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Description
Fiber-Wireless (FiWi) network is the future network configuration that uses optical fiber as backbone transmission media and enables wireless network for the end user. Our study focuses on the Dynamic Bandwidth Allocation (DBA) algorithm for EPON upstream transmission. DBA, if designed properly, can dramatically improve the packet transmission delay and overall bandwidth utilization. With new DBA components coming out in research, a comprehensive study of DBA is conducted in this thesis, adding in Double Phase Polling coupled with novel Limited with Share credits Excess distribution method. By conducting a series simulation of DBAs using different components, we found out that grant sizing has the strongest impact on average packet delay and grant scheduling also has a significant impact on the average packet delay; grant scheduling has the strongest impact on the stability limit or maximum achievable channel utilization. Whereas the grant sizing only has a modest impact on the stability limit; the SPD grant scheduling policy in the Double Phase Polling scheduling framework coupled with Limited with Share credits Excess distribution grant sizing produced both the lowest average packet delay and the highest stability limit.
ContributorsZhao, Du (Author) / Reisslein, Martin (Thesis advisor) / McGarry, Michael (Committee member) / Fowler, John (Committee member) / Arizona State University (Publisher)
Created2011
Description
A proposed visible spectrum nanoscale imaging method requires material with permittivity values much larger than those available in real world materials to shrink the visible wavelength to attain the desired resolution. It has been proposed that the extraordinarily slow propagation experienced by light guided along plasmon resonant structures is a viable approach to obtaining these short wavelengths. To assess the feasibility of such a system, an effective medium model of a chain of Noble metal plasmonic nanospheres is developed, leading to a straightforward calculation of the waveguiding properties. Evaluation of other models for such structures that have appeared in the literature, including an eigenvalue problem nearest neighbor approximation, a multi- neighbor approximation with retardation, and a method-of-moments method for a finite chain, show conflicting expectations of such a structure. In particular, recent publications suggest the possibility of regions of invalidity for eigenvalue problem solutions that are considered far below the onset of guidance, and for solutions that assume the loss is low enough to justify perturbation approximations. Even the published method-of-moments approach suffers from an unjustified assumption in the original interpretation, leading to overly optimistic estimations of the attenuation of the plasmon guided wave. In this work it is shown that the method of moments approach solution was dominated by the radiation from the source dipole, and not the waveguiding behavior claimed. If this dipolar radiation is removed the remaining fields ought to contain the desired guided wave information. Using a Prony's-method-based algorithm the dispersion properties of the chain of spheres are assessed at two frequencies, and shown to be dramatically different from the optimistic expectations in much of the literature. A reliable alternative to these models is to replace the chain of spheres with an effective medium model, thus mapping the chain problem into the well-known problem of the dielectric rod. The solution of the Green function problem for excitation of the symmetric longitudinal mode (TM01) is performed by numerical integration. Using this method the frequency ranges over which the rod guides and the associated attenuation are clearly seen. The effective medium model readily allows for variation of the sphere size and separation, and can be taken to the limit where instead of a chain of spheres we have a solid Noble metal rod. This latter case turns out to be the optimal for minimizing the attenuation of the guided wave. Future work is proposed to simulate the chain of photonic nanospheres and the nanowire using finite-difference time-domain to verify observed guided behavior in the Green's function method devised in this thesis and to simulate the proposed nanosensing devices.
ContributorsHale, Paul (Author) / Diaz, Rodolfo E (Thesis advisor) / Goodnick, Stephen (Committee member) / Aberle, James T., 1961- (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2013
Description
With internet traffic being bursty in nature, Dynamic Bandwidth Allocation(DBA) Algorithms have always been very important for any broadband access network to utilize the available bandwidth effciently. It is no different for Passive Optical Networks(PON), which are networks based on fiber optics in the physical layer of TCP/IP stack or OSI model, which in turn increases the bandwidth in the upper layers. The work in this thesis covers general description of basic DBA Schemes and mathematical derivations that have been established in research. We introduce a Novel Survey Topology that classifes DBA schemes based on their functionality. The novel perspective of classification will be useful in determining which scheme will best suit consumer's needs. We classify DBA as Direct, Intelligent and Predictive back on its computation method and we are able to qualitatively describe their delay and throughput bounds. Also we describe a recently developed DBA Scheme, Multi-thread polling(MTP) used in LRPON and describes the different viewpoints and issues and consequently introduce a novel technique Parallel Polling that overcomes most of issues faced in MTP and that promises better delay performance for LRPON.
