Este trabalho buscou analisar o potencial educativo/subversivo das rádios comunitárias, tendo como base um trabalho feito pela Secretaria de Assistência Social do Município de Duque de Caxias no período de 2007, que foi a implantação do Projeto Agente Jovem de Desenvolvimento Social e Humano na rádio comunitária, Radio Juventude. Através do diálogo com os autores pós-estruturalistas Deleuze, Guattari , Negri, dentre outros, e utilizando-se dos conceitos de Singularidade, Linhas de fuga e Império tentou esboçar as possibilidades de enfrentamento existentes na contemporaneidade. Tal potencialidade, nos ajuda a entender por que desde o movimento das primeiras rádios livres na Itália , até os dias atuais , as rádios comunitárias , representam uma ameaça as mídias de massa a medida que potencializa e possibilita novos agenciamentos coletivos de produção de subjetividade sendo seu produto resultante de processos de cooperação.Atuando como canais de expressão da cultura local e de fortalecimento da democracia. Resagata os princípios filosóficos das teorias anarquistas, de afirmação da liberdade e de negação da dominação, afim de reiventar uma Educação dinâmica e autônoma. / This study aimed to analyze the educational potential/subversive of community radios, on the basis of a work done by the Secretariat of Social Assistance of Duque de Caxias in the period of 2007, which was the implementation of the Project Young Agent of Social and Human Development in the communitarian radio, radio Juventude. Through the dialog with the authors powders ? structuralists Deleuze, Guattari, Negri, among others, and making use of the concepts of Peculiarity, Lines of escape and Empire it tried to sketch the means of enfrentamento existent in the contemporaneousness. Such a potentiality, in it helps to understand why from the movement of the first free radios in Italy, up to the current days, the communitarian radios, the measure represents a threat the media of mass that potencializa and it makes possible new collective agenciamentos of production of subjectivity being his resultant product of processes of cooperation.Acting as channels for the expression of the local culture and strengthen democracy. It Rescues the philosophical principles of anarchist theories, of affirmation of freedom and of denial of domination, in order to reinvent a education dynamic and autonomous.

Este trabalho buscou analisar o potencial educativo/subversivo das rádios comunitárias, tendo como base um trabalho feito pela Secretaria de Assistência Social do Município de Duque de Caxias no período de 2007, que foi a implantação do Projeto Agente Jovem de Desenvolvimento Social e Humano na rádio comunitária, Radio Juventude. Através do diálogo com os autores pós-estruturalistas Deleuze, Guattari , Negri, dentre outros, e utilizando-se dos conceitos de Singularidade, Linhas de fuga e Império tentou esboçar as possibilidades de enfrentamento existentes na contemporaneidade. Tal potencialidade, nos ajuda a entender por que desde o movimento das primeiras rádios livres na Itália , até os dias atuais , as rádios comunitárias , representam uma ameaça as mídias de massa a medida que potencializa e possibilita novos agenciamentos coletivos de produção de subjetividade sendo seu produto resultante de processos de cooperação.Atuando como canais de expressão da cultura local e de fortalecimento da democracia. Resagata os princípios filosóficos das teorias anarquistas, de afirmação da liberdade e de negação da dominação, afim de reiventar uma Educação dinâmica e autônoma. / This study aimed to analyze the educational potential/subversive of community radios, on the basis of a work done by the Secretariat of Social Assistance of Duque de Caxias in the period of 2007, which was the implementation of the Project Young Agent of Social and Human Development in the communitarian radio, radio Juventude. Through the dialog with the authors powders ? structuralists Deleuze, Guattari, Negri, among others, and making use of the concepts of Peculiarity, Lines of escape and Empire it tried to sketch the means of enfrentamento existent in the contemporaneousness. Such a potentiality, in it helps to understand why from the movement of the first free radios in Italy, up to the current days, the communitarian radios, the measure represents a threat the media of mass that potencializa and it makes possible new collective agenciamentos of production of subjectivity being his resultant product of processes of cooperation.Acting as channels for the expression of the local culture and strengthen democracy. It Rescues the philosophical principles of anarchist theories, of affirmation of freedom and of denial of domination, in order to reinvent a education dynamic and autonomous.

