• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 105
  • 78
  • 31
  • 30
  • 27
  • 17
  • 11
  • 10
  • 9
  • 9
  • 7
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 364
  • 70
  • 53
  • 44
  • 41
  • 39
  • 37
  • 30
  • 29
  • 29
  • 28
  • 27
  • 27
  • 25
  • 24
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Handover Optimization in GSM

Pavski, Johann Joachim January 2015 (has links)
In telecommunications in general and in GSM in particular, the handover is a feature that guarantees a smooth transition of a call from one base station - that is for the purpose of this project an antenna - to another. In the recent ten years, the amount of data traffic through mobile telecommunications has doubled annually, putting an enormous strain on the network and forcing operators to upgrade with more and more base stations and new features. Although 3G and 4G are responsible for data traffic in most countries, GSM still provides more than 80% of the coverage for mobile devices around the world. Due to the increase in data traffic, 3G and 4G need to use more and more frequencies at the expense of GSM. An optimization of the GSM network is thus vital. In this project, we research two methods to automatically choose the parameters of interest (PoI) that govern the handover feature in each cell which is, roughly speaking, the area of coverage of one antenna. In one of these methods, the choice of cell- and cell-to-cell-specific parameters has its origins in control theory while the other method is based on mathematical optimization. In the mathematical sense, our goal is to optimize the quality of service over PoIs. Extensive simulations have been run using these PoIs in order to evaluate if and how the two different methods can effectively be used in reality. Several useful insights have been gained that will provide the basis for future work. The optimization approach in particular has proved to deliver good results within the limitations of the simulated environment used for testing.
182

Implicit Channel Allocation in GSM/EDGE radio networks

Leiviskä, Emily January 2012 (has links)
Efficient channel allocation in GSM communication is difficult and believed to be a performance bottleneck. This thesis is dedicated to studying the performance of GSM/EDGE networks in modern usage scenarios (surfing the web, chatting and streaming services) under the assumption that explicit channel allocation is not needed. Users are able to be (re-)allocated at any time without explicit signaling and the typically associated delay. The radio hardware of these users is identical to that of typically used devices and the theoretical peak performance is not affected. This allows the network to use the radio channels in a more efficiently way and the delays from signaling are reduced or eliminated. The thesis studies this problem by statistically modeling such usage scenarios and the resulting channel utilization patterns. The study finds that the latency can be reduced by 40-70% for typical radio hardware, and that network throughput can be improved by up to 20%. However, further studies are needed on the subject.
183

A simulation framework for service continuity over multi access wireless networks

Abuhaija, Belal Saleh January 2010 (has links)
Mobile communication systems have continued to evolve by the release of new standards for HSPA and the release of new standards for LTE in release 8 and release 9. The new releases aim at providing higher data rates to accommodate the envisioned services of 3GPP in voice, data, image transmission, video, multimedia service and broadband services. Catering for a wide variety of services to satisfy the demands imposed on mobile networks by the user diversity and demanding applications, the air interface has been identified as the major bottleneck in the mobile networks. Network planning engineers and operators are deploying the new air interfaces in the same cell sites, which gives rise to several internetworking issues among the different air interfaces from radio resources management to service call continuity issues due to user's mobility and changing point of attachment. Deployment of different air interfaces coupled with traffic diversity requests further complicates the managements of the mobile networks. One of The main objectives of this research is to propose and evaluate solutions that address the internetworking of the different radio air interfaces in proposing a call admission control algorithm that can utilize different air interfaces capabilities and to determine which traffic types are better suited to be serviced by an interface. The proposed algorithm will consider the availability of the interface, the load of the network and the user equipment capabilities. Another main objective of this research is to propose and evaluate solutions that address changing the point of attachment of the users due to mobility in the form of handover algorithm. The proposed algorithm will consider the coverage of the node, direction and speed of the user, the network load, the air interface availability and the user equipment capabilities. Another main objective of this research is to design and implement a simulation system which includes all 3GPP standardized technologies. The simulation tool was designed as a discrete event simulation (DBS) system which includes all the standardized air interface technologies and services. The simulation tool was designed using Visual C# to take advantage of the object oriented capabilities of the Windows environment and libraries. The simulation tool was essential in evaluating the proposed algorithms in the first two objectives.
184

Vliv dynamiky klimatických a stanovištních podmínek na změny početnosti a migračního chováni zimujících a migrujících vodních ptáků / Effect of climatic and environmental variables on changes in numbers and migratory behaviour of wintering and migrating waterbirds.

