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  • 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.
251

Load balancing in heterogeneous wireless communications networks. Optimized load aware vertical handovers in satellite-terrestrial hybrid networks incorporating IEEE 802.21 media independent handover and cognitive algorithms.

Ali, Muhammad January 2012 (has links)
Heterogeneous wireless networking technologies such as satellite, UMTS, WiMax and WLAN are being used to provide network access for both voice and data services. In big cities, the densely populated areas like town centres, shopping centres and train stations may have coverage of multiple wireless networks. Traditional Radio Access Technology (RAT) selection algorithms are mainly based on the ¿Always Best Connected¿ paradigm whereby the mobile nodes are always directed towards the available network which has the strongest and fastest link. Hence a large number of mobile users may be connected to the more common UMTS while the other networks like WiMax and WLAN would be underutilised, thereby creating an unbalanced load across these different wireless networks. This high variation among the load across different co-located networks may cause congestion on overloaded network leading to high call blocking and call dropping probabilities. This can be alleviated by moving mobile users from heavily loaded networks to least loaded networks. This thesis presents a novel framework for load balancing in heterogeneous wireless networks incorporating the IEEE 802.21 Media Independent Handover (MIH). The framework comprises of novel load-aware RAT selection techniques and novel network load balancing mechanism. Three new different load balancing algorithms i.e. baseline, fuzzy and neural-fuzzy algorithms have also been presented in this thesis that are used by the framework for efficient load balancing across the different co-located wireless networks. A simulation model developed in NS2 validates the performance of the proposed load balancing framework. Different attributes like load distribution in all wireless networks, handover latencies, packet drops, throughput at mobile nodes and network utilization have been observed to evaluate the effects of load balancing using different scenarios. The simulation results indicate that with load balancing the performance efficiency improves as the overloaded situation is avoided by load balancing.
252

Balanced antennas for mobile handset applications. Simulation and Measurement of Balanced Antennas for Mobile Handsets, investigating Specific Absorption Rate when operated near the human body, and a Coplanar Waveguide alternative to the Balanced Feed.

Alhaddad, A.G. January 2012 (has links)
The main objectives of this research are to investigate and design low profile antennas for mobile handsets applications using the balanced concept. These antennas are considered to cover a wide range of wireless standards such as: DCS (1710¿1880 MHz), PCS (1850¿1990 MHz), UMTS (1920¿2170 MHz), WLAN (2400¿2500 MHz and 5000 ¿ 5800 MHz) and UWB frequency bands. Various antennas are implemented based on built-in planar dipole with a folded arm structure. The performance of several designed antennas in terms of input return loss, radiation patterns, radiation efficiency and power gain are presented and several remarkable results are obtained. The measurements confirm the theoretical design concept and show reasonable agreement with computations. The stability performance of the proposed antenna is also evaluated by analysing the current distribution on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar waveguide structure is also proposed, discussed and tested; this is intended to eliminate the balanced feed network. The predicted and measured results show good agreement, confirming good impedance bandwidth characteristics and excellent dual-band performance. In addition, a hybrid method to model the human body interaction with a dual band balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented. Results for several test cases of antenna locations on the body are presented and discussed. The near and far fields were incorporated to provide a full understanding of the impact on human tissue. The cumulative distribution function of the radiation efficiency and absorbed power are also evaluated. / UK Engineering and Physical Sciences Research Council (EPSRC)
253

Balanced antennas for mobile handset applications : simulation and measurement of balanced antennas for mobile handsets, investigating specific absorption rate when operated near the human body, and a coplanar waveguide alternative to the balanced feed

