No description available.

A novel printed diversity monopole antenna is presented for WiFi/WiMAX applications. The antenna comprises two crescent shaped radiators placed symmetrically with respect to a defected ground plane and a neutralization lines is connected between them to achieve good impedance matching and low mutual coupling. Theoretical and experimental characteristics are illustrated for this antenna, which achieves an impedance bandwidth of 54.5% (over 2.4-4.2 GHz), with a reflection coefficient <;-10 dB and mutual coupling <;-17 dB. An acceptable agreement is obtained for the computed and measured gain, radiation patterns, envelope correlation coefficient, and channel capacity loss. These characteristics demonstrate that the proposed antenna is an attractive candidate for multiple-input multiple-output portable or mobile devices

Yes / Recent studies suggest that multicarrier systems using wavelets outperform conventional OFDM systems using the FFT, in that they have well-contained side lobes, improved spectral efficiency and BER performance, and they do not require a cyclic prefix. Here we study the wavelet packet and discrete wavelet transforms, comparing the BER performance of wavelet transform-based multicarrier systems and Fourier based OFDM systems, for multipath Rayleigh channels with AWGN. In the proposed system zero-forcing channel estimation in the frequency domain has been used. Results confirm that discrete wavelet-based systems using Daubechies wavelets outperform both wavelet packet transform- based systems and FFT-OFDM systems in terms of BER. Finally, Alamouti coding and maximal ratio combining schemes were employed in MIMO environments, where results show that the effects of multipath fading were greatly reduced by the antenna diversity.

Yes / A four-element compact dual-band patch antenna having a common ground plane operating at 28/38 GHz is proposed for millimeter-wave communication systems in this paper. The multiple-input-multiple-output (MIMO) antenna geometry consists of a slotted ellipse enclosed within a hollow circle which is orthogonally rotated with a connected partial ground at the back. The overall size of the four elements MIMO antenna is 2.24λ × 2.24λ (at 27.12 GHz). The prototype of four-element MIMO resonator is designed and printed using Rogers RT Duroid 5880 with εr = 2.2 and loss tangent = 0.0009 and having a thickness of 0.8 mm. It covers dual-band having a fractional bandwidth of 15.7% (27.12–31.34 GHz) and 4.2% (37.21–38.81 GHz) for millimeter-wave applications with a gain of more than 4 dBi at both bands. The proposed antenna analysis in terms of MIMO diversity parameters (Envelope Correlation Coefficient (ECC) and Diversity Gain (DG)) is also carried out. The experimental result in terms of reflection coefficient, radiation pattern, gain and MIMO diversity parameter correlates very well with the simulated ones that show the potential of the proposed design for MIMO applications at millimeter-wave frequencies. / This work is supported by the Moore4Medical Project, funded within ECSEL JU in collaboration with the EU H2020 Framework Programme (H2020/2014-2020) under Grant Agreement H2020-ECSEL-2019-IA-876190, and Fundação para a Ciência e Tecnologia (ECSEL/0006/2019). This work is also funded by the FCT/MEC through national funds and when applicable co-financed by the ERDF, under the PT2020 Partnership Agreement under the UID/EEA/50008/2020 Project.

Yes / This paper presented a planar printed multiple-input-multiple-output (MIMO) antenna with a dimension of 100 x 45 mm2. It composed of two crescent shaped radiators placed symmetrically with respect to the ground plane. Neutralization line applied to suppress mutual coupling. The proposed antenna examined both theoretically and experimentally, which achieves an impedance bandwidth of 18.67% (over 2.04-2.46 GHz) with a reflection coefficient < -10 dB and mutual coupling minimization of < -20 dB. An evaluation of MIMO antennas is presented, with analysis of correlation coefficient, total active reflection coefficient (TARC) and capacity loss. These characteristics indicate that the proposed antenna suitable for some wireless applications.

No / This paper presented a planar printed multiple-input-multiple-output (MIMO) antenna with a dimension of 100 x 45 mm 2 . It composed of two crescent shaped radiators placed symmetrically with respect to the ground plane. Neutralization line applied to suppress mutual coupling. The proposed antenna examined both theoretically and experimentally, which achieves an impedance bandwidth of 18.67% (over 2.04-2.46 GHz) with a reflection coefficient < -10 dB and mutual coupling minimization of < -20 dB. An evaluation of MIMO antennas is presented, with analysis of correlation coefficient, total active reflection coefficient (TARC) and capacity loss. These characteristics indicate that the proposed antenna suitable for some wireless applications. Mutual Coupling Reduction of Two Elements Antenna for Wireless Applications. Available from: https://www.researchgate.net/publication/261064207_Mutual_Coupling_Reduction_of_Two_Elements_Antenna_for_Wireless_Applications [accessed Aug 1, 2017].

