Дисертації з теми "Antenne intelligenti"
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Comisso, Massimiliano. "Beamforming techniques for wireless communications in low-rank channels: analytical models and synthesis algorithms." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2582.
Повний текст джерелаThe objective of this thesis is discussing the application of multiple antenna technology in some selected areas of wireless networks and fourth-generation telecommunication systems. The original contributions of this study involve, mainly, two research fields in the context of the emerging solutions for high-speed digital communications: the mathematical modeling of distributed wireless networks adopting advanced antenna techniques and the development of iterative algorithms for antenna array pattern synthesis. The material presented in this dissertation is the result of three-year studies performed within the Telecommunication Group of the Department of Electronic Engineering at the University of Trieste during the course of Doctorate in Information Engineering. In recent years, an enormous increase in traffic has been experienced by wireless communication systems, due to a significant growth in the number of users as well as to the development of new high bit rate applications. It is foreseen that in the near future this trend will be confirmed. This challenging scenario involves not only the well established market of cellular systems, but also the field of emerging wireless technologies, such as WiMAX (Worldwide interoperability for Microwave Access) for wireless metropolitan area networks, and Wi-Fi (Wireless Fidelity) for wireless local area networks, mobile ad-hoc networks and wireless mesh networks. The rapid diffusion of architectures adopting an ad-hoc paradigm, in which the network infrastructure is totally or partially absent and that can be deployed using low-cost self-configuring devices, has further enlarged the number of systems that have to coexist within a limited frequency spectrum. In such evolving environment, the development of interference mitigation methods to guarantee the communication reliability, the implementation of proper radio resource allocation schemes for managing the user mobility as well as for supporting multimedia and high speed applications, represent the most relevant topics. Classic approaches are focused on the use of the time-frequency resources of the propagation channel. However, to satisfy the increasing demand of network capacity, while guaranteeing at the same time the necessary levels in the quality of the offered services, operators and manufacturers must explore new solutions. In this scenario, the exploitation of the spatial domain of the communication channel by means of multiple antenna systems can be a key improvement for enhancing the spectral efficiency of the wireless systems. In a rich scattering environment, the use of multiple antennas enables the adoption of diversity and spatial multiplexing techniques for mitigating and, respectively, exploiting multipath fading effects. In propagation environments characterized by small angular spreads, the combination of antenna arrays and beamforming algorithms provides the possibility to suppress the undesired sources and to receive the signals incoming from the desired ones. This leads to an increase of the signal to interference plus noise ratio at the receiver that can be exploited to produce relevant benefits in terms of communication reliability and/or capacity. A proper design of the medium access control layer of the wireless network can enable the simultaneous exchange of packets between different node pairs as well as the simultaneous reception of packets from multiple transmitters at a single node. Switched-beam antennas, adaptive antennas (also referred to as smart antennas), and phased-antenna arrays represent some of the available beamforming techniques that can be applied to increase the overall system capacity and to mitigate the interference, in a scenario where several different technologies must share the same frequency spectrum. In the context of distributed wireless networks using multiple antenna systems, the core of this thesis is the development of a mathematical model to analyze the performance of the network in presence of multipath fading, with particular reference to a scenario in which the signal replicas incoming at the receiver are confined within a small angle and are characterized by small relative delays. This propagation environment, referred to as low-rank, is the typical operating scenario of smart antennas, which necessitate high spatial correlation channels to work properly. The novel aspects of this study are represented by the theoretical and numerical modeling of the sophisticated adaptive antennas in conjunction with a detailed description of the channel statistics and of the IEEE 802.11 medium access control scheme. A theoretical model providing a more realistic perspective may be desirable, considering that, at present, not only cost and competition issues, but also too optimistic expectations, as compared to the first measurements on the field, have induced the wireless operators to delay the adoption of smart antenna technology. The presented analysis includes the most relevant elements that can influence the network behavior: the spatial channel model, the fading statistic, the network topology, the access scheme, the beamforming algorithm and the antenna array geometry. This last aspect is numerically investigated considering that the size of the user terminal represents a strict constraint on the number of antennas that can be deployed on the device, and so the maximization of the performance becomes related to the geometrical distribution of the radiators. In ad-hoc and mesh networks, the typical communication devices, such as laptops, palmtops and personal digital assistants require compact and cheap antenna structures as well as beamforming algorithms easy to implement. In particular, the low-cost characteristics have guaranteed a wide popularity to wireless mesh technology, which have encouraged the birth of a new social phenomenon, known as wireless community networks, whose objective is the reduction of the Internet access cost. The adoption of multi-antenna systems is the purpose of the IEEE 802.11n amendment, which, however, not considering modifications of the medium access control layer, provides higher bit rates for the single link, but does not allow simultaneous communications between different couples of nodes. This aspect must be taken into account together with the fact that, nowadays, IEEE 802.11x represents the leading family of standards for wireless local communications, and enhancement proposals have to pay careful attention to the backward compatibility issues. The mathematical model presented in this thesis discusses the suitable parameter settings to exploit advanced antenna techniques in 802.11-based networks when the access scheme supports multiple communications at the same time, maintaining a realistic description for the antenna patterns and the channel behavior. The presentation of two new iterative algorithms for antenna array pattern synthesis represents the core of the last part of this dissertation. The proposed solutions are characterized by implementation simplicity, low computational burden and do not require the modification of the excitation amplitudes of the array elements. These advantages make the presented algorithms suitable for a wide range of communication systems, while matching also the inexpensiveness of mesh and ad-hoc devices. In particular, phase-only synthesis techniques allow the adoption of a cheaper hardware, including only phase shifters, which are available at a reasonable price, while avoiding the use of the more expensive power dividers. The first presented algorithm employs the spatial statistic of the channel for properly placing the pattern nulls, in order to suppress the undesired power incoming from a given angular interval. This solution exploits the improved knowledge of the spatial properties of the propagation environment for enhancing the interference suppression capabilities at the transmitter and receiver sides. The second algorithm is a phase-only technique that is able to generate multiple nulls towards the undesired directions and multiple main lobes towards the desired ones. This method provides the possibility to perform spatial multiplexing adopting low-cost electronic components. The thesis is organized in three parts. The first one provides the background material and represents the basics of the following arguments, while the other two parts are dedicated to the original results developed during the research activity. With reference to the first part, the fundamentals of antenna array theory are briefly summarized in the first chapter. The most relevant aspects of the wireless propagation environment are described in the second chapter, focusing on the characteristics of the spatial domain in a low-rank scenario. The third chapter presents a classification of the different multiple antenna techniques according to the channel properties and provides an overview of the most common beamforming algorithms. The fourth chapter introduces the most significant aspects of the distributed wireless networks, presenting the main open issues and the current proposals for the exploitation of the potential offered by antenna array systems. The second part describes the original results obtained in the mathematical modeling of ad-hoc and mesh networks adopting smart antennas in realistic propagation scenarios. In particular, the fifth chapter presents the theoretical analysis to evaluate the number of simultaneous communications that can be sustained by a distributed wireless network using adaptive antennas in presence of multipath. The sixth chapter extends this model to switched-beam antennas, while addressing the mobility aspects and discussing the cost-benefit tradeoff that is related to the use of multiple antenna techniques in today's wireless networks. A detailed throughput-delay analysis is performed in the seventh chapter, where the impact of advanced antenna systems on 802.11-based networks is investigated using a Markov chain model. The influence of the antenna array geometry is examined in the eighth chapter adopting a numerical approach based on a discrete-time simulator, which is able to take into account the details of the channel and of the antenna system behavior. The third part describes the original results obtained in the field of antenna array pattern synthesis. The ninth chapter presents the technique developed to modify the excitation phases of an antenna array in order to reject interferers spread over an angular region according to a given spatial statistic. The tenth chapter describes the iterative algorithm for phased arrays, which is able to produce low side-lobe level patterns with multiple prescribed main lobes and nulls. Finally, the eleventh chapter summarizes the thesis contributions and remarks the most important conclusions. The intent of the work presented hereafter is to examine the benefits that derive from the employment of smart antenna techniques from a realistic perspective, as well as to provide some useful solutions to improve the reliability of the communications and to increase the network capacity.
