Pour supporter l’évolution constante des standards de communication numérique, du GSM vers la 5G, les équipements de communication doivent continuellement s’adapter. Face à l’utilisation croissante de l’internet, on assiste à une explosion du trafic de données, ce qui augmente la consommation d'énergie des appareils de communication sans fil et conduit donc à un impact significatif sur les émissions mondiales de CO2. De plus en plus de recherches se sont concentrées sur l'efficacité énergétique de la communication sans fil. La radio Intelligente, ou Cognitive Radio (CR), est considérée comme une technologie pertinente pour les communications radio vertes en raison de sa capacité à adapter son comportement à son environnement. Sur la base de métriques fournissant suffisamment d'informations sur l'état de fonctionnement du système, une décision optimale peut être effectuée en vue d'une action de reconfiguration, dans le but de réduire au minimum la dissipation d'énergie tout en ne compromettant pas les performances. Par conséquent, tout équipement intelligent doit disposer d’une architecture de gestion de la reconfiguration. Nous avons retenu l’architecture HDCRAM (Hierarchical and Distributed Cognitive Radio Architecture Management), développée dans notre équipe, et nous l’avons déployée sur des plates-formes hétérogènes. L'un des objectifs est d'améliorer l'efficacité énergétique par la mise en œuvre de l’architecture HDCRAM. Nous l’avons appliquée à un système OFDM simplifié pour illustrer comment HDCRAM permet de gérer efficacement le système et son adaptation à un environnement évolutif. / As the digital communication systems evolve from GSM and now toward 5G, the supported standards are also growing. The desired communication equipments are required to support different standards in a single device at the same time. And more and more wireless Internet services have been being provided resulting in the explosive growth in data traffic, which increase the energy consumption of the communication devices thus leads to significant impact on global CO2 emission. More and more researches have focused on the energy efficiency of wireless communication. Cognitive Radio (CR) has been considered as an enabling technology for green radio communications due to its ability to adapt its behavior to the changing environment. In order to efficiently manage the sensing information and the reconfiguration of a cognitive equipment, it is essential, first of all, to gather the necessary metrics so as to provide enough information about the operating condition thus helping decision making. Then, on the basis of the metrics obtained, an optimal decision can be made and is followed by a reconfiguration action, whose aim is to minimize the power dissipation while not compromising on performance. Therefore, a management architecture is necessary to be added into the cognitive equipment acting as a glue to realize the CR capabilities. We introduce a management architecture, namely Hierarchical and Distributed Cognitive Radio Architecture Management (HDCRAM), which has been proposed for CR management by our team. This work focuses on the implementation of HDCRAM on heterogeneous platforms. One of the objectives is to improve the energy efficiency by the management of HDCRAM. And an example of a simplified OFDM system is used to explain how HDCRAM works to efficiently manage the system to adapt to the changing environment.

Submitted in fulfilment of the academic requirements for the Degree Master of Engineering: Electrical Engineering, Durban University of Technology. Durban. South Africa, 2015. / This dissertation describes the development and construction of the Multi-frequency Interferometer Telescope for Radio Astronomy (MITRA) at the Durban University of Technology. The MITRA station consists of 2 antenna arrays separated by a baseline distance of 8 m. Each array consists of 8 Log-Periodic Dipole Antennas (LPDAs) operating from 200 MHz to 800 MHz. The design and construction of the LPDA antenna and receiver system is described. The receiver topology provides an equivalent noise temperature of 113.1 K and 55.1 dB of gain. The Intermediate Frequency (IF) stage was designed to produce a fixed IF frequency of 800 MHz. The digital Back-End and correlator were implemented using a low cost Software Defined Radio (SDR) platform and Gnu-Radio software. Gnu-Octave was used for data analysis to generate the relevant received signal parameters including total power, real, and imaginary, magnitude and phase components. Measured results show that interference fringes were successfully detected within the bandwidth of the receiver using a Radio Frequency (RF) generator as a simulated source. This research was presented at the IEEE Africon 2013 / URSI Session Mauritius, and published in the proceedings.

published_or_final_version / abstract / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

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Antropóloga Social / En la presente investigación exploratoria descriptiva, se plantea la importancia de estudiar la relación radio comunitaria – identidad, desde la perspectiva de las mediaciones sociales y culturales, utilizando principalmente el aparataje teórico de Jesús Martín-Barbero. Este paradigma de comprensión actual, nos permitirá conocer las relaciones que se entretejen entre las “lógicas productivas” de los radialistas y las “lógicas de los usos” de sus radioescuchas, las cuales nos llevarán a analizar el tipo de identidades que la radio comunitaria pone en escena y activa, así como la importancia de la dimensión local en el estudio de estas. El caso de estudio seleccionado corresponde a la radio comunitaria Konciencia, ubicada en la localidad de Rosario, comuna de Rengo, la cual posee un discurso crítico y propositivo sobre los temas que aquejan a su territorio, y cuenta con una alta participación ciudadana. Se utilizó un enfoque cualitativo etnográfico y contextual, haciendo uso de observación participante y de entrevistas semiestructuradas, también se recurrió a información municipal y fuentes históricas. A partir de estas estrategias, se realizó la caracterización de la localidad, de la práctica de los radialistas y de las prácticas de los radioescuchas, lo cual nos llevó a identificar un discurso aglutinador de identidades que dentro de la diversidad de gustos e intereses, recurre a lo local como referente de identificación

Digital communications devices designed with application-specific integrated circuit (ASIC) technology suffer from one very significant limitation�the integrated circuits are not programmable. Therefore, deploying a new algorithm or an updated standard requires new hardware. Field-programmable gate arrays (FPGAs) solve this problem by introducing what is essentially reconfigurable hardware. Thus, digital communications devices designed on FPGAs are capable of accommodating multiple communications protocols without the need to deploy new hardware, and can support new protocols in a matter of seconds. In addition, FPGAs provide a means to update systems that are physical difficult to access. For these reasons, FPGAs provide us with an ideal platform for implementing adaptive communications algorithms. This thesis focuses on using FPGAs to implement an adaptive digital communications system. Using the Universal Software Radio Peripheral (USRP) as a base, this thesis aims to create a highly-adaptive, plug and play software-defined radio (SDR) that fits CubeSat form-factor satellites. Such a radio platform would enable CubeSat engineers to develop new satellites faster and with lower costs. This thesis presents a new system, the COSMIAC CubeSat SDR, that adapts the USRP platform to better suit the space and power limitations of a CubeSat.

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Typewritten copy Includes bibliography.