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Proposta de roteamento plano baseado em uma métrica de OU-Exclusivo e visibilidade local; A flat routing proposal based on the XOR metric and local visibility

Rafael Pasquini
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 06/06/2011 Português
Relevância na Pesquisa
35.76%
Roteamento é uma das principais funções em redes de computadores, sendo responsável pelo encaminhamento de tráfego entre todos os pares de nós de origem e destino. O princípio de roteamento comum a protocolos usados mundialmente requer a presença de informação sobre todos os destinos disponíveis, em todos os roteadores compondo a rede, de tal forma a garantir a entrega de tráfego. Desta forma, construir redes em grande escala usando tal princípio de roteamento é amplamente aceito como não escalável. O problema intrínseco destes mecanismos está relacionado ao fato de que as tabelas de roteamento acompanham o crescimento da informação de roteamento presente na rede. Por outro lado, existem mecanismos de roteamento disponíveis na literatura que requerem apenas uma fração de toda a informação de roteamento presente na rede, provendo um melhor controle para a taxa à qual as tabelas de roteamento crescem. Neste cenário, um espaço de identificação plano é usado para identificar, univocamente, todos os nós presentes na rede e relações de vizinhança no espaço de identificação plano são estabelecidas através de uma rede sobreposta, construída sob um substrato de rede, como, por exemplo, uma rede IP. Entretanto...

The need for standardized tests to evaluate the reliability of data transport in wireless medical systems

Fernández-López, Helena; Afonso, José A.; Correia, J. H.; Simões, Ricardo
Fonte: Springer - Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering Publicador: Springer - Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering
Tipo: Conferência ou Objeto de Conferência
Publicado em /06/2012 Português
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Wireless medical systems are comprised of four stages, namely the medical device, the data transport, the data collection and the data evaluation stages. Whereas the performance of the first stage is highly regulated, the others are not. This paper concentrates on the data transport stage and argues that it is necessary to establish standardized tests to be used by medical device manufacturers to provide comparable results concerning the communication performance of the wireless networks used to transport medical data. Besides, it suggests test parameters and procedures to be used to produce comparable communication performance results.; Fundação para a Ciência e a Tecnologia (FCT); Grupo AMI – Assistência Médica Integral (Casa de Saúde Guimarães, SA)

Communication between nodes for autonomic and distributed management

Guardalben, Lucas
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
35.77%
Over the last decade, the most widespread approaches for traditional management were based on the Simple Network Management Protocol (SNMP) or Common Management Information Protocol (CMIP). However, they both have several problems in terms of scalability, due to their centralization characteristics. Although the distributed management approaches exhibit better performance in terms of scalability, they still underperform regarding communication costs, autonomy, extensibility, exibility, robustness, and cooperation between network nodes. The cooperation between network nodes normally requires excessive overheads for synchronization and dissemination of management information in the network. For emerging dynamic and large-scale networking environments, as envisioned in Next Generation Networks (NGNs), exponential growth in the number of network devices and mobile communications and application demands is expected. Thus, a high degree of management automation is an important requirement, along with new mechanisms that promote it optimally and e ciently, taking into account the need for high cooperation between the nodes. Current approaches for self and autonomic management allow the network administrator to manage large areas, performing fast reaction and e ciently facing unexpected problems. The management functionalities should be delegated to a self-organized plane operating within the network...

A Survey on the Taxonomy of Cluster-Based Routing Protocols for Homogeneous Wireless Sensor Networks

Naeimi, Soroush; Ghafghazi, Hamidreza; Chow, Chee-Onn; Ishii, Hiroshi
Fonte: Molecular Diversity Preservation International (MDPI) Publicador: Molecular Diversity Preservation International (MDPI)
Tipo: Artigo de Revista Científica
Publicado em 30/05/2012 Português
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The past few years have witnessed increased interest among researchers in cluster-based protocols for homogeneous networks because of their better scalability and higher energy efficiency than other routing protocols. Given the limited capabilities of sensor nodes in terms of energy resources, processing and communication range, the cluster-based protocols should be compatible with these constraints in either the setup state or steady data transmission state. With focus on these constraints, we classify routing protocols according to their objectives and methods towards addressing the shortcomings of clustering process on each stage of cluster head selection, cluster formation, data aggregation and data communication. We summarize the techniques and methods used in these categories, while the weakness and strength of each protocol is pointed out in details. Furthermore, taxonomy of the protocols in each phase is given to provide a deeper understanding of current clustering approaches. Ultimately based on the existing research, a summary of the issues and solutions of the attributes and characteristics of clustering approaches and some open research areas in cluster-based routing protocols that can be further pursued are provided.

