• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 4
  • 1
  • 1
  • Tagged with
  • 9
  • 9
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 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

Classification of digital modulation schemes using linear and nonlinear classifiers

Geisinger, Nathan P. January 2010 (has links) (PDF)
Thesis (Electrical Engineer and M.S. in Electrical Engineering)--Naval Postgraduate School, March 2010. / Thesis Advisor(s): Fargues, Monique P. ; Cristi, Roberto ; Robertson, Ralph C. "March 2010." Description based on title screen as viewed on .April 27, 2010. Author(s) subject terms: Blind Modulation Classification, Cumulants, Principal Component Analysis, Linear Discriminant Analysis, Kernel-based functions. Includes bibliographical references (p. 211-212). Also available in print.
2

Simultaneous transmission of baseband signal and in band RF signal

Chen, Cheng January 2015 (has links)
No description available.
3

Optimised radio over fibre links for next generation radio access networks

Abbood, Abdul Nasser Abdul Jabbar January 2018 (has links)
Optical fibre has become the dominant theme of transmission in long haul, high data rate communication systems due to its tremendous bandwidth and low loss. Radio over Fibre (RoF) technology facilitates the seamless integration between wireless and optical communication systems and found to be the most promising solution to meet the exponential bandwidth demands expected for the upcoming years. However, the main bit-rate/distance limitation in RoF systems is the chromatic dispersion. In this thesis, the two generations of RoF technologies, namely Analogue RoF (ARoF) and Digital RoF (DRoF) are investigated. The overall aim of this research is to optimise the optical bandwidth utilisation of these two approaches for a typical transmission of the fronthaul link proposed in the next generation Centralised Radio Access Network (C-RAN). Consequently, a number of physical layer design scenarios for the optimised transmission of the Radio Frequency (RF) signals over a Standards Single Mode Fibre (SSMF) are demonstrated. Firstly, for an ARoF transmission, where the analogue RF signals are transported over SSMF using an optical carrier, a bidirectional link transmitting four Downlink/Uplink channels in a chromatic dispersion limited scenario is designed. Simulation results have shown a clear constellation diagram of a 2.5 Gb/s RF signal transmission over 120 km fibre length. Secondly, a DRoF system with reduced optical bandwidth occupancy is proposed. This system employs an optical Duobinary transmission to the digitised RF signal at the transmitter side to reduce its spectrum and to address the chromatic dispersion effect, simultaneously. Simulation results demonstrate the capability of the proposed system to maintain high-quality transmission of the digitised signals over 70 km of fibre distance without dispersion compensation requirements. Finally, an advanced DRoF transmission link based on integrating digital Optical Single Sideband (OSSB) transmission with Duobinary encoding scheme is designed. Simulation results have clearly verified system's robustness against transmission impairments and have better performances in terms of the obtained BER and EVM with respect to the 3GPP standardised values. Moreover, the results show that both transmission distance and power budget are furtherly improved in comparison with two other digital transmission scenarios.
4

Wireless optimisation based on economic criteria.

