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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.
31

Metodika měření kvality služeb ve Wi-Fi sítích / Methods for Quality of Service measurement in Wi-Fi networks

Bachan, Jiří January 2008 (has links)
This work deals with the wireless Wi-Fi networks, that used unlicenced ISM frequency band 2,4 GHz. These wireless networks are very extended in these days and used mainly for the Internet connection. With the multimedia data transfers expanding it’s necessary to ensure the specific quality of service QoS in wireless networks mainly for applications, which are sensitive to delay or packets lost. The main aim of this work is to describe Wi-Fi networks based on IEEE 802.11b/g/n standards, description of QoS techniques according to IEEE 802.11e standard and description of parameters describing QoS for the VoIP services. The practical part is divided on a two parts. The problems of measuring the radio link quality and the creation of simple program for quality of wireless connection analysis are solved in the first part. The second part incluledes measuring of the lost packets number in Wi-Fi network with the commercial application AirMagnet Laptop Wireless LAN Analyzer and measuring of the signal noise influence with the help of spectrum analyzer and vector signal generator.
32

Integrované telekomunikační prostředí / Integrated telecommunication environment

Tomeček, Jan January 2009 (has links)
The thesis described the proposal for a wireless network problems. There are recorded and compared the characteristics of different wireless technologies. The possibility of voice communication securing is outlined and solutions implemented in the form of ZRTP protocol. The requirements for quality of service are discussed and the solutions to this issue are proposed. Other chapters are devoted to the actual design of specific equipment, including antennas and advance resource. The whole network is practically implemented in the mountainous countryside of eastern Wallachia. In conclusion, this work is network mate in terms of QoS (quality of service) and tested in terms of prioritization of voice communication.
33

Impact of interfering rouge access points on modulationand coding in IoT network / Påverkan av störande obehörigaåtkomstpunkter på modulation ochkodning i IoT-nätverk

Saif, Amgad Shaher January 2023 (has links)
This Bachelor thesis presents an in-depth investigation into the effects of RogueAccess Point interference within Internet of Things networks. The study focuses onthe impact of rogue APs on the modulation and coding scheme indices, round triptime, and overall network performance. The presence of a rogue AP was found toshift devices from dual-stream to single-stream operation, causing a decrease in themodulation and coding scheme indices and data rates. Additionally, a significantincrease in round trip time was observed, emphasizing the detrimental impact ofrogue AP interference on network latency. The insights gained from this researchcontribute to a greater understanding of the challenges posed by rogue APinterference. This deeper comprehension paves the way for devising effectivestrategies to mitigate these impacts, thereby enhancing the reliability, security, andperformance of IoT networks. / Detta examensarbete presenterar en grundlig undersökning av effekterna avstörande åtkomstpunkter (Rogue Access Points) inom nätverk för Sakernas Internet(Internet of Things). Studien fokuserar på störande åtkomstpunkter inverkan påmodulations- och kodningsschemaindex (MCS), round trip time och denövergripande nätverksprestandan. När en störande åtkomstpunkt blev närvarandetvingades enheterna att omställa sig från att använda dubbelströmsoperation tillenkelströmsoperation, vilket ledde till en minskning av MCS-index ochdatahastigheter. Dessutom observerades en betydande ökning av RTT, vilketbetonar den skadliga inverkan av störande åtkomstpunkt interferens pånätverkslatens. De insikter som vunnits bidrar till en större förståelse för deutmaningar som störande åtkomstpunkter interferens medför. Denna djupareförståelse banar väg för att utforma effektiva strategier för att mildra dessa effekter,vilket i sin tur förbättrar tillförlitligheten, säkerheten och prestanda för IoT-nätverk.
34

Σχεδιασμός και ανάπτυξη λογισμικού ΕΛ/ΛΑΚ (open source) για διαχείριση οποιασδήποτε ενσωματωμένης (embedded) και μη συσκευής / Extending and customizing OpenRSM for wireless embedded devices and LINUX

