Le besoin d'améliorer la capacité des réseaux sans-fil, pour la transmission de données et les applications multimédia des systèmes de communications numériques, a amené à s'intéresser aux techniques de communication MIMO (Multiple Input Multiple Output) pour augmenter le débit et la qualité des transmissions. Les systèmes MIMO se servent de réseaux d'antennes, à la fois à l'émission et à la réception d'une communication radio et ainsi exploitent la dimension spatiale pour la transmission de l'information. Les performances expérimentales d'un système de communication peuvent être évaluées en utilisant un simulateur matériel du canal de propagation. Cette thèse a pour objectif la conception et la réalisation de la partie numérique d'un simulateur matériel pour les canaux de propagation MIMO, pour les réseaux UMTS et WLAN. La simulation matérielle du canal radio assure la vitesse de traitement nécessaire. D'autres avantages de la simulation matérielle sont l'évaluation des performances en temps réel et la comparaison de divers systèmes de radiocommunication dans un canal de propagation variant dans le temps, dans les mêmes conditions de test. L'étude de faisabilité a permis d'établir deux approches, l'une pour les environnements indoor, l'autre pour les environnements outdoor. Les architectures numériques proposées ont été étudiées et implémentées dans un composant programmable FPGA. L'évaluation des performances et de la complexité montre l'intérêt de ces architectures. Ce travail a été réalisé dans le cadre du projet PRIR SIMPAA 2, avec le soutien de la Région Bretagne.

Πρόθεση της παρούσας διπλωματικής εργασίας είναι ο σχεδιασμός και υλοποίηση συγκεκριμένης τεχνικής προσδιορισμού της θέσης του συνδρομητή (η γνωστή Power of Arrivals), καθώς αυτά τα δεδομένα μπορούσαν να μας παραχωρηθούν από την εταιρία Vodafone. Έως και σήμερα, στα Universal Mobile Telecommunications System (UMTS) δίκτυα δεν υπάρχει κανένας συγκεκριμένος αλγόριθμος, ενσωματωμένος στο λογισμικό, για τον προσδιορισμό της θέσης ενός συνδρομητή. Η μόνη δυνατότητα εντοπισμού που υλοποιείται ως και σήμερα, είναι είτε χρησιμοποιώντας τεχνολογία Global Positioning System (GPS) είτε κάποιο ειδικό σταθερό τμήμα λογισμικού υπολογιστή (firmware). Σε αυτή την εργασία παρουσιάζεται μια λεπτομερής περιγραφή της πλέον γνωστής μεθόδου Power Of Arrivals (POA). Η προσπάθεια που καταβλήθηκε είχε ως βασικό άξονα την εφαρμογή αυτής της τεχνικής με τις ελάχιστες δυνατές τροποποιήσεις στο δίκτυο αλλά και έχοντας ως γνώμονα ότι η εταιρία Vodafone είναι αυτή που μας παραθέτει τα δεδομένα λήψης των σημάτων. / -

Made available in DSpace on 2008-05-13T13:48:27Z (GMT). No. of bitstreams: 1 2142.pdf: 937600 bytes, checksum: 2ea39c80c8dbfa4f1a4c9e92d891f5f3 (MD5) Previous issue date: 2006-08-11 / A research was accomplished on the UMTS frequency spectrum licensing on Europe on the years 2000 and 2001. It was analyzed the bidders behaviors’, the auction rules’, the auction environment and each auction objective. After the European auction analysis was done a discussion on the specifics aspects of brazilian market for those types of auction. / Atualmente, o leilão de espectro tem sido evento de considerável relevância para o mercado de telecomunicações. As cifras alcançadas nos leilões, a oportunidade que eles representam para as empresas interessadas em explorar o mercado de telecomunicações, e o interesse do governo em alocar de forma eficiente este recurso, trouxeram notoriedade e magnitude para este mecanismo de seleção. Com o advento de novas tecnologias de comunicação móvel, detentoras de características inovadoras que permitem preencher cada vez mais a cesta de necessidades do consumidor, e a partir da alocação destas tecnologias a distintas faixas de espectro, tornou-se necessário, a determinação do mecanismo de escolha mais adequado daquele que será o gestor do recurso que permitirá a oferta desses serviços ao mercado: o espectro de freqüência. Com o intuito de se avaliar esse cenário, e os distintos papéis de seus participantes, busca-se nesse trabalho, através da análise do mais recente conjunto de leilões realizados para alocação deste recurso, o leilão das licenças 3G na Europa, compreender os pormenores envolvidos desde a elaboração até o desfecho deste processo. Objetiva-se, por fim, enriquecer o debate sobre esse tema ao discutir-se o cenário brasileiro. O trabalho ao analisar os leilões europeus nos permite identificar que as regras do leilão, como comentado por diversos autores, não são diretamente transplantáveis entre diferentes ambientes. Afinal dentro do ambiente homogêneo caracterizado pelo continente europeu, apesar da semelhança entre os diversos modelos de leilão utilizados, o sucesso obtido em países como Reino Unido e Alemanha, não foi repassado aos demais, ao compararmos o preço pago per capta. Entretanto, o espectro tem seu valor altamente conectado à disponibilidade tecnológica de sua utilização, logo, espectro sem tecnologia adequada para seu uso é observado como de valor privado aproximadamente zero pelos participantes. Esse fenômeno foi caracterizado pelo baixo valor atribuído ao espectro não pareado. Apesar de valor ser relativamente nulo, não é zero, pois a aquisição do direito de uso do espectro pode representar um 'hedge' para ser utilizado, senão hoje, quando a tecnologia estiver disponível. Porém sendo o espectro recurso escasso, a alocação deste para tecnologia ainda indisponível pode ser considerado ineficiente. Observa-se, também, que o 'incumbent' tende a valorizar mais uma licença, porém não se conseguiu determinar se isso ocorre devido a maior quantidade de informação que este detém sobre o mercado, ou devido à tentativa de manter o 'status quo' do oligopólio atual. Baseado no comentado anteriormente e nos resultados dos leilões torna-se evidente que caso o entrante não seja protegido, como o 'incumbent' valoriza mais a licença este sempre pagará mais por esta. E caso, o entrante tenha esta certeza, este não virá participar do leilão, o que na maior parte dos casos inviabilizaria o leilão pois haveriam tantas licenças quanto participantes. Ao analisar-se o caso brasileiro identifica-se a presença de um jogo nacional e um subjogo regional, onde os participantes podem ser simultaneamente 'incumbents' para uma região, porém entrantes em outra.