Hew, Siew Lee January 2007 (has links)
The rapid growth in demand due to the emergence of mobile communication services with variable rates, coupled with the resource scarcity of mobile air interface, has encouraged researchers to find technological solutions to increase spectral efficiency in order to support different levels of Quality of Service (QoS). Radio resource management (RRM) plays a major role in QoS provisioning and congestion control for wireless networks. The main problem with the congestion control mechanisms provided by current RRM schemes is that they are mostly reactive, triggered only when congestion occurs. The common, traditional solution to congestion has been for system planners to over-engineer a network by assigning more resources than are necessary. This approach is very costly because busy periods are usually brief, causing the network to be often under-utilised outside of these periods. Current static, usage-based pricing models also fail to assist in traffic shaping to even out loads. Economic modelling offers a new perspective into current RRM schemes and enables efficient utilisation of scarce resources and congestion prevention based on concepts such as utility, price, Pareto optimality and game theory. Dynamic pricing has been proposed as a mechanism to encourage users to adapt their resource consumption level according to network conditions. A good pricing model can provide the necessary positive incentives to increase users’ arrival rate when the network load is relatively low and negative incentives for users to defer their usage when the load is relatively high. In this dissertation, we propose an economic framework for pricing and RRM for 3G and beyond systems. Our aim is two-fold: to calculate an optimal integrated dynamic pricing and RRM policy; and to allocate scarce network resources in a fair and Pareto-optimal manner. The optimal integrated dynamic pricing and RRM policy is computed based on the stochastic distribution of users’ budget, arrivals, handoffs and departures. Our results show that the integrated policy is superior in terms of average reward improvement and congestion prevention to current schemes that use static pricing models. In interferencebased networks such as WCDMA, we suggest users be charged according to their noise rise factor, i.e. an estimate of the amount of interference generated by the call. This interference-based pricing model improves on the conventional load-based model in by delivering higher revenue and lower call blocking and handoff probabilities. Using the axiomatic bargaining concepts from cooperative game theory, we derive a class of fair and Pareto-optimal bargaining solutions that allocate wireless resources based on users’ minimum and maximum rate requirements. We propose two models: symmetric and asymmetric. In the latter, resource is allocated according to the price paid by the users. An important significance of the asymmetric bargaining model is that this solution is still Pareto-optimal and fair according to the users’ bargaining power. Our approach is also a departure from current works using noncooperative game theory that can only achieve an inefficient outcome, i.e. the Nash equilibrium; or cooperative game theory that focus on only one solution on the Pareto-optimal boundary. By analysing a range of bargaining solutions instead of specific ones, operators can proceed to select the best outcome out of these Pareto-optimal solutions based on criteria like revenue. / Thesis (Ph.D) -- University of Adelaide, School of Electrical and Electronic Engineering, 2007
5

Critical and global perspectives of multiculturalism: contested identities of Toronto Sri Lankan Tamils /

Bernard, Maria, January 1900 (has links)
Thesis (M.A.)--Carleton University, 2008. / Includes bibliographical references (p. 183-192). Also available in electronic format on the Internet.
6

Intera??o no r?dio: a participa??o do ouvinte no programa debates do povo

Andrade, M?nica Ara?jo 29 April 2014 (has links)
Made available in DSpace on 2014-12-17T15:08:36Z (GMT). No. of bitstreams: 1 MonicaAA_DISSERT.pdf: 1247194 bytes, checksum: cb1c306d6bf5eee4c0adef1c03fda223 (MD5) Previous issue date: 2014-04-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The radio is just not seen as conveying information, but a media able to establish ways that generate certain direction. We see an inclusion of the listener in the construction of programs, is exposing their life stories, commenting on facts, answering questions, choosing subjects and participating in some form of radio programming. This insertion of the listener in radio programs is generally thought of as a constituent element of the message. This study aims to analyze the participation of the listener and the forms of interaction in the " Debates of the People" that thirty- past two years is the schedule for CBN Fortaleza. The investigation was conducted through observation in studio, interview, transcription, content analysis and association analysis. This is a qualitative and quantitative research while. We found that the listeners of the program had no acceptance of interactive tools such as the Internet and social networks to make their holdings. In clipping analyzed, we noted that the participation of the listener was selected according to their relationship and proximity to the topic discussed. Also detected that the opinion is superior to the listener questions on the topic. The presenter has the function to put the questions in the listener program. Among the public comments are questions and opinions on the subject and speaks of the debaters. Among the authors, use Barbosa (2009 ), Ferraretto (2007 ), Lopez (2010 ), Ortriwano (2001 ), Peruzzo (2004 ), Prata (2009 ), Primo (2006 ), Thompson (2009 ), among others / O R?dio n?o ? considerado apenas como transmissor de informa??o, mas uma m?dia capaz de estabelecer formas que geram determinado sentido. Percebemos uma inclus?o do ouvinte na constru??o dos programas, seja expondo suas hist?rias de vida, comentando fatos, tirando d?vidas, escolhendo temas e participando de alguma forma da programa??o radiof?nica. Essa inser??o do ouvinte nos programas de r?dio geralmente ? pensada como um elemento constituinte da mensagem. Este trabalho tem como objetivo, analisar a participa??o do ouvinte e as formas de intera??o no programa Debates do Povo que h? trinta e dois anos est? na programa??o da CBN Fortaleza. A investiga??o foi realizada atrav?s da observa??o no est?dio, entrevista, transcri??o, an?lise de conte?do e an?lise associativa. Trata-se de uma pesquisa qualitativa e quantitativa ao mesmo tempo. Identificamos que os ouvintes do programa n?o tiveram aceita??o de ferramentas interativas como a Internet e as redes sociais para realizar suas participa??es. No recorte analisado, notamos que a participa??o do ouvinte foi selecionada de acordo com sua rela??o e proximidade com o tema debatido. Detectamos ainda que a opini?o ? superior ?s perguntas do ouvinte sobre o tema. O apresentador tem a fun??o de inserir as quest?es do ouvinte no programa. Entre os coment?rios do p?blico est?o perguntas e opini?es a respeito do tema e da fala dos debatedores. Entre os autores, utilizamos Barbosa (2009), Ferraretto (2007), Lopez (2010), Ortriwano (2001), Peruzzo (2004), Prata (2009), Primo (2006), Thompson (2009), entre outros
7