Κουμούτσος, Κωνσταντίνος 25 May 2011 (has links)
Οι ενσωματωμένες συσκευές αποτελούν μια κατηγόρια υπολογιστών ειδικού σκοπού με ραγδαία αύξηση τα τελευταία χρόνια. Σε αντίθεση με τους γνωστούς σε όλους υπολογιστές γενικού σκοπού που μπορούν να επιτελέσουν σχεδόν οποιαδήποτε λειτουργία, οι ενσωματωμένες συσκευές επιτελούν μόνο συγκεκριμένες λειτουργίες, οι οποίες είναι προκαθορισμένες κατά τον σχεδιασμό τους. Η διαχείριση τέτοιων και μη συσκευών αποτελεί ένα τεράστιο κεφάλαιο αφού η διαφορετικότητα των λειτουργιών τους, δημιουργεί ένα διαφορετικό τρόπο αντιμετώπισης τους κατά την πρακτική της διαχείρισης. Υπάρχει περιορισμός στα διαθέσιμα εργαλεία για την διαχείριση όλων των ενσωματωμένων συστημάτων με ένα εργαλείο, αλλά η ερεύνα μας επικεντρώνεται στη διαχείριση οικογενειών τέτοιων συσκευών με κριτήριο τη λειτουργία του ειδικού σκοπού που επιτελούν. Σκοπός λοιπόν της εργασίας είναι ο σχεδιασμός και η ανάπτυξη λογισμικού για την ομαδική διαχείριση οικογένειας ενσωματωμένων συσκευών και κοινών υπολογιστών γενικού σκοπού οπουδήποτε λειτουργικού συστήματος. Η συνεισφορά της υπάρχουσας εργασίας συνοψίζεται στις εξής συνιστώσες: 1. Οι ενσωματωμένες συσκευές στις οποίες επικεντρωθήκαμε αφορούν δικτυακές συσκευές (ασύρματες ή ενσύρματες) πολλών λειτουργιών (Access Points, Clients, Repeaters,Points to Points, WDS, Transparent Clients, Routers). 2. Το λογισμικό για υπολογιστές ειδικού σκοπού που δημιουργήθηκε μπορεί να εκτελεστεί τόσο σε λειτουργικά συστήματα MS Windows όσο και σε *ΝΙΧ. 3. Η ανάπτυξη του λογισμικού έγινε βάση του συστήματος ORSM, το οποίο είναι ένα εργαλείο ανοικτού κώδικα για την απομακρυσμένη διαχείριση συστημάτων και δικτύων. (Με αστερίσκο * τόσο στα περιεχόμενα όσο και στο κύριο μέρος της εργασίας δείχνουμε τις δυνατότητες του νέου λογισμικού σε σχέση με το σύστημα ORSM). Συνοπτικά οι δυνατότητες διαχείρισης αφορά τις παρακάτω λειτουργίες: • Ανακάλυψη περιουσιακών στοιχείων (Inventory Process). • Παρακολούθηση απόδοσης συστημάτων (Monitoring). • Εγκατάσταση και απεγκατάσταση λογισμικού (Software Deployment). • Απομακρυσμένο έλεγχο (Remote Desktop). • Εκτέλεση εντολών κελύφους (Remote Command). / An embedded system is a special-purpose computer system designed to perform one or a few dedicated functions, often with real-time computing constraints. It is usually embedded as a part of a complete device including hardware and mechanical parts. In contrast, a general-purpose computer, such as a personal computer, can do many different tasks depending on programming. Embedded systems control many of the common devices in use today. Managing infrastructure with such devices (embedded and general purpose computers) is usually demanding and expensive but nevertheless essential for organizations. There is a limit in tools which achieve effective management to those infrastructure topologies. At present, open management solutions are few and immature however there are tools such as OpenRSM aiming to deliver lightweight, remote and customizable management, easily customizable to cover the needs of small organizations. OpenRSM implements a generic management framework that models generalized use cases that can be exploited by users to adapt the tool to their needs. However, given maturity of the tool, it is unclear how easy it would be for users to extend it in order to include management of new types of devices. As network environments grow to digital ecosystems, the management targets increase in number and diversity. Wireless active elements, handheld systems or embedded devices are becoming common and need to be brought under standard management practices in the same manner as routers or workstations. This paper describes how the OpenRSM management functionality can be extended in order to provide customizable management of embedded devices and more specifically of wireless access points (the symbol * shows the new extension of ORSM). In general the management capabilities which are embed to OPENRSM system and target to wireless active elements are: (Inventory process, monitoring, firmware upgrade, save/reload configuration settings, remote commands, and discovery process).
35

