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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.
391

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
392

SIM cards for cellular networks : An introduction to SIM card application development

Edsbäcker, Peter January 2011 (has links)
A SIM, Subscriber Identity Module, is the removable circuit board found in a modern cellular phone. It carries the network identity information and is a type of smart card which can also be found on payment cards (EMV), ID cards and so on. A smart card is basically a small computer, providing a safe and controlled execution environment. Historically smart card software was very hardware dependent and mostly developed by the manufacturers themselves. With the introduction of the open Java Card standard created by Sun Microsystems (Oracle) this was meant to change. However, information still remains scattered and is hard to obtain. This paper is meant to serve both as an introduction to the field and also as a good foundation for future studies. It begins with a theoretical discussion about smart card hardware and software architectures, network standards in the context of SIM cards, typical applications, coming trends and technologies and ends off with an overview of the Java Card standard. The following section discusses the supplied example SIM card application coupled with an introduction how to use the Gemalto Developer Suite for application development and testing. The paper ends with an extensive appendix section going in depth about some of the more important subjects.
393

IP Multicasting over DVB-T/T2/H and eMBMS using PARPS : Effect of the number of transmitters

Voladri, Ranjith Reddy January 2013 (has links)
With the advancement in the current wireless technology standards such as terrestrial digital video broadcasting systems (DVB-T, DVB-T2, and DVB-H) and the massive usage of the Internet over mobile devices, streaming of television channels in smart phones has become a necessary advancement for mobile users. As, UMTS dominating the entire mobile market globally and with the evolution of LTE, several mobile operators are working on an MBMS framework which will help to launch mobile TV services on respective operators. This paper deals with terrestrial and mobile TV with IP multicasting and broadcasting and is aimed to improve system spectral efficiency.  With the help of IP multicasting, the base station can be able to provide with significantly less spectrum by saving it from the channels which the user is not viewing currently. This case is analysed from several sets, called schemes of resource plan sets. The transmitter scheduling is dealt with by means of a Packet and Resource Plan Scheduling (PARPS) algorithm, and the simulated results are plotted in Matlab which assists in analysing the efficiency in the spectrum management and the coverage probability for the number of transmitters used for each scheme. The schemes are simulated in Matlab for different number of transmitters (2-7) in both the static and random model. The SFN schemes are offering greater coverage probability than MFN schemes, in all cases. Multicasting over Continuous Transmission Dynamic Single Frequency Network (CT-DSFN) offers a 1342% and 582% gain in Multi-user System Spectral Efficiency (MSSE) for 7 transmitters, from Broadcasting over MFN and Broadcasting over SFN respectively.  For 7 transmitters, Multicasting over CT-DSFN offers a 1213% and 428% gain in System Spectral Efficiency (SSE) from Broadcasting over MFN and Broadcasting over SFN respectively.
394

New cryptanalysis and modelling for wireless networking

Alzaabi, Mohamed Abdulla Hasan Saif January 2015 (has links)
High data rates and interoperability of vender devices have made WiMAX a prime desire for use worldwide. WiMAX is based on the IEEE 802.16 standard. IEEE 802.16a, b, c & d versions were updated within three years of the first launch of WiMAX. However, during those early years reports were published that highlighted the security weaknesses of the standard. These weaknesses prompted the IEEE to issue a new version, 802.16e to tackle the security issues. Despite this security enhancement, WiMAX remains vulnerable. This research project looks at the vulnerability of WiMAX 802.16e Subscriber Station/Mobile Station authentication at the initial entry and proposes approaches to the prevention of Denial of Service (DoS) attacks at this point in order to secure the Media Access Control (MAC) layer from such threats. A new protocol has been designed and developed to provide confidentiality, authentication and integrity to WiMAX users. This new protocol is integrated with Z algorithm (an algorithm described later in this paper) to provide: • Confidentiality of management messages • Message Authentication code • ID to provide for message integrity and user authentication. A simulation package was also required, to prove that a linear load of DoS attack would disable or exhaust the capacity of the base station of a WiMAX network, as well as providing other simulation functions. The freely available simulation tool NIST (NIST IPSec (Internet Protocol Security) and IKE (Internet Key Exchange) Simulation) is oriented towards fixed network communications (NIIST, 2003). There are no other relevant simulation tools; hence the purpose of this research project is to develop a new tool to simulate WiMAX security vulnerabilities and test the new protocol.
395

The Combined Effect Of Reduced Feedback, Frequency-Domain Scheduling, And Multiple Antenna Techniques On The Performance Of LTE