XX Ciclo
1973
LONGHI, PATRICK ETTORE. "Circuiti e sottosistemi a microonde e onde millimetriche per ricevitori a basso rumore e antenne intelligenti." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/917.
Повний текст джерелаThis work deals with aspects relating to analysis and design methodologies and techniques for some circuits in high sensitivity and reconfigurable front-end RF receivers. These circuits are: low noise amplifier and RF attenuators. Finally, further investigation has focused aspects and issues of multi-function high integration circuits. A methodology for designing microwave low noise amplifiers is reported. The latter has led to define the I/O matching relationships simultaneously achievable in an LNA. The main result of this investigation is the identification of a chart that allows to synoptically evaluating the achievable gain and I/O matching of a 2-port amplifier, once the source impedance is fixed and consequently the LNA noise factor. A set of analytical and synthetic methods on millimetre wave low noise amplifiers has been proposed, covering topics from the active device technology selection to test the realized LNA. The meaning of the noise measure parameter is reprised for designing millimetre wave low-noise. The issues of and 3D planar EM millimetre wave simulation is also investigated. The parasitic phase shift in digital attenuators has been investigated in depth. Such parasitic effect is related to the change of state in digital switched attenuators. A technique has been suggested and circuit equations were derived that allow to compensate such unwanted phase shift, providing design relations that allows to estimate the value of the reactive element that compensates for this undesirable effect. Finally, in the field of multi-function high-integration circuits design, the feasibility of a module containing several functionalities has been investigated. The latter are: control of the signal amplitude, amplification, selection of Tx/Rx mode, control the phase of the signal and serial to parallel control data conversion. The design procedures of some sub-modules, together with the criteria and the steps followed in the process of integration, have been reported.
Jaeck, Vincent. "Développement d’antennes de communication reconfigurables en bande C pour munitions intelligentes." Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S104/document.
Повний текст джерелаNowadays wireless communications have become a useful and universal mean to exchange a wide range of information between different systems, some of them being moving, as UAVs among others. In this context we consider here the link between a projectile and a base station. The shape of the structure and the aerodynamic constraints involve the use of patch antennas in the conical front part. This class of antenna is easy to be integrated into the platform as a conformal array, while respecting space constraint. Communications have to be reliable and discrete in disturbed or hostile environment. Antennas array radiation patterns must have some specific characteristics, in particular in the case of flying objects with spin which involves the use of a switched phased array considering its roll position. A fixed-radiation pattern antenna may presents a relevant level or gain toward the interlocutor, but also toward sensitive directions, in which may be located others systems, interfering with the current communication. The solution to switch on and off vertical sub-arrays to steer the beam in the azimuthal plane seem convenient ant fitting the requirements of rotating platform. A conical phased array was studied and two prototypes were manufactured, one at ISL. Sub-arrays are distributed around the conical shape in order to be able to radiate in each direction. Moreover, each sub-array are composed of three radiating elements allowing to steer the main antenna beam in many direction (along the projectile fuze axes). A beam forming network was developed to control the 12 radiating elements conical array. The antenna array and the feeding network were characterized independently in order to optimized the phase of each radiating element. Finally, measurements were done on the whole system in the DGA-MI and ISL anechoic chambers and are in good agreement with simulation results
Nguyen, Trong Duc. "Conception d'antenne intelligente reconfigurable pour la radio cognitive." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENT027/document.
Повний текст джерелаReconfigurable antennas offer multiple functions by dynamically changing their properties such as operating frequency, polarization, radiation pattern, and a combination of all these factors. Their agility and diversity create a wide range of different and new applications for radio systems such as local networks, satellites, and especially in cognitive radio. In this thesis, two new frequency reconfigurable antennas are proposed. The frequency reconfiguration is obtained by changing the geometry of radiating patch. Their dimensions have been optimized by genetic algorithm embedded in the electromagnetic simulation software. These antennas operate at the frequency band for IEEE 802.11b/g standard with satisfactory radiation characteristics. This thesis also presents a method of controlling the operation of the frequency reconfigurable antenna by a micro-controller. The operation of electronic switches (PIN diodes) are carried out through programs which allows an adaptive operating system like smart antennas and work well in cognitive radio environment
Thévenard, Julian. "Contribution à la conception à bas coût d'antennes 3D reconfigurables : solutions originales d'intégration en technologie plastique pour les systèmes sans fil du futur." Brest, 2008. http://www.theses.fr/2008BRES2011.
Повний текст джерелаThis thesis is dedicated to the design of 3D smart antennas for forthcoming wireless devices. Our research work has been motivated by the actual wireless trends leading to service concentration within WLAN and device miniaturisation. Thus, antenna design is nowadays guided by size constraints and their capacity to deal with fading interference, wireless environments while improving the performances of devices in terms of communication quality, power consumption. This thesis presents a multi-sector antenna solution associating many Vivaldi-antennas to provide a solution for the targeted application which is an embedded system constituting of high definition wireless cameras. A theoretical analysis of the Vivaldi antenna is first performed and then a novel concept of multi-sector antenna has been introduced and validated. Then, in order to target consumer market and to reduce the manufacturing costs in high volume production, the metallized molded plastic technology which enables molding 3D complex structures has been retained. An original without-welding transfer system has been developed for integrating the antenna to the rest of the system. The characterization of a prototype has resulted in the validation of the use of plastics for such applications. This antenna has been integrated in a wireless camera ; a protective radome having as additional property to improve the overall performances of the device is finally designed. This simplified integration procedure associated to a monitoring of the performances and the flexibility of the system makes it a good candidate for various applications like domestic WLAN, mesh networks or for MIMO technology
Nguyen, Trong duc. "Conception d'antenne intelligente reconfigurable pour la radio cognitive." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00859818.
Повний текст джерелаBletsas, Aggelos Anastasiou 1975. "Intelligent antenna sharing in cooperative diversity wireless networks." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/33876.
Повний текст джерелаIncludes bibliographical references (p. 143-152).
Cooperative diversity has been recently proposed as a way to form virtual antenna arrays that provide dramatic gains in slow fading wireless environments. However, most of the proposed solutions require simultaneous relay transmissions at the same frequency bands, using distributed space-time coding algorithms. Careful design of distributed space-time coding for the relay channel is usually based on global knowledge of some network parameters or is usually left for future investigation, if there is more than one cooperative relay. We propose a novel scheme that eliminates the need for space-time coding and provides diversity gains on the order of the number of relays in the network. Our scheme first selects the best relay from a set of M available relays and then uses this "best" relay for cooperation between the source and the destination. Information theoretic analysis of outage probability shows that our scheme achieves the same diversity-multiplexing gain tradeoff as achieved by more complex protocols, where coordination and distributed space-time coding for M relay nodes is required. Additionally, the proposed scheme increases the outage and ergodic capacity, compared to non-cooperative communication with increasing number of participating relays, at the low SNR regime and under a total transmission power constraint.
(cont.) Coordination among the participating relays is based on a novel timing protocol that exploits local measurements of the instantaneous channel conditions. The method is distributed and allows for fast selection of the best relay as compared to the channel coherence time. In addition, a methodology to evaluate relay selection performance for any kind of wireless channel statistics is provided. Other methods of network coordination, inspired by natural phenomena of decentralized time synchronization, are analyzed in theory and implemented in practice. It was possible to implement the proposed, virtual antenna formation technique in a custom network of single antenna, half-duplex radios.
by Aggelos Anastasiou Bletsas.