Spectrum sharing is possible, but lacks R & D support for practical solutions that satisfy both the incumbent and secondary or opportunistic users. The author found a lack of an openly available framework supporting experimental research on the performance of a Spectrum Access System (SAS) and propose to build an open-source Software Defined Radio (SDR) based framework. This framework will test different dynamic spectrum scenarios in a wireless testbed. This thesis presents our Spectrum Access System prototype, discusses the design choices and trade-offs and provides a proof of concept implementation. We show that an Internet-accessible CORNET test bed provides the ideal platform for developing and testing the SAS functionality and its building blocks and offerss the hardware and software as a community resource for research and education. This design provides the necessary interfaces for researchers to develop and test their SAS-related modules, waveforms and scenarios. / Master of Science / In this information age, the number of wireless devices is growing faster than the infrastructure required to make wireless communication possible. This creates a possibility of not having enough radio spectrum to keep up with this growing demand. To alleviate this issue, there is a need to research and find more ways of efficiently utilizing the current spectrum resources available. Dynamic spectrum allocation is one way forward to archiving this goal. Frequency channels are assigned to devices based on prevailing conditions like device location and availability of channels that would cause low interference to other devices. Spectrum utilization is based on time, frequency and space with devices having the ability to hop to the best channel available. In this thesis, an open-source Spectrum Access System (SAS) was created as a platform through which dynamic spectrum allocation research can be done. The SAS is centralized management system that logs information about the prevailing spectrum usage, and in turn uses this information to dynamically allocate spectrum to devices and networks. This thesis shows how it was implemented, its current performance, and the steps that different researchers can take to add their own functionalities.

This thesis extensively analyses the performance of an energy detector which is widely employed to perform spectrum sensing in cognitive radio over different generalised channel models. In this analysis, both the average probability of detection and the average area under the receiver operating characteristic curve (AUC) are derived using the probability density function of the received instantaneous signal to noise ratio (SNR). The performance of energy detector over an ŋ --- µ fading, which is used to model the Non-line-of-sight (NLoS) communication scenarios is provided. Then, the behaviour of the energy detector over к --- µ shadowed fading channel, which is a composite of generalized multipath/shadowing fading channel to model the lineof- sight (LoS) communication medium is investigated. The analysis of the energy detector over both ŋ --- µ and к --- µ shadowed fading channels are then extended to include maximal ratio combining (MRC), square law combining (SLC) and square law selection (SLS) with independent and non-identically (i:n:d) diversity branches. To overcome the problem of mathematical intractability in analysing the energy detector over i:n:d composite fading channels with MRC and selection combining (SC), two different unified statistical properties models for the sum and the maximum of mixture gamma (MG) variates are derived. The first model is limited by the value of the shadowing severity index, which should be an integer number and has been employed to study the performance of energy detector over composite α --- µ /gamma fading channel. This channel is proposed to represent the non-linear prorogation environment. On the other side, the second model is general and has been utilised to analyse the behaviour of energy detector over composite ŋ --- µ /gamma fading channel. Finally, a special filter-bank transform which is called slantlet packet transform (SPT) is developed and used to estimate the uncertain noise power. Moreover, signal denoising based on hybrid slantlet transform (HST) is employed to reduce the noise impact on the performance of energy detector. The combined SPT-HST approach improves the detection capability of energy detector with 97% and reduces the total computational complexity by nearly 19% in comparison with previously implemented work using filter-bank transforms. The aforementioned percentages are measured at specific SNR, number of selected samples and levels of signal decomposition.