Communications par lumière visible et radio pour la conduite coopérative autonome : application à la conduite en convois / Visible light and radio communication for cooperative autonomous driving : applied to vehicle convoy

Abualhoul, Mohammad 21 December 2016 (has links)
L'objectif de cette thèse CIFRE est de contribuer à la communication véhiculaire autonome et au développement de la mobilité urbaine. Les travaux sont basés sur les limitations et défis de la communication par radio pour les applications de sécurité et envisagent de déployer le système d'éclairage des véhicules en tant que solution de communication de soutien pour le platooning d'IVC-activées par VC Véhicules autonomes. L'objectif principale de cette recherche doctorale consiste à intégrer le système VLC dans l'architecture existante de C-ITS en développant un prototype VLC, ainsi que des algorithmes de transfert suffisants permettant VLC, RF et des solutions basées sur la perception afin d'assurer les exigences de sécurité maximales et l'échange continu d'informations entre les véhicules. La faisabilité et l'efficacité de la mise en oeuvre du système et des algorithmes de transfert ont fait l'objet de recherches approfondies sur six chapitres, destinés à faciliter une progression logique des matériaux et permettre un accès relativement facile. En plus de l'amélioration de la capacité routière en utilisant les systèmes de conduite autonome à la base de convoi. Les simulations réalisées ainsi que les résultats expérimentaux ont montré que l'intégration de VLC avec les solutions existantes RF a un avantage certain dans la qualité du canal de communication et les exigences de sécurité d'un système de platooning quand un algorithme approprié est utilisé. / This thesis effort contributes to the autonomous vehicular communication and urban mobility improvements. The work addresses the main radio-based V2V communication limitations and challenges for ITS hard-safety applications and intends to deploy the vehicular lighting system as a supportive communication solution for platooning of IVC-enabled autonomous vehicles. The ultimate objectives of this Ph.D research are to integrate the VLC system within the existing C-ITS architecture by developing a VLC prototype, together with sufficient, hand-over algorithms enabling VLC, RF, and perception-based solutions in order to ensure the maximum safety requirements and the continuous information exchange between vehicles. The feasibility and efficiency of the VLC-RF system implementation and hand-over algorithms were subjects to deep investigations over six self-contained chapters meant to facilitate a logical progression of materials and to enable a relatively easy access. In addition to the improvement in road capacity by utilizing the convoy-based autonomous driving systems. The carried out simulations followed-up by experimental results proved that the integration of VLC with the existed RF solutions lead to a definite benefit in the communication channel quality and safety requirements of a platooning system when a proper hand-over algorithm is utilized.
8

