La radio impulsionnelle UWB (IR-UWB) est une technologie de communication relativement récente, qui apporte une solution intéressante au problème de l’encombrement du spectre RF, et qui répond aux exigences de haut débit et localisation précise d’un nombre croissant d’applications, telles que les communications indoor, les réseaux de capteurs personnels et corporels, l’IoT, etc. Ses caractéristiques uniques sont obtenues par la transmission d’impulsions de très courte durée (inférieure à 1 ns), occupant une largeur de bande allant jusqu’à 7,5 GHz, et ayant une densité spectrale de puissance extrêmement faible (inférieure à -43 dBm/MHz). Les meilleures performances d’un système IR-UWB sont obtenues avec des récepteurs cohérents de type Rake, au prix d’une complexité accrue, due notamment à l’étape d’estimation du canal UWB, caractérisé par de nombreux trajets multiples. Cette étape de traitement nécessite l’estimation d’un ensemble de composantes spectrales du signal reçu, sans pouvoir faire appel aux techniques d’échantillonnage usuelles, en raison d’une limite de Nyquist particulièrement élevée (plusieurs GHz).Dans le cadre de cette thèse, nous proposons de nouvelles approches, à faible complexité, pour l’estimation du canal UWB, basées sur la représentation parcimonieuse du signal reçu, la théorie de l’acquisition compressée, et les méthodes de reconstruction des signaux à taux d’innovation fini. La réduction de complexité ainsi obtenue permet de diminuer de manière significative le coût d’implémentation du récepteur IR-UWB et sa consommation. D’abord, deux schémas d’échantillonnage compressé, monovoie (filtre SoS) et multivoie (MCMW) identifiés dans la littérature sont étendus au cas des signaux UWB ayant un spectre de type passe-bande, en tenant compte de leur implémentation réelle dans le circuit. Ces schémas permettent l’acquisition des coefficients spectraux du signal reçu et l’échantillonnage à des fréquences très réduites ne dépendant pas de la bande passante des signaux, mais seulement du nombre des trajets multiples du canal UWB. L’efficacité des approches proposées est démontrée au travers de deux applications : l’estimation du canal UWB pour un récepteur Rake cohérent à faible complexité, et la localisation précise en environnement intérieur dans un contexte d’aide à la dépendance.En outre, afin de réduire la complexité de l’approche multivoie en termes de nombre de voies nécessaires pour l’estimation du canal UWB, nous proposons une architecture à nombre de voies réduit, en augmentant le nombre d’impulsions pilotes émises.Cette même approche permet aussi la réduction de la fréquence d’échantillonnage associée au schéma MCMW. Un autre objectif important de la thèse est constitué par l’optimisation des performances des approches proposées. Ainsi, bien que l’acquisition des coefficients spectraux consécutifs permette une mise en oeuvre simple des schémas multivoie, nous montrons que les coefficients ainsi choisis, ne donnent pas les performances optimales des algorithmes de reconstruction. Ainsi, nous proposons une méthode basée sur la cohérence des matrices de mesure qui permet de trouver l’ensemble optimal des coefficients spectraux, ainsi qu’un ensemble sous-optimal contraint où les positions des coefficients spectraux sont structurées de façon à faciliter la conception du schéma MCMW. Enfin, les approches proposées dans le cadre de cette thèse sont validées expérimentalement à l’aide d’une plateforme expérimentale UWB du laboratoire Lab-STICC CNRS UMR 6285. / Ultra-wideband impulse radio (IR-UWB) is a relatively new communication technology that provides an interesting solution to the problem of RF spectrum scarcity and meets the high data rate and precise localization requirements of an increasing number of applications, such as indoor communications, personal and body sensor networks, IoT, etc. Its unique characteristics are obtained by transmitting pulses of very short duration (less than 1 ns), occupying a bandwidth up to 7.5 GHz, and having an extremely low power spectral density (less than -43 dBm / MHz). The best performances of an IR-UWB system are obtained with Rake coherent receivers, at the expense of increased complexity, mainly due to the estimation of UWB channel, which is characterized by a large number of multipath components. This processing step requires the estimation of a set