Adam, Matyáš January 2016 (has links)
Waterbirds with their specific habitat and food requirements varying during their annual cycle (Riffell et al. 2003; Taft and Haig 2006) are able to indicate the wetland diversity and quality due to their rapid responses on changes in environment (Delany 1999; Fernández et al. 2005; Amat and Green 2010). Remarkable land cover changes and climate warming led to significant shifts in distribution and abundance of many waterbird species across Europe in recent decades (Delany et al. 2006; Fox et al. 2010; Lehikoinen et al. 2013; Pavón-Jordán et al. 2015). To understand the dynamic of migratory birds in space and time and to assess effects of global conditions as well as local conditions of individual sites during their annual cycle there is need of international monitoring and research. Since the start of International Waterbird Census in 1967 both increasing and decreasing trends have been recorded in nearly fifty percent of waterbird species in Western Palearctic (Delany et al. 2006, Wetlands International 2016) and they consequently have affected trends in particular countries, including the Czech Republic. Wetland sites in the Czech Republic are generally situated on the edge of wintering range of most waterbird species (Gilissen et al. 2002), however the prevailing increase in abundance of waterbird species has been recorded here in recent decades (Musil et al. 2011). Though, the considerable growth of winter temperatures has not been noticed in the Czech Republic (Klein Tank et al. 2002; Musilová et al. 2009; Dušek et al. 2013), and the accessibility of the wetland sites, due to their freezing, varies year to year. Hence, we can assume that waterbirds have likely began using the alternative habitats with available food resources, i.e. cold-weather refuges, probably regardless of their conservation status (Musilová et al. 2015). Special protection areas were implemented to Czech legislation in 2004 to protect migratory birds (Birds Directive 2009/147/EC). So far there has not been tested the effectivity and impact of legislative protection on wintering waterbird species. Moreover, some previous studies indicated that SPA network do not match the species distribution pattern (López-López et al. 2007; Briggs et al. 2012; Albuquerque et al. 2013), so this issue urgently calls for scientific research. The second part of the thesis focused on Greylag Geese, whose abundance has rapidly grown across the Europe in recent decades (Madsen et al. 1999; Fox et al. 2010), and that have become ideal model species to observe their responses to habitats and climate changes as well as their reactions to human disturbance (Fox and Madsen 1997; Ramo et al. 2015). This requires appropriate knowledge of geese distribution, abundance and their behaviour. Since 1930s, when the geese started to be ringed in the Czech Republic, the ringing intensity have markedly varied and have been reflected in numbers of recoveries. In last ten years the intensity have increased (Podhrazský 2010). However, complex of the historical data until 2002 (Cepák et al. 2008) and recent data have not been analysed so far. In the light of recent shifts in wintering ranges and migration phenology of many goose populations these analyses require increased attention. Furthermore, the satellite monitoring of geese is coming to detect more detailed information about behaviour of individuals.
185