ContributorsMercian, Anu (Author) / Reisslein, Martin (Thesis advisor) / McGarry, Michael (Committee member) / Tepedelenlioğlu, Cihan (Committee member) / Zhang, Yanchao (Committee member) / Arizona State University (Publisher)
Created2012
Description
Multiport antennas offer greater design flexibility than traditional one-port designs. An antenna array is a special case of a multiport antenna. If the antenna's inter-element spacing is electrically small, the antenna is capable of achieving superdirectivity. Superdirective antenna arrays are known to be narrow band and have low radiation resistance which leads to low radiation efficiency and high VSWR. However, by increasing the self-impedance of the antenna elements, the radiation resistance is increased but the bandwidth remains narrow. A design methodology is developed using the ability to superimpose electric fields and multi-objective optimization to design antenna feed networks. While the emphasis in this dissertation is on antenna arrays and superdirectivity, the design methodology is general and can be applied to other multiport antennas. The design methodology is used to design a multiport impedance-matching network and optimize both the input impedance and radiation pattern of a two-port superdirective antenna array. It is shown that the multiport impedance-matching network is capable of improving the input impedance of the antenna array while maintaining high directionality. The antenna design is critical for the methodology to improve the bandwidth and radiation characteristics of the array. To double the bandwidth of the two-port impedance matched superdirective antenna array, a three-port Yagi-Uda antenna design is demonstrated. The addition of the extra antenna element does not increase the footprint of the antenna array. The design methodology is then used to design a symmetrical antenna array capable of steering its main beam in two directions.
ContributorsArceo, Diana (Author) / Balanis, Constantine A (Thesis advisor) / Aberle, James T., 1961- (Committee member) / Moeller, Karl (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2012
Description
Nanophotonics studies the interaction of light with nanoscale devices and nanostructures. This thesis focuses on developing nanoscale devices for optical modulation (saturable absorber and all-optical modulator) and investigating light scattering from nanoparticles for underwater navigation and energy sector application. Saturable absorbers and all-optical modulators are essential to generate ultrashort high-power laser pulses and high-speed communications. Graphene-based devices are broadband, ultrafast, and compatible with different substrates and fibers. Nevertheless, the required fluence to saturate or modulate the optical signal with graphene is still high to realize low-threshold, compact broadband devices, which are essential for many applications. This dissertation emphasizes that the strong light-matter interaction in graphene-plasmonic hybrid metasurface greatly enhances monolayer graphene’s saturable absorption and optical signal modulation effect while maintaining graphene’s ultrafast carrier dynamics. Furthermore, based on this concept, simulation models and experimental demonstrations are presented in this dissertation to demonstrate both subwavelength (~λ/5 in near-infrared and ~λ/10 in mid-infrared) thick graphene-based saturable absorber (with record-low saturation fluence (~0.1μJ/cm2), and ultrashort recovery time (~60fs) at near-infrared wavelengths) and all-optical modulators ( with 40% reflection modulation at 6.5μm with ~55μJ/cm2 pump fluence and ultrafast relaxation time of ~1ps at 1.56μm with less than 8μJ/cm2 pump fluence).
Underwater navigation is essential for various underwater vehicles. However, there is no reliable method for underwater navigation. This dissertation presents a numerical simulation model and algorithm for navigation based on underwater polarization mapping data. With the methods developed, for clear water in the swimming pool, it is possible to achieve a sun position error of 0.35˚ azimuth and 0.03˚ zenith angle, and the corresponding location prediction error is ~23Km. For turbid lake water, a location determination error of ~100Km is achieved. Furthermore, maintenance of heliostat mirrors and receiver tubes is essential for properly operating concentrated solar power (CSP) plants. This dissertation demonstrates a fast and field deployable inspection method to measure the heliostat mirror soiling levels and receiver tube defect detection based on polarization images. Under sunny and clear sky conditions, accurate reflection efficiency (error ~1%) measurement for mirrors with different soiling levels is achieved, and detection of receiver tube defects is demonstrated.
ContributorsRafique, Md Zubair Ebne (Author) / Yao, Yu (Thesis advisor) / Palais, Joseph (Committee member) / Zhang, Yong-Hang (Committee member) / Sukharev, Maxim (Committee member) / Arizona State University (Publisher)
Created2022
Description
Existing radio access networks (RANs) allow only for very limited sharing of thecommunication and computation resources among wireless operators and heterogeneous
wireless technologies. The introduced LayBack architecture facilitates communication
and computation resource sharing among different wireless operators and technologies.
