Engineering Commons^™

Novel Multiuser Detection And Multi-Rate Schemes For Multi-Carrier Cdma, Pingping Zong

Dissertations

A large variety of services is [sic] expected for wireless systems, in particular, high data rate services, such as wireless Internet access. Users with different data rates and quality of service (QoS) requirements must be accommodated. A suitable multiple access scheme is key to enabling wireless systems to support both the high data rate and the integrated multiple data rate transmissions with satisfactory performance and flexibility. A multi-carrier code division multiple access (MC-CDMA) scheme is a promising candidate for emerging broadband wireless systems. MC-CDMA is a hybrid of orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). The …

Plasma Induced Damage To Si And Sige Devices And Materials, Wei Zhong

Dissertations

This thesis studied the plasma-induced damage to Si and strained Si_1-xGe_x, and the resulting change in device characteristics. The energetic particles (ions, electrons and photons) in plasma reactor present a potentially hostile environment for processing VLSI devices. An inductively coupled plasma (ICP) reactor was used to study its damage effects to thin gate oxides. Electrical characterizations by C-V, ramped voltage breakdown (RVB) and deep-level transient spectroscopy (DLTS) measurement, and x-ray photoelectron spectroscopy (XPS) analysis were employed to investigate the damages to thin gate oxides and Si/SiO₂ interface. The shift of flat band voltage, the reduction …

Performance Analysis And Resource Allocation In Cdma Wireless Networks For Multimedia Services, Sebnem Zorlu

Dissertations

The proliferation of Internet and demand for wireless services necessitate large increases in capacity and data rates in order to support different multimedia services. Wireless systems will be required to support sources with a variety of traffic characteristics and quality of service requirements. This requires algorithms for admission control and resource allocation at the session, burst and packet levels. The purpose of this research is to develop and analyze optimal resource allocation strategies to maximize throughput of wireless systems with integrated services. Given the multimedia user requirements, the problem addressed can be formulated as a constrained optimization problem. The objective …

Buffer Management And Cell Switching Management In Wireless Packet Communications, Jongho Bang

Dissertations

The buffer management and the cell switching (e.g., packet handoff) management using buffer management scheme are studied in Wireless Packet Communications.

First, a throughput improvement method for multi-class services is proposed in Wireless Packet System. Efficient traffic management schemes should be developed to provide seamless access to the wireless network. Specially, it is proposed to regulate the buffer by the "Selective- Delay Push-In (SDPI)" scheme, which is applicable to scheduling delay-tolerant non-real time traffic and delay-sensitive real time traffic. Simulation results show that the performance observed by real time traffics are improved as compared to existing buffer priority scheme in …

Design Of Traffic Shaper / Scheduler For Packet Switches And Diffserv Networks : Algorithms And Architectures, Surong Zeng

Dissertations

The convergence of communications, information, commerce and computing are creating a significant demand and opportunity for multimedia and multi-class communication services. In such environments, controlling the network behavior and guaranteeing the user's quality of service is required. A flexible hierarchical sorting architecture which can function either as a traffic shaper or a scheduler according to the requirement of the traffic load is presented to meet the requirement. The core structure can be implemented as a hierarchical traffic shaper which can support a large number of connections with a wide variety of rates and burstiness without the loss of the granularity …

Optical Properties Of Photonic Crystals, Anand G. Shenoy

Theses

The ability to confine light in three dimensions has important implications for quantum optics and quantum-optical devices. Photonic crystals, the optical analog of electronic crystals, provide us a means of achieving this goal. This analogy has motivated a whole new series of experimental and theoretical searches for elusive photonic band-gap structures. Combinations of metallic and dielectric materials can be used to obtain the required three-dimensional (3D) periodic variation in the dielectric constant. This could pave the way for photonic crystal structures that have widespread applications.

