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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.
231

Low-complexity OFDM transceiver design for UMTS-LTE

Osman, Ammar January 2007 (has links)
Over the past two decades the mobile wireless communication systems has been growing fast and continuously. Therefore, the standardization bodies together with wireless researchers and mobile operators around the globe have been constantly working on new technical specifications in order to meet the demand for this rapid growth. The 3rd Generation Partnership Project (3GPP) one of the largest of such standardization bodies, works on developing the current third generation (3G) mobile telecommunication systems towards the future 4th generation. Research towards meeting the higher demands for higher data rates was the main reason for the birth of an evolution technology towards the 4th generation mobile systems. This evolution to the current 3rd generation UMTS systems was given the name E-UTRA/UTRAN Long Term Evolution (LTE) by the 3GPP. This thesis research has been carried out at the Telecommunications Research Center (ftw.) in Vienna. It was conducted in the framework of the C10 project “Wireless Evolution Beyond 3G”. One of the fields of research within this project is to have a special focus on the OFDM modulation schemes that are discussed under the new evolution technology (LTE) of the UMTS mobile networks. Therefore, this thesis focuses mainly in analyzing the new requirements, and evaluating them by designing a low-complexity UMTS-LTE OFDM based transceiver. This thesis aims mainly in studying the feasibility of this technology by means of simulation. / Tel: +46-704469795 Email: osman@ftw.at,amos04@student.bth.se, ammarmao@gmail.com
232

Analýza trhu vysokorychlostního připojení k internetu v ČR / Analýza trhu vysokorychlostního připojení k internetu v ČR

Poloczek, Bronislav January 2011 (has links)
The objective of the thesis is to provide a view of the situation in high-speed Internet connection in the Czech Republic. At the beginning we present a history of internet and describes in particular the most frequently used technology of high-speed connectivity to the Internet. This is followed by a comparison of the current supply and demand in a market of Internet connection in the Czech Republic. This study not only compare technological aspects, but takes into consideration the economic situation, government regulations and changes from 2009 as well. Finally, there is a summarization and an evaluation of the results and a reflection on possible future on a market of high-speed connection in Czech republic.
233

Mejora de la Arquitectura de Acceso Radio UMTS mediante Multinodos B

Monserrat del Río, José Francisco 07 May 2008 (has links)
Dada la creciente demanda de servicios multimedia en movilidad, las operadoras de telefonía móvil necesitan aumentar constantemente la capacidad de sus sistemas. En ocasiones la única solución posible para mejorar las prestaciones del sistema es incrementar el número de transmisores, siendo ésta una solución costosa. Además, en UMTS utilizar más emplazamientos macro-celulares no siempre garantiza una mayor capacidad del sistema, por los grandes problemas de interferencia mutua que sufren dos macro-celdas si se encuentran demasiado próximas. La única solución que se puede adoptar en estos casos es hacer uso de redes jerárquicas celulares, añadiendo micro-celdas que utilicen una frecuencia de portadora distinta. Esta Tesis Doctoral aporta una visión complementaria al despliegue de las redes jerárquicas y propone aprovechar dicho despliegue para modificar las redes de acceso radio UMTS con nueva arquitectura de nodos B múltiples o Multinodo B. El sistema a desarrollar utiliza la tecnología de nodos B UMTS a los que se conectan un número de antenas distribuidas en diferentes puntos del área de servicio, conformando el equivalente a un array distribuido espacialmente. La incorporación de técnicas de procesado en array junto con mecanismos de gestión dinámica de recursos y la tecnología de enlaces ópticos proporcionarán a este sistema una estructura de acceso radio óptima en entornos micro-celulares y en interiores, con gran flexibilidad y adaptabilidad. Las ventajas de utilizar esta configuración, que se detallan a lo largo de la Tesis Doctoral, son fundamentalmente la mejora de la capacidad de la red de acceso, minimización del impacto radioeléctrico y óptima gestión de recursos. En primer lugar, en esta Tesis Doctoral se demuestra que la nueva arquitectura radio es capaz de dotar al sistema UMTS de una diversidad espacial adicional, diversidad que mejorará los requerimientos de potencia recibida en los terminales, sobre todo en los escenarios micro-celulares. Respecto / Monserrat Del Río, JF. (2007). Mejora de la Arquitectura de Acceso Radio UMTS mediante Multinodos B [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/1937 / Palancia
234