Design of a low-power 60 GHz transceiver front-end and behavioral modeling and implementation of its key building blocks in 65 nm CMOS / Conception et modélisation d'une tête RF à faible consommation pour un émetteur-récepteur à 60 GHz en CMOS 65 nm

Kraemer, Michael M. 03 December 2010 (has links)
La réglementation mondiale, pour des appareils de courte portée, permet l’utilisation sans licence de plusieurs Gigahertz de bande autour de 60 GHz. La bande des 60 GHz répond aux besoins des applications telles que les réseaux de capteurs très haut débit autonome en énergie,ou les transmissions à plusieurs Gbit/s avec des contraintes de consommation d’énergie. Il y a encore peu de temps, les interfaces radios fonctionnant dans la bande millimétrique n’étaient réalisables qu’en utilisant des technologies III-V couteuses. Aujourd’hui, les avancées des technologies CMOS nanométriques permettent la conception et la production en masse des circuits intégrées radiofréquences (RFIC) à faible coût.Cette thèse s’inscrit dans des travaux de recherches dédiés à la réalisation d’un système dans un boîtier (SiP, System in Package) à 60 GHz contenant à la fois l’interface radio (bande de base et circuits RF) ainsi qu’un réseau d’antennes. La première partie de cette thèse est dédiée la conception de la tête RF de l’émetteur-récepteur à faible consommation pour l’interface radio. Les blocs clefs de cette tête RF (amplificateurs, mélangeurs et un oscillateur commandé en tension) sont conçus, réalisés et mesurés en utilisant la technologie CMOS 65 nm de ST Microelectronics. Des éléments actifs et passifs sont développés spécifiquement pour l’utilisation au sein de ces blocs. Une étape importante vers l’intégration de la tête RF complète de l’émetteur-récepteur est l’assemblage de ces blocs de base afin de réaliser une puce émetteur et une puce récepteur. A ce but, une tête RF pour le récepteur a été réalisée. Ce circuit présent une consommation et un encombrement plus réduit que l’état de l’art.La deuxième partie de cette thèse présente le développement des modèles comportementaux des blocs de base conçus. Ces modèles au niveau système sont nécessaires afin de simuler le comportement du SIP, qui devient trop complexe si des modèles détaillés du niveau circuitsont utilisés. Dans cette thèse, une nouvelle technique modélisant le comportement en régime transitoire et régime permanent ainsi que le bruit de phase des oscillateurs commandés en tension est proposée. Ce modèle est implémenté dans le langage de description de matérielVHDL-AMS. La technique proposée utilise des réseaux de neurones artificiels pour approximer la caractéristique non linéaire du circuit. La dynamique est décrite dans l’espace d’état. Grâce à ce modèle, il est possible de réduire d’une façon drastique le temps de calcul des simulations système tout en conservant une excellente précision / Worldwide regulations for short range communication devices allow the unlicensed use of several Gigahertz of bandwidth in the frequency band around 60GHz. This 60GHz band is ideally suited for applications like very high data rate, energy-autonomous wireless sensor networks or Gbit/s multimedia links with low power constraints. Not long ago, radio interfaces that operate in the millimeter-wave frequency range could only be realized using expensive compound semiconductor technologies. Today, the latest sub-micron CMOS technologies can be used to design 60GHz radio frequency integrated circuits (RFICs)at very low cost in mass production. This thesis is part of an effort to realize a low power System in Package (SiP) including both the radio interface (with baseband and RF circuitry) and an antenna array to directly transmit and receive a 60GHz signal. The first part of this thesis deals with the design of the low power RF transceiver front-end for the radio interface. The key building blocks of this RF front-end (amplifiers, mixers and a voltage controlled oscillator (VCO)) are designed, realized and measured using the 65nm CMOS technology of ST Microelectronics. Full custom active and passive devices are developed for the use within these building blocks. An important step towards the full integration of the RF transceiver front-end is the assembly of these building blocks to form basic transmitter and receiver chips. Circuits with small chip size and low power consumption compared to the state of the art have been accomplished.The second part of this thesis concerns the development of behavioral models for the designed building blocks. These system level models are necessary to simulate the behavior of the entire SiP, which becomes too complex when using detailed circuit level models. In particular, a novel technique to model the transient, steady state and phase noise behavior of the VCO in the hardware description language VHDL-AMS is proposed and implemented. The model uses a state space description to describe the dynamic behavior of the VCO. Its nonlinearity is approximated by artificial neural networks. A drastic reduction of simulation time with respect to the circuit level model has been achieved, while at the same time maintaining a very high level of accuracy
9