The working of 3D photonic crystals into the wavelength regimes where most optoelectronic devices operate, …

Propagation And Scattering Of Collimated Beam Wave In Vegetation Using Scalar Transport Theory, Michael Yu-Chi Wu

Theses

The scalar time-dependent equation of radiative transfer is used to develop a theory of pulse beamwave propagation and scattering in a medium character ized by many random discrete scatterers which scatter energy strongly in the forward scattering direction. Applications include the scattering of highly collimated millimeter waves in vegetation and optical beams in the atmosphere. The specific problem analyzed is that of a periodic sequence of Gaussian shaped pulses normally incident from free space onto the planar boundary surface of a random medium half-space, such as a forest, that possesses a power scatter (phase) function consisting of a strong, narrow …

Overview Of Acousto-Optic Bistability, Chaos, And Logical Applications, Monish Ranjan Chatterjee, Erol Sonmez

Electrical and Computer Engineering Faculty Publications

An overview is presented of the key results in the field of acousto-optic bistability in the past two decades. It is shown that the basic acousto-optic bistable device may be described as a nonlinear dynamical system which satisfies a quadratic map. Thereafter, details are presented of several analytical methods, computer modeling approaches, including the SPICE circuit modeling technique, and experiments that have been used to understand the phenomenon.

Extensions to logical and digital applications are also discussed.

Wavelet-Based Audio Embedding & Audio/Video Compression, Michael J. Mendenhall

Theses and Dissertations

With the decline in military spending, the United States relies heavily on state side support. Communications has never been more important. High-quality audio and video capabilities are a must. Watermarking, traditionally used for copyright protection, is used in a new and exciting way. An efficient wavelet-based watermarking technique embeds audio information into a video signal. Several highly effective compression techniques are applied to compress the resulting audio/video signal in an embedded fashion. This wavelet-based compression algorithm incorporates bit plane coding, first difference coding, and Huffman coding. To demonstrate the potential of this audio embedding audio/video compression system, an audio signal …

Broadband Application Of High Impedance Ground Planes, Keven J. Golla

Theses and Dissertations

Electrical conductors have long been the only materials available to antenna designers for reflecting structures. However, recently reported high impedance ground plane (HIGP) structures offer an alternative by creating image currents and reflections, within a limited frequency stop-band, that are in-phase with a source rather than out-of-phase as for a perfect electric conducting (PEC) surface. Also, the high impedance structures suppress surface waves while surface waves propagate on PEC surfaces. This research explores broadband antenna applications for HIGP structures. A broadband surface mount antenna is applied to both a homogeneous narrowband HIGP and a spatially varying broadband HIGP design. Measurements …

Tilted Bilayer Membranes As Simple Transmission Quarter-Wave Retardation Plates, R. M.A. Azzam, Fadi A. Mahmoud

Electrical Engineering Faculty Publications

A tilted bilayer membrane, which consists of two thin films of transparent optically isotropic materials of different refractive indices, can function as a transmission quarter-wave retarder (QWR) at a high angle of incidence. A specific design using a cryolite-Si membrane in the infrared is presented, and its tolerances to small shifts of wavelength, incidence angle, and film thickness errors are discussed. Some designs provide a dual QWR in transmission and reflection. Such devices provide simple linear-to-circular (and circular-to-linear) polarization transformers. Bilayer eighth-wave retarders without diattenuation are also introduced.

Video Indexing And Summarization Using Motion Activity, Kadir Askin Peker

Dissertations

In this dissertation, video-indexing techniques using low-level motion activity characteristics and their application to video summarization are presented. The MPEG-7 motion activity feature is defined as the subjective level of activity or motion in a video segment. First, a novel psychophysical and analytical framework for automatic measurement of motion activity in compliance with its subjective perception is developed. A psychophysically sound subjective ground truth for motion activity and a test-set of video clips is constructed for this purpose. A number of low-level, compressed domain motion vector based, known and novel descriptors are then described. It is shown that these descriptors …