of spectral components for the received signal, without being able to adopt usual sampling techniques, because of the extremely high Nyquist limit (several GHz).In this thesis, we propose new low-complexity approaches for the UWB channel estimation, relying on the sparse representation of the received signal, the compressed sampling theory, and the reconstruction of the signals with finite rate of innovation. The complexity reduction thus obtained makes it possible to significantly reduce the IR-UWB receiver cost and consumption. First, two existent compressed sampling schemes, single-channel (SoS) and multi-channel (MCMW), are extended to the case of UWB signals having a bandpass spectrum, by taking into account realistic implementation constraints. These schemes allow the acquisition of the spectral coefficients of the received signal at very low sampling frequencies, which are not related anymore to the signal bandwidth, but only to the number of UWB channel multipath components. The efficiency of the proposed approaches is demonstrated through two applications: UWB channel estimation for low complexity coherent Rake receivers, and precise indoor localization for personal assistance and home care.Furthermore, in order to reduce the complexity of the MCMW approach in terms of the number of channels required for UWB channel estimation, we propose a reduced number of channel architecture by increasing the number of transmitted pilot pulses. The same approach is proven to be also useful for reducing the sampling frequency associated to the MCMW scheme.Another important objective of this thesis is the performance optimization for the proposed approaches. Although the acquisition of consecutive spectral coefficients allows a simple implementation of the MCMW scheme, we demonstrate that it not results in the best performance of the reconstruction algorithms. We then propose to rely on the coherence of the measurement matrix to find the optimal set of spectral coefficients maximizing the signal reconstruction performance, as well as a constrained suboptimal set, where the positions of the spectral coefficients are structured so as to facilitate the design of the MCMW scheme. Finally, the approaches proposed in this thesis are experimentally validated using the UWB equipment of Lab-STICC CNRS UMR 6285.

[pt] Este trabalho apresenta a geração de pulsos de microondas linearmente e não-linearmente modulados em frequência (LFM e NLFM) através da técnica fotônica de auto-heterodinagem. Ao utilizar eletrônica de baixa frequência para modular um diodo laser de feedback distribuído, a variação da portadora óptica no tempo (chirp) é observada, o que é causado predominantemente por efeito térmico. Este efeito, combinado com batimento auto-heteródino, foi capaz de produzir pulsos LFM com alto produto largura de banda-tempo (TBWP). Uma outra abordagem é necessária para geração de pulsos NLFM. Primeiro, é introduzida a técnica Espectroscopia Óptica Resolvida no Tempo para caracterização do chirp de um diodo laser. Em seguida, um estímulo de corrente em formato de função degrau é aplicado ao diodo laser para aquisição da função de transferência de seu chirp, H(s). Com a posse de H(s), uma simulação numérica foi usada para descobrir o estímulo necessário de corrente i(t) para obtenção de pulsos de microondas NLFM através da técnica de auto-heterodinagem. Os resultados experimentais coincidem com a simulação. / [en] This work reports the photonic generation of both linear and non-linear frequency modulation (LFM and NLFM) microwave pulses through a self-heterodyne scheme. By using low-frequency electronics to drive a distributed feedback laser diode, optical chirping is generated predominantly by thermal effect. Combining laser chirping and self-heterodyning, LFM pulses with high time-bandwidth product (TBWP) were achieved. A different approach is required for generation of NLFM microwave pulses. First, for characterization of the laser diode chirp, it is introduced a technique named Time- Resolved Optical Spectroscopy. Then, by using a step-shaped current stimulus, the laser chirp transfer function H(s) was obtained. With knowledge on H(s), a numerical simulation produced the suitable current stimulus i(t) needed to generate NLFM microwave pulses through self-heterodyning. Experimental results agreed with the numerical simulations.

