- Milan, Lombardy, Italy
Ada Vittoria Bosisio
Consiglio Nazionale delle Ricerche (CNR), IEIIT, Department Member
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The RF characteristics in terms of reflection and coupling loss of a microwave target composed of a periodic distribution of pyramids are obtained through a Floquet, s fullwave simulation including higher order modes. The so-obtained... more
The RF characteristics in terms of reflection and coupling loss of a microwave target composed of a periodic distribution of pyramids are obtained through a Floquet, s fullwave simulation including higher order modes. The so-obtained scattering parameters are combined in a single figure-of-merit related to the emissivity behavior of the target itself. The relevance of the proposed analysis is demonstrated on a target design example operating from 14 to 220 GHz.
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A heuristic algorithm based on two threshold values of a scalar indicator, given by the ratio of the brightness temperatures measured by a ground-based radiometer at 31.4 and 23.8 GHz, is employed to detect the presence, if any, of rain... more
A heuristic algorithm based on two threshold values of a scalar indicator, given by the ratio of the brightness temperatures measured by a ground-based radiometer at 31.4 and 23.8 GHz, is employed to detect the presence, if any, of rain events along the Earth to satellite propagation path in the framework of the Alphasat Aldo Paraboni Propagation Experiment. The promising preliminary results have single out the need of a finer identification of the initial and final time of the event toward the prediction of the rain contribution to the total tropospheric attenuation.
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ABSTRACT This ray tracing technique addresses the profiling of the field intensity in radio links in presence of tropospheric multipath. Care is taken in the identification and separation of the different field contributions due to wave... more
ABSTRACT This ray tracing technique addresses the profiling of the field intensity in radio links in presence of tropospheric multipath. Care is taken in the identification and separation of the different field contributions due to wave folding and the interaction between the rays and the terrain. Unwrapping the ray comb enables interpolation on single folds without ambiguity. The various steps toward the field estimation are detailed with two examples: with an atmosphere with only vertical variation and with variations in both directions.
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In the framework of the incoming Alphasat communication and propagation experiment, an operative real time criterion (SSI) to discriminate among the three main atmospheric propagation statuses (clear, cloudy and rainy sky conditions) and... more
In the framework of the incoming Alphasat communication and propagation experiment, an operative real time criterion (SSI) to discriminate among the three main atmospheric propagation statuses (clear, cloudy and rainy sky conditions) and to trigger Fading Mitigation Techniques (FMT) is proposed and analysed. Two SSI boundary threshold values were estimated: SSICC for demarcating between clear and cloudy conditions and SSICR between cloudy and rainy sky. SSI is based on brightness temperature measurements observed at 20/30 GHz by ground-based radiometer. On the two SSI thresholds, a robustness analysis was performed to account for brightness measurements accuracy as well as for improper radiometric calibration. Furthermore, an analysis of the SSI discrimination performances based on the Neyman-Pearson optimal detection is addressed.
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Radiosounding data and numerical outputs from a cloud-resolving model in conjunction with a Monte Carlo statistical scheme and a radiative transfer algorithm (SNEM) are used to characterize propagation parameters at V- and W-band in Rome,... more
Radiosounding data and numerical outputs from a cloud-resolving model in conjunction with a Monte Carlo statistical scheme and a radiative transfer algorithm (SNEM) are used to characterize propagation parameters at V- and W-band in Rome, NY, for any meteorological scenario including clear-air, cloudy coverage, stratiform rain and convective precipitation. The analysis aims at exploiting these databases for the design of simple estimators of propagation parameters up to W-band from ground-based microwave radiometers measurements collected in various atmospheric conditions.