Improving the reliability and performance of real-time communications in mobile ad hoc networks

Numanoglu, Tolga ; Heinzelman, Wendi
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xvi, 182 leaves
Português
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Thesis (Ph. D.)--University of Rochester. Dept. of Electrical and Computer Engineering, 2009.; Mobile ad-hoc networks (MANETs) are expected to provide certain levels of Quality of Service (QoS) under varying wireless channel capacity and noise constraints. These noisy and varying channel conditions make it difficult to provide reliable and efficient real-time communication in MANETs. In this thesis, we explore three techniques to enable better utilization of mobile ad hoc networks under varying channel conditions: (1) employing a sufficient level of coordination among the nodes, (2) using a superposed coding scheme to provide multiple data rates for users with different channel capacities through a single transmission, and (3) utilizing a mesh networking inspired multicasting approach to vary the amount of redundancy in the routing process to overcome the performance loss due to channel errors. Specifically, we explore the effects of channel noise on different types of mobile ad-hoc networking protocols when channel capacities vary dynamically due to the unpredictable nature of the wireless channel. Our work shows that utilizing coordination among the nodes in MANETs leads to better throughput and energy efficiency for the network while maintaining acceptable packet delay as imposed by the application...

Delta Send-Recv: Run-time Support for Dynamic Pipelining of Coarse-grained Computation and Communication

Bao, Bin (1982 - ); Ding, Chen (1970 - ); Gao, Yaoqing ; Archambaul, Roch
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
Português
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The paper presents delta send-recv, an MPI extension for overlapping coarse-grained computation and communication. It provides an interface for marking the data computation and its communication. It automatically blocks computation and divides communication into increments. Delta sends and recvs are dynamically chained to effect sender-receiver pipelining, which is superior to pipelining only at the sender or the receiver side. The evaluation uses kernel tests to find the best increment size for different MPI implementations and types of machines and networks. It shows 2 to 3 times performance improvement for large-volume data reduce involving 16 or 32 processors. In addition, the new interface enables computation and communication pipelining in an interpreted programming language, Rmpi.

As novas tecnologias da comunicação e as formas de participação política; New communication technologies and forms of political participation

Tavares, Laura dos Santos
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Comunicação (FIC); Faculdade de Informação e Comunicação - FIC (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Comunicação (FIC); Faculdade de Informação e Comunicação - FIC (RG)
Tipo: Dissertação Formato: application/pdf
Português
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Increasingly, initial conceptions about political practice are adapting to the new realities in which not only the mass media, as well as new virtual medial play vital role in forming the opinions, values and preferences of individuals. This research aims to analyze the new communication technologies as a new public sphere, where participation and political action can take place directly and contribute to the leveling of power. In times media, the conditions under which they develop the theory and practice of politics undergo abrupt changes as regards the forms of sociability and the streamlining and strengthening of interactions between individuals with the advent of new communication technologies. This dissertation proposes a discussion on the relevance of the aspects and processes of social and political discussions made possible by new communication technologies, especially social networks, and more specifically Twitter. Reflect until this point in the discussion and broadening popular participation in political life contributes for the emergence of a new democratic system where the citizen has a communication channel to interact less complicated and even charge actions of the ruling elite. We sought to examine whether these new forms of mediated interaction...

Participatory Communication : A Practical Guide

Tufte, Thomas; Mefalopulos, Paolo
Fonte: World Bank Publicador: World Bank
Português
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Many communication practitioners and development workers face obstacles and challenges in their practical work. A participatory communication strategy offers a very specific perspective on how to articulate social processes, decision-making processes, and any change process for that matter. Participatory approaches are nothing new. However, what is new is the proliferation of institutions, especially governmental but also nongovernmental organizations (NGOs) that seek participatory approaches in their development initiative. This guide concerns to provide perspectives, tools and experiences regarding how to go about it with participatory communication strategies. It is conceived as a guide to be of relevance and utility for development workers in the field. It is targeted at both at government and their officials, the World Bank staff, and at civil society. The particular relevance of this guide is three-fold: 1) placing the practitioner debate about participatory communication within a conceptual framework...

