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Wyszukujesz frazę "propagation models" wg kryterium: Temat

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    Wyświetlanie 1-5 z 5
    Tytuł:
    Extending the sheba propagatio model to reduce parameter-related uncertainties
    Autorzy:
    Pierantoni, G.
    Coghlan, B.
    Kenny, E.
    Gallagher, P.
    Perez-Suarez, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/305331.pdf
    Data publikacji:
    2013
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    heliophysics
    HELIO
    SCI-BUS
    distributed computation infrastructure
    propagation models
    Opis:
    Heliophysics is the branch of physics that investigates the interactions and correlation of different events across the Solar System. The mathematical models that describe and predict how physical events move across the solar system (ie. Propagation Models ) are of great relevance. These models depend on parameters that users must set, hence the ability to correctly set the values is key to reliable simulations. Traditionally, parameter values can be inferred from data either at the source (the Sun) or arrival point (the target) or can be extrapolated from common knowledge of the event under investigation. Another way of setting parameters for Propagation Models is proposed here: instead of guessing a priori parameters from scientific data or common knowledge, the model is executed as a parameter-sweep job and selects a posteriori the parameters that yield results most compatible with the event data. In either case ( a priori and a posteriori ), the correct use of Propagation Models requires information to either select the parameters, validate the results, or both. In order to do so, it is necessary to access sources of information. For this task, the HELIO project proves very effective as it offers the most comprehensive integrated information system in this domain and provides access and coordination to services to mine and analyze data. HELIO also provides a Propagation Model called SHEBA, the extension of which is currently being developed within the SCI-BUS project (a coordinated effort for the development of a framework capable of offering to science gateways seamless access to major computing and data infrastructures).
    Źródło:
    Computer Science; 2013, 14 (2); 253-272
    1508-2806
    2300-7036
    Pojawia się w:
    Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A workflow-oriented approach to Propagation Models in Heliophysics
    Autorzy:
    Pierantoni, G.
    Carley, E.
    Byrne, J.
    Perez-Suarez, D.
    Gallagher, P. T.
    Powiązania:
    https://bibliotekanauki.pl/articles/305701.pdf
    Data publikacji:
    2014
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    heliophysics
    workflow
    TAVERNA
    Coronal Mass Ejection
    propagation models
    Opis:
    The Sun is responsible for the eruption of billions of tons of plasma and the generation of near light-speed particles that propagate throughout the solar system and beyond. If directed towards Earth, these events can be damaging to our tecnological infrastructure. Hence there is an effort to understand the cause of the eruptive events and how they propagate from Sun to Earth. However, the physics governing their propagation is not well understood, so there is a need to develop a theoretical description of their propagation, known as a Propagation Model, in order to predict when they may impact Earth. It is often difficult to define a single propagation model that correctly describes the physics of solar eruptive events, and even more difficult to implement models capable of catering for all these complexities and to validate them using real observational data. In this paper, we envisage that workflows offer both a theoretical and practical framework for a novel approach to propagation models. We define a mathematical framework that aims at encompassing the different modalities with which workflows can be used, and provide a set of generic building blocks written in the TAVERNA workflow language that users can use to build their own propagation models. Finally we test both the theoretical model and the composite building blocks of the workflow with a real Science Use Case that was discussed during the 4th CDAW (Coordinated Data Analysis Workshop) event held by the HELIO project. We show that generic workflow building blocks can be used to construct a propagation model that succesfully describes the transit of solar eruptive events toward Earth and predict a correct Earth-impact time.
    Źródło:
    Computer Science; 2014, 15 (3); 271-291
    1508-2806
    2300-7036
    Pojawia się w:
    Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Optimized Propagation Model based on Measurement Data for Indoor Environments
    Autorzy:
    Morocho-Yaguana, M.
    Ludeňa-González, P.
    Sandoval, F.
    Poma-Vélez, B.
