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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Generalized Three Dimensional Geometrical Scattering Channel Model for Indoor and Outdoor Propagation Environments

Alsehaili, Mohammad 19 January 2011 (has links)
The well known geometrical scattering channel modeling technique has been suggested to describe the spatial statistical distribution of the received multipath signals at various types of wireless communication environments and for different wireless system applications. This technique is based on the assumption that the scatterers, i.e. objects that give rise to the multipath signals, are randomly distributed within a specified geometry that may include the base station and/or the mobile station. The geometrical scattering channel models can provide convenient and simple statistical functions for some of the important physical quantities of the received multipath fading signals, such as: angle of arrival, time of arrival, angular spread, delay spread and the spatial correlation function. In this thesis, a new three dimensional geometrical scattering channel model has been developed for outdoor and indoor wireless communication environments. The probability density functions of the angle of arrival of the received multipath signals are provided in compact forms. These functions facilitate independent control of the angular spread in both the azimuth and the elevation angles via the model's parameters. To establish the model verification, the developed model has been compared against the results from a site-specific propagation prediction technique in indoor and outdoor wireless communication environments. The developed three dimensional model has been extended to include the temporal statistical distribution of the received multipath signals for uniform and non-uniform distributions of the scatterer. Several of the probability density functions of the angle of arrival and time of arrival of the received multipath signals are provided. The probability density functions of the angle of arrival have been validated by comparing them against the results from real channel measurements data. In addition, the developed three dimensional geometrical scattering channel model has been extended for multiple input multiple output wireless channel modeling applications. A three dimensional spatial correlation function has been developed in terms of some of the physical channel's parameters, such as: displacements and orientation of the employed antenna elements. The developed correlation function has been used to simulate and investigate the performance of wireless multiple input multiple output systems in different scenarios.
2

Generalized Three Dimensional Geometrical Scattering Channel Model for Indoor and Outdoor Propagation Environments

Alsehaili, Mohammad 19 January 2011 (has links)
The well known geometrical scattering channel modeling technique has been suggested to describe the spatial statistical distribution of the received multipath signals at various types of wireless communication environments and for different wireless system applications. This technique is based on the assumption that the scatterers, i.e. objects that give rise to the multipath signals, are randomly distributed within a specified geometry that may include the base station and/or the mobile station. The geometrical scattering channel models can provide convenient and simple statistical functions for some of the important physical quantities of the received multipath fading signals, such as: angle of arrival, time of arrival, angular spread, delay spread and the spatial correlation function. In this thesis, a new three dimensional geometrical scattering channel model has been developed for outdoor and indoor wireless communication environments. The probability density functions of the angle of arrival of the received multipath signals are provided in compact forms. These functions facilitate independent control of the angular spread in both the azimuth and the elevation angles via the model's parameters. To establish the model verification, the developed model has been compared against the results from a site-specific propagation prediction technique in indoor and outdoor wireless communication environments. The developed three dimensional model has been extended to include the temporal statistical distribution of the received multipath signals for uniform and non-uniform distributions of the scatterer. Several of the probability density functions of the angle of arrival and time of arrival of the received multipath signals are provided. The probability density functions of the angle of arrival have been validated by comparing them against the results from real channel measurements data. In addition, the developed three dimensional geometrical scattering channel model has been extended for multiple input multiple output wireless channel modeling applications. A three dimensional spatial correlation function has been developed in terms of some of the physical channel's parameters, such as: displacements and orientation of the employed antenna elements. The developed correlation function has been used to simulate and investigate the performance of wireless multiple input multiple output systems in different scenarios.
3

SIMULATION OF THE AERONAUTICAL RADIO CHANNEL FOR TELEMETRY APPLICATIONS

Mwangi, Patricia A. W., Haj-Omar, Amr, Montaque, Kishan 10 1900 (has links)
ITC/USA 2006 Conference Proceedings / The Forty-Second Annual International Telemetering Conference and Technical Exhibition / October 23-26, 2006 / Town and Country Resort & Convention Center, San Diego, California / The aeronautical channel is an air to ground channel characterized by multipath, high doppler shifts, Rayleigh fading and noise. Use of a channel sounder ensures proper estimation of the parameters associated with the impulse response of the channel. These estimates help us to characterize the radio channels associated with aeronautical telemetry. In order to have a satisfactory channel characterization, the amplitudes, phase shifts and delays associated with each multipath component in the channel model must be determined.
4

Radio channel modelling for 5G telecommunication system evaluation and over the air testing