Challenges and Opportunities of Mobile Phone-Based Data Collection : Evidence from South Sudan

Demombynes, Gabriel; Gubbins, Paul; Romeo, Alessandro
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
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The proliferation of mobile phones in developing countries has generated a wave of interest in collecting high-frequency socioeconomic surveys using this technology. This paper considers lessons from one such survey effort in a difficult environment -- the South Sudan Experimental Phone Survey, which gathered data on living conditions, access to services, and citizen attitudes via monthly interviews by phones provided to respondents. Non-response, particularly in later rounds of the survey, was a substantial problem, largely due to erratic functioning of the mobile network. However, selection due to non-response does not appear to have markedly affected survey results. Response rates were much higher for respondents who owned their own phones. Both compensation provided to respondents in the form of airtime and the type of phone (solar-charged or traditional) were varied experimentally. The type of phone was uncorrelated with response rates and, contrary to expectation, attrition was slightly higher for those receiving the higher level of compensation. The South Sudan Experimental Phone Survey experience suggests that mobile phones can be a viable means of data collection for some purposes...

Advancing Development with Mobile Phone Locational Data

Haddad, Ryan; Kelly, Timothy; Leinonen, Teemu; Saarinen, Vesa
Fonte: World Bank Group, Washington, DC Publicador: World Bank Group, Washington, DC
Tipo: Brief
Português
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Mobile phones, and especially smartphones, are opening new ways to assess and improve assistance and the delivery of basic services in the developing world. Each year, developing countries see an annual gain of about 500 million new smartphones, virtually all of which generate not only call data records but also, with their GPS and Wi-Fi capabilities, a rich set of more precise data on location and movement. The rapid diffusion of the phones and the locational data they generate are helping fuel the science of delivery, the evidence-based, experimental approach to project assessment and improvement. The technology is finding an expanding variety of uses. Recent examples involving transport and logistics include: transit route mapping in Abidjan; supply chain management for community health workers in Malawi; transport planning in Cote d’Ivoire; and malaria tracking in Kenya. A notable and more impromptu use arose after a tsunami hit Japan in March 2011. Health care authorities used call data records (CDRs) generated by mobile phones to track the evacuation from the vicinity of the damaged Fukushima nuclear power plant. They then meshed the CDRs with health records to optimize the delivery of needed emergency health treatment.

Cyclostationary Feature Analysis of CEN-DSRC for Cognitive Vehicular Networks

SITHAMPARANATHAN Kandeepan; BALDINI Gianmarco; DIETER Smely
Fonte: IEEE Publicador: IEEE
Tipo: Contributions to Conferences Formato: Online
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Cognitive vehicular networks provide the necessary intelligence for vehicular communication networks in order to optimally utilize the limited resources and maximize the performance. One of the important functions of cognitive networks is to learn the radio environment by means of detecting and identifying existing radios. In this context we use the cyclostationarity features of dedicated short range communication (DSRC) signals to blindly detect them in the environment. We present experimental results on the cyclostationarity properties of DSRC wireless transmissions considering the CEN (European) standards for both uplink and downlink signals. By performing cyclostationarity analysis we compute the cyclic power spectrum (CPS) of the CEN DSRC signals which is then used for detecting the presence of the CEN DSRC radios. We obtain CEN DSRC signals from experiments and use the recorded data to perform post-signal analysis to determine the detection performance. The probability of false alarm and the probability of missed detection are computed and the results are presented for different detection strategies. Results show that the cyclostationarity feature based detection can be robust compared to the well known energy based technique for low signal to noise ratio levels.; JRC.G.7-Digital Citizen Security

The framework for an integrated defense communication network for the Republic of China Armed Forces.

Wang, Yu-Lin.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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This thesis discusses communication systems currently in use by the Republic of China (R.O.C.) Armed Forces and explores ways that the R.O.C. may increase the capability of its national defense by improving current communication networks. Modern network communication and components techniques such as digital data transmission, network protocols, network topologies, switching technologies, and transmission media are discussed. The U.S. Defense Data Network (DDN) is used as a model for a successful military network. The DDN technology and Integrated Services Digital Network (ISDN) standards are combined with concepts from modern communication technologies to develop the conceptual framework for a proposed Integrated Defense Communication Network (IDCN) for the R.O.C. Armed Forces. This framework is intended for use by the R.O.C. Department of Defense in establishing a nation-wide communication system that will improve its administration management, logistic supply, intelligence collection, and auxiliary tactical communication capabilities.