Next generation wireless communications require transmission of reliable high data rate services. Second generation wireless communications systems use single-input multiple-output (SIMO) channel in the reverse link, meaning one transmit antenna at the user terminal and multiple receive antennas at the base station. Recently, information theoretic research has shown an enormous potential growth in the capacity of wireless systems by using multiple antenna arrays at both ends of the link. Space-time coding exploits the spatial-temporal diversity provided by the multiple input multiple output (MIMO) channels, significantly increasing both system capacity and the reliability of the wireless link. The Virginia Tech Space-Time Advanced Radio (VT-STAR) system presents a test bed to demonstrate the capabilities of space-time coding techniques in real-time. Core algorithms are implemented on Texas Instruments TMS320C67 Evaluation Modules (EVM). The radio frequency subsystem is composed of multi-channel transmitter and receiver chains implemented in hardware for over the air transmission. The capabilities of the MIMO channel are demonstrated in a non-line of sight (NLOS) indoor environment. Also to characterize the capacity gains in an indoor environment this test bed was modified to take channel measurements. This thesis reports the system design of VT-STAR and the channel capacity gains observed in an indoor environment for MIMO channels. / Master of Science

Cette thèse porte sur l'analyse des performances en traitement du signal et se compose de deux parties: Premièrement, nous étudions les bornes inférieures dans la caractérisation et la prédiction des performances en termes d'erreur quadratique moyenne (EQM). Les bornes inférieures de l'EQM donne la variance minimale qu'un estimateur peut atteindre et peuvent être divisées en deux catégories: les bornes déterministes pour le modèle où les paramètres sont supposés déterministes (mais inconnus), et les bornes Bayésiennes pour le modèle où les paramètres sont supposés aléatoires. En particulier, nous dérivons les expressions analytiques de ces bornes pour deux applications différentes: (i) La première est la localisation des sources en utilisant un radar multiple-input multiple-output (MIMO). Nous considérons les bornes inférieures dans deux contextes c'est-à-dire avec ou sans erreurs de modèle. (ii) La deuxième est l'estimation de phase d'impulsion de pulsars à rayon X qui est une solution potentielle pour la navigation autonome dans l'espace. Pour cette application, nous avons calculé plusieurs bornes inférieures de l'EQM dans le contexte de données modélisées par une loi de Poisson (complétant ainsi les travaux disponibles dans la littérature où les données sont modélisées par une loi gaussienne). Deuxièmement, nous étudions le seuil statistique de résolution limite (SRL), qui est la distance minimale en termes des paramètres d'intérêts entre les deux signaux permettant de séparer / estimer correctement les paramètres d'intérêt. Plus précisément, nous dérivons le SRL dans deux contextes: le traitement d'antenne et le radar MIMO en utilisant deux approches basées sur la théorie de l'estimation et sur la théorie de l'information. Finalement, nous proposons des expressions compactes du SRL dans le cas d'erreurs de modèle. / This manuscript concerns the performance analysis in signal processing and consists into two parts : First, we study the lower bounds in characterizing and predicting the estimation performance in terms of mean square error (MSE). The lower bounds on the MSE give the minimum variance that an estimator can expect to achieve and it can be divided into two categories depending on the parameter assumption: the so-called deterministic bounds dealing with the deterministic unknown parameters, and the so-called Bayesian bounds dealing with the random unknown parameter. Particularly, we derive the closed-form expressions of the lower bounds for two applications in two different fields: (i) The first one is the target localization using the multiple-input multiple-output (MIMO) radar in which we derive the lower bounds in the contexts with and without modeling errors, respectively. (ii) The other one is the pulse phase estimation of X-ray pulsars which is a potential solution for autonomous deep space navigation. In this application, we show the potential universality of lower bounds to tackle problems with parameterized probability density function (pdf) different from classical Gaussian pdf since in X-ray pulse phase estimation, observations are modeled with a Poisson distribution. Second, we study the statistical resolution limit (SRL) which is the minimal distance in terms of the parameter of interest between two signals allowing to correctly separate/estimate the parameters of interest. More precisely, we derive the SRL in two contexts: array processing and MIMO radar by using two approaches based on the estimation theory and information theory. We also present in this thesis the usefulness of SRL in optimizing the array system.