Desenvolvimento de um protótipo veicular destinado às atividades de campo

Vist, Helio Larri January 2007 (has links)
O Sistema de Posicionamento Global (GPS) permite uma grande variedade de aplicações civis e militares. Dentre as várias aplicações, uma de especial interesse é a navegação, que tem crescido muito nos últimos anos devido a fatores como menor custo, e fácil utilização desta tecnologia. Num sistema de navegação terrestre, assim como na navegação marítima, fluvial e aérea, um mapa digitalizado, ou imagem de satélite disponível da região de interesse é exibida na tela do computador de bordo e a posição do veículo é apresentada em "tempo real" a partir da posição fornecida por receptores GPS. Além disso, a comunicação disponível nos dias de hoje permite uma maior integração entre o veículo e o escritório. Finalmente, o Google Earth permite que se tenha acesso a uma grande quantidade de informações necessárias ao desenvolvimento de inúmeros trabalhos, permitindo inclusive a inserção de fotos e imagens para registro dos acontecimentos. O potencial deste tipo de sistema só foi possível a partir de maio de 2000, com a eliminação da SA (Selective Availability).Com isso, o posicionamento absoluto realizado por receptores de navegação (menos precisos do que os receptores geodésicos) foi aprimorado, podendo conseguir precisões da ordem de 10m, o que aumenta a qualidade de aplicações como a navegação terrestre. A proposta desta dissertação é descrever o desenvolvimento de um protótipo veicular para aplicações de campo em Geociências, onde foi incluída a navegação em tempo real, o uso da internet para a comunicação pessoal e interface de acesso ao Google Earth. O protótipo desenvolvido permite a extensão de parte da infra-estrutura de um laboratório para apoio das atividades de campo. / In our days the Global Positioning Systems (GPS) is a technology with a great variety of military and civilian applicability. Among this uses, navigation is one activity that is largely increasing in reason to lowering equipment prices and introduced facilities as easy to use technology. In practice, a system structured to navigate in terrestrial, maritime, fluvial or aerial way is formed by a GPS connected to an onboard computer and video equipped with appropriate software that process in a instantaneous mode (real time) all the information necessary to show on screen the geographical position of the vehicle. In parallel, new advances in network communication open the possibility to integrate completely the vehicle in movement with the staff in the office. Also, the Geoogle Earth™ and World Wide Web increase the facilities to view online the terrain and open the possibility to user interact directly with routines that insert local photo and images. Navigate with accuracy using a single-receiver GPS linked to a computer was only possibly after May of 2000, when the SA (Selective Availability) was excluded from GPS signal. Consequently, absolute positioning with one band handled GPS (low accuracy when compared to geodetic two bands GPS) was tested and the results show the availability to locate points in the Earth surface with an uncertainty degree not above than 10 meters (in terms of planimmetric coordinates). This performance increases the data quality and the ability of single-receiver GPS to be used to navigation purposes. In this work, it is assembled and tested a navigation system prototype installed in a vehicle with the objective to optimize field survey and adapted to some geosciences necessities, including the possibility to navigate in real time integrated with Internet facilities to personal communication and with an interface to access the Google Earth™. The configuration of the navigation system prototype elaborated in this project permit to extend to the field some facilities only accessible in a laboratory environment and consequently the results obtained with the system increased the performance of all the field work stages.
186

Sistema de monitoramento remoto baseado em rede de celular GSM/GPRS para gerenciamento de desgaste de pastilha de freio e vibração da torre em aerogeradores