Ph.D.
Somda, Flavien Hervé. "Développement de stratégies de commande et de perception pour une régulation de vitesse intelligente." Rennes 1, 2009. https://tel.archives-ouvertes.fr/tel-00449772.
Повний текст джерелаMonitoring and Perception Strategies Design for Intelligent Cruise Control Today's trac conditions call for the event of Intelligent Transportation Systems for road safety improvement. In Intelligent vehicles driven by such technologies, at least, part of the driving task is managed by embeded systems. In this thesis report, we oer a new longitudinal control strategy based on a nonlinear, second order, and exponential prole model. The approach is safe, robust, comfortable and consistent with Intelligent Cruise Control as well as Stop&Go applications. We also propose a detection approach based on an antenna beam scanning strategy that drastically improves distance of detection and enables identication of traffic scenarios. Such results are essential for an efficient longitudinal control strategy design
Rodrigues, de Araujo Ricardo. "Traitement spatio-temporel basé sur l'utilisation de bases orthonormales généralisées : application aux réseaux de paquets." Paris 11, 2003. http://www.theses.fr/2003PA112101.
Повний текст джерелаThe packet radio access is an interesting option for multimedia traffic in radio mobile networks. This technique allows a radio resource allocation based on the user's activity in such a way that the canal may be used in a multi-user mode. So, the MAC protocol plays a fundamental role in this context. The S-Aloha and R-Aloha protocols are the most popular schemes due to their simplicity. Nevertheless, they offer a poor spectral efficiency. The use of smart antennas is widely proposed as a way of increasing the spectral efficiency of these MAC protocols. Actually, several papers were dedicated to performance analysis of packet networks with smart antennas. However, most of then have focussed only on the systemic aspects in detriment of signal processing ones. In this work, we evaluate the advantage of using smart antennas in a packet network with S-Aloha and R-Aloha MAC. We focus on the channel and the array geometry influences over the network performances. In the packet networks, the signal processing must be accomplished within the packet transmission time slot. That is the why the algorithm complexity must be limited. In order to decrease the overall system complexity, we propose the use of generalized orthonormal basis for the space-time equalizers. This strategy allows an equalizer order reduction if the base poles are correctly chosen. In this thesis, we compare the proposed structure performance with the conventional FIR one. Our simulations show that the proposed strategy leads to an efficient equalizer order reduction
Rafael, Marcos César. "Projeto e desenvolvimento de um sistema inteligente para alinhamento de uma antena parabólica receptora." Universidade de Taubaté, 2011. http://www.bdtd.unitau.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=256.
Повний текст джерелаThe objective of this work is to design and develop an intelligent automated system for the alignment of a receiving antenna with parabolic reflector applied to satellite communication. Based on empirical procedures manual for the manual alignment of a parabolic antenna, we designed and developed a technological solution using hardware and software. The system uses a GPS to provide the initial spatial location of the receiving antenna and a digital receiver to provide the carrier-to-noise ratio. The main contribution of this work was the design and development of an intelligent computational system which aims at automating the receiving antenna alignment. For a given satellite, through the dynamic handling of relocate the receiving antenna, the system uses information about the quality of the received signal to drive the servo responsible for aligning the antenna. We found that, the antenna is in the desired position, the carrier-to-noise ratio should be above 8 dB for a good reception quality. We developed the project of an intelligent system to scan around the reference antenna position value, which was called the antenna position fine tuning. Our new approach consisted in a fuzzy controller type Mandani, generated according to the manual process of maneuvering the dish. Our solution has improved the carrier-to-noise ratio by repositioning the antenna in the desired position.
Chew, Kwan Chong Daniel. "Practical implementation of the intelligent quadrifilar helix antenna for terminal applications." Thesis, University of Surrey, 2004. http://epubs.surrey.ac.uk/843571/.
Повний текст джерелаManara, Luca. "Investigating Antenna Placement on Autonomous Mining Vehicle." Thesis, KTH, Skolan för informations- och kommunikationsteknik (ICT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-204908.
Повний текст джерелаFramtidens gruvor kommer att gynnas av sammankopplade, intelligenta transportsystem. Autonoma gruvfordon kommer att förbättra säkerhet och produktivitet, och samtidigt minska bränslekonsumtion. Därför är det nödvändigt för Scania att öka kunskapen om design av kommunikationssystem för fordon i hård gruvmiljö. Målet för detta projekt är att undersöka kraven för antennplacering hos ett framtida autonomt gruvfordon och att ge förslag på passande antenntyper och -positioner. Det elektromagnetiska simuleringsverktyget CST Microwave Studio används för att uppskatta påverkan från en förenklad fordonsgeometri på grundläggande antennstrålningsmönster. Utvalda antennkonfigurationer utvärderas genom undersökningar av dess strålningsmönster. För att kunna stråla ut tillräcklig effekt i området kring fordonet och garantera tillförlitlig kommunikation krävs centralt placerade runtstrålande antenner, eller alternativt en patchantenn till varje sida. Problemlösningsmetoden utvärderas också: Flexibiliteten simuleringsmetoden ger betonas, medan några relevanta begränsningar diskuteras. Hårdvarukrav, tillgängligheten av modeller och begränsade resultat från mjukvaran kan bidra till att göra simuleringen olämplig för att utvärdera antennplaceringen.
Pujol, Hadrien. "Antennes microphoniques intelligentes : localisation de sources acoustiques par Deep Learning." Thesis, Paris, HESAM, 2020. http://www.theses.fr/2020HESAC025.
Повний текст джерелаFor my PhD thesis, I propose to explore the path of supervised learning, for the task of locating acoustic sources. To do so, I have developed a new deep neural network architecture. But, to optimize the millions of learning variables of this network, a large database of examples is needed. Thus, two complementary approaches are proposed to constitute these examples. The first is to carry out numerical simulations of microphonic recordings. The second one is to place a microphone antenna in the center of a sphere of loudspeakers which allows to spatialize the sounds in 3D, and to record directly on the microphone antenna the signals emitted by this experimental 3D sound wave simulator. The neural network could thus be tested under different conditions, and its performances could be compared to those of conventional algorithms for locating acoustic sources. The results show that this approach allows a generally more precise localization, but also much faster than conventional algorithms in the literature
Fiacco, Mauro. "Intelligent picocells for adaptive indoor coverage and capacity." Thesis, University of Surrey, 2001. http://epubs.surrey.ac.uk/844492/.
Повний текст джерелаBucheli, Garcia Juan. "Electromagnetic aspects of ESPAR and digitally controllable scatterers with a look at low-complexity algorithm design." Electronic Thesis or Diss., Institut polytechnique de Paris, 2020. http://www.theses.fr/2020IPPAT004.