Ultra Wideband (UWB) communication has recently drawn considerable attention from academia and industry. This is mainly owing to the ultra high speeds and cognitive features it could offer. The employability of UWB in numerous areas including but not limited to Wireless Personal Area Networks, WPAN's, Body Area Networks, BAN's, radar and medical imaging etc. has opened several avenues of research and development. However, still there is a disagreement on the standardization of UWB. Two contesting radios for UWB are Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) and DS-UWB (Direct Sequence Ultra Wideband). As nearly all of the reported research on UWB hasbeen about a very narrow/specific area of the communication system, this thesis looks at the end-to-end performance of an MB-OFDM approach. The overall aim of this project has been to first focus on three different aspects i.e. interference, antenna and propagation aspects of an MB-OFDM system individually and then present a holistic or an end-to-end system analysis finally. In the first phase of the project the author investigated the performance of MB-OFDM system under the effect of his proposed generic or technology non-specific interference. Avoiding the conventional Gaussian approximation, the author has employed an advanced stochastic method. A total of two approaches have been presented in this phase of the project. The first approach is an indirect one which involves the Moment Generating Functions (MGF's) of the Signal-to-Interference-plus-Noise-Ratio (SINR) and the Probability Density Function (pdf) of the SINR to calculate the Average Probabilities of Error of an MB-OFDM system under the influence of proposed generic interference. This approach assumed a specific two-dimensional Poisson spatial/geometric placement of interferers around the victim MB-OFDM receiver. The second approach is a direct approach and extends the first approach by employing a wider class of generic interference. In the second phase of the work the author designed, simulated, prototyped and tested novel compact monopole planar antennas for UWB application. In this phase of the research, compact antennas for the UWB application are presented. These designs employ low-loss Rogers duroid substrates and are fed by Copla-nar Waveguides. The antennas have a proposed feed-line to the main radiating element transition region. This transition region is formed by a special step-generating function-set called the "Inverse Parabolic Step Sequence" or IPSS. These IPSS-based antennas are simulated, prototyped and then tested in the ane-choic chamber. An empirical approach, aimed to further miniaturize IPSS-based antennas, was also derived in this phase of the project. The empirical approach has been applied to derive the design of a further miniaturized antenna. More-over, an electrical miniaturization limit has been concluded for the IPSS-based antennas. The third phase of the project has investigated the effect of the indoor furnishing on the distribution of the elevation Angle-of-Arrival (AOA) of the rays at the receiver. Previously, constant distributions for the AOA of the rays in the elevation direction had been reported. This phase of the research has proposed that the AOA distribution is not fixed. It is established by the author that the indoor elevation AOA distributions depend on the discrete levels of furnishing. A joint time-angle-furnishing channel model is presented in this research phase. In addition, this phase of the thesis proposes two vectorial or any direction AOA distributions for the UWB indoor environments. Finally, the last phase of this thesis is presented. As stated earlier, the overall aim of the project has been to look at three individual aspects of an MB-OFDM system, initially, and then look at the holistic system, finally. Therefore, this final phase of the research presents an end-to-end MB-OFDM system analysis. The interference analysis of the first phase of the project is revisited to re-calculate the probability of bit error with realistic/measured path loss exponents which have been reported in the existing literature. In this method, Gaussian Quadrature Rule based approximations are computed for the average probability of bit error. Last but not the least, an end-to-end or comprehensive system equation/impulse response is presented. The proposed system equation covers more aspects of an indoor UWB system than reported in the existing literature.

