Systems and Communications Commons^™

Data Chunking In Quasi-Synchronous Ds-Cdma, Trevor Dalke

Master's Theses

DS-CDMA is a popular multiple access technique used in many mobile networks to efficiently share channel resources between users in a cell. Synchronization between users maximizes the user capacity of these systems. However, it is difficult to perfectly synchronize users in the reverse link due to the geographic diversity of mobile users in the cell. As a result, most commercial DS-CDMA networks utilize an asynchronous reverse link resulting in a reduced user capacity. A possible compromise to increase the user capacity in the reverse link is to implement a quasi-synchronous timing scheme, a timing scheme in which users are allowed …

Using Near-Field Coupled Circularly Polarized Antennas As Frequency Independent Variable Phase-Shifters, Vit Sipal, Adam Narbudowicz, Max Ammann

Articles

This paper introduces a novel concept of frequency-independent variable phase-shifters. It is based on the use of circularly polarized (CP) antennas coupled in the near-field. For transmission between two CP antennas in the far-field, a rotation around the boresight axis produces a phase change in the transfer function. This concept is exploited and validated also for near-field coupling between two CP antennas. Therefore, two close-coupled CP antennas can act as a adjustable phase-shifter with the phase-shift controlled by the angle between the structures. The bandwidth depends on the CP bandwidth of the antenna. This concept is valuable for future phase-shifters …

On Over-Determined Frequency Domain Bss, Christopher Osterwise, Steven L. Grant

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces two new frequency domain overdetermined blind source separation (BSS) algorithms: Inter-frequency Correlation with Microphone Diversity (ICMD), and ICA with Triggered Principal component analysis (ITP). In the first, we consider different sets of microphones, where in each set the number of microphones and sources are equal. In the second, we extract principal components from an overdetermined mixture to form a determined mixture for separation. Both techniques utilize inter-frequency correlation to align permutations via energy profiles. Both monitor the condition number of an inter-frequency cross-correlation matrix of the normalized de-mixed signals' envelopes to determine if separation has failed for …

Numerical Examination Of The Nonlinear Dynamics Of A Hybrid Acousto-Optic Bragg Cell With Positive Feedback Under Profiled Beam Propagation, Fares S. Almehmadi, Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

In standard weak interaction theory, acousto-optic Bragg analysis typically assumes that the incident light and sound beams are uniform plane waves. Acousto-optic Bragg diffraction with nonuniform profiled input beams is numerically examined under open loop via a transfer function formalism. Unexpected deviations in the first-order diffracted beam from the standard theory are observed for high �� values. These deviations are significant because the corresponding closed-loop system is sensitive to input amplitudes and initial conditions, and the overall impact on the dynamical behavior has not been studied previously in standard analyses. To explore the effect of such nonuniform output profiles on …

Measuring Political Brand Equity In Ireland, Ewan Alexander Mcdonald, Roger Sherlock, John Hogan Dr

Articles

Measuring Political Brand Equity in the Republic of Ireland

This paper will apply cognitive mapping techniques to understand the manner in which political brand equity is formed and distributed amongst the four largest Irish political parties from the perspective of citizens. It assesses the fundamental aspects of branding and brand equity in the marketing and political marketing literatures and offers and overview of the market in question – the Irish political environment. Primary data was generated through the participation of 232 citizens in the political brand elicitation stage and a further 75 citizens were involved in the construction of the …

Studies In Software-Defined Radio System Implementation, Harold A. Haldren Iii

Senior Honors Theses

Over the past decade, software-defined radios (SDRs) have an increasingly prevalent aspect of wireless communication systems. Different than traditional hardware radios which implement radio protocols using static electrical circuit, SDRs implement significant aspects of physical radio protocol using software programs running on a host processor. Because they use software to implement most of the radio functionality, SDRs are much more easily modified, edited, and upgraded than their hardware-defined counterparts. Consequently, researchers and developers have been developing previously hardware-defined radio systems within software. Thus, communication standards can be tested under different conditions or swapped out entirely by simply changing some code. …

Large-Scale Site And Frequency Diversity In Urban Peer-To-Peer Channels For Six Public Safety Frequency Bands, David W. Matolak, Kate A. Remley, Christopher L. Holloway, Qian Zhang, Qiong Wu

