The Experts below are selected from a list of 35811 Experts worldwide ranked by ideXlab platform
Petri Mahonen - One of the best experts on this subject based on the ideXlab platform.
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a week in london spectrum usage in metropolitan london
Personal Indoor and Mobile Radio Communications, 2013Co-Authors: Alexandros Palaios, Janne Riihijarvi, Oliver Holland, Petri MahonenAbstract:We present results from an 8-day spectrum Measurement Campaign in the centre of the London metropolis. We analyze results from one of the densest central areas in our Campaign from the perspective of spectrum Measurements at a very exposed location at the roof of a high building. We present the main results of this Measurement Campaign in terms of spectrum utilization, powers received, and evolution of the activity among different days. The results presented in this paper here are very close to an upper bound of what one might expect to find in any given radio environment in terms of utilization and received power Measurements. In addition to producing valuable Measurement data on its own, special attention was given on acquiring comparable datasets with previous Measurements Campaigns we have conducted to allow direct comparisons with other European cities we have studied. In particular, we show a detailed comparison between the downtown London results against Measurements carried out in other cities, quantifying the significantly higher levels of spectrum occupancy in London compared to other locations.
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Measurements of spectrum use in london exploratory data analysis and study of temporal spatial and frequency domain dynamics
IEEE International Symposium on Dynamic Spectrum Access Networks, 2012Co-Authors: Alexandros Palaios, Janne Riihijarvi, Oliver Holland, Andreas Achtzehn, Petri MahonenAbstract:In this paper we present results from a week long Measurement Campaign on spectrum use in London (UK). The Measurements were conducted in order to understand the characteristics and especially the variability in spectrum use over different types of areas in a major metropolitan area. Three spectrum analyzers were used in the Measurement Campaign, one used for long-term Measurements at a single location in a given area, with the other two used to sample spectrum use around the stationary Measurement point. This Measurement approach yields much more detailed information about spectrum use than the typical single-location Campaigns reported in the literature. We give a detailed description of the Measurement Campaign, including the equipment setup and rationale for the choice of areas in which the Measurements were conducted. We also present results from the first exploratory data analysis of the obtained data, and study in detail the correlation structures and dynamics in spectrum use in temporal, spatial and frequency domains.
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Lessons Learned from an Extensive Spectrum Occupancy Measurement Campaign and a Stochastic Duty Cycle Model
Mobile Networks and Applications, 2010Co-Authors: M Wellens, Petri MahonenAbstract:Several Measurement Campaigns have shown that numerous spectrum bands are vacant although licenses have been issued by the regulatory agencies. Dynamic spectrum access (DSA) has been proposed in order to alleviate this problem and increase the spectral utilization. In this paper we present our spectrum Measurement setup and discuss lessons learned during our Measurement activities. We compare Measurement results gathered at three locations and show differences in the background noise processes. Additionally, we introduce a new model for the duty cycle distribution that has multiple applications in the DSA research. We point out that fully loaded and completely vacant channels should be modelled explicitly and discuss the impact of duty cycle correlation in the frequency domain. Finally, we evaluate the efficiency of an adaptive spectrum sensing process as an example for applications of the introduced model.
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lessons learned from an extensive spectrum occupancy Measurement Campaign and a stochastic duty cycle model
Testbeds and Research Infrastructures for the DEvelopment of NeTworks and COMmunities, 2009Co-Authors: M Wellens, Petri MahonenAbstract:Several Measurement Campaigns have shown that numerous spectrum bands are vacant although licenses have been issued by the regulatory agencies. Dynamic spectrum access (DSA) has been proposed in order to alleviate this problem and increase the spectral utilization. In this paper we present our spectrum Measurement setup and discuss lessons learned during our Measurement activities. We compare Measurement results gathered at three locations and show differences in the background noise processes. Additionally, we introduce a new model for the duty cycle distribution that has multiple applications in the DSA research. Finally, we show that the primary user signal bandwidth has major impact on the correlation properties of the duty cycle in the frequency domain.
Moises V Ribeiro - One of the best experts on this subject based on the ideXlab platform.
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cooperative in home power line communication analyses based on a Measurement Campaign
IEEE Transactions on Communications, 2016Co-Authors: Michelle S P Facina, Haniph A Latchman, Moises V RibeiroAbstract:This work focuses on analyses of cooperative protocols to enhance the performance of power line communication systems. Based on a Measurement Campaign and considering a sum power constraint, achievable data rates for amplify-and-forward (AF) and decode-and-forward (DF) protocols are analyzed. Similar investigations are performed for the maximum data rates attained using Hermitian-symmetric orthogonal frequency division multiplexing (HS-OFDM) together with equal gain combining (EGC), selection combining (SC) and maximal ratio combining (MRC) techniques. The influences of optimally and uniformly allocated transmission power and frequency bandwidth are are also analyzed and the efficiency of combination before and after equalization is compared. Results show that the relative distances among source, relay and destination nodes significantly impact system performance. Also, they reveal a range of total transmission power and bandwidth in which benefits can be verified. Among combining techniques, MRC and SC present similar results, but MRC offers a slightly better performance. In relation to computational complexity, SC is the most favorable. Maximum data rate analyses of HS-OFDM with frequency domain equalization based on zero forcing and minimum mean square error criteria show that the former scheme offers almost the same performance as the latter. Furthermore, it is shown that equalization after combination is more advantageous.