    Erreyes-Dota, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/308451.pdf
    Data publikacji:
    2018
    Wydawca:
    Instytut Łączności - Państwowy Instytut Badawczy
    Tematy:
    indoor
    ITU model
    log-distance model
    loss measurement
    one-slope model
    path loss
    propagation measurements
    propagation models
    radio propagation
    Opis:
    Propagation is an essential factor ensuring good coverage of wireless communications systems. Propagation models are used to predict losses in the path between transmitter and receiver nodes. They are usually defined for general conditions. Therefore, their results are not always adapted to the behavior of real signals in a specific environment. The main goal of this work is to propose a new model adjusting the loss coefficients based on empirical data, which can be applied in an indoor university campus environment. The Oneslope, Log-distance and ITU models are described to provide a mathematical base. An extensive measurement campaign is performed based on a strict methodology considering different cases in typical indoor scenarios. New loss parameter values are defined to adjust the mathematical model to the behavior of real signals in the campus environment. The experimental results show that the model proposed offers an attenuation average error of 2.5% with respect to the losses measured. In addition, comparison of the proposed model with existing solutions shows that it decreases the average error significantly for all scenarios under evaluation.
    Źródło:
    Journal of Telecommunications and Information Technology; 2018, 2; 69-75
    1509-4553
    1899-8852
    Pojawia się w:
    Journal of Telecommunications and Information Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance Analysis of Empirical Radio Propagation Models in Wireless Cellular Networks
    Autorzy:
    Rahul, Rahul
    Bansal, Bajrang
    Kapoor, Rajiv
    Powiązania:
    https://bibliotekanauki.pl/articles/1075552.pdf
    Data publikacji:
    2019
    Wydawca:
    Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
    Tematy:
    2G
    3G
    4G
    5G Cellular Networks
    Cell Coverage
    Path Loss
    Radio Propagation Models
    Opis:
    This paper presents the performance analysis of different empirical radio propagation models used in wireless cellular networks. It particular, the parameters such as path loss and cell coverage area are studied for different cellular networks from second generation (2G) to fifth generation (5G). Accurate prediction of path loss and coverage area is highly desirable for planning of any wireless communication systems. Considering the urban terrain, the comparison is made between Hata model, Stanford University Interim (SUI) model, and modified SUI models. As a motivation for new millimeter wave (mm-wave) cellular systems, i.e., for 5G communication, the analysis is performed at 28 GHz. Considering -75 dBm as the desired minimum received power, it is observed that 2G communication (at 900 MHz using Hata model) experiences the lowest path loss and thus results into largest coverage area. The path loss is observed to be maximum for the future mm-wave systems (at 28 GHz using modified SUI model) that directly imply the smallest coverage area.
    Źródło:
    World Scientific News; 2019, 121; 35-41
    2392-2192
    Pojawia się w:
    World Scientific News
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adaptation of Propagation Models to Improve the Coverage Range Prediction of LoRaWAN Technology at 915 MHz in an Urban Environment
    Autorzy:
    Suarez-Suare, Carlos René
    Rueda, Diego F
    Timaná-Eraso, Luis Carlo
    Leon-Leon, Jose
    Powiązania:
    https://bibliotekanauki.pl/articles/27311960.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    LoRaWAN
    propagation models
    Internet of things
    urban coverage
    fitted model
    Opis:
    Long Range Wide Area Network (LoRaWAN) technology has established new concepts for long-range wireless communication, being widely used in the implementation of IoT solutions. Therefore, it is crucial to validate the coverage of the signal and to know the distance at which a LoRAWAN communication system can be connected. This document investigates LoRaWAN technology for cases based on urban environments, so it can be used as a guide for those projects that require predicting the connection distance range of a LoRaWAN link. In addition, it serves as a tool for the reader when it comes to predicting the coverage of Long-Range Wide Area Network (LoRaWAN) technology. Measurements were made in a LoRaWAN network deployed in urban environments, where RSSI measurements were made in the city of Bogotá D.C., Colombia. Experimentally RSSI values were compared with four different propagation models at a frequency of 915 MHz in urban environments. The contribution of this work is an adjustment to widely used prediction models, according to the recommendation of the International Telecommunications Union (ITU) ITU-R P.1546, which allows estimating coverage in scenarios with characteristics similar to Bogotá D.C. This allows to know with precision the coverage before implementing the LoRaWAN communications system at 915 MHz. The results of comparing field measurements with fitted propagation models show that the Okumura model is the best predictor of coverage with a minimum error rate.
    Źródło:
    International Journal of Electronics and Telecommunications; 2023, 69, 4; 733--744
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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