L’ouverture du secteur audiovisuel camerounais a consacré l’avancée du processus d’acquisition et de l’octroi des libertés individuelles commencé autour des années 1990. Le décret d’application d’avril 2003 a entériné une dizaine d’années plus tard, le dispositif enclenché par la loi n°90-052 du 19 décembre 1990 relative à la liberté de communication sociale. Depuis lors, organes de presse et audiovisuels se côtoient et se heurtent à des pesanteurs susceptibles de limiter leur efficacité, en tant qu’outils et moyens de communication de proximité. Leur jeunesse, les problèmes endogènes et exogènes au paysage médiatique camerounais justifierait une étude sur l’existence et la manière dont les organes de communication sociale produisent et diffusent informations et nouvelles en direction des populations ciblées. A ce sujet, la radio communautaire, tout en cherchant à les impliquer et à les faire participer à cet objectif de communication sociale, promeut par ses programmes, la propre image des populations à laquelle elle est destinée. Il ne reste qu’à garantir les modalités pratiques, les conditions nécessaires pour une participation transparente des différents acteurs à la gestion et au fonctionnement de la radio. Pour une grande part, les populations sont prêtes à soutenir les projets de radios communautaires qui s’installent dans les localités. Les différentes techniques d’appropriation et d’usage des médias permettent d’appréhender de l’extérieur les différents enjeux qui se tissent. Elles permettent d’observer les pratiques mises en place et les conditions d’engagement des acteurs sociaux pour garantir, une longue vie à la radio. / The opening of the Cameroonian audiovisual sector dedicated the overhang of the process of acquisition and the granting of the personal freedoms begun around 1990s. The application decree of April, 2003 confirmed a decade later, the plan engaged by the law 90/052 of December 19th, 1990 relative to the freedom of social communication. Since then, newspapers and broadcasting mix and come up against gravities susceptible to limit their efficiency, as tools and means of communication of nearness. Their youth, the endogenous and exogenous problems in the Cameroonian media landscape justify a study on the existence and the way the organs of social communication produce and broadcast information and news in the direction of the targeted populations. For this subject, the community radio, while trying to imply them and to make them participate in this objective of social communication, promotes by its programs, the own image of the populations for which is intended. It remains only to guarantee the practical methods, the necessary conditions for a transparent participation of the various actors in the management and in the functioning of the radio. Mostly, the populations are ready of supporting the projects of community radios which settle down in villages. The various techniques of appropriation and uses of the media allow dreading from the outside the various stakes which weave. They allow observing the organized practices and the conditions of commitment of the civil society to guarantee, a long life on the radio.

Memoria para optar al Título Profesional de Ingeniero Forestal / El estudio de la anatomía y variabilidad de la madera, además de ser una mirada a las posibilidades productivas de la especie, es un indicador de adaptaciones ecológicas y una retrospección al pasado, abriéndonos una posibilidad de comprensión de nuestro medio natural aplicable a la conservación de nuestro patrimonio natural y cultural. Bajo este marco, se caracterizó anatómicamente el leño secundario de Nothofagus glauca (Phil.) Krasser, (Hualo), determinando su variabilidad en sentido radial y axial. Se trabajó con un árbol de Diámetro a la Altura del Pecho (DAP) de 20 cm y 9 metros de alto proveniente del predio Pastor Justo León perteneciente a la Universidad de Chile, ubicado en las cercanías de Constitución, Chile. Se extrajeron seis rodelas a diferentes alturas, para las cuales, en sentido radial, cada diez años se realizaron cortes histológicos en los tres planos de la madera y maceraciones, para así realizar una descripción completa de la anatomía de la madera considerando la variación del largo de fibras, ancho de poros, largo y ancho de radios en el leño, con el fin de realizar una comparación con descripciones de otros autores tanto para la especie actual como para especies fósiles. Destacan entre los resultados tendencias, con significancia estadística. En sentido longitudinal el largo de fibras disminuye desde la base (1000 μm) hacia el ápice (770 μm). En sentido radial, el diámetro de poros aumenta desde la médula (35 μm) hacia la corteza (50 μm).