Dynamic multicommodity flow schedules

Feit, Adam
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
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35.77%
Some new results in the scheduling of dynamic multicommodity flows in data communication networks are presented. A new performance measure for effective delivery of backlogged data to their destinations is defined and the solution to the resulting delivery problem is obtained through a sequential linear optimization methodology. Properties of an optimal dynamic multicommodity flow schedule are studied in detail, taking advantage where possible of the linear programming formulation. The special case of the delivery problem in a single destination network also is analyzed. Application of the results to stochastic delivery problems in which the data inputs to the network are modelled as Poisson processes is addressed, and a new dynamic data communication network analysis is presented. Finally, the delivery problem on networks with capacitated links and with traversal delays is considered and some new results obtained

Synchronization Landscapes in Small-World-Connected Computer Networks

Guclu, H.; Korniss, G.; Novotny, M. A.; Toroczkai, Z.; Racz, Z.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
35.78%
Motivated by a synchronization problem in distributed computing we studied a simple growth model on regular and small-world networks, embedded in one and two-dimensions. We find that the synchronization landscape (corresponding to the progress of the individual processors) exhibits Kardar-Parisi-Zhang-like kinetic roughening on regular networks with short-range communication links. Although the processors, on average, progress at a nonzero rate, their spread (the width of the synchronization landscape) diverges with the number of nodes (desynchronized state) hindering efficient data management. When random communication links are added on top of the one and two-dimensional regular networks (resulting in a small-world network), large fluctuations in the synchronization landscape are suppressed and the width approaches a finite value in the large system-size limit (synchronized state). In the resulting synchronization scheme, the processors make close-to-uniform progress with a nonzero rate without global intervention. We obtain our results by ``simulating the simulations", based on the exact algorithmic rules, supported by coarse-grained arguments.; Comment: 20 pages, 22 figures

Improving Data Forwarding in Mobile Social Networks with Infrastructure Support: A Space-Crossing Community Approach

Li, Zhong; Wang, Cheng; Yang, Siqian; Jiang, Changjun; Stojmenovic, Ivan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 27/07/2013 Português
Relevância na Pesquisa
35.78%
In this paper, we study two tightly coupled issues: space-crossing community detection and its influence on data forwarding in Mobile Social Networks (MSNs) by taking the hybrid underlying networks with infrastructure support into consideration. The hybrid underlying network is composed of large numbers of mobile users and a small portion of Access Points (APs). Because APs can facilitate the communication among long-distance nodes, the concept of physical proximity community can be extended to be one across the geographical space. In this work, we first investigate a space-crossing community detection method for MSNs. Based on the detection results, we design a novel data forwarding algorithm SAAS (Social Attraction and AP Spreading), and show how to exploit the space-crossing communities to improve the data forwarding efficiency. We evaluate our SAAS algorithm on real-life data from MIT Reality Mining and UIM. Results show that space-crossing community plays a positive role in data forwarding in MSNs in terms of deliver ratio and delay. Based on this new type of community, SAAS achieves a better performance than existing social community-based data forwarding algorithms in practice, including Bubble Rap and Nguyen's Routing algorithms.

Dynamic Localization Protocols for Mobile Sensor Networks

Tilak, Sameer; Kolar, Vinay; Abu-Ghazaleh, Nael B.; Kang, Kyoung-Don
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 18/08/2004 Português
Relevância na Pesquisa
35.78%
The ability of a sensor node to determine its physical location within a network (Localization) is of fundamental importance in sensor networks. Interpretating data from sensors will not be possible unless the context of the data is known; this is most often accomplished by tracking its physical location. Existing research has focused on localization in static sensor networks where localization is a one-time (or low frequency) activity. In contrast, this paper considers localization for mobile sensors: when sensors are mobile, localization must be invoked periodically to enable the sensors to track their location. The higher the frequency of localization, the lower the error introduced because of mobility. However, localization is a costly operation since it involves both communication and computation. In this paper, we propose and investigate adaptive and predictive protocols that control the frequency of localization based on sensor mobility behavior to reduce the energy requirements for localization while bounding the localization error. We show that such protocols can significantly reduce the localization energy without sacrificing accuracy (in fact, improving accuracy for most situations). Using simulation and analysis we explore the tradeoff between energy efficiency and localization error due to mobility for several protocols.; Comment: 10 Pages