Alhaddad, Abdolrauf Gawad January 2012 (has links)
The main objectives of this research are to investigate and design low profile antennas for mobile handsets applications using the balanced concept. These antennas are considered to cover a wide range of wireless standards such as: DCS (1710-1880 MHz), PCS (1850-1990 MHz), UMTS (1920-2170 MHz), WLAN (2400-2500 MHz and 5000-5800 MHz) and UWB frequency bands. Various antennas are implemented based on built-in planar dipole with a folded arm structure. The performance of several designed antennas in terms of input return loss, radiation patterns, radiation efficiency and power gain are presented and several remarkable results are obtained. The measurements confirm the theoretical design concept and show reasonable agreement with computations. The stability performance of the proposed antenna is also evaluated by analysing the current distribution on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar waveguide structure is also proposed, discussed and tested; this is intended to eliminate the balanced feed network. The predicted and measured results show good agreement, confirming good impedance bandwidth characteristics and excellent dual-band performance. In addition, a hybrid method to model the human body interaction with a dual band balanced antenna structure covering the 2.4 GHz and 5.2 GHz bands is presented. Results for several test cases of antenna locations on the body are presented and discussed. The near and far fields were incorporated to provide a full understanding of the impact on human tissue. The cumulative distribution function of the radiation efficiency and absorbed power are also evaluated.
254

WORKSHOP "MOBILITÄT"

Anders, Jörg 12 June 2001 (has links)
Gemeinsamer Workshop von Universitaetsrechenzentrum und Professur "Rechnernetze und verteilte Systeme" der Fakultaet fuer Informatik der TU Chemnitz. Workshop-Thema: Mobilitaet
255

Diseño de migración de nodos B aplicado para una RNC caida de una red movil

Mallqui Morales, Nayda Isabel January 2015 (has links)
La presente tesina consiste en el diseño de migración de nodos B aplicado para una RNC caída de una red móvil, con la finalidad de solucionar los problemas que se presenten ante un incidente que afecte los servicios de voz y datos de los usurarios de una red móvil. En el desarrollo de la tesina, se describe el planteamiento del problema, el marco teórico de la tecnología UMTS y posteriormente nos centramos en los elementos principales de esta tecnología. También describimos los equipos importantes a utilizar en desarrollo del proyecto, en este caso nos enfocamos en la descripción de la RNC. Y finalmente describimos el desarrollo del proyecto, el diseño de la solución e implementación de la misma, y en donde se presentan los resultados del diseño. This thesis is the design of migration of nodes B and its a applied when RNC fall for a mobile network, in order to solve the problems that arise before an incident affecting voice and data services from a mobile network. In developing the thesis, we describe the theoretical framework of UMTS technology and then we focus on the main elements of this technology. We also describe the important equipment used in project development; in this case we focus on the description of the RNC. And finally we describe the solution of design and implementation .Also, the results of this project.
256

Workshop Audiovisuelle Medien

Eibl, Maximilian, Kürsten, Jens, Ritter, Marc 03 June 2009 (has links) (PDF)
Audiovisuelle Medien stellen Archive vor zunehmende Probleme. Ein stark wachsender (Web-)TV-Markt mit Sende- oder Rohmaterial, zunehmender Einsatz von medial aufbereitetem Lehrmaterial in Schulen, Hochschulen und Firmen, die Verbreitung der Videoanalyse als Forschungs- und Lehrmethode, die Ausbreitung von Überwachungskameras sowie die immer günstigeren Produktionsbedingungen vom professionellen Produzenten bis zum Heimvideo sind nur einige Stichworte um die neuen quantitativen Dimensionen zu umreißen. Die archivarischen und dokumentarischen Werkzeuge sind heute mit dieser Situation überfordert. Der Workshop versucht hier Probleme und Lösungsmöglichkeiten zu umreißen und beschäftigt sich mit den technologischen Fragestellungen rund um die Archivierung audiovisueller Medien, seien es analoge, digitalisierte oder digitale Medien. Dabei werden zum einen die technologischen Probleme angesprochen, die zum Aufbau und Management eines Archivs bewältigt werden müssen. Zum anderen wird der praktische Einsatz von der Gestaltung der Benutzungsoberfläche bis zur Frage des Umgangs mit kritischem Material diskutiert.
257

An optimised QPSK-based receiver structure for possibly sparse data transmission over narrowband and wideband communication systems

