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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.
1

Satellite-UMTS : specification of protocols and traffic performance /

Oh, Seong-Hoon. January 2005 (has links)
Zugl.: Diss., RWTH Aachen.
2

Zeitduplexbasierte Mobilkommunikation, untersucht am Beispiel eines TD-CDMA-Mobilfunksystems

Bing, Torsten. January 2001 (has links) (PDF)
Kaiserslautern, Univ., Diss., 2001. / Computerdatei im Fernzugriff.
3

Simulation and Performance evaluation of co-existing GSM and UMTS systems

Cutillas Sanchez, Laura January 2010 (has links)
<p> </p><p>Mobile users need more capacity and higher velocity to work with new data applications. In </p><p>order to satisfy these requirements, mobile systems of third generation were created and they </p><p>are established every day in more places. Consequently second and third generation of system </p><p>have to coexist. </p><p>In this paper is presented a study about the co-existence between GSM and UMTS, the most </p><p>popular systems in Europe. 900MHz is the frequency chosen to work with both systems, due to </p><p>this low frequency allows: less path loss and more coverage, than 2100MHz the usual </p><p>frequency for UMTS system.  </p><p>The situation evaluated is focused on introducing a UMTS carrier in a GSM operator, with the </p><p>aim to determine the advantages and cons produced in the mobiles with this change. Two </p><p>cases are distinguished: coordinated operation, GSM and UMTS900 in the same operator and </p><p>un-coordinated operation, UMTS900 respect to other GSM operator. Users under study belong </p><p>to both modified operator and a next GSM operator. Power control was programmed in both </p><p>systems. </p><p>It was determined how affect the interferences in system capacity of the operators and which </p><p>is the guard band necessary to protect the system. Spectral efficiency (user/cluster/MHz) in </p><p>the case GSM and UMTS900 in same band is twice as much as in a GSM operator. The </p><p>separation between operators is set in 300KHz.But is important to know that UMTS carriers do </p><p>not cause damage in others operators because is located in the middle of GSM carriers. The </p><p>guard band fixed to protect each mobile in operator with shared spectrum is not necessary. </p><p>The distance between carriers GSM and UMTS necessary is 2.4MHz while the width of one </p><p>UMTS carrier is 2.5MHz. </p>
4

Simulation and Performance evaluation of co-existing GSM and UMTS systems

Cutillas Sanchez, Laura January 2010 (has links)
Mobile users need more capacity and higher velocity to work with new data applications. In  order to satisfy these requirements, mobile systems of third generation were created and they  are established every day in more places. Consequently second and third generation of system  have to coexist.  In this paper is presented a study about the co-existence between GSM and UMTS, the most  popular systems in Europe. 900MHz is the frequency chosen to work with both systems, due to  this low frequency allows: less path loss and more coverage, than 2100MHz the usual  frequency for UMTS system.   The situation evaluated is focused on introducing a UMTS carrier in a GSM operator, with the  aim to determine the advantages and cons produced in the mobiles with this change. Two  cases are distinguished: coordinated operation, GSM and UMTS900 in the same operator and  un-coordinated operation, UMTS900 respect to other GSM operator. Users under study belong  to both modified operator and a next GSM operator. Power control was programmed in both  systems.  It was determined how affect the interferences in system capacity of the operators and which  is the guard band necessary to protect the system. Spectral efficiency (user/cluster/MHz) in  the case GSM and UMTS900 in same band is twice as much as in a GSM operator. The  separation between operators is set in 300KHz.But is important to know that UMTS carriers do  not cause damage in others operators because is located in the middle of GSM carriers. The  guard band fixed to protect each mobile in operator with shared spectrum is not necessary.  The distance between carriers GSM and UMTS necessary is 2.4MHz while the width of one  UMTS carrier is 2.5MHz.
5

Simulation und Analyse von Verschlüsselungsalgorithmen am Beispiel von UMTS

Bolta, Axel. January 2003 (has links)
Weingarten, Diplomarbeit, 2003.
6

QoS in IP over UMTS networks

Dias, Jaime Sousa January 2005 (has links)
Tese de mestrado. Redes e Serviços de Comunicação. Faculdade de Engenharia. Universidade do Porto. 2005
7