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Attenuation over forested areas can be predicted by the physical scatter models employed in remote sensing. This paper deals with the validation of two such scatter models. The attenuation data were collected through a small-scale radar... more
Attenuation over forested areas can be predicted by the physical scatter models employed in remote sensing. This paper deals with the validation of two such scatter models. The attenuation data were collected through a small-scale radar experimental campaign at 2.2 and 5.8 GHz, performed June 1996 and March 1997, in the Etude de la Rétrodiffusion et de l'Affaiblissement par les Bois sur les Liaisons Electromagnétiques (ERABLE) project where the objective was, apart from validating predictions against measurements, to assess whether scatter models are useful to predict radio link performance in a forest environment. Our models of choice were the Michigan microwave canopy scattering (MIMICS) model and one developed by Karam et al., and the forest site was a 20-year-old oak stand and a 6-year-old pine stand in the Fontainebleau forest, 60 km SE of Paris. Besides radar measurements of the stands, environmental parameters were collected through ground measurements, including geometrical and electromagnetic ones. These parameters were used as the input to numerical codes to simulate summer (leafy) and winter (not leafy) conditions. The agreement between the measured and the predicted data is discussed.
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ABSTRACT In this paper, emphasis is placed on a “real time” criterion for the identification of the presence of rain events along a satellite link. The criterion is based on an empirical sky status indicator (SSI) based on ground-based... more
ABSTRACT In this paper, emphasis is placed on a “real time” criterion for the identification of the presence of rain events along a satellite link. The criterion is based on an empirical sky status indicator (SSI) based on ground-based radiometric measurements, collected at 23.8 and 31.4 GHz.
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... M. Dechambre, AV Bosisio, J.-P. Vinson and J.-Y. Delahaye CETP / CNRS 10-12 Avenue de I'Europe 78140 V6liiy ... to wideband mobile 900 MHz propagation measurements", Proceedings of the 40th Vehicular technology Conference,... more
... M. Dechambre, AV Bosisio, J.-P. Vinson and J.-Y. Delahaye CETP / CNRS 10-12 Avenue de I'Europe 78140 V6liiy ... to wideband mobile 900 MHz propagation measurements", Proceedings of the 40th Vehicular technology Conference, VT90, pp5 13-519 (Orlando, Florida, USA ...
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This paper presents the preliminay steps needed to address the space/time variation of air masses deduced by the analysis of brightness temperature observed by a satellite-borne radiometer. A comparison with radiometric data... more
This paper presents the preliminay steps needed to address the space/time variation of air masses deduced by the analysis of brightness temperature observed by a satellite-borne radiometer. A comparison with radiometric data simultaneously collected at the ground indicates that the observed variations are related to atmospheric layer and not to the land emission temperature. Preliminary results are relative to structures that show low and moderate evolution during their motion. I. INTRODUCTION The analysis of the atmospheric effects on signal propagation is useful for many applications such as telecommunications, geodesy and meteorological studies interested in water cycle or humidity dynamic modeling. Analysis based on joint observations (satellite and ground- based equipment) of the radiometric brightness temperature may give a contribution in this direction. In this preliminary work, an approach based on Ka band data measured by a satellite radiometer (Meteosat) and on data collected at the ground (in Spino d'Adda, Italy) is presented. These two different types of sensor give complementary information about the atmosphere status. The satellite image captures - at a given time - a snapshot of the spatial structure of the underlying scenario, while the ground-based radiometer collects time series of the brightness temperature TB along a given path (fixed the spatial coordinates). There is an excellent trend agreement between the time series of data collected at the ground and the time series extracted from the corresponding pixel. In spite of the different antenna beamwidth of the two radiometers, and of the slightly different observation path, the agreement shows that the two systems are sensing the same process. This is helpful since it allows to observe the space and time variations of brightness temperature satellite maps, with the additional information of a reference point at the ground. Based upon these considerations, qualitatively validated by the observations, the space/time evolution of air masses (i.e. clouds) is described by evaluating the cross-correlation between each map and one or more following in time. This approach gives an estimate of the displacement of the air mass and of the convection velocity. This technique helps in recovering horizontal variation and in distinguishing between slow and fast movements of humidity masses. Besides, the degree of knowledge of the transversal structure of the atmosphere is less determined than its vertical variation. The paper discusses about the possibility of recovering this kind of information.