Schoeman, Johan P. 24 August 2010 (has links)
In this dissertation an in-depth study was conducted into the design, implementation and evaluation of a QPSK-based receiver structure for application in a UMTS WCDMA environment. The novelty of this work lies with the specific receiver architecture aimed to optimise the BER performance when possibly sparse data streams are transmitted. This scenario is a real possibility according to Verd´u et al [1] and Hagenauer et al [2–6]. A novel receiver structure was conceptualised, developed and evaluated in both narrowband and wideband scenarios, where it was found to outperform conventional receivers when a sparse data stream is transmitted. In order to reach the main conclusions of this study, it was necessary to develop a realistic simulation platform. The developed platform is capable of simulating a communication system meeting the physical layer requirements of the UMTS WCDMA standard. The platform can also perform narrowband simulations. A flexible channel emulator was developed that may be configured to simulate AWGN channel conditions, frequency non-selective fading (either Rayleigh or Rician with a configurable LOS component and Doppler spread), or a full multipath scenario where each path has a configurable LOS component, Doppler spread, path gain and path delay. It is therefore possible to even simulate a complex, yet realistic, COST207-TU channel model. The platform is also capable of simulating MUI. Each interfering user has a unique and independent multipath fading channel, while sharing the same bandwidth. Finally, the entire platform executes all simulations in baseband for improved simulation times. The research outputs of this work are summarised below: <ul> <li>A parameter, the sparseness measure, was defined in order to quantify the level by which a data stream differs from an equiprobable data stream.</li> <li>A novel source model was proposed and developed to simulate data streams with a specified amount of sparseness.</li> <li>An introductory investigation was undertaken to determine the effect of simple FEC techniques on the sparseness of an encoded data stream.</li> <li>Novel receiver structures for both narrowband and wideband systems were proposed, developed and evaluated for systems where possibly sparse data streams may be transmitted.</li> <li>Analytic expressions were derived to take the effect of sparseness into account in communication systems, including expressions for the joint PDF of a BPSK branch, the optimal decision region of a detector in AWGN conditions as well as the BER performance of a communication system employing the proposed optimal receiver in both AWGN channel conditions as well as in flat fading channel conditions.