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Articles 1 - 13 of 13
Full-Text Articles in Engineering
Performance Evaluation Of Mission Critical Communications Services Over Lte Networks, Kehinde Olumide Olasupo
Performance Evaluation Of Mission Critical Communications Services Over Lte Networks, Kehinde Olumide Olasupo
Theses and Dissertations
he existing Private/Professional Mobile Radio (PMR) technologies designed specifically for Mission Critical Communication (MCC) systems are narrowband and wideband devices, with limited network data capacity in emergency scenarios. They are majorly used to support MCC voice communications and low data rate applications during mission critical operations. However, the need for broadband systems that would support high radio data capacity keep increasing during major incidents and accident scenarios. Because of this, the MCC agencies were attracted by the broadband capabilities of Long Term Evolution (LTE) technology. But, the uplink capacity of LTE- based MCC systems is still a concern. In planning …
Efficiency Analysis And Optimization Of Light Trapping In Amorphous Silicon Heterojunction Solar Cell With Lumerical Fdtd/Device, Muhammad Riaz
Efficiency Analysis And Optimization Of Light Trapping In Amorphous Silicon Heterojunction Solar Cell With Lumerical Fdtd/Device, Muhammad Riaz
Theses and Dissertations
This study investigated the two-dimensional computer analysis of a tandem solar cell: c-Si/a-Si:H/µc-SiGe, with Lumerical FDTD/DEVICE 4.6. Optical characterization was performed in FDTD and then the total generation rate was transported into DEVICE for electrical characterization. Electrical characterization of the solar cell was carried out in DEVICE. In the first stage, a single junction solar cell was studied with both a-Si and µc-SiGe, respectively, as its absorbing layers. The thickness for both layers was kept the same. For the a-Si absorbing layer Jsc = 10.959 mA/cm2 , Voc = 696.97 mV, FF = 78.985%, and η = 6.033% were achieved. …
Comparison Of Reference Signal Received Power Measurements Between Cell Phone And Scanning Receiver In Lte, Sahin Gullu
Comparison Of Reference Signal Received Power Measurements Between Cell Phone And Scanning Receiver In Lte, Sahin Gullu
Theses and Dissertations
In cellular technology, before giving service to customers, coverage estimation, network optimization, and maintenance rely on RSRP (Received Signal Reference Power) measurements that are collected in a given area. This measurement collection is called “drive test or drive testing” that is very common practical experiment for RF engineers. These measurements are usually recorded by a professional receiver or a professional phone with appropriate software and license. A scanning receiver, PCTEL SeeGull EX scanning Receiver in this thesis, is a common professional tool for RF engineers to collect data. A cell phone, HTC One M7 for this experiment, has an appropriate …
Mathematical Model And Experimental Verification Of Spatially Multiplexed System Using Ray Theory And Modified Laguerre Gaussian Beams, Saud Alanzi
Theses and Dissertations
Spatial/Space Division Multiplexing (SDM) is based on a channel spacing technique in optical fibers that has the potential to inspire a revolution in optical communications. This patented technique provides a method to launch, transport, and detect two or more optical channels that operate at exactly the same wavelength inside a single multimode optical fiber. In addition, the patented technique added a new dimension and a new degree of photon freedom to the existing fiber multiplexing techniques and complements Time Division Multiplexing (TDM) and Wavelength Division Multiplexing (WDM). As a result, the bandwidth of existing and new optical fiber systems maybe …
Low Complexity Transmission Schemes For Future Wireless Communication Systems, Geamel Alyami
Low Complexity Transmission Schemes For Future Wireless Communication Systems, Geamel Alyami
Theses and Dissertations
Future of mobile communication technologies is coupled with multi-antenna systems. Recent research results encourage a massive increase in the number of base station antenna elements in order to meet high data rate demands. However, at the current mobile communication frequencies (< 6 GHz), the amount of spectrum is very limited. Therefore, increase number of antenna elements and higher carrier frequencies in millimeter wavelength range need to be understood and their corresponding potentials need to be identified. Studies proposed in this work aim to identify the degree of orthogonality of millimeter wave massive MIMO channels. For this purpose, various simulation based experiments have been done which are based on the state of the art millimeter channel models. Effect of certain propagation parameters such as the probability of existence of LOS link, number of clusters, inter-antenna elements spacing and number of base station antennas in the array have been investigated. It has been found that probability of LOS link has the highest impact at the multiuser orthogonality of the multiuser channels. In general, millimeter wave massive MIMO channels are found to be low rank. Therefore, in the last part of this work a low complexity user selection algorithm is proposed. Novelty of the work is established by both performance and computational complexity comparison. Computational cost of the proposed algorithm is significantly lower than state of the art user algorithms while the sum rate performance is exactly the same as that of best user selection algorithm
Arabic Speech Recognition Systems, Hamda M. M. Eljagmani
Arabic Speech Recognition Systems, Hamda M. M. Eljagmani
Theses and Dissertations
Arabic automatic speech recognition is one of the difficult topics of current speech recognition research field. Its difficulty lies on rarity of researches related to Arabic speech recognition and the data available to do the experiments. Moreover, to build Arabic speech recognition system with an optimal word error rate (WER), the system has to be completely trained to the individual user. Even though speaker dependent system can effectively achieve this by training it explicitly for this one speaker, it requires a large amount of training data. In addition speaker dependent system requires to be trained to each speaker individually. For …