Повний текст джерелаThe thesis focuses on the idea of exploiting the spatial domain (as opposed to the exploitation of the time-frequency resource) of wireless environments from two fronts: a) ESPAR antennas (standing for Electronically Steerable Parasitic Array Radiator) as a potential inexpensive alternative to conventional multi-antenna architectures (inexpensive in relation to the number of radio frequency front-ends these conventional architectures are often assumed to be provided with), and b) the study of reactively loaded arrays to deliver controllable scattering as a mean of adding degrees of freedom to the propagation environment itself. The latter is achieved here via digitally controllable scatterers (DCS).Particularly, the thesis focuses on the goal of better conditioning optimization problems as means of proposing low-complexity algorithms. Therefore, one key aspect is the required balance between the accuracy and complexity of the adopted electromagnetic models.Thus, it is appropriate to highlight the importance given to the interface between electromagnetism and the signal characterization. More specifically, both ESPAR and DCS require the understanding of electromagnetic (EM) phenomena that is not fully accounted for through conventional link-level descriptions. More importantly, the latter is proof of the need to join the approaches of two related research communities to cope with the scarcity of resources that is only expected to grow in the decades to come. In fact, the document is mostly positioned from the view of someone with a background in telecommunications (unlike pure electromagnetism) with looks at enlightening the underlying EM mechanisms. It is roughly composed of three parts, namely: fundamentals, the ESPAR antenna and digitally controllable scatterers. In fact, the aim of having one part of the document dedicated purely to fundamentals is to describe the EM phenomena while highlighting all relevant details to the remaining two.The part "fundamentals" begins with Maxwell's equations (and their convenient solution for far-field radiation problems) all the way to the well-known (y=hx+n) signal characterization. As the seemingly least appropriate description to work with, but most complete characterization of the EM phenomena, Maxwell's equations are the basis that link our mathematical description to the very same reality. Thus, the objective of this part is to expose the connection between fields and signals, as well as to open the door to questioning the conventional transmitter-receiver signal model. The latter becomes one of the most exciting outcomes of this project in line with the research-related aim of challenging our vision to expand our understanding of a problem.To continue, the second part is dedicated to the ESPAR antenna as a preamble of what is meant by "questioning the conventional transmitter-receiver signal model". Particularly, ESPAR obliges us to depart from the abstract signal space in which traditional multi-antenna link-level characterizations are depicted. As a contribution of this work, it will be shown how a local approximation of the system model offers an alternative view. Notably, through such an approximation of the system model, a computationally-efficient solution to the non-trivial problem of channel-based adaptation of the radiation characteristics of ESPAR is found.Last, but not least, the third part deals with digitally controllable scatterers as a mean of improving energy efficiency. Such an exciting concept has gained significant attention in the recent years and, in a sense, opens the door to a radically different way to conceive communication problems. Even though these devices are in their infancy, it is not difficult for me to imagine how the decades to come could be marked by the massification of this technology
Jaber, Zouhair. "Conception d'une antenne intelligente à faisceau commutable assistée par un système de locaisation des mobiles." Mémoire, École de technologie supérieure, 2008. http://espace.etsmtl.ca/99/1/JABER_Zouhair.pdf.
Повний текст джерелаJaber, Zouhair. "Conception d'une antenne intelligente à faisceau commutable assistée par un système de locaisation des mobiles /." Thèse, Montréal : École de technologie supérieure, 2008. http://proquest.umi.com/pqdweb?did=1472139881&sid=1&Fmt=2&clientId=46962&RQT=309&VName=PQD.
Повний текст джерела"Mémoire présenté à l'École de technologie supérieure comme exigence partielle à l'obtention de la maîtrise en génie électrique." "par Jaber, Zouhair" -- p. de t. CaQMUQET CaQMUQET Bibliogr : f. [155]-159. Également disponible en version électronique. CaQMUQET
Porsch, Marco. "Layer 2 Path Selection Protocol for Wireless Mesh Networks with Smart Antennas." Master's thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-74743.
Повний текст джерелаBoé, Alexandre. "Conception et réalisation de commutateurs MEMS millimétriques pour les antennes intelligentes." Lille 1, 2006. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2006/50376-2006-372.pdf.
Повний текст джерелаPradhan, Chandan. "Beamforming and Resource Allocation for Multiple Antenna Transmission." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24273.
Повний текст джерелаJabban, Ahmad. "Optimisation et analyse des résesaux intelligents et des réseaux hétérogènes." Phd thesis, INSA de Rennes, 2013. http://tel.archives-ouvertes.fr/tel-00881045.
Повний текст джерелаFadlallah, Najib. "Contribution à l'optimisation de la synthèse du lobe de rayonnement pour une antenne intelligente : Application à la conception de réseaux à déphasage." Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/2b3c153f-58e2-4152-a5cd-53cf1fc0ae35/blobholder:0/2005LIMO0008.pdf.
Повний текст джерела. This report joins within the framework of a project CEDRE (Collaboration between the University of Limoges and the Lebanese university) on the topic of the intelligent antennas in the radio mobile communications. Work consisted with a contribution to the optimization of the lobe of radiation for an intelligent antenna. Two complementary approaches were developed to implement the technique of forming of the lobe, one based on an algorithm of optimization which calculates the phases of the excitations according to the specifications desired (pointed lobe, multiple lobes and creation of the zeros) and the other using the results of the first technique to implement a model with networks of neurons. The first method has a disadvantage concerning the computing time (some seconds), the second is almost an application in real time. The taking into account of the effect of coupling on the radiation was implemented directly in technique of synthesis, and a practical validation of this effect was carried out. Many measurements of an antenna arrays 8 elements, excited only in phase, made it possible to validate our developed tools
Sron, Seng thail. "Algorithmes intelligents de pilotages d'antennes reconfigurables à partir de données en bande de base pour la norme LTE." Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0138.
Повний текст джерелаThe development of modal antennas which are radiation pattern reconfigurable active antennas, but not arrays, started in order to implement beam forming in cellphones. This solution is generally made with an antenna array, which is very difficult, even impossible, in a mobile phone. Beam forming could improve the link budget and increase the data rate. The first aim of this thesis is the development of modal antennas for LTE standard. Three modal antennas concepts were presented. The first one is a reconfigurable “folded loop” active antenna by permutation of feed and ground points. The second one is a solution to gather the main and the diversity antenna in the bottom part of the phone, and to support MIMO and carrier aggregation, which are two features of LTE. The last one optimizes the use of the second antenna in LTE MIMO systems in order to perform beam forming. These modal antennas will provide their real potential only by being used by a driving algorithm which will choose the best mode or configuration according to the situation. So, the second aim of this thesis is the development of smart modal antenna driving algorithms. The first algorithm, developed and patented by Ethertronics, has the specificity to predict, at each moment, which mode will be the best for the next moment, by using baseband data for LTE. The second algorithm is deterministic and can estimate and track the direction of arrival of the signal. Then, it selects the mode which has the best gain in this direction in order to improve the link budget
Borderon, Caroline. "Développement et étude des matériaux ferroélectriques accordables en vue d'une application pour les antennes intelligentes." Nantes, 2008. http://www.theses.fr/2008NANT2045.
Повний текст джерелаToday, ferroelectric materials are studied for their high and tunable permittivity for the realization of intelligent antennas. The high tunability required is often related to increased dielectric losses and a compromise between large tunability and weak losses thus has to be found. The aim of the present research work is to study the phenomena related to the dielectric permittivity of ferroelectric materials in order to describe the influence of the domain walls on this permittivity. A complex dielectric model is used which takes into account the electric field independent losses and a hyperbolic law is suggested which allows to distinguish the contributions stemming from domain wall motion and pinning and from the material itself. The stability in frequency and time of the dielectric properties is discussed by identifying the influence of the domain walls on the relaxation phenomena observed. Examination of the ferroelectric phase is extended to the paraelectric phase by studying the dielectric properties of the BST as a function of the strontium rate. This allows understanding the mechanisms responsible of the tunability in the ferroelectric and the paraelectric state and at the phase transition. The ferroelectric materials being considered for the use at microwave frequencies, characterization based on the static analysis of conformal mapping method of a coplanar waveguide, is studied. The hyperbolic law allows knowing the BST composition which presents the best compromise between tunability and losses and thus knowing the optimum conditions for the use of ferroelectric materials
Abdallah, Ayman. "Contribution à l'étude d'une antenne adaptative et à la conception d'un démonstrateur." Limoges, 2007. http://www.theses.fr/2007LIMO4009.
Повний текст джерелаDorica, Mark. "Novel electromagnetic design system enhancements using computational intelligence strategies." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102972.