In the literature, most distributed detection developed so far mainly focuses on the test rule based on fixed sample size. However, in the real situations, sequential tests are more suitable to be utilized since it might achieve the same detection performance by using fewer number of samples as compared with the fixed-sample-size test. Thus, this theses will propose a new distributed sequential detection approach for the applications in wireless sensor networks(WSNs) and cognitive radios(CRs). First we refer to the sequential detection, and it has been developed by Wald in 1994, which is well known as the sequential probability ratio test (SPRT). The SPRT is proved to be able to decrease the required average sample numbers or reducing the average detection time. Indeed, the SPRT is the optimal sequential detection in terms of the minimizing the required number of samples given the constraint of false alarm and miss probabilities when the observation samples are independent and identical distributed (i.i.d.). However, if the observation samples are not dentically distributed, by simulation results show that the SPRT is not the optimal test. Based on a heuristic approach, this thesis then developed a new distributed detection scheme based on the sorted samples. Finally , the simulation results obtained by this thesis shows that the proposed scheme can further reduce the number of samples required for making the final decision as compared with SPRT.

abstract: Cognitive Radios (CR) are designed to dynamically reconfigure their transmission and/or reception parameters to utilize the bandwidth efficiently. With a rapidly fluctuating radio environment, spectrum management becomes crucial for cognitive radios. In a Cognitive Radio Ad Hoc Network (CRAHN) setting, the sensing and transmission times of the cognitive radio play a more important role because of the decentralized nature of the network. They have a direct impact on the throughput. Due to the tradeoff between throughput and the sensing time, finding optimal values for sensing time and transmission time is difficult. In this thesis, a method is proposed to improve the throughput of a CRAHN by dynamically changing the sensing and transmission times. To simulate the CRAHN setting, ns-2, the network simulator with an extension for CRAHN is used. The CRAHN extension module implements the required Primary User (PU) and Secondary User (SU) and other CR functionalities to simulate a realistic CRAHN scenario. First, this work presents a detailed analysis of various CR parameters, their interactions, their individual contributions to the throughput to understand how they affect the transmissions in the network. Based on the results of this analysis, changes to the system model in the CRAHN extension are proposed. Instantaneous throughput of the network is introduced in the new model, which helps to determine how the parameters should adapt based on the current throughput. Along with instantaneous throughput, checks are done for interference with the PUs and their transmission power, before modifying these CR parameters. Simulation results demonstrate that the throughput of the CRAHN with the adaptive sensing and transmission times is significantly higher as compared to that of non-adaptive parameters. / Dissertation/Thesis / M.S. Computer Science 2012

Recent measurements show that the spectrum is under-utilized by licensed users in wireless communication. Cognitive radio (CR) has been proposed as a suitable solution to manage the inefficient usage of the spectrum and increase coverage area of wireless networks. The concept is based on allowing a group of secondary users (SUs) to share the unused radio spectrum originally owned by the primary user (PUs). The operation of CR should not cause harmful interference to the PUs. In the other hand, relayed transmission increases the coverage and achievable capacity of communication systems and in particular in CR systems. In fact there are many types of cooperative communications, however the two main ones are decode-and-forward (DAF) and amplify-and-forward (AAF). Adaptive relaying scheme is a relaying technique by which the benefits of the amplifying or decode and forward techniques can be achieved by switching the forwarding technique according to the quality of the signal. In this dissertation, we investigate the power allocation for an adaptive relaying protocol (ARP) scheme in cognitive system by maximizing the end-to-end rate and searching the best carriers pairing distribution. The optimization problem is under the interference and power budget constraints. The simulation results confirm the efficiency of the proposed adaptive relaying protocol in comparison to other relaying techniques, and the consequence of the choice of the pairing strategy.

This thesis explores the use of the Naïve Bayesian classifier as a method of determining high-level information about secondary users in a Dynamic Spectrum Access (DSA) network using a low complexity channel sensing method.  With a growing number of users generating an increased demand for broadband access, determining an efficient method for utilizing the limited available broadband is a developing current and future issue.  One possible solution is DSA, which we simulate using the Universal DSA Network Simulator (UDNS), created by our team at Virginia Tech. However, DSA requires user devices to monitor large amounts of bandwidth, and the user devices are often limited in their acceptable size, weight, and power.  This greatly limits the usable bandwidth when using complex channel sensing methods.  Therefore, this thesis focuses on energy detection for channel sensing. Constraining computing requirements by operating with limited spectrum sensing equipment allows for efficient use of limited broadband by user devices.  The research on using the Naïve Bayesian classifier coupled with energy detection and the UDNS serves as a strong starting point for supplementary work in the area of radio classification. / Master of Science