Faculty Publications

We report on peer-to-peer large-scale wireless channel characteristics for an urban environment in six public-safety bands, for five simultaneous receiving sites. Results are based upon measurements taken in Denver in July 2009 with stationary receivers and a pedestrian transmitter. The six frequencies at which we measured are (in MHz) 430, 750, 905, 1834, 2400, and 4860. We quantify both site and frequency diversity, and show that 5-site selection yields minimum average gains of 15 dB in mean received power levels; 5-site selection diversity also reduces received power variation by 17-29 dB, depending on frequency. Frequency diversity yields similar gains. By …

Studies In Error Correction Coding, Hannah Kirse

Senior Honors Theses

For a proper understanding of the implementation of error correction coding schemes, a basic knowledge of communication channels and networks is necessary. Communication channels incur several types of errors, including noise and signal attenuation. Consequently, the benefits of a particular error control scheme are determined by the errors which occur most frequently. First, the types of transmissions across which errors occur will be considered. Subsequently, the types of errors that can appear during these transmissions and a short discussion of the cause of errors are necessary to understand the several types of errors that can occur. Afterward, the implementation of …

Memristor-Based Neuron Circuit And Method For Applying Learning Algorithm In Spice, Christopher Yakopcic, R. Hasan, T.M. Taha, M. Mclean, D. Palmer

Electrical and Computer Engineering Faculty Publications

The learning of nonlinearly separable functions in cascaded memristor crossbar circuits is described and the feasibility of using them to develop low-power neuromorphic processors is demonstrated. This is the first study evaluating the training of memristor crossbars through SPICE simulations. It is important to capture the alternate current paths and wire resistance inherent in these circuits. The simulations show that neural network learning algorithms are able to train in the presence of alternate current paths and wire resistances. The fact that the approach reduces the area by three times and power by two orders of magnitude compared with the existing …

A Cavity-Backed Spiral Slot Antenna With Wide Axial Ratio Beamwidth For Gps System, Xiulong Bao, Max Ammann

Articles

A monofilar spiral slot antenna with a cavity-backed reflector is described. presented, which can achieve the performance of the wide Axial Ratio beamwave for Global Positioning System GPS system. It comprises an arrangement of a single printed spiral slots fed by a 50 Ω microstrip line. By using cavity-backed covering the slot structure, a wide axial ratio beamwidth performance is achieved in the GPS L1 frequency. The angle with less than 3 dB axial ratio at 1.575 GHz in the YoZ plane is about 215 degree. The measured results show that the HPWB beamwidths at 1.575 GHz are 100 degree …

Numerical Analysis Of First-Order Acousto-Optic Bragg Diffraction Of Profiled Optical Beams Using Open-Loop Transfer Functions, Monish Ranjan Chatterjee, Fares S. Almehmadi

Electrical and Computer Engineering Faculty Publications

In standard acousto-optic Bragg analysis, the incident light and sound beams are assumed to be uniform plane waves (with constant profiles) leading to the results based on standard weak interaction theory. As a follow-up to earlier work dealing with nonuniform incident optical beams, we revisit the problem of Bragg diffraction under nonuniform profiles, and include Gaussian, third-order Hermite–Gaussian, and zeroth-order Bessel profiles in our investigation, along with a few others. The first-order diffracted beam is examined (using a transfer function formalism based on angular spectra) under several parametric limits [such as the Klein–Cook parameter Q, the effective profile width, and …

Analytical Models For Distribution Of The Envelope And Phase Of Linearly Modulated Signals In Awgn Channel, Taleb Moazzeni, Yingtao Jiang, Henry Selvaraj, Tianding Chen

Electrical & Computer Engineering Faculty Research

In this paper, analytical expressions for the distribution of the envelope and phase of linearly modulated signals such as BPSK, M-PSK, and M-QAM in AWGN are presented. We perform numerical simulations for different orders of signal constellations. The results show that the proposed theoretical models are in excellent agreement with the estimated distributions from various numerical experiments.

Investigation Of Profiled Beam Propagation Through A Turbulent Layer And Temporal Statistics Of Diffracted Output For A Modified Von Karman Phase Screen, Monish Ranjan Chatterjee, Fathi H.A. Mohamed

Electrical and Computer Engineering Faculty Publications

Gaussian beam propagation through a turbulent layer has been studied using a split-step methodology. A modified von Karman spectrum (MVKS) model is used to describe the random behavior of the turbulent media. Accordingly, the beam is alternately propagated (i) through a thin Fresnel layer, and hence subjected to diffraction; and (ii) across a thin modified von Karman phase screen which is generated using the power spectral density (PSD) of the random phase obtained via the corresponding PSD of the medium refractive index for MVKS turbulence.

