Literatura académica sobre el tema "High-Resolution quantization"

The massive MIMO system is one of the main technologies in the fifth generation (5G) of telecommunication systems, also recognized as a highly large-scale system. Constantly in massive MIMO systems, the base station (BS) is provided with a large number of antennas, and this large number of antennas need high-quantization resolution levels analog-to-digital converters (ADCs). In this situation, there will be more power consumption and hardware costs. This paper presents the simulation performance of a suggested method to investigate and analyze the effects of different quantization resolution levels of ADCs on the bit error rate (BER) performance of massive MIMO system under different operating scenarios using MATLAB software. The results show that the SNR exceeds 12 dB accounts for only 0.001% of BER signals when the number of antennas 60 with low quantization a 2 bits’ levels ADCs, approximately. But when the antenna number rises to 300, the SNR exceeds 12 dB accounts for almost 0.01% of BER transmitted signals. Comparably with the BER performance of high quantization, 4 bits-quantization resolution levels ADCs with the same different antennas have a slight degradation. Therefore, the number of antennas is a very important influence factor.

Vertical resolution is an essential indicator of digital storage oscilloscope (DSO) and the key to improving resolution is to increase digitalizing bits and lower noise. Averaging is a typical method to improve signal to noise ratio (SNR) and the effective number of bits (ENOB). The existing averaging algorithm is apt to be restricted by the repetitiveness of signal and be influenced by gross error in quantization, and therefore its effect on restricting noise and improving resolution is limited. An information entropy-based data fusion and average-based decimation filtering algorithm, proceeding from improving average algorithm and in combination with relevant theories of information entropy, are proposed in this paper to improve the resolution of oscilloscope. For single acquiring signal, resolution is improved through eliminating gross error in quantization by utilizing the maximum entropy of sample data with further noise filtering via average-based decimation after data fusion of efficient sample data under the premise of oversampling. No subjective assumptions and constraints are added to the signal under test in the whole process without any impact on the analog bandwidth of oscilloscope under actual sampling rate.