Donthi, Sushruth N 04 1900 (has links) (PDF)
Frequency-domain scheduling, multiple antenna techniques, and rate adaptation enable next generation orthogonal frequency division multiple access (OFDMA) cellular systems such as Long Term Evolution (LTE) to achieve significantly higher downlink spectral efficiencies. However, this comes at the expense of increased feedback overhead on the uplink. LTE uses a pragmatic combination of several techniques to reduce the channel state feedback required by a frequency-domain scheduler. In subband-level feedback scheme specified in LTE, the user reduces feedback by only reporting the channel quality indicator (CQI) computed over groups of resource blocks called subbands. LTE also specifies an alternate user selected subband feedback scheme, in which the feedback overhead is reduced even further by making each user feed back the indices of the best M subbands and only one CQI value averaged over all the M subbands. The coarse frequency granularity of the feedback in the above schemes leads to an occasional incorrect determination of rate by the scheduler for some resource blocks. The overall throughput of LTE depends on the method used to generate the CQI and the statistics of the channel, which depends on the multiple antenna technique used. In this thesis, we develop closed-form expressions for the throughput achieved by the user selected and subband-level CQI feedback schemes of LTE. The comprehensive analysis quantifies the joint effects of four critical components on the overall system throughput, namely, scheduler, multiple antenna mode, CQI feedback scheme, and CQI generation method. The performance of a wide range of schedulers, namely, round robin, greedy, and proportional fair schedulers and several multiple antenna diversity modes such as receive antenna diversity and open-and closed-loop transmit diversity is analyzed. The analysis clearly brings out the dependence of the overall system throughput on important parameters such as number of resource blocks per subband and the rate adaptation thresholds. The effect of the coarse subband-level frequency granularity of feedback is explicitly captured. The analysis provides an independent theoretical reference and a quick system parameter optimization tool to an LTE system designer. It also helps us theoretically understand the behavior of OFDMA feedback reduction techniques when operated under practical system constraints. Another contribution of this thesis is a new statistical model for the effective exponential SNR mapping (EESM), which is a highly non-linear mapping that is widely used in the design, analysis, and simulation of OFDMA systems. The statistical model is shown to be both accurate and analytically tractable, and plays a crucial role in facilitating the analysis of the throughput of LTE when EESM is used to generate the CQI.
396

Analýza současných služeb vybraného mobilního operátora / Analysis of current mobile operator selected services

Havlíčková, Klára January 2011 (has links)
The theme of the thesis is an analysis of current mobile operator selected services. This work focuses on the present and the future development of mobile internet connection. The aim is to analyze existing services at Telefónica Czech Republic and The work is divided into several parts. The first part focuses on the selection of a particular operator. I described at al. Czech Republic and Telefónica, which is the first integrated operator in the Czech Republic. The company currently operates more than seven million mobile numbers and fixed lines, making it one of the leading providers of fully converged services in Europe. I focused on the organizational structure of the company and its description. The second part is historical, describes the history of mobile networks in the CR, the history of mobile communications in the data and the development of mobile connections in the country. The third part is theoretical, describes al. Czech Republic Telefonica SpA in terms of services it offers in this section is also described ISO certification, EMS policy and business principles. Are described voice and mobile services, mobile data services and connectivity technologies and different types of technologies (GSM, GPRS, EDGE, UMTS, HSDPA, HSPA + and LTE). Another section includes the development of mobile connections in the CR, the current situation where Telefónica provides 3G connection for almost 71% of the population and the current state of commercial LTE network. I tried to describe the current mobile platforms, and even telecommunications market in the Czech Republic. The penultimate section specifies the geographic traffic distribution network operator and the last part, I dealt with the analysis and comparison services. The total contribution of the thesis see the approach and evaluation of existing services together. Telefónica Czech Republic, as, which is one of the largest telecommunications companies in the world.
397

Spectroscopic Study of Highly Ionised Plasmas : Detailed and Statistical Approaches / Etude spectroscopique des plasmas hautement ionisés : approche détaillée et statistique

Na, Xieyu 16 November 2017 (has links)
La description des propriétésspectrales des plasmas hautement ionisés –comme ceux rencontrés en fusion nucléaire,en astrophysique et en expérimentationlaser-plasmas –peut nécessiter différentstypes d’interprétation, parmi lesquelsl’approche détaillée ou raie-par-raieimpliquant de la diagonalisation del’Hamiltonien du système et, l’approchestatistique basée sur la caractérisation desstructures spectrales à travers les momentsde distribution.Ce travail de thèse a pour objectif d'étudier etde mettre en œuvre les méthodes statistiquestraitant des cas où de nombreuses raies seregroupent en faisceaux de transition nonrésolus (UTA pour Unresolved TransitionArray).Pour cela, des études analytique et numériqueont été menées. D’une part, les momentsd’ordre élevé de la distribution d’énergies spinorbiteont été obtenus, en utilisant lestechniques de calcul de moyennes qui fontintervenir les résultats de la secondequantification et de l’algèbre de momentangulaire. D’autre part, après avoir implémentéun programme de post-traitement des donnéesatomiques produites par le code FAC (FlexibleAtomic Code), en mode détaillée comme enmode UTA, les spectres d’émission et / The description of spectralproperties of highly ionized plasmas – asthose studied in stellar atmospheres, facilitiesfor nuclear fusion, or laser-plasmasexperiments – may require different types ofinterpretation, among which the detailed line by-line accounting which relies on Hamiltoniandiagonalization and the statistical approachbased on the characterization of spectralstructures through distribution moments.My PhD work aims at developing statisticalmethods dealing with situations whereabundant lines gather in Unresolved TransitionArrays (UTA).To this end, analytical and numerical analysishave been carried out. On one hand, high-ordermoments of spin-orbit energy have beenderived using averaging calculation techniquesbased on second quantization results andangular momentum algebra. On the other hand,after implementing a post-processing programfor both detailed and UTA computations of theFlexible Atomic Code (FAC), emission andabsorption spectra of tungsten plasmas havebeen studied in tokamak-equivalentthermodynamic conditions.Results of this thesis should hopefully stimulatefurther analysis on averages computationinvolving complex transition processes.
398