Optimalizace přístupové sítě UMTS / Optimization of UMTS access network

Havlíček, Karel January 2008 (has links)
This master’s thesis deals with a UMTS radio access network optimization, containing radio interface analysis, services and procedures description, ways to correct parameters calculations and settings and other issues necessary for a correct access network operation. The goal is effective network operation, minimum costs and maximum performance and flexibility of the network. The optimization during system operation is important because of the system character. The UMTS system uses the WCDMA technology, where particular users share the same frequency band and they are distinguished from one another via code sequences. The capacity of such a system is then given by the interference level - each particular user increases the interference level by the value corresponding to his transmit power. The maximum cell capacity is determined by the maximum interference level at which users can still operate with required services, so it is related not only to the number of users, but also to their bit rate. The optimization allows effective usage of the system for different services with different requirements. The main optimization tool is the radio resource management, containing number of algorithms, such as admission control, which decides the acceptance or rejection of a new user demanding certain service, power control, which ensure that users transmit with a minimal power sufficient for required service, handover and cell selection algorithms etc. The major parameter used by these algorithms is a cell load factor, which is related to the interference level margin. There are several methods for the load factor estimation and some of them are described in this work. Some other optimization techniques are mentioned here, too. This work also contains a laboratory exercise proposal for radio resource management introduction using the OPNET Modeler network simulation tool.
235

Základy mobilního internetu / Mobile internet principles

Jehličková, Lenka January 2011 (has links)
Thesis concerns with mobile communications theory with focus on data transfer. In the introduction the history, the origin and individual mobile systems generations are described. It is followed by detailed description of second, third and fourth generation mobile systems. Frequency band allocation, signal processing, the system architecture itself, security management and basic features are also discussed. The GSM system is described together with individual data transmission types based on circuit switching – CSD and HSCSD and packet switching – GPRS and EDGE. For UMTS, FDD and TDD modes are listed as well as changes in individual releases, corresponding technologies and provided services. Next, there is the description of LTE and WiMAX systems, together with their improvements whose are part of the fourth generation of mobile systems. Last of the described systems is the still work in progress HAPS, also known as the system of stratospheric platforms. In the end important parameters are summarized and systems are compared with each other.
236

Speciální bezpečnostní systém / Special security system

Náhlík, Ondřej January 2015 (has links)
This master’s thesis is focused on design and realisation of special security system for space and property protection. System is devided into two parts, transmitting and receiving. Transmitting part is formed by Raspberry Pi Model B+, motion sensor, webcam and USB LTE modem Huawei E398. Receiving part consists of computer with suitable application for communication with FTP server. Data transfer in mobile systems is described in the first part of this thesis, transmitting part is designed in the second part. There is one transmitting option chosen in the third part and there are also described applications of the transmitting part. The last part of this thesis is focused on the receiving part and its application.
237

Mitteilungen des URZ 3/2001

Dippmann, Flohrer, Heik, Kempe, Richter, Riedel, Schier, Scholz, Trapp 17 August 2001 (has links)
Moderne Intranet-Infrastruktur in der Universitätsbibliothek Neue Technologien im Patentinformationszentrum Einsatz bargeldloser Zahlungsmittel an der TU Chemnitz GPRS - General Packet Radio Service UMTS - mehr als nur zum Telefonieren gut Hinweise für WWW-Autoren: Zugriffskontrolle WFM: WWW-basierter Datei-Manager Automatisierte Freischaltung von Datendosen in öffentlichen Räumen der TU Chemnitz Aufrüstung der Computerpools Reichenhainer Str. B401/404 Neuigkeiten zu Campuslizenzen
238

P2P-based Mobility Management for Heterogeneous Wireless Networks and Mesh Networks

Nawrath, Thomas 14 July 2006 (has links)
Today Moblity Management is one of the most important tasks that need to be accomplished to secure availability and performance of communication between people. This paper explains how moblity management is currently structured and what algorithms and approaches from Peer-To-Peer technology could be used to increase availability and performance.
239