Le paradigme classique pour concevoir un émetteur (codeur) et un récepteur (décodeur) est de concevoir ces éléments en assurant que l'information reconstruite par le récepteur soit suffisamment proche de l'information que l'émetteur a mis en forme pour l'envoyer sur le médium de communication. On parle de critère de fidélité ou de qualité de reconstruction (mesurée par exemple en termes de distorsion, de taux d'erreur binaire, de taux d'erreur paquet ou de probabilité de coupure de la communication).Le problème du paradigme classique est qu'il peut conduire à un investissement injustifié en termes de ressources de communication (surdimensionnement de l'espace de stockage de données, médium de communication à très haut débit et onéreux, composants très rapides, etc.) et même à rendre les échanges plus vulnérables aux attaques. La raison à cela est que l'exploitation de l'approche classique (fondée sur le critère de fidélité de l'information) dans les réseaux sans fil conduira typiquement à des échanges excessivement riches en information, trop riches au regard de la décision que devra prendre le destinataire de l'information. Il s'avère qu'actuellement, l'ingénieur n'a pas à sa disposition une méthodologie lui permettant de concevoir une telle paire émetteur-récepteur qui serait adaptée à l'utilisation (ou les utilisations) du destinataire.Par conséquent, un nouveau paradigme de communication appelé la communication orientée objectif est proposé pour résoudre le problème des communications classiques. Le but ultime des communications orientées objectifs est d'accomplir certaines tâches ou certains objectifs au lieu de viser un critère de reconstruction du signal source. Les tâches sont généralement caractérisées par des fonctions d'utilité ou des fonctions de coût à optimiser.Dans la présente thèse, nous nous concentrons sur le problème de quantification des communication orientées objectifs, c'est-à-dire la quantification orientée objectif. Nous formulons d'abord formellement le problème de quantification orientée objectif. Deuxièmement, nous proposons une approche pour résoudre le problème lorsque seules des réalisations de fonction d'utilité sont disponibles. Un scénario spécial avec quelques connaissances supplémentaires sur les propriétés de régularité des fonctions d'utilité est également traité. Troisièmement, nous étendons la théorie de la quantification à haute résolution à notre problème de quantification orientée objectif et proposons des schémas implémentables pour concevoir un quantificateur orienté objectif. Quatrièmement, le problème de quantification orientée but est développé dans un cadre de jeux sous forme stratégique. Il est montré que la quantification orientée objectif pourrait améliorer les performances globales du système si le fameux paradoxe de Braess existe. Enfin, l'équilibre de Nash d'un jeu de canaux d'accès multiples à entrées multiples et sorties multiples multi-utilisateurs avec l'efficacité énergétique étant l'utilité est étudié et réalisé selon différentes méthodes
The classic paradigm for designing a transmitter (encoder) and a receiver (decoder) is to design these elements by ensuring that the information reconstructed by the receiver is sufficiently close to the information that the transmitter has formatted to send it on the communication medium. This is referred to as a criterion of fidelity or of reconstruction quality (measured for example in terms of distortion, binary error rate, packet error rate or communication cut-off probability).The problem with the classic paradigm is that it can lead to an unjustified investment in terms of communication resources (oversizing of the data storage space, very high speed and expensive communication medium, very fast components, etc.) and even to make exchanges more vulnerable to attacks. The reason for this is that the use of the classic approach (based on the criterion of fidelity of information) in the wireless networks will typically lead to exchanges excessively rich in information, too rich regarding the decision which will have to be taken. the recipient of the information; in the simpler case, this decision may even be binary, indicating that in theory a single bit of information could be sufficient. As it turns out, the engineer does not currently have at his disposal a methodology to design such a transceiver pair that would be suitable for the intended use (or uses) of the recipient.Therefore, a new communication paradigm named the goal-oriented communication is proposed to solve the problem of classic communications. The ultimate objective of goal-oriented communications is to achieve some tasks or goals instead of improving the accuracy of reconstructed signal merely. Tasks are generally characterized by some utility functions or cost functions to be optimized.In the present thesis, we focus on the quantization problem of the goal-oriented communication, i.e., the goal-oriented quantization. We first formulate the goal-oriented quantization problem formally. Secondly, we propose an approach to solve the problem when only realizations of utility function are available. A special scenario with some extra knowledge about regularity properties of the utility functions is treated as well. Thirdly, we extend the high-resolution quantization theory to our goal-oriented quantization problem and propose implementable schemes to design a goal-oriented quantizer. Fourthly, the goal-oriented quantification problem is developed in a framework of games in strategic form. It is shown that goal-oriented quantization could improve the overall performance of the system if the famous Braess paradox exists. Finally, Nash equilibrium of a multi-user multiple-input and multiple output multiple access channel game with energy efficiency being the utility is studied and achieved in different methods

