A BCS microwave imaging algorithm for object detection and shape reconstruction tested with experimental data

An approach based on the Green function and the Born approximation is used for impulsive radio ultra-wideband (UWB) microwave imaging, in which a permittivity map of the illuminated scenario is estimated using the scattered fields measured at several positions. Two algorithms are applied to this model and compared: the first one solves the inversion problem using a linear operator. The second one is based on the Bayesian compressive sensing (BCS) technique, where the sparseness of the contrast function is introduced as extit{a priori} knowledge in order to improve the inverse mapping. In order to compare both methods, measurements in real scenarios are taken using an UWB radar prototype. The results with real measurements illustrate that, for the considered scenarios, the BCS imaging algorithm has a better performance in terms of range and cross-range resolution allowing object detection and shape reconstruction, with a reduced computational burden, and fewer space and frequency measurements, as compared to the linear operator.Fil: Zilberstein, Nicolás. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Maya, Juan Augusto. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaFil: Altieri, Andrés Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; Argentin

A Low-Cost Ultra-Wideband Test-Bed

This paper presents the design and implementation of a simple transceiver test-bed for implementing and testing algorithms for impulsive UWB applications. The platform has been developed using low-cost off-the-shelf components. We have conceived a simple modular architecture that was targeted to low power, short-range applications. The test-bed is discussed,commenting on the main design decisions and the benefits of the chosen architecture. Measurements of some blocks of the system are also presented.Fil: Altieri, Andrés Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaFil: Gámez, Pablo. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Marchi, Edgardo Jose. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Cervetto, Marcos. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Bouza, Magadalena. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; ArgentinaFil: Galarza, Cecilia Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaXXXV Simpósio Brasileiro de Telecomunicações e Processamento de SinaisSan PedroBrasilSociedade Brasileira de Telecomunicaçõe

Subjective Media Quality Recovery from Noisy Raw Opinion Scores: A Non-Parametric Perspective

Recent parametric approaches to recover subjective media quality from noisy opinion scores involve assumptions that are challenged by numerous complex factors influencing viewer behavior in subjective tests. These approaches commonly involve modeling scoring behavior using parametric distributions, with parameters estimated through methods like maximum likelihood or Bayesian techniques. This paper proposes instead a nonparametric perspective to address the media quality recovery problem, without making any a priori assumption on the subjects' scoring behavior. We propose and motivate an approach to measure the reliability of each single opinion score of a subject. The proposed measure of reliability is then leveraged to formulate an Entropy-based Subjective Quality Recovery (ESQR) algorithm. Simulations and experiments on real datasets show that the proposed ESQR algorithm compares favorably to several state-of-the-art approaches in terms of robustness to noise across various testing conditions. The code to run ESQR and reproduce the results in this paper is made freely available at: http://media.polito.it/ESQR

High Gain Flatness Discrete Low Noise Amplifier for 3 to 5 GHz UWB Operation

This work presents the design of a discrete low-noiseamplifier which operates in the 3-5 GHz band. Considering thatthis amplifier was to be used for the amplification of narrowmodulated pulses, the design efforts were targeted towardsachieving a flat gain and a flat group delay in the band ofinterest, while keeping noise figure under 3 dB. It is shown thatthe resulting design attains a gain of 14dB±0.2dB in the band of interest and noise figure is less than 2.4 dB.Fil: Gámez, Pablo. Instituto Nacional de Tecnología Industrial; ArgentinaFil: Altieri, Andrés Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaFil: Galarza, Cecilia Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; Argentina2019 Argentine Conference on ElectronicsMar del PlataArgentinaUniversidad de Mar del Plat