Mauro Tucci - One of the best experts on this subject based on the ideXlab platform.
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Analysis of Power-Line Communication Channels in Ships
IEEE Transactions on Vehicular Technology, 2010Co-Authors: Sami Barmada, Lisa Bellanti, Marco Raugi, Mauro TucciAbstract:This paper presents a theoretical and experimental analysis on the application of power-line communication (PLC) on a cruise ship. The authors have developed an accurate model of the power grid of a ship when it is used as a PLC channel. The model is developed based on a theoretical approach and validated by a thorough Measurement Campaign. The accuracy of the model is addressed by a comparison between simulation results and measured data, and its use gives an insight into the performance of the power network to be used as PLC channel.
J M Haywood - One of the best experts on this subject based on the ideXlab platform.
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The CLoud–Aerosol–Radiation Interaction and Forcing: Year 2017 (CLARIFY-2017) Measurement Campaign
'Copernicus GmbH', 2021Co-Authors: J M Haywood, Kn Bower, Sj Abel, Pa Barrett, Bellouin N, Blyth A, Brooks M, Carslaw K, Che H, Coe HAbstract:This is the final version. Available on open access from the European Geosciences Union via the DOI in this recordData availability: All core and quality-assured non-core observational data, model forecast data, mission scientist logs, and flight summaries pertaining to the CLARIFY-2017 Campaign are available from the UK's Natural Environment Research Council's central data archive at http://data.ceda.ac.uk/badc/faam/data/ (last access: 22 January 2021) (CEDA, 2021a). Flight data for specific flights (including test flights) are available from http://data.ceda.ac.uk/badc/faam/data/2017/c026-jul-31 (last access: 22 January 2021) (CEDA, 2021b) through to http://data.ceda.ac.uk/badc/faam/data/2017/c056-sep-09 (last access: 22 January 2021) (CEDA, 2021c).The representations of clouds, aerosols, and cloud–aerosol–radiation impacts remain some of the largest uncertainties in climate change, limiting our ability to accurately reconstruct past climate and predict future climate. The south-east Atlantic is a region where high atmospheric aerosol loadings and semi-permanent stratocumulus clouds are co-located, providing an optimum region for studying the full range of aerosol–radiation and aerosol–cloud interactions and their perturbations of the Earth's radiation budget. While satellite Measurements have provided some useful insights into aerosol–radiation and aerosol–cloud interactions over the region, these observations do not have the spatial and temporal resolution, nor the required level of precision to allow for a process-level assessment. Detailed Measurements from high spatial and temporal resolution airborne atmospheric Measurements in the region are very sparse, limiting their use in assessing the performance of aerosol modelling in numerical weather prediction and climate models. CLARIFY-2017 was a major consortium programme consisting of five principal UK universities with project partners from the UK Met Office and European- and USA-based universities and research centres involved in the complementary ORACLES, LASIC, and AEROCLO-sA projects. The aims of CLARIFY-2017 were fourfold: (1) to improve the representation and reduce uncertainty in model estimates of the direct, semi-direct, and indirect radiative effect of absorbing biomass burning aerosols; (2) to improve our knowledge and representation of the processes determining stratocumulus cloud microphysical and radiative properties and their transition to cumulus regimes; (3) to challenge, validate, and improve satellite retrievals of cloud and aerosol properties and their radiative impacts; (4) to improve the impacts of aerosols in weather and climate numerical models. This paper describes the modelling and Measurement strategies central to the CLARIFY-2017 deployment of the FAAM BAe146 instrumented aircraft Campaign, summarizes the flight objectives and flight patterns, and highlights some key results from our initial analyses.Natural Environment Research Council (NERC)European CommissionNorges Forskningsrå
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Overview: The CLoud-Aerosol-Radiation Interaction and Forcing: Year-2017 (CLARIFY-2017) Measurement Campaign
'Copernicus GmbH', 2020Co-Authors: J M Haywood, Kn Bower, Sj Abel, Pa Barrett, Bellouin N, Blyth A, Brooks M, Carslaw K, Che H, Coe HAbstract:The representation of clouds, aerosols and cloud-aerosol-radiation impacts remain some of the largest uncertainties in climate change, limiting our ability to accurately reconstruct and predict future climate. The south-east Atlantic is a region where high atmospheric aerosol loadings and semi-permanent stratocumulus clouds are co-located, providing a natural laboratory for studying the full range of aerosol-radiation and aerosol-cloud interactions and their perturbations of the Earth’s radiation budget. While satellite Measurements have provided some useful insights into aerosol-radiation and aerosol cloud interactions over the region, these observations do not have the spatial and temporal resolution, nor the required level of precision to allow for a process level assessment. Detailed Measurements from high spatial and temporal resolution airborne atmospheric Measurements in the region are very sparse, limiting their use in assessing the performance of aerosol modelling in numerical weather prediction and climate models. CLARIFY-2017 was a major consortium programme consisting of 5 principal UK universities with project partners from the UK Met Office and European and USA-based universities and