LayBack organizes the RAN communication and multiaccess edge computing (MEC)
resources into layers, including a devices layer, a radio node (enhanced Node B and
access point) layer, and a gateway layer. The layback optimization study addresses
the problem of how a central SDN orchestrator can flexibly share the total backhaul
capacity of the various wireless operators among their gateways and radio nodes
(e.g., LTE enhanced Node Bs or Wi-Fi access points). In order to facilitate
flexible network service virtualization and migration, network functions (NFs) are increasingly
executed by software modules as so-called "softwarized NFs" on General-Purpose
Computing (GPC) platforms and infrastructures. GPC platforms are not specifically
designed to efficiently execute NFs with their typically intense Input/Output (I/O)
demands. Recently, numerous hardware-based accelerations have been developed to
augment GPC platforms and infrastructures, e.g., the central processing unit (CPU)
and memory, to efficiently execute NFs. The computing capabilities of client devices
are continuously increasing; at the same time, demands for ultra-low latency (ULL)
services are increasing. These ULL services can be provided by migrating some
micro-service container computations from the cloud and multi-access edge computing
(MEC) to the client devices.
ContributorsShantharama, Prateek (Author) / Reisslein, Martin (Thesis advisor) / McGarry, Michael (Committee member) / Thyagaturu, Akhilesh (Committee member) / Zhang, Yanchao (Committee member) / Arizona State University (Publisher)
Created2022
Description
This dissertation consists of four parts: design of antenna in lossy media, analysisof wire antennas using electric field integral equation (EFIE) and wavelets, modeling and measurement of grounded waveguide coplanar waveguide (GCPW) for automotive radar, and E-Band 3-D printed antenna and measurement using VNA. In the first part, the antenna is modeled and simulated in lossy media. First, the vector wave functions is solved in the fundamental mode. Next the energy flow velocity is plotted to show near-field energy distribution for both TM and TE in air and seawater environment. Finally the power relation in seawater is derived to calculate the source dipole moment and required power.
In the second part, the current distribution on the antenna is derived by solving EFIE with moment of methods (MoM). Both triangle and Coifman wavelet (Coiflet) are used as basis and weight functions. Then Input impedance of the antenna is computed and results are compared with traditional sinusoid current distribution assumption. Finally the input impedance of designed antenna is computed and matching network is designed and show resonant at designed frequency.
In the third part, GCPW is modeled and measured in E-band. Laboratory measurements are conducted in 75 to 84 GHz. The original system is embedded with error boxes due to misalignment and needed to be de-embedded. Then the measurement data is processed and the results is compared with raw data.
In the fourth part, the horn antennas and slotted waveguide array antenna (SWA) are designed for automotive radar in 75GHz to 78GHz. The horn antennas are fabricated using 3D printing of ABS material, and electro-plating with copper. The analytic solution and HFSS simulation show good agreement with measurement.
ContributorsZhou, Sai (Author) / Pan, George (Thesis advisor) / Aberle, James (Committee member) / Palais, Joseph (Committee member) / Allee, David (Committee member) / Arizona State University (Publisher)
Created2021
Description
Antenna arrays are widely used in wireless communication, radar, remote sensing, and other fields. Compared to traditional linear antenna arrays, novel nonlinear antenna arrays have fascinating advantages in terms of structural simplicity, lower cost, wider bandwidth, faster scanning speed, and lower side-lobe levels. This dissertation explores a novel design of a phased array antenna with an augmented scanning range, aiming to establish a clear connection between mathematical principles and practical circuitry. To achieve this goal, the Van der Pol (VDP) model is applied to a single-transistor oscillator to obtain the isolated limit cycle. The coupled oscillators are then integrated into a 1 times 7 coupled phased array, using the Keysight PathWave Advanced Design System (ADS) for tuning and optimization. The VDP model is used for analytic study of bifurcation, quasi-sinusoidal oscillation, quasi-periodic chaos, and oscillator death, while ADS schematics guide engineering implementation and physical fabrication. The coupled oscillators drive cavity-backed antennas, forming a one-dimensional scanning antenna array of 1 times 7. The approaches for increasing the scanning range performance are discussed.