Повний текст джерелаThe analysis module of an electromagnetic analysis and design system typically comprises mesh generation and mesh improvement stages. A novel method for discovering optimal orderings of mesh improvement operators is proposed and leads to a suite of novel mesh improvement techniques. The new techniques outperform existing methods in both mesh quality improvement and computational cost.
The remaining contributions pertain to the design module. Specifically, a novel space mapping method is proposed, which allows for the optimization of response surface models. The method is able to combine the accuracy of fine models with the speed of coarse models. Optimal results are achieved for a fraction of the cost of the standard optimization approach.
Models built from computational data often do not take into consideration the intrinsic characteristics of the data. A novel model building approach is proposed, which customizes the model to the underlying responses and accelerates searching within the model. The novel approach is able to significantly reduce model error and accelerate optimization.
Automatic design schemes for 2D structures typically preconceive the final design or create an intractable search space. A novel non-preconceived approach is presented, which relies on a new genome structure and genetic operators. The new approach is capable of a threefold performance improvement and improved manufacturability.
Automatic design of 3D wire structures is often based on "in-series" architectures, which limit performance. A novel technique for automatic creative design of 3D wire antennas is proposed. The antenna structures are grown from a starting wire and invalid designs are avoided. The high quality antennas that emerge from this bio-inspired approach could not have been obtained by a human designer and are able to outperform standard designs.
Leach, Steve M. "Optimum control of hand-portable antennas for satellite and terrestrial mobile communications." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326810.
Повний текст джерелаVyhnalek, Brian. "Bio-Inspired Optimization of Ultra-Wideband Patch Antennas Using Graphics Processing Unit Acceleration." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1398262685.
Повний текст джерелаKobeissi, Hussein. "Eigenvalue Based Detector in Finite and Asymptotic Multi-antenna Cognitive Radio Systems." Thesis, CentraleSupélec, 2016. http://www.theses.fr/2016SUPL0011/document.
Повний текст джерелаIn Cognitive Radio, Spectrum Sensing (SS) is the task of obtaining awareness about the spectrum usage. Mainly it concerns two scenarios of detection: (i) detecting the absence of the Primary User (PU) in a licensed spectrum in order to use it and (ii) detecting the presence of the PU to avoid interference. Several SS techniques were proposed in the literature. Among these, Eigenvalue Based Detector (EBD) has been proposed as a precious totally-blind detector that exploits the spacial diversity, overcome noise uncertainty challenges and performs adequately even in low SNR conditions. The first part of this study concerns the Standard Condition Number (SCN) detector and the Scaled Largest Eigenvalue (SLE) detector. We derived exact expressions for the Probability Density Function (PDF) and the Cumulative Distribution Function (CDF) of the SCN using results from finite Random Matrix Theory; In addition, we derived exact expressions for the moments of the SCN and we proposed a new approximation based on the Generalized Extreme Value (GEV) distribution. Moreover, using results from the asymptotic RMT we further provided a simple forms for the central moments of the SCN and we end up with a simple and accurate expression for the CDF, PDF, Probability of False-Alarm, Probability of Detection, of Miss-Detection and the decision threshold that could be computed and hence provide a dynamic SCN detector that could dynamically change the threshold value depending on target performance and environmental conditions. The second part of this study concerns the massive MIMO technology and how to exploit the large number of antennas for SS and CRs. Two antenna exploitation scenarios are studied: (i) Full antenna exploitation and (ii) Partial antenna exploitation in which we have two options: (i) Fixed use or (ii) Dynamic use of the antennas. We considered the Largest Eigenvalue (LE) detector if noise power is perfectly known and the SCN and SLE detectors when noise uncertainty exists
Mursia, Placido. "Multi-antenna methods for scalable beyond-5G access networks." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS532.
Повний текст джерелаThe exponential increase of wireless user equipments (UEs) and network services associated with current 5G deployments poses several unprecedented design challenges that need to be addressed with the advent of future beyond-5G networks and novel signal processing and transmission schemes. In this regard, massive MIMO is a well-established access technology, which allows to serve many tens of UEs using the same time-frequency resources. However, massive MIMO exhibits scalability issues in massive access scenarios where the UE population is composed of a large number of heterogeneous devices. In this thesis, we propose novel scalable multiple antenna methods for performance enhancement in several scenarios of interest. Specifically, we describe the fundamental role played by statistical channel state information (CSI) that can be leveraged for reduction of both complexity and overhead for CSI acquisition, and for multiuser interference suppression. Moreover, we exploit device-to-device communications to overcome the fundamental bottleneck of conventional multicasting. Lastly, in the context of millimiter wave communications, we explore the benefits of the recently proposed reconfigurable intelligent surfaces (RISs). Thanks to their inherently passive structure, RISs allow to control the propagation environment and effectively counteract propagation losses and substantially increase the network performance
Juswardy, Budi. "Integrated broadband microphotonic beamformer for adaptive nulling in smart antennas." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2010. https://ro.ecu.edu.au/theses/1843.
Повний текст джерелаMouhamadou, Moctar. "Contribution au développement et à l'optimisation d'un démonstrateur d'antennes adaptatives : Application à des systèmes de communications sans fil haut débit : WiMax." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/361df6d6-7ddc-43a3-b186-747beed431b9/blobholder:0/2007LIMO4010.pdf.
Повний текст джерелаThe current tendency is to use the multi-antennas systems in emission and/or reception in order to optimize the radioelectric spectrum as well as possible and to improve the radio connexion for the wireless communication systems. It is in this context that this thesis is related to the study and optimization of a demonstrator of smart antennas. After having carried out a thorough study of the detection methods of directions of arrival of the RF signals and having developed a beamforming technique, two prototypes of adaptive antenna system were developed in the WiMax band (3. 4 - 3. 5 GHz) and experimentally validated. The first system functioning in reception is based on the Uplink. It uses the five-port demodulators and the numerical beamforming system where the weights are calculated by the SQP algorithm (technique of pattern synthesis developed) and directly applied to the signals in baseband in order to improve quality of the received signals i. E. To improve the signal to interference plus noice ratio. The second system functioning in emission is based on the Downlink ; it is an analogical beamforming system using the vectors modulators controlled numerically, starting form the weight given by the array pattern synthesis (SQP algorithm) in order to concentrate the radiation emitted in the desired direction of the useful receiver. These two systems are complementary insofar as the last one uses the results of measurement of DoA of the first one to adapt its radiation pattern according to the position angular of the sources
Farhat, Hadi. "Dispositif de détection et localisation basé sur un système RFID UHF intelligent : application au domaine de la grande distribution." Thesis, Lille, 2019. http://www.theses.fr/2019LIL1I025.
Повний текст джерелаUHF RFID technology, also known as RAIN RFID, is a passive technology that enables the automatic identification of items. Thus, it bridges the gap between the physical and digital worlds by allowing an item to become alive on the Internet of things thanks to inexpensive and battery-free RFID tags. Passive UHF RFID technology has witnessed a significant development due to the accelerated growth of sophisticated technological devices. This development is largely driven by the supply chain and the retail industries. Passive UHF RFID Gen2, among other tracing and identification solutions, is the logical choice given the low costs of large-volume tags, ease of printing and being battery-free, the need for maintenance is completely eliminated.The main concern of resellers, the withdrawal of the product, is mainly affected by errors related to visibility (stock gap, theft, loss) and human errors. It is, therefore, necessary to improve visibility and automate the process. Despite its advantages, RFID deployment in supermarkets is still facing many obstacles and challenges. In this thesis, we focus on technological availability by defining and analyzing the different challenges and possibly proposing the appropriate solutions.First, the maximum reading distances of passive tags are evaluated in different environments in order to identify the factors impacting them. At the end of this study, an alternative characterization method is proposed to control tag performance and identify tagged objects with poor performance. Secondly, we will use this method to propose a new solution to improve detection. The algorithms behind this solution allow readers to negotiate their configurations with the environment and with each other. Finally, a new location algorithm is proposed to improve accuracy. This algorithm is based on the exploitation of the answers of the reliable tags of the medium. The proposed solutions are universal, compatible with market readers and add no cost to the hardware used for detection
Anand, K. "Methods for Blind Separation of Co-Channel BPSK Signals Arriving at an Antenna Array and Their Performance Analysis." Thesis, Indian Institute of Science, 1995. http://hdl.handle.net/2005/123.