Průmyslová hala / Industrial hall

Forman, Radek January 2012 (has links)
Two-bay hall for warehouse and manufacturing purposes with supporting steel structure and thermally insulating sheating with width of 36 metres and lenght of 72 metres. The hall incorporates two overhead cranes with maximum load of 32 and 40 tonnes. The main supporting structure is a system of plate girders and beams. The beams are connected with hinges and are placed with intervals of 6 metres. The hall design is intended for 1st snowing area
36

Design and Analysis of 5G/IoT Antennas for sub-6 GHz Applications using Characteristic Modes Analysis.

Molins Benlliure, Jaime 30 December 2024 (has links)
[ES] El escenario actual de las comunicaciones inalámbricas está definido por el progresivo despliegue del 5G que ha establecido altos estándares en tasas binarias, fiabilidad, eficiencia, número de conexiones y latencia. El despliegue inicial del 5G se ha producido en las bandas denominadas sub-6 GHz debido a su compatibilidad con la infraestructura ya desplegada. Una de las novedades del 5G es la subdivisión en pequeñas celdas que requerirá la instalación de puntos de acceso interiores mediante antenas de múltiples puertos, altamente eficientes y compatibles con la tecnología MIMO. Como consecuencia, la necesidad de este tipo de antenas ha experimentado un crecimiento en su demanda. El diseño de este tipo de antenas resulta complejo y requiere de muchos recursos computacionales cuando el número de puertos es elevado. Esta tesis aborda el diseño y análisis de antenas respaldadas por cavidades con alimentación múltiple con la novedad de introducir nuevas metodologías basadas en el análisis de modos característicos (CMA) para el diseño sistemático de este tipo de soluciones para simplificar el proceso de diseño y simulación. Además, todas las soluciones se analizan desde la perspectiva de canal para su evaluación en un entorno real de un sistema con tecnología MIMO. Otro desafío que ha supuesto el sistema 5G es el crecimiento exponencial en la demanda de pequeñas antenas para su integración en dispositivos de tamaño reducido debido al desarrollo de nuevas aplicaciones para el Internet de las Cosas (IoT). En particular, las bandas ISM de 433 MHz, 868/915 MHz y 2.4 GHz son las que más atención han recibido para albergar estas aplicaciones. Las técnicas de miniaturización se vuelven imprescindibles cuando el espacio es tan limitado y considerando que el dispositivo puede ser incluso entre 10 y 20 veces más pequeño que la longitud de onda de la frecuencia de la banda utilizada. Los fabricantes de antenas han introducido antenas cerámicas conocidas como chip antenas que se instalan en placas de circuito impreso (PCB) como solución a esta problemática. Junto con las antenas chip, se proporcionan unas pautas de instalación genéricas en las que falta información del funcionamiento físico de la antena. En esta tesis, varias antenas tipo chip se han diseñado y fabricado con tecnología LTCC para proporcionar más información sobre sus propiedades de radiación y su localización óptima para excitar los modos deseados de la PCB donde se instalan. Un nuevo parámetro basado en CMA se ha propuesto mediante la correlación entre los campos totales y modales para proporcionar información física sobre esta temática. / [CA] L'escenari actual de les comunicacions sense fils està definit pel progressiu desplegament del 5G que ha establit alts estàndards en taxes binàries, fiabilitat, eficiència, nombre de connexions i latència. El desplegament inicial del 5G s'ha produït en les bandes denominades sub-6 GHz a causa de la seua compatibilitat amb la infraestructura ja desplegada. Una de les novetats del 5G és la subdivisió en xicotetes cèl·lules que requerirà la instal·lació de punts d'accés interiors que requeriran antenes de múltiples ports altament eficients compatibles amb la tecnologia MIMO. Com a consequencia, la necessitat d'este tipus d'antenes ha experimentat un creixement en la seua demanda. El disseny d'estes antenes es torna complex i requerix molts recursos computacionals quan s'augmenta el nombre de ports. Esta tesi aborda el disseny i anàlisi de solucions recolzades per cavitats amb alimentació múltiple amb la novetat d'introduir noves metodologies basades en l'anàlisi de modes característics (CMA) per simplificar el procés de disseny i simulació de estes antenes. A més, totes les solucions s'analitzen des de la perspectiva de canal per a la seua avaluació en un entorn real de sistema MIMO. Un altre desafiament que ha suposat el sistema 5G és el creixement exponencial en la demanda d'integració de xicotetes antenes en