ContributorsZhang, Kaiyue (Author) / Pan, George (Thesis advisor) / Yu, Hongbin (Committee member) / Aberle, James (Committee member) / Palais, Joseph (Committee member) / Arizona State University (Publisher)
Created2023
Description
Polarization imaging and polarization microscopy is of great interest in industrial inspection, defense, biomedical and clinical research, food safety, etc. An ideal polarization imaging system suitable for versatile applications should be full-Stokes, compact, broadband, fast, and highly accurate within a large operation angle. However, such a polarization imaging system remains elusive among state-of-the-art technology. Recently, flat optics based on metasurfaces have been explored for polarization detection and imaging. Compared with state-of-art, metasurface-based solutions have the advantages of compactness, great design flexibility, and feasibility for on-chip integration. This dissertation reports a dual wavelength (630 to 670nm and 480nm to 520nm) chiral metasurfaces featured with sub-wavelength dimension, extinction ratio over 10 across a broad operation bandwidth (175nm) and efficiency over 60%, which can be used for detection and generation of circular polarization (Chapter 2).
This dissertation then reports a chip-integrated full-Stokes polarimetric Complementary metal–oxide–semiconductor (CMOS) imaging sensor based on metasurface polarization filter arrays (MPFA) mentioned above. The sensor has high measurement accuracy of polarization states with an angle of view up to 40°. Calibration and characterization of the device are demonstrated, whereby high polarization states measurement accuracy (measurement error <4%) at incidence angle up to ±20° and full Stokes polarization images of polarized objects are shown. (Chapter 3).
A scalable fabrication approach based on nano imprint lithography is demonstrated, with improved fabrication efficiency, lower cost, and higher optical performance up to 10 times compared to EBL process. (Chapter 4).
Several polarization imaging applications including a dual-camera full-Stokes underwater polarization navigation system are discussed. Polarization mapping under clear sky and clear water is demonstrated for proof concept. Enhancing contrast of objects through turbid water and polarization images of silver dendrites are also discussed (Chapter 5).
Though distinctive in its advantages in rich polarization information, most existing Mueller matrix microscope (MMM) operate at single mode, narrow bandwidth with bulky components. This dissertation reports a compact, dual wavelength, dual mode MMM with satisfactory measurement accuracy (Mueller matrix (MM) measurement error≤ 2.1%) using polarimetric imaging sensor mentioned previously, MM imaging of photonic structures, bio-tissues, etc are demonstrated for proof of concept (Chapter 6).
ContributorsZuo, Jiawei (Author) / Yao, Yu (Thesis advisor) / Wang, Chao (Thesis advisor) / Palais, Joseph (Committee member) / Sinha, Kanupriya (Committee member) / Arizona State University (Publisher)
Created2023
Description
Emerging modular cable network architectures distribute some cable headend functions to remote nodes that are located close to the broadcast cable links reaching the cable modems (CMs) in the subscriber homes and businesses. In the Remote- PHY (R-PHY) architecture, a Remote PHY Device (RPD) conducts the physical layer processing for the analog cable transmissions, while the headend runs the DOCSIS medium access control (MAC) for the upstream transmissions of the distributed CMs over the shared cable link. In contrast, in the Remote MACPHY (R-MACPHY) ar- chitecture, a Remote MACPHY Device (RMD) conducts both the physical and MAC layer processing. The dissertation objective is to conduct a comprehensive perfor- mance comparison of the R-PHY and R-MACPHY architectures. Also, development of analytical delay models for the polling-based MAC with Gated bandwidth alloca- tion of Poisson traffic in the R-PHY and R-MACPHY architectures and conducting extensive simulations to assess the accuracy of the analytical model and to evaluate the delay-throughput performance of the R-PHY and R-MACPHY architectures for a wide range of deployment and operating scenarios. Performance evaluations ex- tend to the use of Ethernet Passive Optical Network (EPON) as transport network between remote nodes and headend. The results show that for long CIN distances above 100 miles, the R-MACPHY architecture achieves significantly shorter mean up- stream packet delays than the R-PHY architecture, especially for bursty traffic. The extensive comparative R-PHY and R-MACPHY comparative evaluation can serve as a basis for the planning of modular broadcast cable based access networks.
ContributorsAlharbi, Ziyad Ghazai (Author) / Reisslein, Martin (Thesis advisor) / Thyagaturu, Akhilesh (Committee member) / Zhang, Yanchao (Committee member) / McGarry, Michael (Committee member) / Arizona State University (Publisher)
Created2019