Gruber, Vilson January 2007 (has links)
Com a necessidade da obtenção da informação ser disponibilizada em vários locais simultaneamente, mostrando resultados on-line, faz com que as redes de comunicação de dados estejam cada vez mais presentes no dia-a-dia das pessoas e das empresas obrigando a constante busca por novas técnicas e meios de estabelecer essa comunicação. Disponibilizar sistemas de monitoração, supervisão e controle de dados on-line em máquinas e equipamentos em tempo real, não é uma tarefa nada fácil. Na estratégia de investimento, a escolha apropriada da rede e o meio de estabelecer essa comunicação na integração dos diversos equipamentos distribuídos em locais diferentes (remotos) é um fator importante para o sucesso dos dados que se queiram monitorar. O presente trabalho mostra as tecnologias de comunicação sem fio – Wireless e Celular através de uma pesquisa e estudo de caso feito em Laboratório da UFRGS e Faculdade SATC com a criação de um protótipo de uma interface de aquisição de dados utilizando a rede celular GSM/GPRS para simular a transmissão e recepção de dados para o monitoramento remoto de 02 (duas) variáveis aqui definidas como vibração da torre e desgaste de pastilha de freio em aerogerador de pequeno porte. Os dados aqui estudados mostram resultados que podem ser úteis para qualquer empresa que planeje implantar um sistema de monitoramento remoto através da Rede Celular (GSM/GPRS). Apesar de no experimento ter sido utilizado variáveis de um aerogerador, são mostradas outras aplicações possíveis de monitoramento remoto utilizando-se o canal de comunicação ar. / With the need to obtain the information be made available in several places simultaneously, showing results online, means that the networks of communication of data are increasingly present in the day-to-day of people and businesses requiring the constant search for new techniques and means to establish such communication. Enabling systems for monitoring, surveillance and control of data online in machinery and equipment in real time, nothing is not an easy task. In investment strategy, the choice of appropriate network and the means to establish this communication in the integration of the various equipment distributed in different locations (remote) is an important factor for the success of the data that we want to track. The present work shows the wireless communication technologies-Wireless and Mobile through a search and case study done in the laboratory and UFRGS and SATC College with the creation of a prototype of an interface for data acquisition using the GSM / GPRS cellular network to simulate the transmission and reception of data to the remote monitoring of 02 (two) variables here defined as vibration of the tower and wear of the brake chip in wind power of small. The data studied here show us results that can be useful for any business that plan deploy a system for remote monitoring via the Network Mobile (GSM / GPRS). Although the experiment have used variables of a wind power, are shown other possible applications of remote monitoring using the channel of communication wireless.
187

Desenvolvimento de um protótipo veicular destinado às atividades de campo

Vist, Helio Larri January 2007 (has links)
O Sistema de Posicionamento Global (GPS) permite uma grande variedade de aplicações civis e militares. Dentre as várias aplicações, uma de especial interesse é a navegação, que tem crescido muito nos últimos anos devido a fatores como menor custo, e fácil utilização desta tecnologia. Num sistema de navegação terrestre, assim como na navegação marítima, fluvial e aérea, um mapa digitalizado, ou imagem de satélite disponível da região de interesse é exibida na tela do computador de bordo e a posição do veículo é apresentada em "tempo real" a partir da posição fornecida por receptores GPS. Além disso, a comunicação disponível nos dias de hoje permite uma maior integração entre o veículo e o escritório. Finalmente, o Google Earth permite que se tenha acesso a uma grande quantidade de informações necessárias ao desenvolvimento de inúmeros trabalhos, permitindo inclusive a inserção de fotos e imagens para registro dos acontecimentos. O potencial deste tipo de sistema só foi possível a partir de maio de 2000, com a eliminação da SA (Selective Availability).Com isso, o posicionamento absoluto realizado por receptores de navegação (menos precisos do que os receptores geodésicos) foi aprimorado, podendo conseguir precisões da ordem de 10m, o que aumenta a qualidade de aplicações como a navegação terrestre. A proposta desta dissertação é descrever o desenvolvimento de um protótipo veicular para aplicações de campo em Geociências, onde foi incluída a navegação em tempo real, o uso da internet para a comunicação pessoal e interface de acesso ao Google Earth. O protótipo desenvolvido permite a extensão de parte da infra-estrutura de um laboratório para apoio das atividades de campo. / In our days the Global Positioning Systems (GPS) is a technology with a great variety of military and civilian applicability. Among this uses, navigation is one activity that is largely increasing in reason to lowering equipment prices and introduced facilities as easy to use technology. In practice, a system structured to navigate in terrestrial, maritime, fluvial or aerial way is formed by a GPS connected to an onboard computer and video equipped with appropriate software that process in a instantaneous mode (real time) all the information necessary to show on screen the geographical position of the vehicle. In parallel, new advances in network communication open the possibility to integrate completely the vehicle in movement with the staff in the office. Also, the Geoogle Earth™ and World Wide Web increase the facilities to view online the terrain and open the possibility to user interact directly with routines that insert local photo and images. Navigate with accuracy using a single-receiver GPS linked to a computer was only possibly after May of 2000, when the SA (Selective Availability) was excluded from GPS signal. Consequently, absolute positioning with one band handled GPS (low accuracy when compared to geodetic two bands GPS) was tested and the results show the availability to locate points in the Earth surface with an uncertainty degree not above than 10 meters (in terms of planimmetric coordinates). This performance increases the data quality and the ability of single-receiver GPS to be used to navigation purposes. In this work, it is assembled and tested a navigation system prototype installed in a vehicle with the objective to optimize field survey and adapted to some geosciences necessities, including the possibility to navigate in real time integrated with Internet facilities to personal communication and with an interface to access the Google Earth™. The configuration of the navigation system prototype elaborated in this project permit to extend to the field some facilities only accessible in a laboratory environment and consequently the results obtained with the system increased the performance of all the field work stages.
188