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This paper presents the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based microwave radiometer. The proposed criterion is based on the sky status indicator (SSI) derived from... more
This paper presents the results of a study aiming at detecting rainy data in measurements collected by a dual band ground-based microwave radiometer. The proposed criterion is based on the sky status indicator (SSI) derived from brightness temperatures observed in the 20–30 GHz band without need of any ancillary information. A major result obtained from the CDF of almost three
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In this letter, the propagation characteristics of normal mode near the cutoff region of a circular waveguide surrounded by a medium of finite conductivity and given permeability is discussed. Several real-time applications require an... more
In this letter, the propagation characteristics of normal mode near the cutoff region of a circular waveguide surrounded by a medium of finite conductivity and given permeability is discussed. Several real-time applications require an accurate solution of the characteristic equation at low computational cost. A fast computed approximate solution for external medium with infinite conductivity is available but inaccurate in the cut off region. Besides, field solvers and other numerical techniques give a precise solution in the whole frequency range, but unacceptable computational time. The proposed solution is derived by a perturbation approach once the characteristic equation has been expanded. A comparison between computed and exact values shows that the approximate solution is quite good for a wide range of conductivity and permeability values of the external medium.
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The identification of rain contaminated ground-based radiometric measurements is addressed by means of two brightness temperature-based criteria, namely SSI, defined as the ratio of temperature at 30 and 23.8 GHz, and TB30 based on the... more
The identification of rain contaminated ground-based radiometric measurements is addressed by means of two brightness temperature-based criteria, namely SSI, defined as the ratio of temperature at 30 and 23.8 GHz, and TB30 based on the 30-GHz temperature value alone. Threshold values of these criteria were chosen according to the rate of misclassification set by the experimenter after classification of a training subset of data on the basis of the atmospheric conditions as observed by a variety of rain sensors. A comparison of the discrimination performances indicates that SSI detects light rain events that are missed by both the rain-gauge and TB30 but it suffers from the intrinsic response time of the brightness temperature in the presence of rain. The analysis is referred to 1 year of measurements collected at the ARM SGP facility in Oklahoma.
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... In that frame, a system approach is proposed that will allow the exploitation of the W ... A first solution could be aimed at counteracting only the deterministic variation ¢CD(Ã) due to the ... It is a low-level protocol that divides... more
... In that frame, a system approach is proposed that will allow the exploitation of the W ... A first solution could be aimed at counteracting only the deterministic variation ¢CD(Ã) due to the ... It is a low-level protocol that divides data volume into frames and manages frames transmission ...
Research Interests: Aerospace Engineering, Mathematics, Computer Science, Telecommunications, Satellite Communications, and 10 moreSatellite Communication, System Approach, Error Control Coding, Geomatic Engineering, Satellite, Extrapolation, Idle channel Measurement, Electrical And Electronic Engineering, Channel Capacity, and Communications System
Site diversity is a useful countermeasure to overcome severe rain attenuation in satellite communication links. several prediction models of the diversity gain. The authors have tested seven different prediction models of site diversity... more
Site diversity is a useful countermeasure to overcome severe rain attenuation in satellite communication links. several prediction models of the diversity gain. The authors have tested seven different prediction models of site diversity gain against the results of 47 experiments with various geometrical/radioelectrical system characteristics, at different frequencies from 11 to 30 GHz. Four models have been classified as empirical, the other three as physical models. The average, RMS, and sigma of the difference between the estimated and measured percent gain show that the empirical Hodge's model (see Radio Sci., vol.17, no.6, p.1393-9, 1982). (which was obtained by a best fit over 22 of the 47 experiments here used) behaves better than the others giving the lowest value of sigma and a small average underestimate. Nevertheless, two physical models-those of Matricciani's and Capsoni et al. (see Eur. Trans. Telecom. Relat. Technol., vol.2, no.6, 715-27, 1991; and Radio Sci., vol.22, no.3, p.387-93, 1987, respectively)-which are intrinsically more powerful as they can be also used to predict other propagation quantities, show results very similar to those of Hodge's that confirm their wide range of applicability. >
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The knowledge of possible impairments due to atmospheric propagation is of importance in the framework of future 5G mobile networks that use spectrum resource up to the W band. Here, the authors propose the scalar Scattering Indicator... more
The knowledge of possible impairments due to atmospheric propagation is of importance in the framework of future 5G mobile networks that use spectrum resource up to the W band. Here, the authors propose the scalar Scattering Indicator (SI), defined as the difference between the simulated TB at 72 GHz and the T̂B value estimated at the same frequency from a nonlinear combination of TB's values at 23.8 and 31.4 GHz under assumed scatter-free condition. On the basis of radiosonde profiles observed in Milan, Linate (Italy) in 2005, clear-sky scenarios are used as reference to define a scatter-free TBs database. A second database of simulated TBs including scattering effects is generated with ARTS to build the SI. Numerical results show that the SI assumes significant positive values with increasing drop effective radius and total liquid water LWP and that it can be used to identify the scattering due to hydrometeors.