Du fait de la nature ouverte et partagée du canal radio, les communications sans fil souffrent de vulnérabilités sérieuses en terme de sécurité. Dans ces travaux de thèse, je me suis intéressé particulièrement à deux classes d’attaques à savoir l’attaque par relais et l’attaque par déni de service (brouillage). La technologie de couche physique UWB-IR a connu un grand essor au cours de cette dernière décennie et elle est une candidate intéressante pour les réseaux sans fil à courte portée. Mon objectif principal était d’exploiter les caractéristiques de la couche physique UWB-IR afin de renforcer la sécurité des communications sans fil. L’attaque par relais peut mettre à défaut les protocoles cryptographiques d’authentification. Pour remédier à cette menace, les protocoles de distance bounding ont été proposés. Dans ce cadre, je propose deux nouveaux protocoles (STHCP : Secret Time-Hopping Code Protocol et SMCP : Secret Mapping Code Protocol) qui améliorent considérablement la sécurité des protocoles de distance bounding au moyen des paramètres de la radio UWB-IR. Le brouillage consiste en l’émission intentionnelle d’un signal sur le canal lors du déroulement d’une communication. Mes contributions concernant le problème de brouillage sont triples. D’abord, j’ai déterminé les paramètres d’un brouilleur gaussien pire cas contre un récepteur UWB-IR non-cohérent. En second lieu, je propose un nouveau modèle de brouillage par analogie avec les attaques contre le système de chiffrement. Troisièmement, je propose une modification rendant la radio UWB-IR plus robuste au brouillage. Enfin, dans une dernière partie de mes travaux, je me suis intéressé au problème d’intégrer la sécurité à un réseau UWB-IR en suivant l’approche d’embedding. Le principe de cette approche consiste à superposer et à transmettre les informations de sécurité simultanément avec les données et avec une contrainte de compatibilité. Ainsi, je propose deux nouvelles techniques d’embedding pour la couche physique UWB-IR afin d’intégrer un service d’authentification. / Due to the shared nature of wireless medium, wireless communications are more vulnerable to security threats. In my PhD work, I focused on two types of threats: relay attacks and jamming. UWB-IR physical layer technology has seen a great development during the last decade which makes it a promising candidate for short range wireless communications. My main goal was to exploit UWB-IR physical layer characteristics in order to reinforce security of wireless communications. By the simple way of signal relaying, the adversary can defeat wireless authentication protocols. The first countermeasure proposed to thwart these relay attacks was distance bounding protocol. The concept of distance bounding relies on the combination of two sides: an authentication cryptographic side and a distance checking side. In this context, I propose two new distance bounding protocols that significantly improve the security of existing distance bounding protocols by means of UWB-IR physical layer parameters. The first protocol called STHCP is based on using secret time-hopping codes. Whereas, the second called SMCP is based on secret mapping codes. Security analysis and comparison to the state of the art highlight various figures of merit of my proposition. Jamming consists in the emission of noise over the channel while communication is taking place and constitutes a major problem to the security of wireless communications. In a first contribution, I have determined worst case Gaussian noise parameters (central frequency and bandwidth) against UWB-IR communication employing PPM modulation and a non-coherent receiver. The metric considered for jammer optimization is the signal-to-jamming ratio at the output of the receiver. In a second contribution, I propose a new jamming model by analogy to attacks against ciphering algorithms. The new model leads to distinguish various jamming scenarios ranging from the best case to the worst case. Moreover, I propose a modification of the UWB-IR physical layer which allows to restrict any jamming problem to the most favorable scenario. The modification is based on using a cryptographic modulation depending on a stream cipher. The new radio has the advantage to combine the resistance to jamming and the protection from eavesdropping. Finally, I focused on the problem of security embedding on an existing UWB-IR network. Security embedding consists in adding security features directly at the physical layer and sending them concurrently with data. The embedding mechanism should satisfy a compatibility concern to existing receivers in the network. I propose two new embedding techniques which rely on the superposition of a pulse orthogonal to the original pulse by the form or by the position. Performances analysis reveal that both embedding techniques satisfy all system design constraints.