An Extrinsic Fabry-Perot Interferometric Sensor Using Intermodal Phase Shifting And Demultiplexing Of The Propagating Modes In A Few-Mode Fiber, Julius Chatterjee
An Extrinsic Fabry-Perot Interferometric Sensor Using Intermodal Phase Shifting And Demultiplexing Of The Propagating Modes In A Few-Mode Fiber, Julius Chatterjee
Theses and Dissertations
This dissertation demonstrates a fiber-optic phase shifted Fabry-Perot interferometer (PS-FPI) as a sensor using modal demultiplexing. Single wavelength Fabry-Perot interferometers suffer from fringe ambiguity and loss of sensitivity at fringe extremes. These hindrances cause it to be a secondary choice when being selected for a measurement task at hand, and more often than not, white light based sensors are selected in favor of the single wavelength Fabry-Perot sensors. This work aims to introduce a technique involving the demultiplexing of the propagating linearly polarized (LP) modes in few mode fibers to obtain two fringe systems from the same sensing cavity. This …
Planar Electromagnetic Band Gap For Broadband Switching Noise Mitigation In High-Speed Pcb, Kevin H. Nguyen
Planar Electromagnetic Band Gap For Broadband Switching Noise Mitigation In High-Speed Pcb, Kevin H. Nguyen
Theses and Dissertations
Electromagnetic band gap (EBG) structure with novel meandered lines for mitigation of simultaneous switching noise (SSN) from multiple switch mode power supplies on a high speed digital circuit card assembly is investigated. The electromagnetic band gap structure is designed for a wideband operation from 200 MHz to 15 GHz. The application interest for this planar structure can be used as high impedance surfaces to suppress EMI noise for EMC compliance in Mil-Std-461, which is an electromagnetic compatibility standard for military equipment operating in the frequency range from 10 KHz to 18 GHz. ANSYS HFSS was used for simulation of these …
Optical Nanoantenna Impedance Matching And Duality And Hybrid Surface Phononic Waveguide, Yuancheng Xu
Optical Nanoantenna Impedance Matching And Duality And Hybrid Surface Phononic Waveguide, Yuancheng Xu
Theses and Dissertations
This work contributes to critical requirements for optical and infrared nanoantenna and waveguide applications; 1) the impedance of an optical nanoantenna is addressed, and 2) long propagation lengths and high confinement waveguide is designed. Optical nanoantennas have been studied as a means to manipulate nanoscale fields, local field enhancements, radiative rates, and emissive directional control. However, a fundamental function of antennas, the transfer of power between a coupled load and far-field radiation, has seen limited development in optical antennas owing largely to the inherent challenges of extracting impedance parameters from fabricated designs. As the transitional element between radiating fields and …
Analysis, A Technique, And Incremental Learning Of Wake-Up-Word Speech Recognition, Ahmad Zuhair S. Hasanain
Analysis, A Technique, And Incremental Learning Of Wake-Up-Word Speech Recognition, Ahmad Zuhair S. Hasanain
Theses and Dissertations
Even thought the cutting-edge speaker-independent Automatic Speech Recognition (ASR) systems demand big training data, they barely handle time-varying speaking rates, tolerate various uttering alterations, or are robust to noise. In contrast, our Wake-Up-Word (WUW) technique is tuned to these challenges in the light ASR systems with minimal number of initial training samples. It is crucial that users of ASR systems be capable of rolling out new WUW calls swiftly and modifying ASR vocabulary at any time, such as in the cases of foreign WUW addition and adaptation to phonetic change. We had tested our proposed methodologies in the acoustic WUW-II …
Hybrid Phonon Polaritons Mimic Te Surface Wave Enhanced Supercoupling, Delroy Dominic Rebello
Hybrid Phonon Polaritons Mimic Te Surface Wave Enhanced Supercoupling, Delroy Dominic Rebello
Theses and Dissertations
The study and excitation of surface plasmon polaritons SPhPs modes in polar dielectrics have attracted the interest of a wide range of research in various fields such as biology, physics and engineering. The excitation of SPhP in optical waveguides is because of TM-component of the incident light. TE-components are usually disbarred because, for TE-polarization component, orthogonal to the TM-polarization components, of the incidence waves, no SPhP mode exists. This thesis presents a novel hybrid TE SPhP mode waveguide in the mid-infrared region. By introducing a thin layer of high index dielectric material on the polar dielectric, where SPhPs are excited, …
Measurement Comparison Of Rf Receivers In Umts 1900mhz, Mohammed Najat Mohammed Sayan
Measurement Comparison Of Rf Receivers In Umts 1900mhz, Mohammed Najat Mohammed Sayan
Theses and Dissertations
In every day engineering practice, drive test systems are used to verify coverage, estimate quality of service and optimize RF network. To accomplish these tasks, drive tests need to be conducted in a systematic and cost efficient way. There are several commercial UMTS drive test systems and they can be classified as high dynamic range, multiband, and phone-based measurement tools. The data obtained from the measurement tools are then analyzed using statistical methods and inference. This thesis presents a detailed and comparative study of some of the physical layer measurements in UMTS 1900MHz frequency band. The collected measurements are compared …
Interpolation Methods For Coverage Area In Cellular Systems, Abdlmagid Mohamed Basere
Interpolation Methods For Coverage Area In Cellular Systems, Abdlmagid Mohamed Basere
Theses and Dissertations
Evaluating the coverage area in a wireless network is very important for cellular system designers in order to provide good service to users. It is hard to collect the Receive Signal Level (RSL) for an entire coverage area because of many obstacles, such as buildings, lakes, and vegetation. Therefore, estimation of the coverage area is essential for locations for which it is difficult to measure the RSL. This dissertation considers the process of RSL interpolation. Two main aspects of the interpolation are considered. Firstly, various interpolation methods are considered and it was determined that a very good performance is obtained …