A QoE Model for Digital Twin Systems in the Era of the Tactile Internet

Alja'Afreh, Mohammad 25 October 2021 (has links)
The idiom by Thomas Fuller fantasizes the fact that seeing is believing, but the feeling is the truth. This ideology has fired the vision and innovation of the Mulsemedia, multiple-sensorial media, and Internet of Skills (IoS) which enable the exchange of control, skills, and expertise anytime/everywhere across the Internet. With the emergence of the new generation of mobile network (5G), Tactile Internet, as well as the deployment of Industry 4.0 and Health 4.0, multimedia systems are moving towards immersed haptic enabled human-machine interaction systems such as the Digital Twin (DT). Specifically, Industry 4.0 will be using DT and robots on a large scale. This will increase human-machine and interaction to a great extent. There will be multimodal communications used to interact with digital twins and robots, specially haptics. Hence, tactile internet will replace the conventional internet today. In fact, a DT system can also be extended in Health 4.0 domain to act as a COVID-19 early warning system. Tracking a person’s temperature and other symptom data in real-time can signal if as well as when it’s time to see a doctor or take a COVID test. Link to a COVID tracing app, the digital twin might help get more information about the virus relative to the person itself. Since there are currently no well-recognized models to evaluate the performance of these systems, to address this research lacuna, we proposed a Quality-of-Experience (QoE) model for DT systems containing multi-levels of subjective, objective, and physiopsychological influencing factors. The model is itemized through a fully detailed taxonomy that deduces the perceived user’s emotional and physical states during and after consuming spatial, temporal, proximal, and abstracted multi-modality media between humans and machines. Further, the taxonomy was modelled using the best practice of machine learning methods to show how QoE for digital twin applications can be inferred and predicted from interactions and biosignals in this class of applications. Furthermore, the taxonomy was applied to two use cases. The first one addresses the objective quality optimization for transmission in a large scale immersed haptic virtual reality over the Internet while the second one aims to objectively infer an important DT QoE physiological aspect i.e, fatigue.
399

Analýza řídicí roviny mobilních sítí 4. generace / Control plane analysis in 4th generation mobile networks

Hajn, Pavel January 2014 (has links)
The thesis is focused on the description of LTE system in terms of signaling on interfaces of LTE and EPC subsystems, such as UE initial network connection. The next section describes the types of diagnostic methods for mobile networks using OSS, drive testing and flow analysis. The thesis also aims at description of key performance indicators (RSRP, RSSI, etc.) and the proposal for measuring of the LTE network physical layer and the data transmission speed.
400

Train-borne Antennas : A business case study

Michailidis, Georgios January 2014 (has links)
The global rail network every year is used to transport approximately 21 billion of people and 10 billion tons of cargo. These numbers is estimated that are going to increase in the future. Railway will become the transportation of the future. The actors involved in the rail market realizing these needs started to invest funds to upgrade both the network and the electronic systems on the trains to meet the demands and attract even more customers. Currently two different electronic systems are installed on-board trains, one related to safety and security and the other for passenger services. For safety and security two different systems have deployed for signaling and train control. The first one is ERTMS system that is mainly deployed in Europe, China and other regions of the world using GSM-R technology operating at 900 MHz while the other one is solely deployed in the USA operating at 220 MHz. For passenger-services more and more operators install Wi-Fi systems on-board the train. Each of these systems has different requirements to function. The common factor of these platforms is the train-borne antenna, which plays an active role to all the systems and can improve the quality of the services provided. SMARTEQ having experience in the transportation sector, more specifically in trucks wanted to explore this growth of rail transport followed by huge investments will create openings to enter the market and expand their business portfolio. The purpose of this report is to deploy a business case for train-antennas in order to help SMARTEQ decide if there is value in the rail sector. To achieve this goal a market analysis was conducted, followed by a technical description of the systems and the needs that exist on antennas and in the end concluding with a business model. This study reveals that antenna-rail market is really difficult to enter for a new company not related to train industry and needs proper acquaintances and partnerships to become a leading supplier. In addition due to the oligopoly of the market, competition is really high and needs a unique and competitive solution both price and technology-wise to attract the end customer.

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