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ABSTRACT The paper reports the preliminary results of a RSSI-based localization algorithm that implements an exhaustive exploration of the data space, i. e. the power maps of the received signal in an indoor environment. The technique... more
ABSTRACT The paper reports the preliminary results of a RSSI-based localization algorithm that implements an exhaustive exploration of the data space, i. e. the power maps of the received signal in an indoor environment. The technique takes advantage of previous experimental results that served to calibrate the signal level simulated by a ray tracer. Numerical precalculated maps include perturbed scenarios that simulate actual conditions in which the signal fluctuates. The localization algorithm draws at random a perturbed map and it extracts the power values corresponding to the probe location. Then, an exhaustive exploration of the spatial domain over an average map is performed to single out the minimum of a cost function expressing the residual between the power values of the test point and those of the candidate points.
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In the framework of the Olympus and Italsat satellites experiment, the Politecnico di Milano carried out a campaign aiming to measure brightness temperatures at different frequencies and to estimate some quantities, as water vapour (V),... more
In the framework of the Olympus and Italsat satellites experiment, the Politecnico di Milano carried out a campaign aiming to measure brightness temperatures at different frequencies and to estimate some quantities, as water vapour (V), liquid water integrated content (L) and atmospheric attenuation, related to absorption phenomena of interest for radio propagation studies
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Research Interests: Engineering, Statistical Analysis, Mobile Systems, Digital Communication, Mobile telephony, and 13 moreStandard Deviation, Power Control, GSM, Mobile phone, Global System for Mobile Communication (GSM), Dosimetry, Electrical And Electronic Engineering, Handset, Finite Difference Time Domain, Base station, Specific absorption rate (SAR), Data Stream, and Finite difference time domain (FDTD)
The launch of L-band passive microwave radiometer satellites in the last decade (SMOS, Aquarius, and SMAP) started a new era in Earth Observation at low frequency. On the trails of these missions, recent studies showed that microwave... more
The launch of L-band passive microwave radiometer satellites in the last decade (SMOS, Aquarius, and SMAP) started a new era in Earth Observation at low frequency. On the trails of these missions, recent studies showed that microwave radiometers operating at even lower frequencies (P-band) can provide new information for cryospheric and ocean science and improve the current understanding of Earth processes. In particular, experimental airborne campaigns were conducted in both Artic and Antarctica, within the NASA's UWBRAD project, by using a wide band radiometer operating in the range 0.5-2 GHz, aimed at investigating the temperature profiles of ice sheets and the sea ice thickness. By leveraging the results of UWBRAD system, a new mission concept was proposed to ESA Earth Explorer 10 and 11 (called CryoRad) and NASA EVI-6 (called PolarRad) featuring a spacebome 0.4-2 GHz nadir-looking microwave radiometer for the monitoring of polar regions. Even though the main goals of all these sensors are related to observables such as soil moisture, ocean salinity, and geophysical parameters of the cryosphere, all of them suffer from the emission due the atmosphere. In the spectral range comprised between 0.5 and 2 GHz the atmosphere is considered almost transparent, being the major contributions to the emission due to the water vapor (in both physical phases) and to the molecular oxygen, however a clear assessment is still lacking in literature. The aim of this paper is to provide an accurate estimate of the atmospheric effect on measured TB from space at low frequency for different climate scenario by using a combination of in-situ data (i.e. radio-sounding) and microwave emission model.