Analytical modeling of HSUPA-enabled UMTS networks for capacity planning

Liu, Tuo January 2009 (has links)
PhD / In recent years, mobile communication networks have experienced significant evolution. The 3G mobile communication system, UMTS, employs WCDMA as the air interface standard, which leads to quite different mobile network planning and dimensioning processes compared with 2G systems. The UMTS system capacity is limited by the received interference at NodeBs due to the unique features of WCDMA, which is denoted as `soft capacity'. Consequently, the key challenge in UMTS radio network planning has been shifted from channel allocation in the channelized 2G systems to blocking and outage probabilities computation under the `cell breathing' effects which are due to the relationship between network coverage and capacity. The interference characterization, especially for the other-cell interference, is one of the most important components in 3G mobile networks planning. This monograph firstly investigates the system behavior in the operation of UMTS uplink, and develops the analytic techniques to model interference and system load as fully-characterized random variables, which can be directly applicable to the performance modeling of such networks. When the analysis progresses from single-cell scenario to multi-cell scenario, as the target SIR oriented power control mechanism is employed for maximum capacity, more sophisticated system operation, `feedback behavior', has emerged, as the interference levels at different cells depend on each other. Such behaviors are also captured into the constructed interference model by iterative and approximation approaches. The models are then extended to cater for the features of the newly introduced HSUPA, which provides enhanced dedicated channels for the packet switched data services such that much higher bandwidth can be achieved for best-effort elastic traffic, which allows network operators to cope with the coexistence of both circuit-switched and packet-switched traffic and guarantee the QoS requirements. During the derivation, we consider various propagation models, traffic models, resource allocation schemes for many possible scenarios, each of which may lead to different analytical models. All the suggested models are validated with either Monte-Carlo simulations or discrete event simulations, where excellent matches between results are always achieved. Furthermore, this monograph studies the optimization-based resource allocation strategies in the UMTS uplink with integrated QoS/best-effort traffic. Optimization techniques, both linear-programming based and non-linear-programming based, are used to determine how much resource should be assigned to each enhanced uplink user in the multi-cell environment where each NodeB possesses full knowledge of the whole network. The system performance under such resource allocation schemes are analyzed and compared via Monte-Carlo simulations, which verifies that the proposed framework may serve as a good estimation and optimal reference to study how systems perform for network operators.
8

Développement de récepteurs avancés pour les systèmes de communication mobile de type WCDMA et HSDPA

Ba, Ahmet 05 1900 (has links) (PDF)
Dans la première partie de la thèse, on considère des méthodes d'estimation des canaux utilisateurs dédiés en liaison descendante. Ces méthodes sont particulièrement avantageuses dans un contexte de transmission à formation de faisceaux. Elles ne supposent aucune connaissance a priori des retards des signaux reçus ainsi que les paramètres de formation des faisceaux; exploitent la totalité des séquences pilotes transmises ainsi que la dynamique structurée du canal.Dans la seconde partie, on commence par considérer un schéma d'égalisation au niveau chip et dite HDD-NLMS. Ce schéma utilise l'estimation de la précédente séquence chip comme réponse cible pour l'adaptation de l'égaliseur. Dans la suite propose les égalisateurs niveau symbole HSDPA N-Griffith et HDD-NLMS qui permettent une vitesse d'adaptation 16 fois plus élevée que dans le cas de l'utilisation des symboles PCPICH. Les solutions spécifiques HSDPA ont une complexité raisonnable et offrent des performances proches aux Max-SINR dans un environnement réel.Dans la dernière partie, nous évaluons l'avantage des égalisateurs au niveau chip par rapport au récepteur Rake conventionnel ainsi que l'avantage d'une décision hard par rapport à l'utilisation d'une contre réaction linéaire dans le contexte d'un récepteur avec élimination itérative parallèle des interférences. Cette contre réaction sera déduite d'un développement polynomial de l'inverse de la matrice de covariance en amont du premier étage d'égalisation. Etant donné que les égalisateurs à chaque étage sont différents, nous utilisons les résultats d'analyse des étages précédents afin de pouvoir estimer les paramètres de l'égalisateur à un étage donné.
9