UWB target classification using SVM

Ultra-Wideband(UWB) radar signals are characterized for having both high frequency carrier and high bandwidth. This makes the scattered field from the targets when irradiated with UWB pulses highly dependent of the composition and shape of the target. Our goal is toclassify objects by their composition from their scattered responses. In this paper, we propose to use a Support Vector Machine (SVM) to solve the problem for distinct dielectric materials and sphere elements. For a problem considering Mdifferent materials andRradii, we compare performance of three different SVM configurations. The first one considersthe general problem where each class corresponds to adifferent material. In this approach, each class is trained withdata corresponding to all Rradii. On a second approach,we classify by both radii and material. This gives a largerproblem to solve, where the number of classes of the SVM is M×R+ 1. Finally, a third approach considers a cascadeof SVMs where the first layer consists of a SVM for R+ 1classes, each class associated with one radius, while the secondlayer is composed of Rdifferent SVMs, each corresponding to a different radius, that classify between the Mmaterials. Monte Carlo experiments are run to compare performanceamong the different proposed schemes. We analyze the results considering both classification and algorithmic complexity.Fil: Bouza, Magdalena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaFil: Altieri, Andrés Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaFil: Galarza, Cecilia Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Simulación Computacional para Aplicaciones Tecnológicas; ArgentinaIEEE Biennial Congress of ArgentinaSan Miguel de TucumanArgentinaInstitute of Electrical and Electronics Engineer

Cooperation versus Interference in Large Wireless Relay Networks

International audienceThis paper investigates the potential gain of cooperation in large wireless networks with multiple sources and relays, where the nodes form an homogeneous Poisson point process. The source nodes may choose their nearest neighbor from the set of inactive nodes as their relay. Although cooperation can potentially lead to significant improvements on the asymptotic error probability of a communication pair, relaying causes additional interference in the network, increasing the average noise. We address the basic question: how should source nodes optimally balance cooperation vs. interference to guarantee reliability in all communication pairs. Based on the decode-and-forward (DF) scheme at the relays, we derive closed-form approximations to the upper bounds on the error probability, averaging over all node positions. Surprisingly, in the small outage probability regime, there is an almost binary behavior that dictates - depending on network parameters - the activation or not of all relay nodes

On the Balance Between Cooperation and Interference in Dense Wireless Networks

International audienceThis paper explores the balance between cooperation through relay nodes and aggregated interference generation in large decentralized wireless networks using decode-and-forward. The source nodes in the network are modeled using a marked Poisson process. We consider the case in which only a single randomly located relay is added to one source in the network and study the outage probability gains obtained. Then, using a simple model, we study the case in which all sources can potentially use their nearest neighbor from the set of inactive nodes as relays, leading to a mixed transmission scheme in which some users employ decode-and-forward and others employ direct transmission. The optimal relay activation probability for the second case is found, observing that in the small outage probability regime it exhibits a binary behavior, being zero or one. Comparing both scenarios we conclude that activating more relays rapidly reduces the gains observed when only one source can use a relay. We derive closed-form approximations to the upper bounds on the error probability, averaging over all node positions and fading gains realizations, to support our claims

Cooperative Unicasting in Large Wireless Networks

International audienceThis paper investigates the potential gains of half-duplex unicast strategies in a large wireless network consisting of clusters in which a source node attempts to transmit a message with the aid of other inactive-potential relays- nodes within the cluster. The network is modeled as an independently marked Poisson point process and a slow-fading scenario is considered. A two-phase transmission protocol is studied and an achievable (upper) bound on the asymptotic error probability of any cluster in the network is derived in terms of the outage probability (OP). The proposed scheme takes advantage of the spatial distribution of the cooperating nodes to create a distributed virtual antenna array, thus improving the OP over direct transmission (DT) through cooperative diversity. Finally, we obtain a converse (lower) bound on the OP of any unicast strategy when restricting all admissible protocols to belong to the same-still quite general- class of half-duplex codes that includes the one studied

A stochastic geometry approach to distributed caching in large wireless networks

International audienceThis paper introduces a stochastic geometry model of a cellular network in which users exchange videos through out-of-band device-to-device (D2D) communications. Users are grouped into clusters, in which a user-based distributed cache is formed to satisfy in-cluster video requests through D2D, avoiding the base station. This paper studies how many of these requests could be served, considering two service metrics: the global relative density of served requests, and the mean ratio of served requests per cluster. The model considers random user placement, content request statistics, and transmission scheduling and impairments, like fading and path loss. A simple communications strategy to be used in the clusters, involving time-division multiple access and one-hop transmissions, is introduced and the metrics are evaluated in this setup, drawing conclusions on the performance of distributed-caching in large wireless networks