När rumsligt omvälvande projekt skall genomföras är det ofta konsekvenserna för naturmiljö, kulturmiljö, estetiska miljöaspekter som ger upphov till diskussioner. Uppförandet av telemaster till mobiltelefonsystemet 3G är ett infrastrukturprojekt som kommer att vara visuellt påtagliga på många platser i landskapet. I Sverige uppförs två stycken parallella mastsystem och detta har givit upphov till diskussioner kring projektets påverkan på vår omgivning. Uppsatsen studerar hur miljöpåverkan från ett stort infrastrukturprojekt, uppförandet av telemaster för 3G-systemet, behandlats av länsstyrelsen i samrådsärenden enligt 12 kapitlet 6§ miljöbalken, samt diskuterar kring hur handläggare på länsstyrelsen hanterar och upplever dessa ärenden. Studien visar att handläggare på de undersökta länsstyrelserna har begränsat mandat att minska antalet master genom samlokalisering. Önskemålen om att teleoperatörerna ska dela på själva masten är svåra att genomföra eftersom operatörerna inte har samverkansavtal. Laglig rätt att förplikta samlokalisering fanns inte under den studerade perioden. Det är vanskligt att säga om den sammantagna inverkan som masterna sägs ha kunnat begränsas på denna nivå. Det som identifierats som ett problem av aktörer som Boverket och PTS, d.v.s. antalet master, fastlades redan i ett tidigare skede. Samråden är inriktade på att undvika ur naturmiljösynpunkt olämpliga mastplaceringar. Dock utgör den fastslagna utbyggnaden av nätet och kravet på geografisk täckning att det kan uttryckas som att det för länsstyrelsen är inte en fråga om i fall masterna ska uppföras, utan om var. Lokaliseringen av masterna blir ett samspel mellan var operatörerna föredrar att placera master samt var det är lämpligt ut naturmiljösynpunkt. Den på nationell nivå fastlagda geografiska täckningskravet gör att bedömningen av masters påverkan på vissa landskap, där intrycket i landskapsbilden blir stort, upplevs svår av de intervjuade handläggarna. Bedömning av masters påverkan på just landskapsbilden kan upplevas som subjektiv. Det stora antalet anmälningar om samråd har resulterat i få förelägganden och förbud. MKB har endast använts i ett litet antal fall. Samråden synes mycket inriktade på att hitta alternativa lösningar innan förbud utfärdas. Landskapsbilden är den enskilda motivering till förbud som förekommer flest gånger.

Orientador: Michel Daoud Yacoub / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-07T06:00:13Z (GMT). No. of bitstreams: 1 Borgonovo_Marina_M.pdf: 1886438 bytes, checksum: 4d2f8ab684a1762ddb05ea2896b81b03 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta um novo algoritmo de Controle de Admissão de Chamadas (CAC) que funciona em conjunto com o Controle de Fluxo na interface aérea com o objetivo de proporcionar a diferenciação de classes de modo e?ciente. Assim, o mecanismo proposto busca melhorar a utilização da interface aérea a partir da introdução de uma estratégia de bloqueio gradual onde os usuários de menor prioridade têm suas taxas de transmissão reduzidas ao invés de serem diretamente eliminados do sistema. O parâmetro de decisão do CAC e do Controle de Fluxo é a banda efetiva disponível na interface aérea. O algoritmo toma medidas próativas de acordo com a carga do sistema visando manter a qualidade requerida por cada classe. Isto é conseguido com a utilização de três limiares de decisão para os algoritmos de CAC e controle de ?uxo, sendo que o sistema toma medidas distintas de acordo com o limiar . Três classes foram consideradas: Premium, Ouro e Prata. O algoritmo foi implementado e simulado no software MatLab. Os resultados mostram que a diferenciação de classes é atingida e os níveis de bloqueio são iguais ou menores que no caso onde utilizase apenas um limiar e sem diferenciação de classes / Abstract: The current work presents a new multithreshold CAC algorithm that works along with a ?ow control mechanism in order to offer full class differentiation. Furthermore the proposed scheme aims to improve the air interface utilization by introducing a softblocking strategy where the lower classes users have their transmission rates truncated before completely stopped. The decision parameter for the CAC and Flow control is the Air Interface Effective Bandwidth. The algorithm takes proactive steps according to the system load in order to keep the quality level required by each class. That is done by introducing three thresholds for the CAC and Flow Control algorithms, in this way the system takes different actions according to the load it is experiencing in each decision moment. Three classes were considered, premium, gold, and silver. The proposed mechanism was implemented in simulated in the Matlab software. Results show that the class differentiation is achieved and the blocking rates remain on the same levels than in the one threshold case / Mestrado / Telecomunicações e Telemática / Mestre em Engenharia Elétrica