Phase-Locked Loop, Delay-Locked Loop, And Linear Decorrelating Detector For Asynchronous Multirate Ds-Cdma System, Sok-Kyu Lee

Dissertations

The performance of phase synchronization and code tracking of a digital phase-locked loop (PLL) and delay-locked loop (DLL), respectively, is investigated in wideband asynchronous multirate DS-CDMA system. Dynamic Partial Correlation (DPC) method is proposed to evaluate the autocorrelation and its power spectrum density (PSD) of the cross-correlated terms in the presence of multirate multiple access interference (MMAI) under additive white gaussian noise (AWGN) and fading channel environments. The steady-state probability density function (PDF) and variance of the phase estimator error and code tracking jitter is evaluated by solving the first-order Fokker-Planck equation.

Among many linear multiuser detectors which decouple the …

Resource Allocation For Cdma Downlink To Achieve Maximum Throughput, Anil Bircan

Dissertations

Growing interest in cellular phones, wireless modems, instant messaging, pagers with the increasing use of the Internet in daily life indicate that wireless high speed Internet access and wireless multimedia applications are in great demand. The barrier to satisfy this demand is the provision of sufficiently high bit rates in severe wireless mobile channel conditions, for a multitude of services, each requiring different and perhaps even time-varying quality of services (QoS) that can be more demanding than the QoS required by today's voice service. New generation systems will enable provision of a multitude of services each with different QoS and …

Nonlinear Optical Properties Of Nano Structures, Mahesh U. Ajgaonkar

Dissertations

Nonlinear optical properties of nanoscale semiconductors had been a topic of intense research in recent years in attempts to realize all-optical communication systems. These semiconductor nanoclusters, in the range of 1-100nm are hosted in a dielectric material and are considered as a particular example of Conditional Artificial Dielectric (CAD). It has been reported that the dielectric properties of such materials will be greatly changed by light intensity.

Two main paths to realize nano semiconductor clusters are reported in this dissertation. The Pulsed Laser Deposition (PLD) technique is first described. Here we were investigating the effect of surface modification of nano …

Interference Suppression And Diversity For Cdma Systems, Xiaodong Cai

Dissertations

In code-division multiple-access (CDMA) systems, due to non-orthogonality of the spreading codes and multipath channels, the desired signal suffers interference from other users. Signal fading due to multipath propagation is another source of impairment in wireless CDMA systems, often severely impacting performance. In this dissertation, reduced-rank minimum mean square error (MMSE) receiver and reduced-rank minimum variance receiver are investigated to suppress interference; transmit diversity is applied to multicarrier CDMA (MC-CDMA) systems to combat fading; packet combing is studied to provide both interference suppression and diversity for CDMA random access systems.

The reduced-rank MMSE receiver that uses a reduced-rank estimated covariance …

Analysis And Control Of Monolithic Piezoelectric Nano-Actuator, Xuemei Sun

Dissertations

The study of the monolithic piezoelectric actuator, the dominant type of micropositioner is an attractive and challenging area, where realtime control theory and digital signal processing are effectively applied. The actuator can be applied in precision instruments and precision control, such as microscopes, medical and optics instruments because of the piezoelectric ceramic's high resolution, fast transient response, and potential low cost. However, hysteresis nonlinearity and lightly damped vibration exist in the system, which limit the actuator applications.

This work focuses on the hysteresis characteristics in time and frequency domains along with experimental and simulated results to verify the effectiveness of …

Object Detection And Activity Recognition In Digital Image And Video Libraries, Ibrahim Burak Ozer

Dissertations

This thesis is a comprehensive study of object-based image and video retrieval, specifically for car and human detection and activity recognition purposes. The thesis focuses on the problem of connecting low level features to high level semantics by developing relational object and activity presentations. With the rapid growth of multimedia information in forms of digital image and video libraries, there is an increasing need for intelligent database management tools. The traditional text based query systems based on manual annotation process are impractical for today's large libraries requiring an efficient information retrieval system. For this purpose, a hierarchical information retrieval system …