Les réseaux corporels (WBAN) se réfère aux réseaux de capteurs (WSN) "portables" utilisés pour collecter des données personnelles, telles que la fréquence cardiaque ou l'activité humaine. Cette thèse a pour objectif de proposer des algorithmes coopératifs (PHY/MAC) pour effectuer des applications de localisation, tels que la capture de mouvement et la navigation de groupe. Pour cela, nous exploitons les avantages du WBAN avec différentes topologies et différents types de liens: on-body à l'échelle du corps, body-to-body entre les utilisateurs et off-body par rapport à l'infrastructure. La transmission repose sur une radio impulsionnelle (IR-UWB), afin d'obtenir des mesures de distance précises, basées sur l’estimation du temps d'arrivée (TOA). Ainsi, on s’intéresse au problème du positionnement à travers de la conception de stratégies coopératives et en considérant la mobilité du corps et les variations canal. Notre première contribution consiste en la création d'une base de données obtenue avec de scénarios réalistes pour la modélisation de la mobilité et du canal. Ensuite, nous introduisons un simulateur capable d'exploiter nos mesures pour la conception de protocoles. Grâce à ces outils, nous étudions d’abord l'impact de la mobilité et des variations de canal sur l'estimation de la distance avec le protocole "three way-ranging" (3-WR). Ainsi, nous quantifions et comparons l'erreur avec des modèles statistiques. Dans un second temps, nous analysons différentes algorithmes de gestion de ressources pour réduire l'impact de la mobilité sur l'estimation de position. Ensuite, nous proposons une optimisation avec un filtre de Kalman étendu (EKF) pour réduire l'erreur. Enfin, nous proposons un algorithme coopératif basé sur l'analyse d’estimateurs de qualité de lien (LQEs) pour améliorer la fiabilité. Pour cela, nous évaluons le taux de succès de positionnement en utilisant trois modèles de canaux (empirique, simulé et expérimental) avec un algorithme (basé sur la théorie des jeux) pour le choix des ancres virtuelles. / Wireless Body Area Networks (WBAN) refers to the family of “wearable” wireless sensor networks (WSN) used to collect personal data, such as human activity, heart rate, sleep sequences or geographical position. This thesis aims at proposing cooperative algorithms and cross-layer mechanisms with WBAN to perform large-scale individual motion capture and coordinated group navigation applications. For this purpose, we exploit the advantages of jointly cooperative and heterogeneous WBAN under full/half-mesh topologies for localization purposes, from on-body links at the body scale, body-to-body links between mobile users of a group and off-body links with respect to the environment and the infrastructure. The wireless transmission relies on an impulse radio Ultra-Wideband (IR-UWB) radio (based on the IEEE 802.15.6 standard), in order to obtain accurate peer-to-peer ranging measurements based on Time of Arrival (ToA) estimates. Thus, we address the problem of positioning and ranging estimation through the design of cross-layer strategies by considering realistic body mobility and channel variations. Our first contribution consists in the creation of an unprecedented WBAN measurement database obtained with real experimental scenarios for mobility and channel modelling. Then, we introduce a discrete-event (WSNet) and deterministic (PyLayers) co-simulator tool able to exploit our measurement database to help us on the design and validation of cooperative algorithms. Using these tools, we investigate the impact of nodes mobility and channel variations on the ranging estimation. In particular, we study the “three-way ranging” (3-WR) protocol and we observed that the delays of 3-WR packets have an impact on the distances estimated in function of the speed of nodes. Then, we quantify and compare the error with statistical models and we show that the error generated by the channel is bigger than the mobility error. In a second time, we extend our study for the position estimation. Thus, we analyze different strategies at MAC layer through scheduling and slot allocation algorithms to reduce the impact of mobility. Then, we propose to optimize our positioning algorithm with an extended Kalman filter (EKF), by using our scheduling strategies and the statistical models of mobility and channel errors. Finally, we propose a distributed-cooperative algorithm based on the analysis of long-term and short-term link quality estimators (LQEs) to improve the reliability of positioning. To do so, we evaluate the positioning success rate under three different channel models (empirical, simulated and experimental) along with a conditional algorithm (based on game theory) for virtual anchor choice. We show that our algorithm improve the number of positions estimated for the nodes with the worst localization performance.