Les principaux objectifs des opérateurs ferroviaires visent à accroître la sécurité, réduire les coûts d’exploitation et de maintenance et augmenter l’attractivité et les bénéfices du transport ferroviaire en offrant de nouveaux services aux passagers. Ceci ne pourra être atteint que grâce à la multiplication des échanges de données entre les différents acteurs du monde ferroviaire. L’interopérabilité, l’efficacité spectrale, l’optimisation de l’usage des ressources radio et l’amélioration de la fiabilité des communications sont des exigences fortes pour les applications de télécommunication ferroviaires. Les recherches dans le domaine de la radio cognitive ont vu le jour afin de répondre aux besoins de communication de l’armée ainsi qu’aux besoins dans les secteurs de la sécurité publique. Ces domaines partagent souvent les mêmes exigences que les chemins de fers. Ainsi, la radio cognitive a montré un potentiel prometteur pour répondre aux besoins listés précédemment. Une des principales fonctionnalités d’un dispositif de radio cognitive est de prendre conscience de son environnement radioélectrique et de détecter les bandes disponibles. Trois principaux éléments définissent l’environnement de la radio cognitive : l’utilisateur, les règles d’accès au spectre radio et les domaines radio. Cette thèse met en avant plusieurs contributions relatives à la reconnaissance de l’environnement radiofréquence et la détection de bandes libres. Plus spécifiquement, ces contributions portent sur la reconnaissance par la radio cognitive de l’occupation du spectre et de la modulation des signaux présents dans les bandes analysées. Ces fonctions ont été conçues pour le contexte ferroviaire, c’est-à-dire la grande vitesse et un environnement électromagnétique difficile en présence de bruit impulsif. / An essential goal of railway operators is to increase safety, reduce operation and maintenance costs, and increase attraction and profit by offering new services to passengers. These objectives will be reached thanks to a huge increase of data fluxes exchanges between railways stakeholders and infrastructures.Interoperability, spectral efficiency, optimization of radio resource usages, and improvement of communications reliability are of significant interest for railway applications. The Cognitive Radio (CR) research has been successfully applied to meet the communication needs of the military as well as the public-safety sectors, which share many of the same needs as railway. CRs have shown significant promise to answer all of the previously listed requirements. One of the main capabilities of a CR device is to sense and finally become aware of its environment. Three major domains define the environment of the CR, namely, the user, policy, and radio domains. This thesis highlights several contributions to radio environment awareness of a CR device. More specifically, these contributions lie in the spectrum awareness and waveform awareness functions of the CR. We designed these functions for the railways context, that is, a high speed vehicular context, besides difficult electromagnetic environments resulting a heavy-tailed impulsive noise.

Made available in DSpace on 2016-03-15T19:37:56Z (GMT). No. of bitstreams: 1 BRUNO FERRAZ IZARIO.pdf: 4620887 bytes, checksum: bd842cabfdadb0bcb55e0ea548c9fba5 (MD5) Previous issue date: 2015-08-28 / The Long Term Evolution (LTE) system belongs to the 4th generation phone system. It is standardized by 3GPP and utilizes several technologies to improve the performance of data transmission. This permits flexibility for mobile devices, which enables a high data rate in the range of 50 Mbps to 100 Mbps, and admit access to various multimedia services. The study presents the results of deploying an LTE network in the city of Campinas, São Paulo, Brazil, using the 700 MHz band by comparing it to the 2.5 GHz band. By calculating the budget for the LTE system link is information as possible to highlight throughput and cell coverage radius, and other information. The Radio Mobile software was used for verification of results. / O sistema Long Term Evolution (LTE) pertence ao sistema da 4ª geração de telefonia (4G). Ele é padronizado pelo 3GPP e utiliza diversas tecnologias para melhorar o desempenho de transmissão de dados. O mesmo permite uma flexibilidade para dispositivos móveis, possibilitando uma alta taxa de dados na faixa de 50 Mbps a 100 Mbps, além de admitir acesso a diversos serviços multimídias. O estudo apresenta resultados de implantação de uma rede LTE na cidade de Campinas, São Paulo, Brasil, utilizando a faixa de 700 MHz comparando-a com a faixa de 2,5 GHz. Através do cálculo de link budget para o sistema LTE, é possível destacar informações como throughput e raio da célula de cobertura, além de outras informações. O software radio mobile foi utilizado para fins de comprovação de resultados.