research centres involved in the complementary ORACLES, LASIC and AEROCLO-sA projects. The aims of CLARIFY-2017 were four-fold; (1) to improve the representation and reduce uncertainty in model estimates of the direct, semi-direct and indirect radiative effect of absorbing biomass burning aerosols; (2) improve our knowledge and representation of the processes determining stratocumulus cloud microphysical and radiative properties and their transition to cumulus regimes; (3) challenge, validate and improve satellite retrievals of cloud and aerosol properties and their radiative impacts; (4) improve numerical models of cloud and aerosol and their impacts on radiation, weather and climate. This paper describes the modelling and Measurement strategies central to the CLARIFY-2017 deployment of the FAAM BAe146 instrumented aircraft Campaign, summarises the flight objectives and flight patterns, and highlights some key results from our initial analyses
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motivation rationale and key results from the gerbils saharan dust Measurement Campaign
Quarterly Journal of the Royal Meteorological Society, 2011Co-Authors: J M Haywood, Ben Johnson, S Osborne, Anthony J Baran, M E Brooks, Sean Milton, Jane Mulcahy, D N Walters, Richard P AllanAbstract:The Geostationary Earth Radiation Budget Intercomparison of Longwave and Shortwave radiation (GERBILS) was an observational field experiment over North Africa during June 2007. The Campaign involved 10 flights by the FAAM BAe146 research aircraft over southwestern parts of the Sahara Desert and coastal stretches of the Atlantic Ocean. Objectives of the GERBILS Campaign included characterisation of mineral dust geographic distribution and physical and optical properties, assessment of the impact upon radiation, validation of satellite remote sensing retrievals, and validation of numerical weather prediction model forecasts of aerosol optical depths (AODs) and size distributions. We provide the motivation behind GERBILS and the experimental design and report the progress made in each of the objectives. We show that mineral dust in the region is relatively nonabsorbing (mean single scattering albedo at 550 nm of 0.97) owing to the relatively small fraction of iron oxides present (1 –3%), and that detailed spectral radiances are most accurately modelled using irregularly shaped particles. Satellite retrievals over bright desert surfaces are challenging owing to the lack of spectral contrast between the dust and the underlying surface. However, new techniques have been developed which are shown to be in relatively good agreement with AERONET estimates of AOD and with each other. This encouraging result enables relatively robust validation of numerical models which treat the production, transport, and deposition of mineral dust. The dust models themselves are able to represent largescale synoptically driven dust events to a reasonable degree, but some deficiencies remain both in the Sahara and over the Sahelian region, where cold pool outflow from convective cells associated with the intertropical convergence zone can lead to significant dust production. Copyright c
Jim Haywood - One of the best experts on this subject based on the ideXlab platform.
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the cloud aerosol radiation interaction and forcing year 2017 clarify 2017 Measurement Campaign
Atmospheric Chemistry and Physics, 2021Co-Authors: Kn Bower, Jim Haywood, Steven J Abel, Paul A Barrett, Nicolas Bellouin, Alan M Blyth, M Brooks, K S Carslaw, Haochi CheAbstract:The representation of clouds, aerosols and cloud-aerosol-radiation impacts remain some of the largest uncertainties in climate change, limiting our ability to accurately reconstruct and predict future climate. The south-east Atlantic is a region where high atmospheric aerosol loadings and semi-permanent stratocumulus clouds are co-located, providing a natural laboratory for studying the full range of aerosol-radiation and aerosol-cloud interactions and their perturbations of the Earth’s radiation budget. While satellite Measurements have provided some useful insights into aerosol-radiation and aerosol cloud interactions over the region, these observations do not have the spatial and temporal resolution, nor the required level of precision to allow for a process level assessment. Detailed Measurements from high spatial and temporal resolution airborne atmospheric Measurements in the region are very sparse, limiting their use in assessing the performance of aerosol modelling in numerical weather prediction and climate models. CLARIFY-2017 was a major consortium programme consisting of 5 principal UK universities with project partners from the UK Met Office and European and USA-based universities and research centres involved in the complementary ORACLES, LASIC and AEROCLO-sA projects. The aims of CLARIFY-2017 were four-fold; (1) to improve the representation and reduce uncertainty in model estimates of the direct, semi-direct and indirect radiative effect of absorbing biomass burning aerosols; (2) improve our knowledge and representation of the processes determining stratocumulus cloud microphysical and radiative properties and their transition to cumulus regimes; (3) challenge, validate and improve satellite retrievals of cloud and aerosol properties and their radiative impacts; (4) improve numerical models of cloud and aerosol and their impacts on radiation, weather and climate. This paper describes the modelling and Measurement strategies central to the CLARIFY-2017 deployment of the FAAM BAe146 instrumented aircraft Campaign, summarises the flight objectives and flight patterns, and highlights some key results from our initial analyses.