An Efficient Expression Of The Timestamp And Period In Packet-And Cell-Based Schedulers, Dong Wei

Theses

Scheduling algorithms are implemented in hardware in high-speed switches to provide Quality-of-Service guarantees in both cell-based and packet-based networks. Being able to guarantee end-to-delay and fairness, timestamp-based fair queuing algorithms, which include SCFQ, WFQ, WF2Q and WF2Q+, have received much attention in the past few years. In timestamp-based fair queuing algorithms, the size of timestamp and period determines the supportable rates in terms of the range and accuracy. Furthermore, it also determines the scheduler's memory in terms of offchip bandwidth and storage space. An efficient expression can reduce the size of the timestamp and period without compromising the accuracy. In …

Highway Advisory Radio In The State Of New Jersey, Thomas Mark Nemeth

Theses

Highway Advisory Radio (HAR) is a broadcasting system used by transportation agencies to disseminate vital real-time traffic information to motorists. Each transmitter is restricted by the rules and regulations of the Federal Communications Commission (FCC) to an average broadcast radius of three to five miles. Most commonly these transmitters are located at major highway intersections, such that motorists may take alternate routes in case of congestion or emergencies.

All operational HAR transmitters in New Jersey were identified and their coverage zones were quantitatively characterized in terms of the signal to noise ratio at the receiver. These experimental results were then …

A Study And Some Experimental Work Of Digital Image And Video Watermarking, Tsui-Feng Liu

Theses

The rapid growth of digitized media and the emergence of digital networks have created a pressing need for copyright protection and anonymous communications schemes. Digital watermarking (or data hiding in a more general term) is a kind of steganography technique by adding information into a digital data stream. Several most important watermarking schemes applied to multilevel and binary still images and digital videos were studied. They include schemes based on DCT (Discrete Cosine Transform), DWT (Discrete Wavelet Transform), and fractal transforms. The question whether these invisible watermarking techniques can resolve the issue of rightful ownership of intellectual properties was discussed. …

The Determination Of Failure Occurring In The Stator Coil Winding Due To The Over-Voltage Using Matlab Software, Ali Reza Alavizadeh

Morehead State Theses and Dissertations

A thesis presented to the faculty of the College of Science & Technology at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science in Vocational Education / Technology by Ali Reza Alavizadeh on January 8, 2001.

Analysis And Synthesis Of Primary Side Cycle By Cycle Control Of Isolated Flyback Converters, Radoslaw Nalepa

Theses

This work presents the analysis and design of an isolated flyback converter, without feedback from the load side. The converter is controlled from the primary side using the switch voltage and innovative control circuit topologies.

A detail study of the flyback circuit is undertaken including all known parasitics. Besides the standard parasitics, for example the capacitor resistive effect, other more subtle effects are included in the model development such as inter coil couplingj source capacitance etc. Development of these models has provided information about circuit simplifications without losing accuracy of the model. As a consequence of this model development, it …

Study Of Dynamics And Mechanism Of Metal-Induced Silicon Growth, Elena A. Guliants, Wayne A. Anderson

Electrical and Computer Engineering Faculty Publications

The present study addresses the mechanism of metal-induced growth of device-quality silicon thin films. Si deposition was performed by magnetron sputtering on a 25-nm-thick Ni prelayer at 525–625 °C and yielded a continuous, highly crystalline film with a columnar structure. A Ni disilicide intermediate layer formed as a result of the Ni reaction with Si deposit provides a sufficient site for the Si epitaxial growth because lattice mismatch is small between the two materials. The reaction between Ni and Si was observed to progress in several stages. The NixSiy phase evolution in a Ni:Si layer was studied by x-ray photoelectron …

Uniform Random Number Generation Using Pseudorandom Binary Sequences, Susan Rea

Theses

Random numbers have conventionally been used in a range of applications such as numerical analysis, lotteries and computer simulation and as cryptographic keys. The algorithms used for the production of random numbers are termed pseudorandom, as the numbers produced are not truly random as they emanate from a deterministic periodic source that is they are predictable if a subset of the sequence is known. However, for most applications these pseudorandom number sources are entirely suitable.