Object Synchronization and Security for Mobile Communications Devices

Borison, Torbjorn January 2001 (has links)
The main objective of this master’s thesis project was to investigate and find solutions to the problem of how to combine the SyncML synchronisation specification with object security and thus protection of personal information, such as contacts and calendar entries in mobile devices. SyncML is a new synchronisation specification agreed upon by major device developers (Ericsson, Palm, Motorola, etc.) and the major synchronisation server developers (Starfish, Puma, fusionOne, etc.). It is independent of transport (HTTP, WSP, or OBEX) platform, operating system, and application and simplifies synchronisation of personal information between dissimilar SyncML supportive devices. SyncML compliant devices are fully capable of synchronising information with a third party operated Internet based server and a desktop computer. This allows us to access, up-date and maintain information independent of Intranets or geographical position. However, synchronising and storing confidential personal information on an third party operated Internet based server entails weaknesses in our personal information security. Even if transport and storage security are used, how secure is the server where this information is stored since this server has the highest probability of being attacked. Can we really trust that an employee or other person with valid appropriated administrators access to the storage facility with the appropriate knowledge, working together with the third party server operator, won’t try to access our stored information? To prevent this, the personal information’s confidentiality must be guaranteed before the information leaves the device. When synchronising and exchanging personal information, the information is often marked according to a specific format. The three de-facto standard PIM formats are: (1) vCard (contact information), (2) vCalendar, and (3) iCalendar (calendar and scheduling information). These formats divide the personal information into properties. Each property is assigned to contain a small piece of the personal information entry (e.g. a telephone number, an e-mail address, the time when the calendar event begins, etc.). Furthermore to preserve the interoperability between different devices given by SyncML, authorised recipients must automatically be able to reverse the encryption process and decrypt the encrypted property value. Therefore general cryptographic formats are used (e.g. CMS, PGP and the newly developed XML Encryption). They add information needed by the recipients (e.g. algorithm used, padding method used on the plain text, etc.), encrypt the plaintext into cipher text, and decrypt the cipher text into plain text given the correct key.
240

Model and design of small compact dielectric resonator and printed antennas for wireless communications applications. Model and simulation of dialectric resonator (DR) and printed antennas for wireless applications; investigations of dual band and wideband responses including antenna radiation performance and antenna design optimization using parametric studies

Elmegri, Fauzi January 2015 (has links)
Dielectric resonator antenna (DRA) technologies are applicable to a wide variety of mobile wireless communication systems. The principal energy loss mechanism for this type of antenna is the dielectric loss, and then using modern ceramic materials, this may be very low. These antennas are typically of small size, with a high radiation efficiency, often above 95%; they deliver wide bandwidths, and possess a high power handling capability. The principal objectives of this thesis are to investigate and design DRA for low profile personal and nomadic communications applications for a wide variety of spectrum requirements: including DCS, PCS, UMTS, WLAN, UWB applications. X-band and part of Ku band applications are also considered. General and specific techniques for bandwidth expansion, diversity performance and balanced operation have been investigated through detailed simulation models, and physical prototyping. The first major design to be realized is a new broadband DRA operating from 1.15GHz to 6GHz, which has the potential to cover most of the existing mobile service bands. This antenna design employs a printed crescent shaped monopole, and a defected cylindrical DRA. The broad impedance bandwidth of this antenna is achieved by loading the crescent shaped radiator of the monopole with a ceramic material with a permittivity of 81. The antenna volume is 57.0  37.5  5.8 mm3, which in conjunction with the general performance parameters makes this antenna a potential candidate for mobile handset applications. The next class of antenna to be discussed is a novel offset slot-fed broadband DRA assembly. The optimised structure consists of two asymmetrically located cylindrical DRA, with a rectangular slot feed mechanism. Initially, designed for the frequency range from 9GHz to 12GHz, it was found that further spectral improvements were possible, leading to coverage from 8.5GHz to 17GHz. Finally, a new low cost dual-segmented S-slot coupled dielectric resonator antenna design is proposed for wideband applications in the X-band region, covering 7.66GHz to 11.2GHz bandwidth. The effective antenna volume is 30.0 x 25.0 x 0.8 mm3. The DR segments may be located on the same side, or on opposite sides, of the substrate. The end of these configurations results in an improved diversity performance. / General Secretariat of Education and Scientific Research Libya

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