Повний текст джерелаDagher, Roudy. "Sur la radionavigation dans les villes intelligentes du futur : le cas des réseaux de capteurs sans fils." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10079/document.
Повний текст джерелаWith the development of the internet of things, the number of communicating objects is rapidly increasing especially with the emergence of the "Smart City'' concept. As in the case of WiFi access points, many of these objects would operate at fixed and known positions. Such information is made available in the Cloud under the Big Data paradigm, thus leading to the so called geo-referencing of the nodes. In such a context, we pose the problem of opportunistic vehicular radio-localization by means of neighborhood discovery and signal processing of received neighboring signals. We propose a novel approach for vehicle self-localization as a contribution to the field of intelligent transportation systems. The proposed solution is opportunistic, passive and non-intrusive regarding the network operations and deployed applications. The thesis defends a localization system that seamlessly integrates with a standard communication stack and covers two layers: physical and link. At physical level, we use an antenna array for collecting and processing the received signals for both identification and localization. As soon as a packet is detected at MAC layer, the corresponding signals are exploited to localize the source with respect to the vehicle body frame. By using the source identifier, its position in the external (or global) frame is looked up in a database that was previously built off-line and made accessible locally or remotely. By assuming that the vehicle orientation is known, the position of the vehicle is then estimated using basis change equations
Monteiro, Marcos Eduardo Pivaro. "Sistema de verificação de localização com antenas direcionais baseado em teoria da informação." Universidade Tecnológica Federal do Paraná, 2014. http://repositorio.utfpr.edu.br/jspui/handle/1/979.
Повний текст джерелаNesta dissertação, o uso de antenas direcionais em sistemas de verificação de localização é analisado, considerando um cenário realista para redes veiculares. O objetivo é propor um método para a utilização das antenas direcionais nestes sistemas e verificar quais os benefícios proporcionados em termos de desempenho, que representa a capacidade em diferenciar usuários legítimos e maliciosos. Um sistema que utiliza o modelo de propagação log-normal é inicialmente estudado, seguido de uma analise das alterações necessárias para a utilização de um modelo mais realista. Utilizando este modelo, é demonstrado então como o uso de antenas direcionais pode ser introduzido no sistema, adicionando ao processo de verificação uma etapa adicional. Resultados numéricos são obtidos para verificar as expressões analíticas, seguido das comparações entre os desempenhos de cada um dos sistemas apresentados. Através destes resultados, é constatado que a utilização das antenas direcionais proporciona um aumento considerável no desempenho do sistema e, mesmo quando considerado apenas a etapa adicional de verificação, o desempenho é satisfatório. É feita também uma análise da influência do desvanecimento em pequena escala no sistema, demonstrando qual a relação entre o número de amostras e a porcentagem de erro no desempenho do esquema apresentado.
In this master thesis, a performance analysis of an information-theoretic location verification system using directional antennas is performed, considering a vehicular network scenario. Our goal is to develop a method using directional antennas to improve the system performance. First, a recently introduced scheme that uses a simple propagation model is studied, then it is described the modifications needed when a realistic propagation model is considered. Based on the described scheme, it is shown how the use of directional antennas can be introduced into the system, creating a new validation stage called directional verification. Numerical results are used to validate the analytical expressions, showing also the performance differences between the described systems. Using the obtained results, it is shown that the use of directional antennas increase the system performance and that, even when using only the directional verification stage, the performance is satisfactory. An analysis of the relation between the number of samples and the system's error percentage is also performed, when considered a small scale fading model.
Lins, Hertz Wilton de Castro. "An?lise e s?ntese de antenas e superf?cies seletivas de frequ?ncia utilizando computa??o evolucion?ria e intelig?ncia de enxames." Universidade Federal do Rio Grande do Norte, 2012. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15196.
Повний текст джерелаCoordena??o de Aperfei?oamento de Pessoal de N?vel Superior
The frequency selective surfaces, or FSS (Frequency Selective Surfaces), are structures consisting of periodic arrays of conductive elements, called patches, which are usually very thin and they are printed on dielectric layers, or by openings perforated on very thin metallic surfaces, for applications in bands of microwave and millimeter waves. These structures are often used in aircraft, missiles, satellites, radomes, antennae reflector, high gain antennas and microwave ovens, for example. The use of these structures has as main objective filter frequency bands that can be broadcast or rejection, depending on the specificity of the required application. In turn, the modern communication systems such as GSM (Global System for Mobile Communications), RFID (Radio Frequency Identification), Bluetooth, Wi-Fi and WiMAX, whose services are highly demanded by society, have required the development of antennas having, as its main features, and low cost profile, and reduced dimensions and weight. In this context, the microstrip antenna is presented as an excellent choice for communications systems today, because (in addition to meeting the requirements mentioned intrinsically) planar structures are easy to manufacture and integration with other components in microwave circuits. Consequently, the analysis and synthesis of these devices mainly, due to the high possibility of shapes, size and frequency of its elements has been carried out by full-wave models, such as the finite element method, the method of moments and finite difference time domain. However, these methods require an accurate despite great computational effort. In this context, computational intelligence (CI) has been used successfully in the design and optimization of microwave planar structures, as an auxiliary tool and very appropriate, given the complexity of the geometry of the antennas and the FSS considered. The computational intelligence is inspired by natural phenomena such as learning, perception and decision, using techniques such as artificial neural networks, fuzzy logic, fractal geometry and evolutionary computation. This work makes a study of application of computational intelligence using meta-heuristics such as genetic algorithms and swarm intelligence optimization of antennas and frequency selective surfaces. Genetic algorithms are computational search methods based on the theory of natural selection proposed by Darwin and genetics used to solve complex problems, eg, problems where the search space grows with the size of the problem. The particle swarm optimization characteristics including the use of intelligence collectively being applied to optimization problems in many areas of research. The main objective of this work is the use of computational intelligence, the analysis and synthesis of antennas and FSS. We considered the structures of a microstrip planar monopole, ring type, and a cross-dipole FSS. We developed algorithms and optimization results obtained for optimized geometries of antennas and FSS considered. To validate results were designed, constructed and measured several prototypes. The measured results showed excellent agreement with the simulated. Moreover, the results obtained in this study were compared to those simulated using a commercial software has been also observed an excellent agreement. Specifically, the efficiency of techniques used were CI evidenced by simulated and measured, aiming at optimizing the bandwidth of an antenna for wideband operation or UWB (Ultra Wideband), using a genetic algorithm and optimizing the bandwidth, by specifying the length of the air gap between two frequency selective surfaces, using an optimization algorithm particle swarm