For cryptographic key sources, however, the random number sequences must be statistically good and difficult to predict. Linear feedback shift registers are presented in this …

Optical Coherent Communication System Using Phase Shift Keying, Syed Javaid Iqbal

Student Works (2000-2009)

This thesis presents the experimental study and design of a coherent communication system by using phase shift keying (PSK). Systems are designed by using all passive elements, which make the system very easy to operate, and less maintenance is required. All the PSK designs are based on a single light source. In this thesis there are five different types of PSK with a single light source communication systems are designed. All designs are experimentally tested in free space. The systems are • All optical two-channel PSK communication system, by using single light source, "All optical single channel, two-way PSK communication, …

Dynamic Performance Of Isolated Power Converters, David Badia

Theses

Isolated power converters are primarily used in applications where electrical galvanic isolation is required for safety purposes. They are also used in applications, which require various output voltages level. They have been studied from many different aspects, but in this thesis the fundamental circuits of the flyback, the forward and the half-bridge converters are studied and compared extensively, with regard to their dynamic performance.

This analysis will lead us to a better understanding of their behaviour, that is a crucial point in the selection of each topology for a particular application. Moreover, the dynamic response of each converter is different; …

High Electron Mobility In Algan/Gan Heterostructures Grown On Bulk Gan Substrates, E. Frayssinet, W. Knap, P. Lorenzini, N. Grandjean, J. Massies, C. Skierbiszewski, T. Suski, I. Grzegory, S. Porowski, Grigory Simin, X. Hu, M. Asif Khan, M. S. Shur, R. Gaska, D. Maude

Faculty Publications

Dislocation-free high-quality AlGaN/GaN heterostructures have been grown by molecular-beam epitaxy on semi-insulating bulk GaN substrates. Hall measurements performed in the 300 K–50 mK range show a low-temperature electron mobility exceeding 60 000 cm²/V s for an electron sheet density of 2.4×10¹²cm⁻². Magnetotransport experiments performed up to 15 T exhibit well-defined quantum Hall-effect features. The structures corresponding to the cyclotron and spin splitting were clearly resolved. From an analysis of the Shubnikov de Hass oscillations and the low-temperature mobility we found the quantum and transport scattering times to be 0.4 and 8.2 ps, respectively. The …

Phase Tunability In A Conductor Backed Coplanar Waveguide Patch Antenna, Idan Mandelbaum

Theses

Traditionally beam steering in phase array antenna systems is achieved using tunable phase shifters or switched feed networks. Here, a tunable patch antenna element is suggested as a novel alternative to a combination of a radiating element and a phase shifter. A conductor backed coplanar waveguide patch antenna is chosen due to its suitability to mounted external tuning elements, using varactor diodes. Limited types of lumped tuning circuits, using varactor diodes, have been tested, though a lumped as well as distributed tuning is feasible in the chosen antenna configuration. Approximate analytical models for coplanar waveguide patch antennas with finite ground …

Reduction Of Peak To Average Power Ratio In Ofdm And Ofdm-Cdma System, Jie Cheng

Theses

High Peak to Average Power Ratio is a main problem in Orthogonal Frequency Division Multiplexing(OFDM) system and Orthogonal Frequency Division Multiplexing -Code Division Multiple Access (OFDM-CDMA) system. Considering a compensated High Power Amplifier(HPA), in order to keep linearity for amplification, Input Back-Off(IBO) of the HP-A, has to be increased for handling a high PAPR. Higher 1130 will make HPA less efficient. Additionally, a signal with high PAPR will suffer clipping when PAPR is larger than 1130 of the HPA. Clipping can cause the distortion of the signal and deteriorate the performance of the system. Reduction of PAPR is a main …