dispositius de tamany reduït i el desenvolupament de noves aplicacions per a la Internet de les Coses (IoT). En particular, les bandes ISM que operen a 433 MHz, 868/915 MHz i 2.4 GHz són les mes demandades per a estes aplicacions. Les tècniques de miniaturització es tornen imprescindibles quan l'espai és tan limitat i considerant que el dispositiu pot ser fins i tot entre 10 i 20 vegades més xicotet que la longitud d'ona de la banda de freqüència utilitzada. Els fabricants d'antenes han introduït antenes tipus xip ceràmiques instal·lades en plaques de circuit imprés (PCB) com a solució a esta problematica. Juntament amb les antenes xip, es proporcionen unes pautes d'instal·lació genèriques sense cap justificació física adicional. En esta tesi, diverses antenes tipus xip s'han dissenyat i fabricat internament amb tecnologia LTCC per a proporcionar més informació sobre les seues propietats de radiació i la seua localització òptima per a excitar els modes desitjats de la PCB on s'instal·len. Un nou paràmetre basat en CMA s'ha proposat mitjançant la correlació entre els camps totals i modals per a proporcionar informació física sobre esta temàtica. / [EN] The current wireless communication scenario is defined by the progressive deployment of the 5$^{th}$ generation (5G) wireless communication system, which has established high standards in data rate, reliability, efficiency, number of connections, and latency. The early deployment of the 5G has taken place in the so-called sub-6 GHz bands due to its compatibility with the previously deployed infrastructure. One of the novelties of the 5G is the subdivision into small cell coverage areas, which will require the installation of indoor access points requiring multiple port antennas with high efficiency compatible with the Multiple-Input Multiple-Output (MIMO) technology. As a result, the need for this kind of antenna has increased. The design of these antennas becomes complex and time-demanding when the number of ports is increased. This thesis deals with the design and analysis of multiple-fed cavity-backed solutions with the novelty of introducing new characteristic modes analysis (CMA) based methodologies for the systematic design of this kind of solution, which simplifies the design and calculation process. In addition, all the solutions are analyzed regarding the channel perspective for their evaluation in a real MIMO system environment. Another challenge that brings the 5G system is the exponential growth in the demand for the integration of small antennas in size-limited devices introduced by the all-connected concept and the development of new applications for the Internet of Things (IoT). In particular, the 433 MHz, 868/915 MHz, and 2.4 GHz ISM bands are mainly used for these applications. Miniaturization techniques become imperative in such a limited space, considering that the device can be even 10-20 times smaller than the wavelength of the operating band. Antenna manufacturers have introduced ceramic chip antennas installed in printed circuit boards (PCBs) as the solution for this scenario. They are provided with generic installation guidelines without further physical insight. In this thesis, low-temperature co-fired ceramic (LTCC) chip antennas have been designed and fabricated in-house to provide more information about their radiation performance and optimum allocation to excite the desired modes on the installed PCB. A novel CMA parameter based on the correlation between total and modal fields is introduced to provide physical insight into this topic. / Molins Benlliure, J. (2024). Design and Analysis of 5G/IoT Antennas for sub-6 GHz Applications using Characteristic Modes Analysis [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/213673
37

Mobile IP v sítích MANET / Mobile IP in MANETs

Raška, Martin January 2009 (has links)
This thesis discuss about the problem with mobility of stations in IP networks, concretely protocol Mobile IP and about the problems with this protocol in MANET networks, with the scope on Motorola MESH. First part is about design integration of protocol Mobile IP in this networks with usage Tropos 5210 MetroMesh routers and Cisco components (router, switch) to design and configure wireless MESH network, than connect this network with Cisco components and try to implement Mobile IP into this network. Second part is about design and configure wireless network from Cisco Wireless Access Points and about succesfully implementation of Mobile IP protocol into this network. In the last part is some tests of the function and quality of this topology.

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