</li> <li>Numerous BER performance curves were obtained comparing the proposed receiver structure with conventional receivers in a variety of channel conditions, including AWGN, frequency non-selective fading and a multipath COST207-TU channel environment, as well as the effect of MUI</li></ul>. AFRIKAANS : In hierdie verhandeling word ’n in-diepte studie gedoen rakende die ontwerp, implementasie en evaluasie van ’n KPSK-gebaseerde ontvanger struktuur wat in ’n UMTS WKVVT omgewing gebruik kan word. Die bydrae van hierdie werk lˆe in die spesifieke ontvanger argitektuur wat daarop mik om die BFT werksverrigting te optimeer wanneer yl data strome versend word. Hierdie is ’n realistiese moontlikheid volgens Verd´u et al [1] en Hagenauer et al [2–6]. ’n Nuwe ontvanger struktuur is gekonsepsualiseer, ontwikkel en evalueer vir beide noueband en wyeband stelsels, waar dit gevind is dat dit beter werksverrigting lewer as tradisionele ontvangers wanneer yl data strome versend word. Dit was nodig om ’n realistiese simulasie platform te ontwikkel om die belangrikste gevolgtrekkings van hierdie studie te kan maak. Die ontwikkelde platform is in staat om ’n kommunikasie stelsel te simuleer wat aan die fisiese laag vereistes van die UMTS WKVVT standaard voldoen. Die platform kan ook noueband stelsels simuleer. ’n Aanpasbare kanaal simulator is ontwikkel wat opgestel kan word om SWGR kanaal toestande, plat duining (beide Rayleigh of Ricies met ’n verstelbare siglyn komponent en Doppler verspreiding), sowel as ’n veelvuldige pad omgewing (waar elke unieke pad ’n verstelbare siglyn komponent, Doppler verspreiding, pad wins en pad vertraging het) te emuleer. Dit is selfs moontlik om ’n komplekse, maar steeds realistiese COST207-TU kanaal model te simuleer. Die platform het ook die vermo¨e om VGS te simuleer. Elke steurende gebruiker het ’n unieke en onafhanklike veelvuldige pad deinende kanaal, terwyl dieselfde bandwydte gedeel word. Laastens, alle simulasies van die platvorm word in basisband uitgevoer wat verkorte simulasie periodes verseker. Die navorsingsuitsette van hierdie werk kan as volg opgesom word: <ul> <li>’n Parameter, die ylheidsmaatstaf, is gedefin¨ýeer om dit moontlik te maak om die vlak waarmee die ylheid van ’n datastroom verskil van ’n ewekansige stroom te versyfer.</li> <li>’n Nuwe bronmodel is voorgestel en ontwikkel om datastrome met ’n spesifieke ylheid te emuleer.</li> <li>’n Inleidende ondersoek is onderneem om vas te stel wat die effek van VFK tegnieke op die ylheid van ’n enkodeerde datastroom is.</li> <li>Nuwe ontvanger strukture is voorgestel, ontwikkel en evalueer vir beide noueband en wyeband stelsels waar yl datastrome moontlik versend kan word.</li> <li>Analitiese uitdrukkings is afgelei om die effek van ylheid in ag te neem in kommunikasie stelsels. Uitdrukkings vir onder andere die gedeelte WDF van ’n BFVK tak, die optimale beslissingspunt van ’n detektor in SWGR toestande, sowel as die BFT werksverrigting van ’n kommunikasie stelsel wat van die voorgestelde optimale ontvangers gebruik maak, hetsy in SWGR of in plat duinende kanaal toestande.</li> <li>Talryke BFT werksverrigting krommes is verkry wat die voorgestelde ontvanger struktuur vergelyk met die konvensionele ontvangers in ’n verskeidenheid kanaal toestande, insluitend SWGR, plat duinende kanale en ’n veelvuldige pad COST207-TU kanaal omgewing, sowel as in die teenwoordigheid van VGS.</li></ul></p Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Electrical, Electronic and Computer Engineering / unrestricted
258