Actuellement, la majorité des équipements électroniques prenant place dans nos véhicules s'interconnectent encore par des liens câblés. Or, l'établissement d'un réseau sans fil permet de remplacer ces liens existants. Afin de permettre cette connectivité et pour répondre aux exigences futures, une solution qui accepte suffisamment de débit doit être développée. Parmi les solutions actuelles possibles, l'Ultra-Large Bande est le candidat idéal. De manière générale, cette Thèse se consacre à l'étude de la propagation à l'intérieur d'une voiture. Afin d'évaluer les performances de ce type de système à l'intérieur d'un véhicule, un modèle de canal pouvant reproduire avec fidélité la propagation intra-véhiculaire est nécessaire. De par la similarité entre les environnements, le modèle de canal proposé est basé sur la théorie des chambres réverbérantes. Compte tenu des faibles dimensions de l'environnement et de la proximité des antennes par rapport aux passagers, l'idée est de réduire l'énergie absorbée par ces derniers tout en maximisant celle-ci à la position d'un récepteur visé. Parmi les solutions possibles, le retournement temporel apparait comme une technique idéale pour répondre à ces objectifs. Cette technique permet en effet de focaliser temporellement et spatialement le signal électromagnétique au niveau du récepteur. Dans cette Thèse, une évaluation des performances du RT à l'intérieure d'une voiture est proposée. Cette étude nous a amenés à porter notre attention sur les propriétés spatiales de l'énergie totale portée par un signal utilisant le retournement temporel et, de ce fait, nous proposons un nouveau formalisme de la distribution spatiale de cette énergie. / Current vehicles still use wired links to interconnect the embedded electronic equipment. However, advances in wireless technologies permit to replace these links with wireless personal area networks. To enable this connectivity and to meet the future requirements, a solution that provides sufficient data rate must be developed. One technological candidate that can be used to meet the data rate requirements is Ultra-Wide Band. This thesis investigates the ultra-wideband propagation environment in intra-vehicular environments. In order to evaluate the performances of UWB inside a vehicle, channel models that accurately reproduce the intra-vehicular propagation characteristics are required. Because of obvious similarities, the proposed model is based on reverberation chamber theory. Given the small size of the environment and the proximity of the antennas to the passengers, one goal of intra-vehicular communications is to reduce the energy absorbed by the passengers while maximizing the energy at the position of the intended receiver. Among the possible solutions, Time Reversal appears to be the ideal technique to meet this objective. Time Reversal permits to spatially and temporally focus the electromagnetic signal at the receiver. In this thesis, a performance evaluation of Time Reversal inside a car is proposed. Moreover, a model of the spatial properties of the total energy of a signal using Time Reversal is proposed. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Dans cette thèse on s’est intéressé aux méthodes de génération de clés secrètes symétriques en utilisant la couche physique ultra large bande impulsionnelle (IR-UWB). Les travaux ont été réalisés selon trois axes, les deux premiers concernant la communication point-à-point et le dernier, les communications coopératives. Tout d’abord, la quantification des signaux typiques IR-UWB (soit directement échantillonnés, soit estimés) a été investiguée, principalement du point de vue du compromis entre la robustesse (ou réciprocité) des séquences binaires obtenues et leur caractère aléatoire. Différents algorithmes de quantification valorisant l’information temporelle offerte par les canaux IR-UWB pour améliorer ce compromis ont alors été proposés. Ensuite, des études concernant les échanges publics nécessaires à l’étape de réconciliation (visant la correction d’éventuels désaccords entre les séquences binaires générées de part et d’autre du lien) ont montré qu’il était possible d’être plus robuste face aux attaques passives en utilisant des informations de plus haut niveau, inhérentes à cette technologie et disponibles à moindre coût (ex. via une