Orientador: Daniel Mario Ugarte
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-08-08T07:13:58Z (GMT). No. of bitstreams: 1 LagosParedes_MaureenJoel_M.pdf: 3881181 bytes, checksum: 517e8507ccdf35f0fa7a7f9fcb4b3b84 (MD5) Previous issue date: 2007
Resumo: O estudo de fios metálicos de tamanho atômico (NF's) tem atraído grande interesse devido aos novos efeitos químicos e físicos neles observados. Entre esses novos fenômenos podemos destacar a quantização da condutância, efeito que deve ser fundamental no desenho dos novos nanodispositivos eletrônicos. NF's são usualmente gerados através de um procedimento simples de deformação mecânica: duas superfícies metálicas são colocadas em contato e depois afastadas. Nos últimos estágios do estiramento antes da ruptura, um fio de alguns átomos de diâmetro é gerado enquanto a condutância é medida. Os NF's têm sido estudados por diferentes grupos e, em diversas condições de temperatura (4 - 300 K) e pressão (de ambiente a UHV). Os resultados apresentam importantes variações e, têm gerado interpretações muito controversas. Devemos enfatizar que muitas interpretações têm sido feitas sem considerar que a deformação estrutural dos NF's deve depender fortemente da temperatura. Nesta tese estudamos as propriedades estruturais e eletrônicas NF's e, em particular analisamos a influência de efeitos térmicos no arranjo atômico, e sua manifestação na condutância. A estrutura dos NF's foi estudada por microscopia eletrônica de transmissão de alta resolução resolvidas no tempo. A condutância foi medida utilizando um sistema de quebra controlada de junções operado em ultra-alto-vácuo. Os experimentos foram realizados a ~150 e 300 K. Nossos resultados mostraram que, à temperatura ambiente os NF's são sempre cristalinos e livre de defeitos nas regiões mais finas; e deformam unicamente ao longo dos eixos cristalográficos [111], [100] e [110]. A baixa temperatura duas importantes diferenças foram observadas: (i) NF's de ouro apresentam defeitos, principalmente falhas de empilhamento e maclas. (ii) NF's alongados na direção [110] evoluem em cadeias atômicas, de comportamento mecânico muito diferente da temperatura ambiente, onde quebram abruptamente. Segundo as imagens de microscopia eletrônica, discordâncias parciais (Shockley) geram falhas de empilhamento; e cadeias de átomos suspensos são observados a ~150 e 300 K. Histogramas globais de condutância adquiridos a baixa temperatura revelaram: (i) aumento da intensidade do pico ~1 Go; (ii) leve diminuição da condutância devido ao aumento de defeitos; e (iii) a existência de uma sub-estrutura no pico ~2 Go, indicando a formação de dois arranjos atômicos estáveis. Resumidamente, nossos resultados mostram que a formação de defeitos é um evento freqüente a ~150 K. Provavelmente, mais defeitos na estrutura devem acontecer para temperaturas menores (4 - 10 K). Portanto, uma importante mudança na evolução da condutância durante a elongação de NF's deve ser esperado a baixa temperatura. Assim, a comparação direta de medidas de transporte de NF's realizadas a diferentes temperaturas pode levar a sérias discrepâncias. Esperamos ter contribuído a melhorar a compreensão e interpretação de experimentos de transporte realizados em diferentes condições, de modo tal, a gerar um modelo único e coerente que explique as propriedades físicas de NF's metálicos
Abstract: The study of atomic-size metal nanowires (NW's) is attracting a great interest due to occurrence a novel physical and chemical phenomena. Among these new phenomena, we can mention conductance quantization that will certainly influence the design of nanodevices. NW's are usually generated by means of a simple procedure: two metallic surfaces are put into contact and, then retracted. Just before rupture atomic-size NW's are formed, and the conductance is measured during the wire elongation. The interpretation of the results is troublesome, because conductance is measured during the modification of the atomic structure. This kind of experimental study has been performed by many research groups and, a quite wide range of temperatures (4 - 300 K) and vacuum condition have been used (from ambient to UHV). In fact, the results display significant variation, what has generated several controversial interpretations. It must be emphasized that many models have been derived without taking into account that the NW structural deformation should be significantly dependent on temperature. In this Thesis research work, we have studied the structural and electronic properties of gold NW's, in particular addressing how thermal effects influence the atomistic aspects of the NW deformation and how this influences the quantum conductance behavior. The structure of NW's has been studied by means of time-resolved high resolution transmission electron microscopy; the NWs transport measurements were based on a mechanically controlled break junction operated in ultra-high-vacuum. The experiments were performed at ~150 and 300 K. Our results have shown that at room temperature the atomic-size NW's. are always crystalline and free of defects, and the atomic structure is spontaneously deformed such that one of the [111]/[100]/[110] crystallographic axis becomes approximately parallel to the stretching direction. Low temperature observations revealed two important differences: i) Au NWs show extended defects, mainly stacking faults and, twinning; ii) NWs elongated along the [110] axis evolve to suspended atomic chains, while at room temperature they break abruptly. Partial Schockley dislocations generate the staking faults; suspended atoms chains are both observed at ~150 and 300 K. The global histograms of conductance at ~150 K showed that: i) a increase of the 1 Go peak intensity; ii) slight reduction of the NWs conductance due to scattering at defects and; iii) the peak at ~2 Go shows a sub structure, what is due to the occurrence of two different atomic arrangements with similar conductance. Briefly, our results revealed that the formation of defects is very frequent in NWs generated at ~150 K; the occurrence of more defects should be expected when NWs are studied at cryogenic temperatures. Then, a significant modification of the NW conductance behavior should be expected at low temperature. In these terms, the direct comparison of conductance measurements realized at different temperature regimes can lead to serious discrepancies. We hope that this work contribute to improve the interpretation and understanding of NW transport studies in order to develop a coherent and complete model that explain the physical properties of atomic-size metal NWs
Mestrado
Física da Matéria Condensada
Mestre em Física