Sistema de monitoramento remoto baseado em rede de celular GSM/GPRS para gerenciamento de desgaste de pastilha de freio e vibração da torre em aerogeradores

Gruber, Vilson January 2007 (has links)
Com a necessidade da obtenção da informação ser disponibilizada em vários locais simultaneamente, mostrando resultados on-line, faz com que as redes de comunicação de dados estejam cada vez mais presentes no dia-a-dia das pessoas e das empresas obrigando a constante busca por novas técnicas e meios de estabelecer essa comunicação. Disponibilizar sistemas de monitoração, supervisão e controle de dados on-line em máquinas e equipamentos em tempo real, não é uma tarefa nada fácil. Na estratégia de investimento, a escolha apropriada da rede e o meio de estabelecer essa comunicação na integração dos diversos equipamentos distribuídos em locais diferentes (remotos) é um fator importante para o sucesso dos dados que se queiram monitorar. O presente trabalho mostra as tecnologias de comunicação sem fio – Wireless e Celular através de uma pesquisa e estudo de caso feito em Laboratório da UFRGS e Faculdade SATC com a criação de um protótipo de uma interface de aquisição de dados utilizando a rede celular GSM/GPRS para simular a transmissão e recepção de dados para o monitoramento remoto de 02 (duas) variáveis aqui definidas como vibração da torre e desgaste de pastilha de freio em aerogerador de pequeno porte. Os dados aqui estudados mostram resultados que podem ser úteis para qualquer empresa que planeje implantar um sistema de monitoramento remoto através da Rede Celular (GSM/GPRS). Apesar de no experimento ter sido utilizado variáveis de um aerogerador, são mostradas outras aplicações possíveis de monitoramento remoto utilizando-se o canal de comunicação ar. / With the need to obtain the information be made available in several places simultaneously, showing results online, means that the networks of communication of data are increasingly present in the day-to-day of people and businesses requiring the constant search for new techniques and means to establish such communication. Enabling systems for monitoring, surveillance and control of data online in machinery and equipment in real time, nothing is not an easy task. In investment strategy, the choice of appropriate network and the means to establish this communication in the integration of the various equipment distributed in different locations (remote) is an important factor for the success of the data that we want to track. The present work shows the wireless communication technologies-Wireless and Mobile through a search and case study done in the laboratory and UFRGS and SATC College with the creation of a prototype of an interface for data acquisition using the GSM / GPRS cellular network to simulate the transmission and reception of data to the remote monitoring of 02 (two) variables here defined as vibration of the tower and wear of the brake chip in wind power of small. The data studied here show us results that can be useful for any business that plan deploy a system for remote monitoring via the Network Mobile (GSM / GPRS). Although the experiment have used variables of a wind power, are shown other possible applications of remote monitoring using the channel of communication wireless.
189