In this thesis, I examined various signalling both in wired and mobile networks, with more emphasis on SIGTRAN. The SIGTRAN is the protocol suite applicable in the current new generation and next-generation networks, most especially as it enables service provider to be able to interpolate both wireline and wireless services within the same architecture. This concept is an important component in today’s Triple-play communication, and hence this thesis has provided a broad view on Signalling and Protocol Gateways in Traditional and Next Generations Networks. Signal flow in a typical new generation network was examined by carrying out discrete event simulation of UMTS network using OPNET modeller 14.5. Through both Packet-Switching (PS) and Circuit-Switching (CS) signalling, I was able to examine the QoS on a UMTS. Precisely, I looked at throughput on UMTS network by implementing WFQ and MDRR scheduling schemes.

The emerging technologies in the field of telecommunications enable us to access high speed data services through mobile handsets and portable modems over the mobile networks. The recent statistics also shows the use of mobile broad band services are increasing and gaining popularity. In this thesis we have investigated the impact of payload size and data rate on one-way delay and packet loss in operational 3G mobile networks, through network level measurements. To collect the network level traces an experimental testbed is developed. For accurate measurement Endace DAG cards together with GPS synchronization is implemented. Results are gathered from three different commercial mobile operators in Sweden. From the results it is concluded that the combination of maximum payload size and data rate resulted in minimum one-way delay. It is also observed within the big payload size category, that the percentage of packet loss is less as compared to the smaller payload sizes. Such findings will improve efficiency of application developers to meet the challenges of UMTS network conditions.

The Swedish National Testing and Research Institute is maintaining the Swedish realization of the world time scale UTC, called UTC(SP). One area of research and development for The Swedish National Laboratory of Time and Frequency is time synchronization and how UTC(SP) can be distributed in Sweden. Dissemination of time information by SP is in Sweden mainly performed via Internet using the Network Time Protocol (NTP) as well as via a modem dial up service and a speaking clock (Fröken Ur). In addition to these services, time information from the Global Positioning System (GPS) and from the long-wave transmitter DCF77 in Germany, is also available in Sweden. This master’s thesis considers how different available commercial communication systems could be used for multicast time distribution. DECT, Bluetooth, Mobile Telecommunication and Radio Broadcasting are different techniques that are investigated. One application of Radio Broadcasting, DARC, was found to be interesting for a more detailed study. A theoretical description of how DARC could be used for national time distribution is accomplished and a practical implementation of a test system is developed to evaluate the possibilities to use DARC for multicast time distribution. The tests of DARC and the radio broadcast system showed that these could be interesting techniques to distribute time with an accuracy of a couple of milliseconds. This quality level is not obtained today but would be possible with some alterations of the system.

WCDMA is an interference limited multiple access technique .It is widely used in the 3rd generation mobile networks like UMTS. When a new call arrives in the system to get admission, it checks whether the call is admitted or not based on some parameters like signal to interference ratio (SIR), transmission power of the Node B and the air interface load .If the call is accepted this will increase some interference to the ongoing calls. This new interference would degrade the ongoing calls and this will also add some extra load which may also lead to the exceeding capacity. So that the system has to decide this admission policy in a systematic way that all the users should maintain their communication with guaranteed quality of service. This decision making algorithm belongs to the radio resource management functionalities of the Radio Network Controller (RNC) in a WCDMA based UMTS network. This thesis paper focuses on the mathematical representation of the call admission control in an interference based environment. There is also a comparative study with different methods.

Mobile telecommunications belong to one of the fields which still evolves and it is expected that in the future they are going to offer great benefit to the whole world. This work focuses on current and future development of mobile Internet connection in the Czech Republic. At first the technologies used to provide mobile Internet connection are described and compared and then the situation (in terms of technologies and mobile operators) in the Czech market is outlined and its possible evolution in the near future is presented. Furthermore, the tarifs of mobile operators are compared with those in place two years ago. The strengths and weaknesses of the current mobile Internet connection are evaluated based on the conducted questionnaire survey. The latest results are then analyzed and compared with the results from a previous survey conducted in 2007 as part of a bachelor's thesis, which has been further extended in this mater's thesis.