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A new 20/30/50 GHz radiometer has been developed for use in a propagation experiment to characterise atmospheric attenuation up to 50 GHz. The radiometer is being used with the ITALSAT propagation payload and beacon receivers at the CSTS... more
A new 20/30/50 GHz radiometer has been developed for use in a propagation experiment to characterise atmospheric attenuation up to 50 GHz. The radiometer is being used with the ITALSAT propagation payload and beacon receivers at the CSTS experiment station of the Italian Research Council sited at Spino d'Adda, 30 km east of Milan. Details of the radiometer and experimental
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ABSTRACT A common approach to solve an inverse problem, i.e. to single out the model parameters that explain the observed phenomena, is to iteratively minimize a residual function, which expresses the difference between the observations... more
ABSTRACT A common approach to solve an inverse problem, i.e. to single out the model parameters that explain the observed phenomena, is to iteratively minimize a residual function, which expresses the difference between the observations (measured data) and the forward response of the estimated model (recalculated data). The convergence properties of the solver can be difficult to control and to analyse, especially when dealing with global optimizers applied to non-linear inverse problems. In this paper, we plot the residual vs. a single scalar, the Euclidian distance in the variable space. We show how this can be used to avoid misleading solutions given by the local minima. The performance of this approach is investigated in three examples with increasing complexity (in terms of dimensions). Moreover, we propose to exploit the distance indicator in a new hybrid inversion strategy that combines a simulated annealing algorithm and a local approach and that reduces the computational cost of the optimization.
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ABSTRACT A common approach to solve an inverse problem, i.e. to single out the model parameters that explain the observed phenomena, is to iteratively minimize a residual function, which expresses the difference between the observations... more
ABSTRACT A common approach to solve an inverse problem, i.e. to single out the model parameters that explain the observed phenomena, is to iteratively minimize a residual function, which expresses the difference between the observations (measured data) and the forward response of the estimated model (recalculated data). The convergence properties of the solver can be difficult to control and to analyse, especially when dealing with global optimizers applied to non-linear inverse problems. In this paper, we plot the residual vs. a single scalar, the Euclidian distance in the variable space. We show how this can be used to avoid misleading solutions given by the local minima. The performance of this approach is investigated in three examples with increasing complexity (in terms of dimensions). Moreover, we propose to exploit the distance indicator in a new hybrid inversion strategy that combines a simulated annealing algorithm and a local approach and that reduces the computational cost of the optimization.
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A heuristic algorithm based on two threshold values of a scalar indicator, given by the ratio of the brightness temperatures measured by a ground-based radiometer at 31.4 and 23.8 GHz, is employed to detect the presence, if any, of rain... more
A heuristic algorithm based on two threshold values of a scalar indicator, given by the ratio of the brightness temperatures measured by a ground-based radiometer at 31.4 and 23.8 GHz, is employed to detect the presence, if any, of rain events along the Earth to satellite propagation path in the framework of the Alphasat Aldo Paraboni Propagation Experiment. The promising preliminary results have single out the need of a finer identification of the initial and final time of the event toward the prediction of the rain contribution to the total tropospheric attenuation.
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In this paper, an overview of the WAVE mission payload architecture is presented. WAVE (W-band Analysis and VErification) is the new project funded by the Italian Space Agency (ASI). The aim is to design and develop a W-band geostationary... more
In this paper, an overview of the WAVE mission payload architecture is presented. WAVE (W-band Analysis and VErification) is the new project funded by the Italian Space Agency (ASI). The aim is to design and develop a W-band geostationary (GEO) payload to be deployed for scientific experimental studies of the W-band channel and possible utilization in satellite data communications. The large bandwidth availability in the W-band range allows conceiving and proposing advanced services for future scenarios in order to meet high-quality requirements for a large number of users. The major parameters of the payload architecture are discussed in addition to the different requirements and specifications of the on-board transmission and reception components and their dependence on the host platform
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In this paper we propose a novel approach to include stochastic behavior in ray-tracing modeling of the propagation in an indoor environment to be used to interpolate measurements in localization method by attenuation maps. Complex... more
In this paper we propose a novel approach to include stochastic behavior in ray-tracing modeling of the propagation in an indoor environment to be used to interpolate measurements in localization method by attenuation maps. Complex propagation environment is modeled as a combination of deterministic modeling and stochastic component properly optimized. Preliminary results from validation against measurements show that a reasonable RMSE can be achieved from few optimization steps.