Ambulance management system using GIS

Pasha, Imtiyaz January 2006 (has links)
For emergency service providers, giving their service in least time shows their best performance. Emergency hospitals will be at their best if the ambulance reaches the site in Golden hour where life of injured persons can be saved. Ambulance uses the road network to reach the accident site. Today there are many GIS based systems being developed for routing of ambulance using GPS and other real-time technologies. These systems are useful and play a major role in solving the routing problem. But now roads are so congested that it difficult for the Ambulance drivers to travel and reach the accident. In this thesis present study area is studied and problems faced by emergency service providers on road network are identified. In this thesis GIS/GPS/GSM based prototype system has been developed for routing of ambulance on road network of Hyderabad city (AMS). This prototype is designed such that it finds the accident location on the road network and locates the nearest ambulance to incident site using the real-time technologies (GPS/GSM). AMS creates the fastest route from nearest ambulance to accident site, and from there to nearest hospital. Congestion on roads during peak hours is considered, and the fastest route on both major and minor roads is created. In this thesis AMS user interface has been developed using VBA, ArcGIS (network analyst). This Ambulance management system has been developed using software engineering model rapid prototyping model and has been evaluated by GIS users
190

Desenvolvimento de um protótipo veicular destinado às atividades de campo

Vist, Helio Larri January 2007 (has links)
O Sistema de Posicionamento Global (GPS) permite uma grande variedade de aplicações civis e militares. Dentre as várias aplicações, uma de especial interesse é a navegação, que tem crescido muito nos últimos anos devido a fatores como menor custo, e fácil utilização desta tecnologia. Num sistema de navegação terrestre, assim como na navegação marítima, fluvial e aérea, um mapa digitalizado, ou imagem de satélite disponível da região de interesse é exibida na tela do computador de bordo e a posição do veículo é apresentada em "tempo real" a partir da posição fornecida por receptores GPS. Além disso, a comunicação disponível nos dias de hoje permite uma maior integração entre o veículo e o escritório. Finalmente, o Google Earth permite que se tenha acesso a uma grande quantidade de informações necessárias ao desenvolvimento de inúmeros trabalhos, permitindo inclusive a inserção de fotos e imagens para registro dos acontecimentos. O potencial deste tipo de sistema só foi possível a partir de maio de 2000, com a eliminação da SA (Selective Availability).Com isso, o posicionamento absoluto realizado por receptores de navegação (menos precisos do que os receptores geodésicos) foi aprimorado, podendo conseguir precisões da ordem de 10m, o que aumenta a qualidade de aplicações como a navegação terrestre. A proposta desta dissertação é descrever o desenvolvimento de um protótipo veicular para aplicações de campo em Geociências, onde foi incluída a navegação em tempo real, o uso da internet para a comunicação pessoal e interface de acesso ao Google Earth. O protótipo desenvolvido permite a extensão de parte da infra-estrutura de um laboratório para apoio das atividades de campo. / In our days the Global Positioning Systems (GPS) is a technology with a great variety of military and civilian applicability. Among this uses, navigation is one activity that is largely increasing in reason to lowering equipment prices and introduced facilities as easy to use technology. In practice, a system structured to navigate in terrestrial, maritime, fluvial or aerial way is formed by a GPS connected to an onboard computer and video equipped with appropriate software that process in a instantaneous mode (real time) all the information necessary to show on screen the geographical position of the vehicle. In parallel, new advances in network communication open the possibility to integrate completely the vehicle in movement with the staff in the office. Also, the Geoogle Earth™ and World Wide Web increase the facilities to view online the terrain and open the possibility to user interact directly with routines that insert local photo and images. Navigate with accuracy using a single-receiver GPS linked to a computer was only possibly after May of 2000, when the SA (Selective Availability) was excluded from GPS signal. Consequently, absolute positioning with one band handled GPS (low accuracy when compared to geodetic two bands GPS) was tested and the results show the availability to locate points in the Earth surface with an uncertainty degree not above than 10 meters (in terms of planimmetric coordinates). This performance increases the data quality and the ability of single-receiver GPS to be used to navigation purposes. In this work, it is assembled and tested a navigation system prototype installed in a vehicle with the objective to optimize field survey and adapted to some geosciences necessities, including the possibility to navigate in real time integrated with Internet facilities to personal communication and with an interface to access the Google Earth™. The configuration of the navigation system prototype elaborated in this project permit to extend to the field some facilities only accessible in a laboratory environment and consequently the results obtained with the system increased the performance of all the field work stages.

Page generated in 0.3106 seconds