estimation précise du temps de vol aller-retour). Finalement, une nouvelle méthode a été développée afin d’étendre les schémas de génération de clé point-à-point à plusieurs nœuds (trois dans nos études) en utilisant directement la couche physique fournie par les liens radio entre les nœuds. / Emerging decentralized wireless systems, such as sensor or ad-hoc networks, will demand an adequate level of security in order to protect the private and often sensitive information that they carry. The main security mechanism for confidentiality in such networks is symmetric cryptography, which requires the sharing of a symmetric key between the two legitimate parties. According to the principles of physical layer security, wireless devices within the communication range can exploit the wireless channel in order to protect their communications. Due to the theoretical reciprocity of wireless channels, the spatial decorrelation property (e.g., in rich scattering environments), as well as the fine temporal resolution of the Impulse Radio - Ultra Wideband (IR-UWB) technology, directly sampled received signals or estimated channel impulse responses (CIRs) can be used for symmetric secret key extraction under the information-theoretic source model. Firstly, we are interested in the impact of quantization and channel estimation algorithms on the reciprocity and on the random aspect of the generated keys. Secondly, we investigate alternative ways of limiting public exchanges needed for the reconciliation phase. Finally, we develop a new signal-based method that extends the point-to-point source model to cooperative contexts with several nodes intending to establish a group key.

La presenta Tesis Doctoral encuentra su ámbito de aplicación en redes de acceso ópticas de fibra hasta el hogar o FTTH (del inglés fibre-to-the-home). Las redes FTTH han sido ampliamente desplegadas en todo el mundo y se prevé que evolucionen hasta arquitecturas de multiplexación por división en longitud de onda o WDM(dle inglés wavelength division multiplexing). Conforme los requerimientos de capacidady ancho de banda por usuario para servicios de comunicación de banda ancha se incrementan continuamente, tecnologías tales como hybrid wireless-optical, radio de banda ultra ancha o UWB(del inglés ultra-wideband), y radio de onda milimétrica se están investigando como soluciones viables para proporcionar tasas de datos excediendo Gigabit por segundo por usuario. Las redes híbridas inalámbrico-óptico pueden proporcionar backhaul más simple y se prevé que desempeñen un papel importante en redes de acceso de próxima generación que requerirán despliegue flexible, alta capacidad, habilidad de ampliación, escalable en número de usuarios y demanda, y factible económicamente. Las técnicas radio sobre fibra combinadas con sistemas inalámbricos multigigabit que proporcionen capacidades comparables a sistemas de comunicaciones de fibra óptica se ve como una solución rápidamente desplegable y efectiva en coste para proporcionar acceso transparente cableado/inalámbrico integrado a servicios de banda ancha para el usuario final. Los sistemas inalámbricos UWB y de onda milimétrica son capaces de proporcionar comunicaciones multigigabit. UWB en particular permite un uso eficiente del esprectro 3.1-10.6 GHz debido a sus características únicas de coexistencia y tiene madurez de mercado. Sin embargo, la tecnología UWB está restringida por regulación en todo el mundo. Esta restricción de regulación hace de gran interés a la radio de onda milimétrica en 60 GHz debido al aproximadamente 7 GHz de ancho de banda regulado consistentemente en todo el mundo, sin restricciones de coexistencia. / Beltrán Ramírez, M. (2012). Photonic Techniques for Next-Generation Integrated Optical Networks Based on Ultra-Wideband Radio / Técnicas Fotónicas para Redes Ópticas Integradas de Próxima Generación Basadas en Radio de Banda Ultra Ancha [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/15576 / Palancia

