Dans des systèmes de communication sans fil modernes, la demande de débit de transmission des données par utilisateur est en croissance constante. Pour soutenir la forte demande de débit de données des utilisateurs une solution possible est de rapprocher l'utilisateur de la station de base émettrice et donc déployer une infrastructure réseau très dense. Dans cette configuration nous obtenons de fortes interférences. L’interférence a été souvent identifiée comme le principal obstacle des systèmes modernes de communications sans fil cellulaires. Cette considération a conduit à d'intenses activités de recherche qui a récemment poussé les opérateurs de réseaux et les fabricants à inclure de manière plus proactive et efficace pour supprimer/contrôler les interférences. D'un point de vue théorie de l'information, ce problème peut être mathématiquement étudié comme, ce qui est appelé, un canal d'interférence. Dans la première partie de cette thèse, nous concentrons notre attention à la conception de l'émetteur pour le canal d'interférence avec des terminaux avec antennes multiples. Nous proposons l'optimisation conjointe de l'émetteur et du récepteur en fonction de deux critères: l'alignement des interférences et la maximisation la somme pondérée des débits. La deuxième partie de la thèse est consacrée au problème de conception de l'émetteur dans le scénario de la radio cognitive. Nous commençons à considérer un scénario Underlay, ensuite, nous passons au scénario Interweave. L'objectif est de concevoir les émetteurs et les récepteurs, au niveau du réseau secondaire, telle que l'interférence, générée à chaque récepteur principal, est égal à zéro. / In modern wireless communication systems, the per-user data rate demand is constantly growing. To sustain the heavy user data rate demand, network operators try to deploy cellular system with more cells and applying more efficient spectrum reuse techniques. One possible solution to increase system throughput is to get the user closer to the transmitting base station and hence deploy very dense network infrastructure. In this setup strong interference situations will result. Interference has been identified as the main bottleneck of modern wireless cellular communication systems. With small dense cells this is more the case. This consideration has led to intense research activities that has recently pushed network operators and manufacturers to include more proactive and efficient way to suppress/control interference. From an information theoretic point of view this problem can be mathematically studied as an interference channel. In the first part of this thesis, we focus our attention on the beamforming design for the interference channel with particular focus on the MIMO case. There we propose the joint optimization of linear transmitter and receiver according to two criteria : Interference Alignment and weighted sum rate maximization. The second part of the thesis is devoted to the beamforming design problem in cognitive radio settings. We start considering an underlay scenario where the secondary network is modeled as a MISO interference channel. Then we move to the MIMO interweave cognitive radio. There the objective is to design the transmitters and receivers, at the secondary network, such that the interference, generated at each primary receiver, is zero.

Thesis (M.A.)--Liberty University, 2007.

Thesis (Ph. D.)--University of Oregon, 2008. / Typescript. Includes vita and abstract. "The study documents the news operations of four different types of ownership structures within a single radio market, Salt Lake City, Utah"--P. v. Includes bibliographical references (leaves 218-229). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 140-141). Also available via the Internet.

High frequency, HF (3 - 30 MHz), radio communications are greatly affected by ionospheric conditions. Both civilian and military users need reliable, real time propagation information to show at any time the feasibility of communicating to any part of the world on a particular frequency band. For this thesis, an automated receiving/monitoring station for the Northern California DX Foundation (NCDXF)/ International Amateur Radio Union (IARU) International Beacon Project was setup at the Hermanus Magnetic Observatory, HMO (34.42oS, 19.22oE) to monitor international beacons on 20 m, 17 m, 15 m, 12 m and 10 m bands. The beacons form a world wide multiband network. The task of monitoring the beacons was broken down into two steps. Initially the single band station, at 14.10 MHz, was installed and later it was upgraded to a multiband station capable of automatically monitoring all the five HF bands. The single band station setup involved the construction and installation of the half-wave dipole antenna, construction and installation of an HF choke balun; and the choice of Faros 1.3 as the appropriate monitoring software. The multiband monitoring station set-up involved the installation of an MFJ-1778 G5RV multiband antenna, construction and installation of a Communication Interface - V (CI-V) level converter and configuring the Faros 1.3 software to monitor the beacons on all five HF bands. Then a web page was created on the HMO space weather website (http://spaceweather.hmo.ac.za). Here, the real-time signal to noise ratio (SNR) and short path (SP)/long path (LP) plots are uploaded every 3 minutes, showing real time HF propagation conditions on the five HF bands. Historical propagation data are archived for later analysis. A preliminary data analysis was done to confirm the peration of the monitoring station. The archived data were analysed and compared to ICEPAC (Ionospheric Communications Enhanced Profile Analysis and Circuit) predictions. Results show that the real-time signal plots as well as the archive of historical signal plots, convey information on ropagation conditions to users in terms that are easy to interpret and understand.

A new radio telescope composed of an array of antennas is under development at the National Research Council. Each antenna includes a large scale multi-tethered aerostat system to hold the telescope receiver at the reflector focus. This receiver is located at the confluence point of the tethers. Starting from a previously developed dynamics simulation of the triple-tethered aerostat system, an existing statics model of the same system is incorporated into the simulation to provide an initial equilibrium condition for the dynamics. A spherical aerostat is used in both models. The two models show a very good match with each other after being merged together. This combined computer model is further developed to study the use of six tethers and the use of a streamlined aerostat instead of a spherical one. In the case of the six-tethered system, two topics were investigated: using the six tethers to control the position of the airborne receiver only; and using the six tethers to control the orientation of the receiver as well as its position. A streamlined aerostat is also modelled by a component breakdown method and incorporated into the triple-tethered system to replace the spherical one. The main findings from the simulation results are as follows: (1) the six-tethered system with reductions in the tether base radius and the tether diameter exhibited increased stiffness compared to the triple-tethered system when used to control the receiver position only; (2) the six-tethered system showed difficulty achieving satisfactory control for both the position and orientation of the receiver; (3) the streamlined aerostat showed no oscillations typical of a spherical one but the system requires more power to control in the presence of wind turbulence.

No description available.

These files were produced for the series Smuain na Maidne (Thought of the day) for the Radio nan Gaidheal (BBC) in 2005. The speaker is Muriel Fisher. The file was originally transcribed by Christine Primrose, and glossed and translated by the Arizona Scottish Gaelic Syntax Project, April 2008. The files are used with the permission of Muriel Fisher.

Dissertation--Berlin--Humboldt-Universität, 2001. / Originally presented as the author's thesis (doctoral--Humboldt-Universität Berlin, 2001) under the title: Sender für die Hauptstadt : ein struktureller Vergleich zwischen NWDR-Berlin, SFB und Berliner Rundfunk von 1949-1961. Bibliogr. p. 311-317.

Thèse de doctorat : Sciences physiques et de l'ingénieur. Electronique : Bordeaux 1 : 2008. / Titre provenant de l'écran-titre.