Página 1 dos resultados de 5 itens digitais encontrados em 0.010 segundos

Cooperative positioning for heterogeneous wireless systems; Posicionamento cooperativo para redes sem fios heterogéneas

Hadzic, Senka
Fonte: Universidade de Aveiro Publicador: Universidade de Aveiro
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
512.77285%
Future emerging market trends head towards positioning based services placing a new perspective on the way we obtain and exploit positioning information. On one hand, innovations in information technology and wireless communication systems enabled the development of numerous location based applications such as vehicle navigation and tracking, sensor networks applications, home automation, asset management, security and context aware location services. On the other hand, wireless networks themselves may bene t from localization information to improve the performances of di erent network layers. Location based routing, synchronization, interference cancellation are prime examples of applications where location information can be useful. Typical positioning solutions rely on measurements and exploitation of distance dependent signal metrics, such as the received signal strength, time of arrival or angle of arrival. They are cheaper and easier to implement than the dedicated positioning systems based on ngerprinting, but at the cost of accuracy. Therefore intelligent localization algorithms and signal processing techniques have to be applied to mitigate the lack of accuracy in distance estimates. Cooperation between nodes is used in cases where conventional positioning techniques do not perform well due to lack of existing infrastructure...

Exploration and analysis of sensor technologies for efficient indoor location-based services; Erfoschung und Analyse von Senortechnologien fuer die Implementierung effizienter Dienste zur Positionsbestimmung innerhalb Gebaeuden

Subramanian, Ponmalar Suguna
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
713.4152%
In recent years, there is a mounting obligation for indoor location based services Comparable to outdoor location based services . Indoor guidance systems provide ample utilities to a user explicitly huge complex at shopping malls , hospitals and at vast libraries for any directed assistance. Pedestrian navigation is one such promising indoor location based service. Localization remains a basis for all location based services . Although, few pedestrian -based indoor localization are systems available in market , they lack either one of the attributes as such accuracy, reliability, scalability and / or expensive. GPS is not meant for indoors and even if so used at indoors , its relatively weak signal still stay a hurdle for any indoor location based services . In this dissertation , the aim is to build an efficient and precise indoor localization approach that can be implemented for most of the large indoor environments. The projected approach in this study incomparable to GPS that works outdoors will, remain eminently than other available indoor localization based approaches. All prerequisite for efficient localization such as accuracy, reliability, scalability, flexibility, availability, cost efficiency , minimum latency and robustness were evaluated reconstructed for this approach that is herewith demonstrated in my dissertation. The dissertation is structured as various chapters . Each of the chapter in this dissertation portrays novel methods utilizing major sensor technologies such as Bluetooth...

A framework for cooperative localization in ultra-wideband wireless networks

Lien, Jaime
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 93 p.
Português
Relevância na Pesquisa
498.4458%
Location-aware technologies have the potential to revolutionize computing, cellular services, sensor networks, and many other commercial, military, and social applications. In wireless networks, accurate information about an agent's location can give meaning to observed data and facilitate the agent's interactions with its surroundings and neighbors. Determining the location of one or more agents, known as localization or positioning, is a fundamental challenge. Most existing localization methods rely on existing infrastructure and hence lack the flexibility and robustness necessary for large ad-hoc networks. In this thesis, we describe a framework for localization that overcomes these limitations by utilizing cooperation: the agents in the network work together to determine their individual locations. We derive a practical algorithm for cooperative localization by formulating the problem as a factor graph and applying the sum-product algorithm. Each agent uses relative positioning measurements and probabilistic location information from its neighbors to iteratively update its location estimate. We investigate the performance of this algorithm in a network of ultra-wideband (UWB) nodes, which are well-suited for localization due to their potential to measure inter-node distances with high accuracy. Realistic models of UWB ranging error...

A Localization Method for the Internet of Things

Chen, Zhikui; Xia, Feng; Huang, Tao; Bu, Fanyu; Wang, Haozhe
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/12/2011 Português
Relevância na Pesquisa
514.2178%
Many localization algorithms and systems have been developed by means of wireless sensor networks for both indoor and outdoor environments. To achieve higher localization accuracy, extra hardware equipments are utilized by most of the existing localization solutions, which increase the cost and considerably limit the location-based applications. The Internet of Things (IOT) integrates many technologies, such as Internet, Zigbee, Bluetooth, infrared, WiFi, GPRS, 3G, etc, which can enable different ways to obtain the location information of various objects. Location-based service is a primary service of the IOT, while localization accuracy is a key issue. In this paper, a higher accuracy localization scheme is proposed which can effectively satisfy diverse requirements for many indoor and outdoor location services. The proposed scheme composes of two phases: 1) partition phase, in which the target region is split into small grids; 2) localization refinement phase, in which a higher accuracy of localization can be obtained by applying an algorithm designed in the paper. A trial system is set up to verify correctness of the proposed scheme and furthermore to illustrate its feasibility and availability. The experimental results show that the proposed scheme can improve the localization accuracy.; Comment: To appear in Journal of Supercomputing. arXiv admin note: substantial text overlap with arXiv:1011.3097

Architecture for multi-technology real-time location systems

Rodas González, Javier
Fonte: Universidade da Corunha Publicador: Universidade da Corunha
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
551.7036%
[Abstract] Indoor localization is a problem that has generated much interest in recent years. Proximity marketing, eHealth, smart-parking and smart-cities, security and emergency units, logistics management, or industrial control systems are some pf the sectors that have demanded new Location Based Services (LBSs). These services are usually implemented using Wireless Sensor Networks (WSNs), capable of transmitting and receiving Radio Frequency (RF) signals in order to locate mobile devices attached to vehicles, people, or animals. While systems based on satellite systems such as GPS work correctly in outdoor scenarios, indoor localization is still a challenging field of study. On one hand, signal propagation problems are common, not only due to reflections and scattering due to the building structures, but also because of signal attenuation and fading caused mainly by people in movement. To overcome these issues, most of the approaches use several WSNs with a combination of multiple wireless technologies, such asWiFi, ZigBee or Bluetooth, some of them also available in mobile devices such as smartphones and tablets. On the other hand, data received from multiple devices must be filtered and combined by means of location algorithms and techniques in order to obtain precise and robust Real-Time Location Systems (RTLSs). Therefore...