As superf?cies seletivas de freq??ncia, ou FSS (Frequency Selective Surfaces), s?o estruturas constitu?das por arranjos peri?dicos de elementos condutores, denominados patches, geralmente muito finos e impressos sobre camadas diel?tricas, ou de aberturas, perfuradas em superf?cies met?licas muito finas, para aplica??es nas faixas de microondas e ondas milim?tricas. Estas estruturas s?o frequentemente utilizadas em aeronaves, m?sseis, sat?lites, radomes, antenas de refletor, antenas de alto ganho e fornos de microondas, por exemplo. A utiliza??o destas estruturas tem como objetivo principal filtrar bandas de freq??ncia, que podem ser de transmiss?o ou de rejei??o, dependendo da especificidade da aplica??o desejada. Por sua vez, os sistemas de comunica??o modernos, tais como GSM (Global System for Mobile Communications), RFID (Radio Frequency Identification), Bluetooth, Wi-Fi e WiMAX, cujos servi?os s?o altamente demandados pela sociedade, t?m requerido o desenvolvimento de antenas que apresentem, como caracter?sticas principais, baixo custo e perfil, al?m de peso e dimens?es reduzidas. Neste contexto, a antena de microfita se apresenta como uma excelente op??o para os sistemas de comunica??es atuais, pois (al?m de atenderem intrinsicamente aos requisitos mencionados) s?o estruturas planares de f?cil fabrica??o e integra??o com outros componentes de circuitos de microondas. Em consequ?ncia, a an?lise e principalmente a s?ntese destes dispositivos, em face da grande possibilidade de formas, dimens?es e periodicidade de seus elementos, tem sido efetuada atrav?s de modelos de onda completa, tais como o m?todo dos elementos finitos, o m?todo dos momentos e o m?todo das diferen?as finitas no dom?nio do tempo. Entretanto, estes m?todos apesar de precisos requerem um grande esfor?o computacional. Neste contexto, a intelig?ncia computacional (IC) tem sido utilizada com sucesso nos projetos e na otimiza??o de estruturas planares de microondas, como uma ferramenta auxiliar e muito adequada, dada a complexidade das geometrias das antenas e das FSS consideradas. A intelig?ncia computacional ? inspirada em fen?menos naturais como: aprendizado, percep??o e decis?o, utilizando t?cnicas como redes neurais artificiais, l?gica fuzzy, geometria fractal e computa??o evolucion?ria. Este trabalho realiza um estudo de aplica??o de intelig?ncia computacional utilizando metaheur?sticas como algoritmos gen?ticos e intelig?ncia de enxames na otimiza??o de antenas e superf?cies seletivas de frequ?ncia. Os algoritmos gen?ticos s?o m?todos computacionais de busca baseados na teoria da sele??o natural proposta por Darwin e na gen?tica utilizados para resolver problemas complexos como, por exemplo, problemas em que o espa?o de busca cresce com as dimens?es do problema. A otimiza??o por enxame de part?culas tem como caracter?sticas a utiliza??o da intelig?ncia de forma coletiva sendo aplicada em problemas de otimiza??o em diversas ?reas de pesquisa. O objetivo principal deste trabalho consiste na utiliza??o da intelig?ncia computacional, na an?lise e s?ntese de antenas e de FSS. Foram consideradas as estruturas de um monopolo planar de microfita, do tipo anel, e de uma FSS de dipolos em cruz. Foram desenvolvidos os algoritmos de otimiza??o e obtidos resultados para as geometrias otimizadas de antenas e FSS consideradas. Para a valida??o de resultados foram projetados, constru?dos e medidos v?rios prot?tipos. Os resultados medidos apresentaram excelente concord?ncia com os simulados. Al?m disso, os resultados obtidos neste trabalho foram comparados com os simulados atrav?s de um software comercial, tendo sido observada tamb?m uma excelente concord?ncia. Especificamente, a efici?ncia das t?cnicas de IC utilizadas foram comprovadas atrav?s de resultados simulados e medidos, objetivando a otimiza??o da largura de banda de uma antena para opera??o em banda ultralarga, ou UWB (Ultra Wideband), com a utiliza??o de um algoritmo gen?tico e da otimiza??o da largura de banda, atrav?s da especifica??o do comprimento do gap de ar entre duas superf?cies seletivas de frequ?ncia, utilizando um algoritmo de otimiza??o por enxame de part?culas
Albu, Roxana. "Architecture de communication pour les réseaux d'instrumentation sans fil." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2011. http://tel.archives-ouvertes.fr/tel-00619443.
Повний текст джерелаBrigot, Guillaume. "Prédire la structure des forêts à partir d'images PolInSAR par apprentissage de descripteurs LIDAR." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS584/document.
Повний текст джерелаThe objective of this thesis is to predict the structural parameters of forests on a large scale using remote sensing images. The approach is to extend the accuracy of LIDAR full waveforms, on a larger area covered by polarimetric and interferometric (PolInSAR) synthetic aperture radar images using machine learning methods. From the analysis of the geometric properties of the PolInSAR coherence shape, we proposed a set of parameters that are likely to have a strong correlation with the LIDAR density profiles on forest lands. These features were used as input data for SVM techniques, neural networks, and random forests, in order to learn a set of forest descriptors deduced from LIDAR: the canopy height, the vertical profile type, and the canopy cover. The application of these techniques to airborne data over boreal forests in Sweden and Canada, and the evaluation of their accuracy, demonstrate the relevance of the method. This approach can be soon be adapted for future satellite missions dedicated to the forest: Biomass, Tandem-L and NiSAR
Dovelos, Konstantinos. "Terahertz communications: Physical layer enablers and analysis." Doctoral thesis, Universitat Pompeu Fabra, 2021. http://hdl.handle.net/10803/673252.
Повний текст джерелаNegri, Lucas Hermann. "Inteligência computacional no sensoriamento a fibra ótica." Universidade Tecnológica Federal do Paraná, 2017. http://repositorio.utfpr.edu.br/jspui/handle/1/2873.
Повний текст джерелаEsta tese apresenta aplicações de inteligência computacional para o aprimoramento de sensoriamento ótico realizado com sensores em fibra ótica. Para tanto, redes neurais artificiais (perceptron de múltiplas camadas), máquinas de vetor de suporte para regressão, evolução diferencial e métodos de sensoriamento compressivo são empregados em conjunto com transdutores de redes de Bragg em fibras óticas. As redes neurais artificiais, máquinas de vetor de suporte para regressão e redes de Bragg são empregadas na localização de uma carga aplicada sobre uma placa de acrílico. É apresentado um novo método utilizando evolução diferencial para a solução do problema do espalhamento inverso em redes de Bragg em fibra ótica, propondo o uso de restrições para solucioná-lo na ausência de informação de fase do sinal refletido. Um método para a detecção de múltiplas cargas posicionadas acima de uma placa de metal é proposto. Neste método, a placa de metal é suportada por anéis de ferro contendo redes de Bragg em fibra ótica e a detecção das cargas é realizada com o uso de métodos de sensoriamento compressivo para a solução do problema inverso subdeterminado resultante. A troca dos anéis de ferro por blocos de silicone e um novo método baseado em sensoriamento compressivo e evolução diferencial são propostos. Os resultados experimentais mostram que os métodos computacionais propostos auxiliam o sensoriamento e podem permitir uma melhoria da resolução espacial do sistema sem a necessidade do aumento do número de elementos transdutores.
This thesis presents new optical fiber sensing methodologies employing computational intelligence approaches seeking for the improvement of the sensing performance. Particularly, artificial neural networks, support vector regression, differential evolution and compressive sensing methods were employed with fiber Bragg grating transducers. Artificial neural networks (multilayer perceptron) and fiber Bragg gratings were used to determine the location of a load applied to a polymethyl methacrylate sheet. A new method based on the application of differential evolution is proposed to solve the inverse scattering problem in fiber Bragg gratings, where constraints are imposed to solve the problem without the need of phase information. A method for detecting multiple loads on a metal sheet is also proposed. In this method, the metal sheet is supported by iron rings containing fiber Bragg gratings, and compressive sensing methods are employed to solve the resulting underdetermined inverse problem. Further developments of the method replaced the iron rings by silicon blocks and employed a new reconstruction method based on compressive sensing and differential evolution. Experimental results show that the proposed computational methods improve the optical fiber sensing and lead to an enhancement of the spatial resolution without increasing the number of transducers.