The random phase screen in the transverse plane is generated from the phase PSD by …

Numerical Inversion And Assessment Of 2d Laplace Transforms Using The Brancik Algorithm And Its Use In 3d Holography, Monish Ranjan Chatterjee, Le Feng

Electrical and Computer Engineering Faculty Publications

An analytic examination of 3D holography under a 90° recording geometry was carried out earlier in which 2D spatial Laplace transforms were introduced in order to develop transfer functions for the scattered outputs under readout [1,2].

Thereby, the resulting reconstructed output was obtained in the 2D Laplace domain whence the spatial information would be found only by performing a 2D Laplace inversion. Laplace inversion in 2D was attempted by testing a prototype function for which the analytic result was known using two known inversion algorithms, viz., the Brancik and the Abate [2]. The results indicated notable differences in the 3D …

Second-Harmonic Double-Resonance Cones In Dispersive Hyperbolic Metamaterials, Domenico De Ceglia, Maria Antonietta Vincenti, Salvatore Campione, Filippo Capolino, Joseph W. Haus, Michael Scalora

Electrical and Computer Engineering Faculty Publications

We study the formation of second-harmonic double-resonance cones in hyperbolic metamaterials. An electric dipole on the surface of the structure induces second-harmonic light to propagate into two distinct volume plasmon-polariton channels: a signal that propagates within its own peculiar resonance cone and a phase-locked signal that is trapped under the pump's resonance cone. Metamaterial dispersion and birefringence induce a large angular divergence between the two volume plasmon polaritons, making these structures suitable for subwavelength second- and higher-harmonic imaging microscopy.

Omnidirectional Microstrip Patch Antenna With Reconfigurable Pattern And Polarisation, Max Ammann, Xiulong Bao, Adam Narbudowicz

Articles

An omnidirectional microstrip patch antenna, capable of reconfiguring both polarisation and radiation pattern is proposed. It operates with two orthogonal ±45° slanted linear polarisations and can produce two dipole-like radiation patterns, providing 360° coverage in either the horizontal or elevation plane. With appropriate steering, this enables a single antenna to provide full spherical coverage for any polarisation. The reconfiguration is realised by phase shifting, thus does not require switching elements, such as MEMS or pin diodes embedded into antenna. The basic principles of operation are discussed and validated by numerical and measured data.

Design And Analysis Of Circularly Polarized Electrically Small Antennas, Jesse R. Ludwig

College of Graduate Studies: Theses & Dissertations

A growing need for efficient wireless communication is prevalent in the world in which we live. From cell phones to television to GPS applications, wireless communications are vital in consumer electronics and military applications. In these applications, a miniaturized antenna is sometimes necessary for reducing overall size of the communication system. For many satellite based communication applications, circular polarization in antennas is needed for efficient communication. In this thesis, the miniaturization technique known as T-top loading is utilized on two novel antenna designs. One design is an electrically small, circularly polarized planar cross dipole and the other design is a …

Intelligent Approaches For Modeling And Optimizing Hvac Systems, Iii Raymond Tesiero

Dissertations

Advanced energy management control systems (EMCS), or building automation systems (BAS), offer an excellent means of reducing energy consumption in heating, ventilating, and air conditioning (HVAC) systems while maintaining and improving indoor environmental conditions. This can be achieved through the use of computational intelligence and optimization. This research will evaluate model-based optimization processes (OP) for HVAC systems utilizing MATLAB, genetic algorithms and self-learning or self-tuning models (STM), which minimizes the error between measured and predicted performance data. The OP can be integrated into the EMCS to perform several intelligent functions achieving optimal system performance. The development of several self-learning HVAC …

Applying Spiking Neural Network Simulation To Neuromodulatory Autonomous Robot Control, Cameron Muhammad

Phi Kappa Phi Research Symposium (Archived)

In this paper, simulation of the brain based on an artificial spiking neuron model is used to create a self-learning algorithm. The spiking neuron simulation is used to demonstrate a neuromodulation program in which the reward seeking properties of dopamine, the risk-adverse effects of serotonin, and the attention-focusing effects of the cholinergic and noradrenergic systems are applied to a mobile robotic platform as it moves autonomously throughout an environment. External stimuli is recorded by the program as spiking “events” that result in corresponding amounts of dopamine and serotonin influenced spiking patterns. These spiking patterns affect how the robot adapts to …

Translation Of 'Seasons Of Life: A Panoramic Selection Of Songs By Rabindranath Tagore', Monish Ranjan Chatterjee

Electrical and Computer Engineering Faculty Publications

No abstract provided.