Contribution des technologies CPL et sans fil à la supervision des réseaux de distribution d'électricité / Contribution of PLC and wireless technologies to supervision of electric distribution networks

Lefort, Romain 03 February 2015 (has links)
Le déploiement d'une infrastructure de supervision permet une gestion plus intelligente des réseaux de distribution d'électricité comparé à un renforcement traditionnel pour répondre aux nouveaux enjeux de la maitrise de l'énergie (Consommations, EnR, VE, ...). Pour acheminer les données, les Courants Porteurs en Ligne (CPL) possèdent un atout majeur. En effet, cette technologie permet de superposer un signal de plus haute fréquence au signal électrique 50/60 Hz. Toutefois, le support de transmission est difficile et non maîtrisable. Ces travaux de recherche ont pour objectif d'apporter une contribution à cette problématique par l'élaboration d'une plateforme de simulation des réseaux pour des fréquences allant jusqu'à 1 MHz dans un but de transmission de données. Des éléments clés des réseaux sont traités de façon séparés puis assemblés pour estimer les performances des CPL « Outdoor » actuels. La variation du comportement des réseaux en fonction du temps et de la fréquence, en particulier des perturbations en tête d'installation clients sur 24h est étudiée. Les transformateurs entre les réseaux HTA et BT sont modélisés sous la forme d'un « modèle à constantes localisées » et d'un « modèle boite noire ». Les deux modèles sont appliqués sur un transformateur H61 100 kVA. Par la suite, une modélisation des câbles de distribution est proposée sous forme d'un « modèle cascadé ». Celle-ci est appliquée sur un câble souterrain BT. Chaque modèle est obtenu à l'aide de mesures d'impédances, et validé par des mesures de transmissions. Pour compléter, une étude préliminaire sur les communications radio mobile est réalisée pour la supervision des réseaux de distribution. / Establishing a supervisory infrastructure allows a better smart management than an expensive strengthening of distribution network to respond to new constraints at the energies control (Consumption, REN, EV ...). To transmit data, Power Line Communication (PLC) technologies present an advantage in this context. In fact, it enables a superposition of High Frequency (HF) signals on electrical signal 50/60 Hz. However, electric networks have not been developed to this application because of difficult propagation conditions. This research work makes a contribution to develop a simulation platform in objective to transmit data to 1 MHz. In first time, each network element is studied singly and in second time, together, to estimate "Outdoor PLC" transmission performance. The first element studied is the networks variation in function of frequency and time. Several 24h disturbance measurements on LV customers are presented. The second element is the transformers which established connection between Medium Voltage (MV) and Low Voltage (LV). The proposed modeling method is based on a "lumped model" and a "black box model". These models are applied to a 100 kVA H61 transformer most commonly used by French distribution system operator in rural and suburban networks. The third element is the power line used in MV and LV networks. The proposed modeling method is based on a "cascaded model" from the theory of transmission line. This model is applied to one power line used in LV underground network. Each model is obtained from various impedance measurements. To complete, an introductory study on mobile radio communication is performed to remote network distribution.

Page generated in 0.127 seconds