The persistence of social signatures in human communication

Saramaki, J.; Leicht, E. A.; Lopez, E.; Roberts, S. G. B.; Reed-Tsochas, F.; Dunbar, R. I. M.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Português
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35.78%
The social network maintained by a focal individual, or ego, is intrinsically dynamic and typically exhibits some turnover in membership over time as personal circumstances change. However, the consequences of such changes on the distribution of an ego's network ties are not well understood. Here we use a unique 18-month data set that combines mobile phone calls and survey data to track changes in the ego networks and communication patterns of students making the transition from school to university or work. Our analysis reveals that individuals display a distinctive and robust social signature, captured by how interactions are distributed across different alters. Notably, for a given ego, these social signatures tend to persist over time, despite considerable turnover in the identity of alters in the ego network. Thus as new network members are added, some old network members are either replaced or receive fewer calls, preserving the overall distribution of calls across network members. This is likely to reflect the consequences of finite resources such as the time available for communication, the cognitive and emotional effort required to sustain close relationships, and the ability to make emotional investments.; Comment: Revised version...

Tele-cardiology sensor networks for remote ECG monitoring

Jiang, Meng
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado Formato: 3506781 bytes; application/pdf
Português
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One of today’s most pressing matters in medical care is the response time to patients in need. The scope of this thesis is to suggest a solution that would help reduce response time in emergency situations utilizing wireless sensor networks technology. Wireless sensor network researches have recently gained unprecedented momentum in both industries and academia, especially its potential applications in Emergency Medical Services and Intensive Care Units. The enhanced power efficiency, minimized production cost, condensed physical layout, as well as reduced wired connections, presents a much more proficient and simplified approach to the continuous monitoring of patients’ physiological status. This thesis focuses on the areas of remote ECG feature extraction utilizing wavelet transformation concepts and sensor networks technology. The proposed sensor network system provides the following contributions. The low-cost, low-power wearable platforms are to be distributed to patients of concern and will provide continuous ECG monitoring by measuring electrical potentials between various points of the body using a galvanometer. The system is enabled with integrated RF communication capability that will relay the signals wirelessly to a workstation monitor. The workstation is equipped with ECG signal processing software that performs ECG characteristic extractions via wavelet transformation. Lastly...

RFID-Assisted wireless sensor networks for cardiac tele-healthcare

Celentano, Laura J.
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
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As the baby boomers head into old age, America will see a dramatic increase in the number of elderly patients admitted to healthcare facilities, such as nursing homes. Due to this rising elderly population, it will be difficult for nursing home personnel to monitor all patients at once. One way to cut down on the amount of supervision by the staff is for patients to administer their own medication. This leads to new problems though, as a patient incorrectly administering one of their many medications could lead to a disastrous end. Technology to wirelessly transmit a patient’s electrocardiogram (ECG) has also been implemented to reduce supervision. Wireless transmissions are infamous for their error rate, but the ECG is a sensitive signal where every second of data matters and cannot tolerate such losses. Additionally, such existing networks employ an expensive communication infrastructure. Due to this healthcare crisis, the ability for a device to remotely monitor a patient’s medication intake and transmit accurate ECG readings, while being cost efficient, is a major innovation. To combat this crisis, this thesis focuses on a multi-hop wireless sensor network (WSN) composed of many wearable sensors, one for each patient, that host a radio frequency identification (RFID) reader and are capable of RF communication. Each wearable device is also assumed to contain an ECG sensor...

Exploiting Redundancy for Secure Data Dissemination in Wireless Sensor Networks

Palafox,Luis E.; García Macías,J. Antonio
Fonte: Centro de Investigación en computación, IPN Publicador: Centro de Investigación en computación, IPN
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 Português
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Monitoring the environment is one of the main applications of wireless sensor networks. Given that these networks are densely populated and that local variations in the environmental variables are small, a large amount of redundant data is generated by sensor nodes. In this paper we present a protocol for data dissemination in hierarchical clustered sensor networks that integrates security and reduces communication overhead by removing data redundancy from the network. Furthermore, we show that by using our protocol we can provide security to the network without spending additional energy resources, particularly when we are dealing with high levels of redundancy. Additionally, a military monitoring application is introduced as a case study to evaluate the functionality of our protocol.