In this chapter, the authors propose a Super-Resolution (SR) method using a vector quantization codebook and filter dictionary. In the process of SR, we use the idea of compressive sensing to represent a sparsely sampled signal under the assumption that a combination of a small number of codewords can represent an image patch. A low-resolution image is obtained from an original high-resolution image, degraded by blurring and down-sampling. The authors propose a resolution enhancement using an alternative l1 norm minimization to overcome the convexity of l0 norm and the sparsity of l1 norm at the same time, where an iterative reweighted l1 norm minimization is used for optimization. After the reconstruction stage, because the optimization is implemented on image patch basis, an additional deblurring or denoising step is used to globally enhance the image quality. Experiment results show that the proposed SR method provides highly efficient results.

This work targets the challenging issue to produce high throughput and low-cost configurable architecture of Discrete wavelet transforms (DWT). More specifically, it proposes a new hardware architecture of the first and second generation of DWT using a modified multi-resolution tree. This approach is based on serializations and interleaving of data between different stages. The designed architecture is massively parallelized and sharing hardware between low-pass and high-pass filters in the wavelet transformation algorithm. Consequently, to process data in high speed and decrease hardware usage. The different steps of the post/pre-synthesis configurable algorithm are detailed in this paper. A modulization in VHDL at RTL level and implementation of the designed architecture on FPGA technology in a NexysVideo board (Artix 7 FPGA) are done in this work, where the performance, the configurability and the generic of our architecture are highly enhanced. The implementation results indicate that our proposed architectures provide a very high-speed data processing with low needed resources. As an example, with the parameters depth order equal 2, filter order equal 2, order quantization equal 5 and a parallel degree P = 16, we reach a bit rate around 3160 Mega samples per second with low used of logic elements ( ≈ 400) and logic registers ( ≈ 700 ).

Abstract Spectroscopy provides direct and incontrovertible evidence of quantization of energy, and nowhere is this more simply illustrated than in magnetic resonance experiments. Textbooks on quantum mechanics would surely have chosen spin systems as their starting point, rather than atomic spectra, had magnetic resonance been discovered at an earlier date. The resonance lines which we observe in high resolution NMR spectra are transitions between these energy levels. However, in contrast to conventional spectroscopy, the separation between levels is a function of the applied magnetic field. Many modern NMR experiments, for example correlation spectroscopy or multiple-quantum spectroscopy, become clearer if we think in terms of the appropriate energy level diagram. The populations of these energy levels are important in studies of spin-lattice relaxation, the nuclear Over hauser experiment and chemically induced nuclear polarization. On a more mundane level, the general form of the conventional NMR spectrum can be predicted on the basis of the energy level diagram appropriate to that particular spin system.

This chapter simply encapsulates the basics of image restoration, various noise models, and degradation model including some blur and image restoration filters. The mining of high resolution information from the low-resolution images is a very vital task in several applications of digital image processing. In recent times, a lot of research work has been carried out in this field in order to improve the resolution of real medical images especially when the given images are corrupted with some kind of noise. The displayed images are the result of the various stages that might cause imperfections in the digital images, for instance the so-called imaging and capturing process can itself degrade the original scene. The imperfections present in the image need to be studied and analyzed if the noise present in the images is not modelled properly. There are different types of degradations which are considered such as noise, geometrical degradations, imperfections (due to improper illumination and color), and blur. Blurring in the images is generally caused by the relative motion between the camera and the original object being captured or due to poor focusing of an optical system. In the production of aerial photographs for remote sensing purposes, blurs are introduced by the atmospheric turbulence, aberrations in the optical system, and relative motion between the camera and the ground. Apart from the blurring effect, noise also creates imperfections in the images that corrupt the images under analysis. The noise may be introduced by several factors (e.g., medium, recording or capturing system, or by the quantization process). Due to this noise or blur present in the images, resolution needs to be improved and the image is to be restored from the geometrically warped, blurred, and noisy images.