<p>Пасивна индуктивна компонента и нискошумни појачавач у технологији<br />монолитних интегрисаних кола за широкопојасне примјене пројектовани<br />су, фабриковани и карактерисани. Приликом пројектовања индуктора<br />изабрана је топологија меандар, а осим софтверских алата за<br />пројектовање интегрисаних кола, кориштен је и симулатор<br />електромагнетског поља. Осим карактеризације основних параметара,<br />пажња је посвећена и анализи процесних и температурских варијација.<br />Спроведена је механичка карактеризација материјала од којег се састоји<br />заштитни слој фабрикованог интегрисаног кола. Нискошумни појачавач<br />пројектован је као први степен пријемника широкопојасне технологије, а<br />карактеризацијом је потврђена успјешност поступка.</p> / <p>Pasivna induktivna komponenta i niskošumni pojačavač u tehnologiji<br />monolitnih integrisanih kola za širokopojasne primjene projektovani<br />su, fabrikovani i karakterisani. Prilikom projektovanja induktora<br />izabrana je topologija meandar, a osim softverskih alata za<br />projektovanje integrisanih kola, korišten je i simulator<br />elektromagnetskog polja. Osim karakterizacije osnovnih parametara,<br />pažnja je posvećena i analizi procesnih i temperaturskih varijacija.<br />Sprovedena je mehanička karakterizacija materijala od kojeg se sastoji<br />zaštitni sloj fabrikovanog integrisanog kola. Niskošumni pojačavač<br />projektovan je kao prvi stepen prijemnika širokopojasne tehnologije, a<br />karakterizacijom je potvrđena uspješnost postupka.</p> / <p>A passive inductive component and a low-noise amplifier are designed,<br />fabricated in standard monolithic CMOS technology and characterized, both<br />intended for wideband operation. For the design of the inductor, meander<br />topology is chosen. Along with the integrated circuit design tools,<br />electromagnetic field simulator is used. Besides the standard parameter<br />characterization, special attention is dedicated to the analysis of process and<br />temperature variations. Furthermore, mechanical characterization of the<br />material that comprises the protection layer has been undertaken. Low-noise<br />amplifier is designed as the first stage of an ultra wideband receiver and the<br />results show that the circuit is successfully designed.</p>

The emergence of Ultra-wideband (UWB) technology application has yielded tremendous and vital impacts in the field of microwave wireless communications. These applications include military radar imaging, security screening, and tumour detection, especially for early detection of breast cancer. These indicators have stimulated and inspired many researchers to make the best use of this promising technology. UWB technology challenges such as antenna design, the problem of imaging reconstruction techniques, challenges of severe signal attenuation and dispersion in high loss material. Others are lengthy computational time demand and large computer memory requirements are prevalent constraints that need to be tackled especially in a large scale and complex computational electromagnetic analysis. In this regard, it is necessary to find out recently developed optimisation techniques that can provide solutions to these problems. In this thesis, designing, optimisation, development, measurement, and analysis of UWB antennas for near-field microwave imaging applications are considered. This technology emulates the same concept of surface penetrating radar operating in various forms of the UWB spectrum. The initial design of UWB monopole antennas, including T-slots, rectangular slots, and hexagonal slots on a circular radiating patch, was explicitly implemented for medical imaging applications to cover the UWB frequency ranging from 3.1 GHz to 10.6 GHz. Based on this concept, a new bow-tie and Vivaldi UWB antennas were designed for a through-the-wall imaging application. The new antennas were designed to cover a spectrum on a lower frequency ranging from 1 GHz - 4 GHz to ease the high wall losses that will be encountered when using a higher frequency range and to guarantee deeper penetration of the electromagnetic wave. Finally, both simulated and calculated results of the designed, optimised antennas indicate excellent agreement with improved performance in terms of return loss, gain, radiation pattern, and fidelity over the entire UWB frequency. These breakthroughs provided reduced computational time and computer memory requirement for useful, efficient, reliable, and compact sensors for imaging applications, including security and breast cancer detection, thereby saving more lives. / Tertiary Education Trust Fund (TET Fund) Supported by the Nigerian Defence Academy (NDA)