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1رسالة جامعية
المساهمون: Pollard, Ritsuko Hamahata, Florida Atlantic University (Degree grantor), Helmken, Henry (Thesis advisor), College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
مصطلحات موضوعية: Tropospheric radio wave propagation, Meteorological instruments
الوصف: For radiowave propagation on earth-space communication links at high frequencies such as Ka-band, the effect of atmospheric gaseous absorption (mainly due to oxygen and water vapor) is the primary cause of attenuation. This thesis examines the applicability of the surface based Crane's model currently employed by the Advanced Communications Technology Satellite (ACTS) propagation experiment for estimation of attenuation due to atmospheric gaseous absorption (AGA), developed for Oklahoma, to sub-tropical climate regions such as Florida. The Microwave Propagation Model is used as a basis of comparison since it uses the direct atmospheric measurements (temperature, relative humidity, and pressure) made at different levels of the atmosphere with radiosonde instrumentation. The AGA was individually examined for oxygen and water vapor. Finally, accuracy of the Crane's model was verified by computing the attenuation results using real acquired data for both models and comparing their results in various ways for several months. ; College of Engineering and Computer Science ; FAU Electronic Theses and Dissertations Collection ; Thesis (M.S.)--Florida Atlantic University, 1998.
وصف الملف: 98 p.; application/pdf
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2رسالة جامعية
المساهمون: Koro, Zlata., Florida Atlantic University (Degree grantor), Helmken, Henry (Thesis advisor), College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
مصطلحات موضوعية: Artificial satellites in telecommunication, Radio wave propagation, Astronautics--Communication systems, Astronautics in meteorology
الوصف: The rapid growth of satellite services using higher frequency bands such as the Ka-band has highlighted need for analyzing effects of different propagation phenomena. Since the wavelength of radiowaves is comparable with the size of rain drops, rain attenuation is the dominant propagation impairment at Ka frequencies. In addition, other impairments such as gaseous absorption, cloud and fog attenuation, tropospheric refractive effects, as well as depolarization become increasingly important with increasing operating frequency. Theoretical background of radiowave propagation principles, rain systems and gases in the atmosphere are presented to insure comprehension of propagation effects on space communication in Ka-band. Models for predicting rain attenuation and other propagation impairments along Earth-satellite path are provided in order to simplify design of communication systems. Propagation phenomena are explained on example of three propagation experiments performed in U.S., Europe and Japan. Whenever possible, mitigation techniques to overcome severe attenuations are introduced. ; College of Engineering and Computer Science ; FAU Electronic Theses and Dissertations Collection ; Thesis (M.S.)--Florida Atlantic University, 1998.
وصف الملف: 109 p.; application/pdf
الإتاحة: http://purl.flvc.org/fcla/dt/15529Test
https://fau.digital.flvc.org/islandora/object/fau%3A12290/datastream/TN/viewTest/Propagation%20on%20satellite%20path%20in%20Ka-band.jpg -
3رسالة جامعية
المساهمون: Siwiak, Kazimierz., Florida Atlantic University (Degree grantor), Helmken, Henry (Thesis advisor), College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
مصطلحات موضوعية: Telecommunication--Equipment and supplies, Radio wave propagation, Telecommunication systems
الوصف: Body-proximate telecommunications devices are examined in both direct and multipath propagation. The study begins with a characterization of standard field strength sensitivity measurement methods for body-proximate telecommunications devices. Original measurements on a group of anthropometrically diverse people reveal that human adults, in a standard pose, are remarkably similar with respect to belt worn sensitivity performance, which motivates and justifies the use of an existing and a newly introduced light weight simulated human body device for testing, analysis and optimization of body worn telecommunications devices. Standard measurement methods using standard open air test ranges are established and validated by international transfers of measurements. The study extends to optimization of telecommunications devices in multipath, and particularly to the diversity reception of signals. A novel signal simulation model is introduced which includes multipath and shadowing, and is validated against both theoretical statistics and measurements. The signal simulation model is extended to characterize polarization randomization and cross-coupling based on an urban generalization of building height to street width ratio. The model is used to analyze measurements of polarization randomization of signals originating from an airborne transmitter flying a path whose geometry is consistent with low earth orbiting communications satellites. ; College of Engineering and Computer Science ; FAU Electronic Theses and Dissertations Collection ; Thesis (Ph.D.)--Florida Atlantic University, 1998.
