited computation resources. Therefore, one question that we may ask ourselves would be: can (potentially large) semantic datasets be consumed natively on mobile devices? Currently, only a few mobile apps (e.g., [1, 9, 2, 8]) make use of semantic data that they store in the mobile devices, while many others access existing SPARQL endpoints or Linked Data directly. Two main reasons can be considered for this fact. On the one hand, in spite of some initial approaches [6, 3], there are no well-established triplestores for mobile devices. This is an important limitation because any po- tential app must assume both RDF storage and SPARQL resolution. On the other hand, the particular features of these devices (little storage space, less computational power or more limited bandwidths) limit the adoption of seman- tic data for different uses and purposes. This paper introduces our HDTourist mobile application prototype. It con- sumes urban data from DBpedia4 to help tourists visiting a foreign city. Although it is a simple app, its functionality allows illustrating how semantic data can be stored and queried with limited resources. Our prototype is implemented for An- droid, but its foundations, explained in Section 2, can be deployed in any other platform. The app is described in Section 3, and Section 4 concludes about our current achievements and devises the future work.

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En términos generales, m-salud puede definirse como el conjunto de sistemas de información, sensores médicos y tecnologías de comunicaciones móviles para el cuidado de la salud. La creciente disponibilidad, miniaturización, comportamiento, velocidades de transmisión de datos cada vez mayores y la esperada convergencia de tecnologías de red y comunicaciones inalámbricas en torno a los sistemas de salud móviles están acelerando el despliegue de estos sistemas y la provisión de servicios de m-salud, como por ejemplo, la teleasistencia móvil. El concepto emergente de m-salud conlleva retos importantes (estudios técnicos, análisis, modelado de la provisión de servicios, etc.) que hay que afrontar para impulsar la evolución de los sistemas y servicios de e-salud ofrecidos desde tecnologías de telecomunicación que utilizan acceso por cable y redes fijas, hacia configuraciones móviles e inalámbricas de última generación. En este trabajo se analizará primeramente el significado e implicaciones de m-salud y la situación en la que se encuentra; los retos a los que hay que enfrentarse para su implantación y provisión así como su tendencia. De los múltiples y diferentes servicios que se pueden proveer se ha identificado el servicio de Localización de Personas LoPe, lanzado por Cruz Roja en febrero de 2007, para teleasistencia móvil y que permite conocer en todo momento la ubicación de la persona que porta su dispositivo asociado. Orientado a personas con discapacidad, en situación de riesgo o dependencia por deterioro cognitivo, tiene como objetivo ayudarlas a recuperar su autonomía personal. La provisión de este servicio se modelará mediante dinámica de sistemas, ya que esta teoría se considera idónea para modelar sistemas complejos que evolucionan con el tiempo. El resultado final es un modelo que implementado a través de la herramienta Studio 8® de la compañía noruega Powersim Software AS nos ha permitido analizar y evaluar su comportamiento a lo largo del tiempo, además de permitirnos extraer conclusiones sobre el mismo y plantear futuras mejoras sobre el servicio. ABSTRACT. In general terms, m-health can be defined as “mobile computing, medical sensor, and communications technologies for health care.” The increased availability, miniaturization, performance, enhanced data rates, and the expected convergence of future wireless communication and network technologies around mobile health systems are accelerating the deployment of m-health systems and services, for instance, mobile telecare. The emerging concept of m-health involves significant challenges (technical studies, analysis, modeling of service provision, etc.) that must be tackled to drive the development of e-health services and systems offered by telecommunication technologies that use wired and fixed networks towards wireless and mobile new generation networks. Firstly, in this master’s thesis, the meaning and implications of m-health and its current situation are analyzed. This analysis also includes the challenges that must be tackled for the implementation and provision of m-health technologies and services and the m-health trends. Among the many different m-health services already delivered, the Localización de Personas LoPe service has been identified to work with it. This service, launched by Spanish Red Cross in February 2007, enables to locate people who carry the associated device. It’s aimed at people with disabilities, at risk or dependency due to cognitive impairment and helps them to recover their personal autonomy. The provision of this service will be modeled with system dynamics considering that this theory suits very well the modeling of complex systems which evolve over time. The final result is a system dynamics model of the service implemented with Studio 8® tool developed by Powersim Software AS, a Norwegian company. This model has allowed us to analyze and evaluate its behaviour over time, as well as to draw conclusions and to consider some future improvements in the service.