"Multibeam antenna for an intelligent base station." 1998. http://library.cuhk.edu.hk/record=b5889739.
Повний текст джерелаThesis (M.Phil.)--Chinese University of Hong Kong, 1998.
Includes bibliographical references (leaves 158-160).
Abstract also in Chinese.
Chapter Chapter 1: --- Introduction --- p.1
Chapter Chapter 2: --- Background and Theories --- p.3
Chapter 2.1 --- Background History --- p.3
Chapter 2.2 --- Finite Difference Time Domain Method --- p.4
Chapter 2.2.1 --- Basic Formulation --- p.4
Chapter A ) --- Governing Equations --- p.4
Chapter B ) --- Discretization of Differential Equations --- p.6
Chapter C ) --- Numerical Stability --- p.7
Chapter 2.2.2 --- Absorbing Boundary Condition ( PML - Bandlimited ) --- p.8
Chapter A ) --- Berenger Perfectly Matched Layer --- p.8
Chapter B ) --- "Theroy, Two-Dimensional TE Case" --- p.10
Chapter B-1 ) --- Propagation of a Plane Wave in a PML Medium --- p.11
Chapter B-2 ) --- Transmission of a Wave through PML-PML Interfaces --- p.15
Chapter B-3 ) --- PML for the FD-TD technique in 2-D domain --- p.18
Chapter C ) --- Extension to Three-Dimension Case --- p.22
Chapter 2.2.3 --- Modeling of Source and Passive Lumped-Circuit --- p.25
Chapter 2.2.4 --- Obtaining the frequency dependent parameters --- p.27
Chapter 2.2.5 --- Time Domain Extrapolation --- p.29
Chapter 2.2.6 --- Near-to-Far-Field Transformation --- p.33
Chapter A ) --- FD-TD implementation of Near-to-Far-Field Transformation --- p.35
Chapter B ) --- Numerical Techniques to compute the Antenna Directivity --- p.38
Chapter 2.3 --- Transmission Line Circuit Theories --- p.40
Chapter 2.3.1 --- Stripline --- p.43
Chapter 2.3.2 --- Microstrip Line --- p.46
Chapter 2.3.3 --- Quadrature 90° Hybrid --- p.50
Chapter 2.3.4 --- Butler Matrices --- p.50
Chapter A ) --- Types of hybrids --- p.54
Chapter B ) --- Number of hybrids --- p.51
Chapter C ) --- Number of fixed phase shifters --- p.51
Chapter D ) --- Positions and magnitudes of fixed phase shifters --- p.51
Chapter E ) --- Values of total phase shift at output ports and produced by input ports --- p.53
Chapter 2.4 --- Antenna Theories --- p.54
Chapter 2.4.1 --- Microstrip Patch Antenna --- p.54
Chapter A ) --- Bandwidth Enhancement --- p.55
Chapter B ) --- Antenna design methodology --- p.55
Chapter B-1 ) --- Substrate selection --- p.55
Chapter B-2 ) --- Rectangular element analysis and design --- p.56
Chapter 1) --- Electromagnetically coupled patch --- p.57
Chapter 2) --- Aperture coupled patch --- p.61
Chapter 2.4.2 --- Array Antenna --- p.67
Chapter Chapter 3: --- Butler Matrix Analysis and Design --- p.73
Chapter 3.1 --- Circuit Topology --- p.73
Chapter 3.1.1 --- Basic Operation of the 4x4 Butler Matrix --- p.74
Chapter 3.2 --- Design Methodology and Circuit Characteristics --- p.75
Chapter 3.2.1 --- 3 dB branch-line coupler --- p.76
Chapter 3.2.2 --- 0 dB branch-line coupler --- p.79
Chapter 3.2.3 --- 4x4 Butler matrix Beamforming network --- p.82
Chapter Chapter 4: --- Multibeam Array Analysis and Design --- p.90
Chapter 4.1 --- Antenna Architecture --- p.90
Chapter 4.2 --- Antenna Design --- p.91
Chapter 4.2.1 --- Antenna Choice --- p.91
Chapter A ) --- Microstrip Dipole --- p.91
Chapter B ) --- Rectangular Microstrip Patch --- p.91
Chapter C ) --- Circular Patch --- p.92
Chapter D ) --- Compact Patch --- p.93
Chapter E ) --- Annular Resonators --- p.94
Chapter F ) --- Antenna Choice of the 4x4 Butler Matrix Network --- p.94
Chapter 4.2.2 --- Choice of Feeding and Matching Technique --- p.95
Chapter 4.2.3 --- Basic Antenna Parameters and Measurement Technique --- p.95
Chapter A ) --- Radiation Pattern --- p.95
Chapter B ) --- Radiation Pattern Lobes --- p.96
Chapter C ) --- Antenna Gain --- p.97
Chapter D ) --- Input Impedance --- p.97
Chapter E ) --- Bandwidth --- p.97
Chapter 4.2.4 --- FDTD Characterization --- p.98
Chapter 4.3 --- Multibeam Antenna Design and Optimization --- p.104
Chapter 4.4 --- Stripline Fed - Multibeam Antenna --- p.107
Chapter 4.4.1 --- Design Methodology of the Stripline 3 dB Hybrid --- p.109
Chapter 4.4.2 --- Design Methodology of the Stripline 0 dB Hybrid --- p.111
Chapter 4.4.3 --- Design Methodology of the Stripline 4x4 Butler Matrix Network --- p.113
Chapter 4.4.4 --- Design Methodology of the Stripline Aperture Coupled Patch --- p.138
Chapter 4.4.5 --- Design Methodology of the Stripline Multibeam Antenna --- p.142
Chapter Chapter 5: --- Design Examples and Application of Multibeam Antenna --- p.150
Chapter 5.1 --- Wireless Local Loop (WLL) System --- p.150
Chapter Chapter 6: --- Conclusions and Recommendations for Future Work --- p.156
Chapter 6.1 --- Conclusions --- p.156
Chapter 6.2 --- Recommendations for Future Work --- p.157
Bibliography --- p.158
Publication List --- p.160
Bian, Qilei. "Performance improvement of ad hoc networks using directional antennas and power control." Mémoire, 2009. http://www.archipel.uqam.ca/2596/1/M11194.pdf.
Повний текст джерелаMeng, Chao-Li, and 孟昭立. "The Applications of Swarm Intelligence Algorithms in Smart Antenna Array." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/mcqcw6.
Повний текст джерела逢甲大學
電機與通訊工程博士學位學程
105
Smart antenna array has been widely used in mobile communication system. The base station use the main beam with greatest power pointing to the direction of arrival (DOA) of desired user signals to obtain the perfect receiving response and eliminated the interferers’ signals. However, due to the perturbation of noise and the finite sample effect, the performances of beamforming and DOA estimation are degraded for impinging signal. Such that, in this dissertation, we utilize swarm intelligence algorithms to enhance the robustness of beamforming and the accuracy of DOA estimation, and reduce the computation complexity. First, we propose an approach which use particle swarm optimization (PSO) algorithm to enhance the robustness of decision directed (DD) eigenspace-based (ESB) beamformer and promote the accuracy of data bits estimation. Second, the computation complexity and estimation accuracy of the multiple signal classification (MUSIC) method, which has been widely used in DOA estimation of desired user on smart antenna array depends on the size of search grids during the spectrum searching process. For the proposes to reduce computation complexities and promote estimation accuracies, we also utilize PSO algorithm, gravitational search algorithm (GSA) and hybrid PSOGSA strategy to implements spectrum searching respectively, and the estimation results are unlimited by grids size.