QoS v systému UMTS / QoS in UMTS

Kavan, Radovan January 2009 (has links)
This thesis treats of QoS (Quality of Service) in UMTS system. The term quality of service is frequently used, recently, however not only in computer networks, but also more and more in mobile networks also. Present system of 2nd generation (2G) GSM enables only limited exploitation of QoS function. System UMTS is a system of 3rd generation (3G) already and contains quality of service in greater measure which is ensured with number of algorithms and functions. Individual QoS functions enable effective utilization of radio interface, support maintenance of planned coverage and offer high spectral efficiency. Functions that cater to quality of service are called RRM functions (Radio Resource Management). There exist five basic functions in UMTS system that are Admission control (AC), Power control (PC), Load control (LC), Handover control (HC) and Packet scheduler (PS). These functions are responsible for control of network access, control of power, control of network load, control of handover and packet (bit rate) scheduling. Last three functions are usually collectively designated as Congestion control, control of network overload. UMTS layer model, differentiation of services, traffic classes and 3GPP concept are also discussed. In thesis the attention is piad to Admission control algorithm – control of network access – in the uplink direction and to different ways of load (in the cell) modeling. Individual approaches are simulated in MATLAB. A possibility of using algorithm in the real system is discussed in conclusion.
259

Workshop Audiovisuelle Medien

Eibl, Maximilian, Kürsten, Jens, Ritter, Marc 03 June 2009 (has links)
Audiovisuelle Medien stellen Archive vor zunehmende Probleme. Ein stark wachsender (Web-)TV-Markt mit Sende- oder Rohmaterial, zunehmender Einsatz von medial aufbereitetem Lehrmaterial in Schulen, Hochschulen und Firmen, die Verbreitung der Videoanalyse als Forschungs- und Lehrmethode, die Ausbreitung von Überwachungskameras sowie die immer günstigeren Produktionsbedingungen vom professionellen Produzenten bis zum Heimvideo sind nur einige Stichworte um die neuen quantitativen Dimensionen zu umreißen. Die archivarischen und dokumentarischen Werkzeuge sind heute mit dieser Situation überfordert. Der Workshop versucht hier Probleme und Lösungsmöglichkeiten zu umreißen und beschäftigt sich mit den technologischen Fragestellungen rund um die Archivierung audiovisueller Medien, seien es analoge, digitalisierte oder digitale Medien. Dabei werden zum einen die technologischen Probleme angesprochen, die zum Aufbau und Management eines Archivs bewältigt werden müssen. Zum anderen wird der praktische Einsatz von der Gestaltung der Benutzungsoberfläche bis zur Frage des Umgangs mit kritischem Material diskutiert.:Interaction MedioVis 2.0 - A novel User Interface for Seeking Audio-Visual Media Libraries Harald Reiterer, Mathias Heilig and Sebastian Rexhausen SIVA Suite – Konzeption eines Frameworks zur Erstellung von interaktiven Videos B. Meixner, B. Siegel, G. Hölbling, H. Kosch und F. Lehner Online-Werbung als digitales Kulturgut: Analyse, Erschließung und Archivierung Christian Wolff Beyond Basic Blanks – Vertrauenserhaltende, schrittweise Implementierung neuer Funktionen im Information Retrieval Arne Berger Beyond Basic Blanks – Akzeptanz adaptiver Annotations- und Rechercheoberflächen Arne Berger Media Usage Nutzung von Mediatheken öffentlich-rechtlicher Fernsehsender Sven Pagel, Carina Bischoff, Sebastian Goldstein und Alexander Jürgens Video-Tools im Schulunterricht: Psychologisch-pädagogische Forschung zur Nutzung audiovisueller Medien Carmen Zahn, Karsten Krauskopf und Friedrich W. Hesse Special Issues in Multimedia Archiving Einsatz Pixelbasierter Datenfusion zur Objektklassifikation Jan Thomanek, Holger Lietz, Basel Fardi, Gerd Wanielik Grundlagen für das Retrieval rotationssymmetrischer Gefäße Stefan Wagner, Christian Hörr, David Brunner und Guido Brunnett Verschmelzendes Clustering in Artmap Frederik Beuth und Marc Ritter Von der Bildrepräsentation zur Objekterkennung – Bewegungsanalyse als mächtiges Werkzeug der automatischen Bildinterpretation Tobias John, Basel Fardi und Gerd Wanielik Aspekte zur Archivierung audiovisueller Unterlagen im Sächsischen Staatsarchiv Stefan Gööck FusionSystems GmbH Systeme zur Sensor-Daten-Fusion und Szeneninterpretation Ullrich Scheunert und Basel Fardi Multimedia Analysis and Retrieval Visualisierung von Prozessketten zur Shot Detection Marc Ritter Textdetektion und -extraktion mit gewichteter DCT und mehrwertiger Bildzerlegung Stephan Heinich Sprechererkennungssystem auf Basis der Vektorquantisierung mit Störgeräuschfilterung Stephan Heinich Metadatenstandards und –formate für audiovisuelle Inhalte Jens Kürsten Entwurf einer Service-orientierten Architektur als Erweiterung einer Plattform zum Programm-Austausch Jens Kürsten Untersuchungen zu semantischem Retrieval von Bildern mit Hilfe von MPEG7 anhand einer Beispielapplikation Daniel Pötzinger Distribution Aspects Dynamische Distribution personalisierten Mobilfernsehens in hybriden Netzen Albrecht Kurze, Robert Knauf und Arne Berger Multimedia Archives – Music Evaluation of an Image and Music Indexing Prototype Peter Dunker, Ronny Paduschek, Christian Dittmar, Stefanie Nowak and Matthias Gruhne Aspekte inhaltlicher Modellierung von Musikdokumenten in digitalen Archiven Michael Rentzsch und Frank Seifert
260