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Aplicativos móveis de celulares que coletam dados pessoais estão cada vez mais presentes na rotina do cidadão comum. Associado a estas aplicações, há polêmicas sobre riscos de segurança e de invasão de privacidade, que podem se tornar entraves para aceitação destes sistemas por parte dos usuários. Por outro lado, discute-se o Paradoxo da Privacidade, em que os consumidores revelam mais informações pessoais voluntariamente, apesar de declarar que reconhecem os riscos. Há pouco consenso, nas pesquisas acadêmicas, sobre os motivos deste paradoxo ou mesmo se este fenômeno realmente existe. O objetivo desta pesquisa é analisar como a coleta de informações sensíveis influencia a escolha de aplicativos móveis. A metodologia é o estudo de aplicativos disponíveis em lojas virtuais para celulares através de técnicas qualitativas e quantitativas. Os resultados indicam que os produtos mais populares da loja são aqueles que coletam mais dados pessoais. Porém, em uma análise minuciosa, observa-se que aqueles mais buscados também pertencem a empresas de boa reputação e possuem mais funcionalidades, que exigem maior acesso aos dados privativos do celular. Na survey realizada em seguida, nota-se que os consumidores reduzem o uso dos aplicativos quando consideram que o produto coleta dados excessivamente, mas a estratégia para proteger essas informações pode variar. No grupo dos usuários que usam aplicativos que coletam dados excessivamente, conclui-se que o motivo primordial para compartilhar informações pessoais são as funcionalidades. Além disso, esta pesquisa confirma que comparar os dados solicitados pelos aplicativos com a expectativa inicial do consumidor é um constructo complementar para avaliar preocupações com privacidade, ao invés de simplesmente analisar a quantidade de informações coletadas. O processo desta pesquisa também ilustrou que, dependendo do método utilizado para análise, é possível chegar a resultados opostos sobre a ocorrência ou não do paradoxo. Isso pode dar indícios sobre os motivos da falta de consenso sobre o assunto

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This paper proposes an architecture for pervasive computing which utilizes context information to provide adaptations based on vertical handovers (handovers between heterogeneous networks) while supporting application Quality of Service (QoS). The future of mobile computing will see an increase in ubiquitous network connectivity which allows users to roam freely between heterogeneous networks. One of the requirements for pervasive computing is to adapt computing applications or their environment if current applications can no longer be provided with the requested QoS. One of possible adaptations is a vertical handover to a different network. Vertical handover operations include changing network interfaces on a single device or changes between different devices. Such handovers should be performed with minimal user distraction and minimal violation of communication QoS for user applications. The solution utilises context information regarding user devices, user location, application requirements, and network environment. The paper shows how vertical handover adaptations are incorporated into the whole infrastructure of a pervasive system

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In this paper, experimental investigations are performed into assessing the quality of communication link between Bluetooth devices in an indoor environment, as an initial step of demonstrating benefits of diversity and smart antenna techniques in mobile computing.

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Dedicated short range communications (DSRC) has been regarded as one of the most promising technologies to provide robust communications for large scale vehicle networks. It is designed to support both road safety and commercial applications. Road safety applications will require reliable and timely wireless communications. However, as the medium access control (MAC) layer of DSRC is based on the IEEE 802.11 distributed coordination function (DCF), it is well known that the random channel access based MAC cannot provide guaranteed quality of services (QoS). It is very important to understand the quantitative performance of DSRC, in order to make better decisions on its adoption, control, adaptation, and improvement. In this paper, we propose an analytic model to evaluate the DSRC-based inter-vehicle communication. We investigate the impacts of the channel access parameters associated with the different services including arbitration inter-frame space (AIFS) and contention window (CW). Based on the proposed model, we analyze the successful message delivery ratio and channel service delay for broadcast messages. The proposed analytical model can provide a convenient tool to evaluate the inter-vehicle safety applications and analyze the suitability of DSRC for road safety applications.

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The performance of wireless networks is limited by multiple access interference (MAI) in the traditional communication approach where the interfered signals of the concurrent transmissions are treated as noise. In this paper, we treat the interfered signals from a new perspective on the basis of additive electromagnetic (EM) waves and propose a network coding based interference cancelation (NCIC) scheme. In the proposed scheme, adjacent nodes can transmit simultaneously with careful scheduling; therefore, network performance will not be limited by the MAI. Additionally we design a space segmentation method for general wireless ad hoc networks, which organizes network into clusters with regular shapes (e.g., square and hexagon) to reduce the number of relay nodes. The segmentation methodworks with the scheduling scheme and can help achieve better scalability and reduced complexity. We derive accurate analytic models for the probability of connectivity between two adjacent cluster heads which is important for successful information relay. We proved that with the proposed NCIC scheme, the transmission efficiency can be improved by at least 50% for general wireless networks as compared to the traditional interference avoidance schemes. Numeric results also show the space segmentation is feasible and effective. Finally we propose and discuss a method to implement the NCIC scheme in a practical orthogonal frequency division multiplexing (OFDM) communications networks. Copyright © 2009 John Wiley & Sons, Ltd.

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This paper attempts to address the effectiveness of physical-layer network coding (PNC) on the capacity improvement for multi-hop multicast in random wireless ad hoc networks (WAHNs). While it can be shown that there is a capacity gain by PNC, we can prove that the per session throughput capacity with PNC is ? (nR(n))), where n is the total number of nodes, R(n) is the communication range, and each multicast session consists of a constant number of sinks. The result implies that PNC cannot improve the capacity order of multicast in random WAHNs, which is different from the intuition that PNC may improve the capacity order as it allows simultaneous signal reception and combination. Copyright © 2010 ACM.