وصف الملف: 151 p.; application/pdf
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4رسالة جامعية
المساهمون: Hutasingh, Allapon., Florida Atlantic University (Degree grantor), Helmken, Henry (Thesis advisor)
مصطلحات موضوعية: Radio wave propagation, Bluetooth technology
الوصف: Wireless communication has become a significant part of our life. Bluetooth(TM) Radio system is one example of wireless communication, Wireless Local Area Network (WLAN) is another example of wireless technology. Both of systems operate in the same frequency band, the Industrial Scientific Medical (ISM) band, which use a 2.4 GHz carrier frequency. According characteristic of system, multi-path effect are major concern for indoor propagation. A frequency sounding technique is introduced to determine characteristics of the multi-path signal. However, multi-path can not be evaluated directly; some parameters are measured to determine the effect of multi-path. Angles of arrival can be used to facilitate the effect of multi-path signal. Using MatLab programming, Spatial Filter Periodogram (SPF) is introduced to estimate angles of arrival. ; College of Engineering and Computer Science ; FAU Electronic Theses and Dissertations Collection ; Thesis (M.S.)--Florida Atlantic University, 2001.
وصف الملف: 103 p.; application/pdf
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5رسالة جامعية
المساهمون: Efthymoglou, George P., Florida Atlantic University (Degree grantor), Helmken, Henry (Thesis advisor), College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
مصطلحات موضوعية: Mobile communication systems, Wireless communication systems, Radio wave propagation
الوصف: In this dissertation, new semi-analytical expressions for the diversity bit error rate performance of asynchronous direct sequence-code division multiple access (DS-CDMA) systems in multipath fading channels are derived. Also, the PN acquisition time of a DS system with offset frequency periods greater than the code period in a AWGN channel is measured via laboratory experiments. In Part I we consider DS-CDMA systems operating in a cellular environment with multipath reception. Multipath propagation is exploited through the use of RAKE receivers. Coherent, differentially coherent and noncoherent binary demodulation schemes are considered. The multiple access interference is modeled as AWGN, conditioned on the fading statistics of the received signal. The mobile radio channel introduces selective fading, and is modeled as a tapped delay line. The amplitude of each resolvable path is statistically described by the Nakagami distribution, which is a general solution to the random vector problem that causes rapid fading. However, we assume independent but nonidentical fading along the RAKE branches. Therefore our analysis supports unequal mean powers and different amount of fading in the multipath components combined by the receiver. Also, the results can be easily extended to account for diversity from multiple antennas or coding in the generalized Nakagami multipath fading environment. In Part II we consider a land mobile satellite channel. First, a laboratory experiment is setup to evaluate the PN acquisition performance of a digital IF receiver in a AWGN channel with large Doppler offset. The digital conversion receiver uses the inherent aliasing property of sampling to realize the baseband conversion using a single analog-to-digital converter. Thereafter, digital signal processing on the I and Q samples enable for design trade-offs in the acquisition of the PN code with Doppler periods greater than the code period. Two code phase selection criterions, namely the maximum criterion and the threshold crossing ...
وصف الملف: 156 p.; application/pdf
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6رسالة جامعية
المساهمون: Blanc, Sadrac (author), Aalo, Valentine A. (Thesis advisor), Florida Atlantic University (Degree grantor), College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
مصطلحات موضوعية: Data encryption (Computer science), Digital communications -- Reliability -- Mathematics, Internetworking (Telecommunication), Radio wave propagation, Wireless communication systems -- Security measures
الوصف: The open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the presence of an eavesdropper. We investigate the performance of the wireless network at the physical layer that is subject to a variety of fading environments that may be modeled by the Rayleigh, Nakagami-m, and Generalized-K distributions, to mention a few. We use the secrecy outage probability (SOP) as the standard performance metrics to study the performance of the wireless networks. We propose two different approaches to compute the secrecy outage probability, and derive explicit expressions for the secrecy outage probability that allow us to characterize the performance of the wireless networks. Specifically, we use a direct integration approach as well as a Taylor series base approach to evaluate the secrecy outage probability. Finally, we use computer simulations, based on MATLAB, to confirm the analytical results. ; Includes bibliography. ; Thesis (M.S.)--Florida Atlantic University, 2016. ; FAU Electronic Theses and Dissertations Collection
وصف الملف: 97 p.; application/pdf