Granskning av möjliggörande teknik och utveckling av prototyp för geografiskt riktade utskick av SMS

Nordin, Johan, Olsson, Anders January 2004 (has links)
Detta examensarbete på magisternivå genomfördes vårterminen 2004 med Siljan Turism som uppdragsgivare. Målet var att förbättra en befintlig SMS-tjänsten för utskick av erbjudanden genom att möjliggöra geografiskt riktade utskick.Anledningen till att man vill göra denna form av riktade utskick är att man vill kunna minska annonskostnaderna, men fortfarande snabbt nå intresserade konsumenter. Om man idag skulle vilja annonsera ut till exempel biljetter till ett evenemang som äger rum inom den närmaste tiden, där det finns lediga platser kan man endast skicka erbjudanden till samtliga intresserade. Utskicken sker oberoende av var mottagarna befinner sig, trots att de egentligen inte skulle kunna komma fram i tid. Med hjälp av geografiskt riktade utskick skulle man kunna effektivisera utskicken så att de enbart skickas till de som faktiskt har möjlighet att utnyttja erbjudandet.Det befintliga systemet var baserat på en standardiserad tjänst som vi inte hade möjligheter att förbättra. På grund av detta beslutade vi oss för att utveckla en prototyp för att kunna bygga in all ny funktionalitet. Med denna prototyp försökte vi även att eliminera delar av den manuella hantering som krävs med det befintliga systemet.För att kunna realisera dessa riktade utskick behövde vi en typ av positionering som inte existerar idag. De lösningar som finns idag passar inte vår tänkta tjänst. Därför har vi gjort egna undersökningar i GSM och UMTS för att finna lösningsalternativ. Därför kan rapporten vara intressant även för andra än vår uppdragsgivare när det gäller denna typ av geografiskt riktade utskick.
10

Analytical modeling of HSUPA-enabled UMTS networks for capacity planning

Liu, Tuo January 2009 (has links)
PhD / In recent years, mobile communication networks have experienced significant evolution. The 3G mobile communication system, UMTS, employs WCDMA as the air interface standard, which leads to quite different mobile network planning and dimensioning processes compared with 2G systems. The UMTS system capacity is limited by the received interference at NodeBs due to the unique features of WCDMA, which is denoted as `soft capacity'. Consequently, the key challenge in UMTS radio network planning has been shifted from channel allocation in the channelized 2G systems to blocking and outage probabilities computation under the `cell breathing' effects which are due to the relationship between network coverage and capacity. The interference characterization, especially for the other-cell interference, is one of the most important components in 3G mobile networks planning. This monograph firstly investigates the system behavior in the operation of UMTS uplink, and develops the analytic techniques to model interference and system load as fully-characterized random variables, which can be directly applicable to the performance modeling of such networks. When the analysis progresses from single-cell scenario to multi-cell scenario, as the target SIR oriented power control mechanism is employed for maximum capacity, more sophisticated system operation, `feedback behavior', has emerged, as the interference levels at different cells depend on each other. Such behaviors are also captured into the constructed interference model by iterative and approximation approaches. The models are then extended to cater for the features of the newly introduced HSUPA, which provides enhanced dedicated channels for the packet switched data services such that much higher bandwidth can be achieved for best-effort elastic traffic, which allows network operators to cope with the coexistence of both circuit-switched and packet-switched traffic and guarantee the QoS requirements. During the derivation, we consider various propagation models, traffic models, resource allocation schemes for many possible scenarios, each of which may lead to different analytical models. All the suggested models are validated with either Monte-Carlo simulations or discrete event simulations, where excellent matches between results are always achieved. Furthermore, this monograph studies the optimization-based resource allocation strategies in the UMTS uplink with integrated QoS/best-effort traffic. Optimization techniques, both linear-programming based and non-linear-programming based, are used to determine how much resource should be assigned to each enhanced uplink user in the multi-cell environment where each NodeB possesses full knowledge of the whole network. The system performance under such resource allocation schemes are analyzed and compared via Monte-Carlo simulations, which verifies that the proposed framework may serve as a good estimation and optimal reference to study how systems perform for network operators.

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