Kyösti, P. (Pekka) 08 May 2018 (has links)
Abstract This thesis discusses radio channel modelling for evolving radio access and of using the models in practice in a setup for radiated testing of radio devices. New telecommunication systems are constantly being developed to address continuously increasing wireless communication needs. The first pieces of intensively developed fifth generation (5G) networks and devices are planned to be available, in some form, approximately by 2020. An interesting feature of 5G concerning propagation and consequently channel modelling, is the expected utilization of frequencies clearly higher than the legacy cellular systems. This work aims to define a channel model for the simulated evaluation of the coming 5G systems. New requirements for the channel model are identified and addressed. Further, over the air (OTA) testing of 5G devices in fading conditions is examined and a new setup is proposed. The test environment aims to reconstruct a time variant electromagnetic (EM) field around a device under test (DUT) considering the spatial, polarimetric, Doppler, and delay dispersion characteristics specified by the target channel model. Components and key design parameters of the setup are designated. It was found that the proposed map-based channel model is capable of fulfilling the identified requirements. Furthermore, the simulations indicate that the state-of-the-art geometry-based stochastic channel model (GSCM) may give over-optimistic multi-user MIMO (MU-MIMO) performance in an urban micro-cellular environment. The sectored OTA concept was shown appropriate for device testing. Key parameters, such as the physical dimensions of the multi-probe anechoic chamber (MPAC) OTA configuration and the number of active probes, were determined by simulations. The 3GPP is the main forum working towards 5G standards. A channel model for 5G evaluations has recently (2016) been specified. The base-line model is a GSCM inherited from the 4G models. However, the author expects that the proposed map-based models will gain popularity in the future, despite the current widespread use of GSCMs. In the 3GPP working group RAN4 (Radio performance and protocol aspects) the test methods for 5G user equipment (UE) are currently (2017) under investigation. The proposed sectored MPAC method has been contributed to and is under consideration in 3GPP. Even if it is not approved for UE testing, the author expects it to be useful for performance testing of base stations (BSs). / Tiivistelmä Tämän väitöskirjan sisältönä on radiokanavamallinnus langattomia tiedonsiirtojärjestelmiä varten ja lisäksi mallien käyttöönottoa tulevien radiolaitteiden säteilevässä testauksessa. Uusia tietoliikennejärjestelmiä kehitetään jatkuvasti, yhtä lailla jatkuvasti kasvavien tiedonsiirtotarpeiden tyydyttämiseksi. Ensimmäisten verkkojen ja päätelaitteiden pitäisi olla saatavilla tulevaan viidennen sukupolven (5G) järjestelmään vuoden 2020 tietämillä. Työn tarkoituksena on määritellä kanavamalli 5G-järjestelmän simulointeja varten ja sitä edeltäen tunnistaa kanavamallin vaatimukset. Lisäksi tutkimuksen aiheena on 5G-laitteiden säteilevä (OTA) testaus häipyvässä radiokanavassa ja uuden testijärjestelmän määrittely tätä tarkoitusta varten. Ehdotetun testijärjestelmän keskeisenä toimintona on halutun sähkömagneettisen (EM) kentän tuottaminen testattavan laitteen ympärille. EM-kentän pitää olla kanavamallin mukainen ja toteuttaa sen häipymä-, tila-, polarisaatio-, doppler- ja viiveominaisuudet. Testijärjestelmän komponentit ja tärkeimmän suunnitteluparametrit pyritään selvittämään tässä työssä. Tutkimuksessa havaittiin, että ehdotettu karttapohjainen kanavamalli toteuttaa 5G-mallille asetetut vaatimukset. Simuloinnit osoittavat myös, että tyypillisessä kaupunkiympäristössä suosittu GSCM-malli yliarvioi kanavan kapasiteetin monen käyttäjän MIMO-tekniikka käytettäessä. Lisäksi osoitettiin sektoroidun OTA-järjestelmän, jossa hyödynnetään useita antenneja, radiokanavaemulaattoria sekä radiokaiutonta huonetta (MPAC), käyttökelpoisuus 5G-laitteiden testaukseen. Kyseisen testausjärjestelmän parametrit määriteltiin. 3GPP on tärkein foorumi, jolla 5G-standardeja luodaan. Siellä on hiljattain (2016) sovittu 5G-simulointeja varten kanavamalli, joka ei ole tässä työssä ehdotetun kaltainen. Standardoitu malli on tyypiltään GSCM ja se on johdettu suoraan edellisen sukupolven (4G) kanavamallista. Kirjoittaja olettaa tästä GSCM:n nykyisestä vahvasta asemasta huolimatta, että ehdotettu karttapohjainen kanavamalli lisää suosiotaan tulevaisuudessa. Parhaillaan (2017) on 3GPP:n RAN4-työryhmässä käynnissä 5G-päätelaitteiden (UE) testimenetelmien määrittelyvaihe. Väitöskirjassa tutkittua sektoroitua MPAC-menetelmää on ehdotettu työryhmälle standardoitavaksi. Vaikka mainittua menetelmää ei siellä standardoitaisikaan UE-testaukseen, niin voidaan olettaa menetelmän olevan hyödyllinen erityisesti tukiasemien säteilevään testaukseen.

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