無線多媒體傳輸技術發展對無線影音產業價值鏈的影響以歐特斯科技公司為例

葛葆華, Edward Ko Unknown Date (has links)
無線寬頻網路(Mobile Internet Broadband Network)的出現對於無線通訊產業、傳播媒體產業與影音內容產業產生了相當程度的影響,而數位化的科技發展更帶來通訊、傳播及平面媒體產業融合的可能性,無線寬頻影音串流(Mobile Internet Video Streaming)是一架構在此無線通訊媒體匯流後的新產物,透過觀察和分析它的演進發展,可以說明和解釋網路新媒體匯流造成傳統影音產業價值鏈的改變。 吾人將以無線通訊之影音播放技術之演進與發展,以及相對最先發生變化之影音產業經營環境,產生之影響,做產業價值鏈分析研究,進而了解產業經營環境之改變,新的價值創造流程及技術平台的關聯性。並藉由日本NTT DOCOMO之經驗,及對其供應商之觀察,了解台灣產業發展之可能趨勢,及策略建議藍圖。 本研究採P.W. Bane、S.P. Bradley & D.J. Collis (1998)三人提出之寬頻產業五層模式作為分析工具。五層模式分為內容(content)、包裝(package)、傳輸網路(transmission)、操作(manipulation) 及終端設備(terminal)五層架構。主要目的為以整體網路頻寬及技術演進的觀點進行分析五層間價值消長之關係,及整體網路之價值之改變。 我們發現在新的技術導入既有影音市場,由於網路之雙向特性,會產生網路效應及網路外部性,這些地方將產生新的價值所在,而擁有網路外部性的影音操作平台可獲得較高的價值。完整而消費者導向的影音操作平台,將首先累積產業之價值所在,影音操作平台的擁有者將成為產業的領導者,最終將成為標準的制定者。 影音內容的價值獲得來自網路外部性是經由更多人與內容來源(內容提供者)互動,造成下一次消費或其他使用者的外部性以及生產外部性,這樣的外部性是由虛擬連結產生.價值聚集於內容包裝層。 無線寬頻影音操作平台是服務成功的關鍵,有效的整合價值鏈及應用是必須在產業發展前完成,而完整的影音操作平台包含:內容製作壓縮平台、串流平台、訊息平台、及手機之用戶播放平台。 我們發現,新的技術導入市場,需要事先將價值鏈重新定義,整合出可行之新的商業模式,再依據新的價值鏈,新的服務流程去整合新的操作平台,投入服務後,由於是消費者導向的服務設計,可以降低消費者對新科技及新服務的學習門檻及進入障礙,而獲得市場認同。 / “Unlimited boundary & Ubiquitous content” Because of the improving the bandwidth & compression technology of mobile Internet, there are a very extremely industrial convergency in communication, broadcasting, & video audio content industry. There are several new technology including streaming, MPEG, multi media message, 3G which push the whole world going to a new Ubiquitous environment & totally change the old value chain of video audio industry, but we still have no ideal where it should go & what will happen next. We will try to research the technical evolution of video broadcasting which really influence our movie, TV industry. It will change the customer behavior of watching TV, or going to the movie. We especially want to find out where is the new value in the mobile Internet multi media industry. We will use the 5 liars analysis model of broadband industry (P.W. Bane、S.P. Bradley & D.J. Collis (1998))as our basic methodology to find out how the three vertical industries became a new 5 horizontal industries, which are content, package, transmission, manipulation, & terminal. We also want to know how they work internally & externally. We find that the video audio manipulation platform will become the key solution for this value chain, because of its network externality & network effect. The content providers also very important to provide the quality of contents to service the end customers. How to consolidate a new valuable services process & user friendly interface is the big issue here for whom will invest a large of money to creat the new mobile internet portal & new audio vedio manipulation platform. They must think not only the user interface of handset, but also the mechanism of profit sharing between these different providers who never work together in the history.

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