Engineering Commons^™

The Context-Oriented Architecture: Integrating Context Into Semantic Web Services, Aisha Mohamed-Salama Elsafty

Archived Theses and Dissertations

No abstract provided.

Web Services - Based Autonomic Computing Framework (Wsac), Sherif Atef Gurguis

Archived Theses and Dissertations

No abstract provided.

New Hybrid Automatic Repeat Request (Harq) Scheme For 4x4 Mimo System, Based On The Extended Alamouti Quasi-Orthogonal Space-Time Bloc Coding (Q-Stbc), In Invariant And Variant Fading Channel, Jordi Ferrer Torras

Theses

A new Hybrid Automatic Repeat reQuest (HARQ) combining scheme for a 4x4 Multiple Input Multiple Output (MIMO) system in invariant and variant fading channel conditions is proposed and analized. Based on the Extended Alamouti Quasi-orthogonal Space-Time Block Coding (Q-STBC), the use of the so-called Alternative Matrices for transmission, depending on the Channel State Information (CSI) received as feedback, is compared to other existing solutions.

Sign changes and permutations in the retransmission sequences allow reducing the interference while exploiting the spatial diversity to introduce some gain in the signal power. The best transmission order is selected by the Determinant Criterion, which …

Location Estimation In A 3d Environment Using Radio Frequency Identification Tags, Adwitiya Akash Jain

Theses

RFID tag location estimation in a 3D environment is investigated. The location of the tag with unknown coordinates can be estimated with certain accuracy. However, accuracy can be improved using the knowledge based on measurement of additional reference tags with known location. This thesis studies the mathematical formulation and practical realization of location sensing using RFID tags.

Deviating from the standard use of RFID technology which employs one tag reader to identify the presence of tag, here multiple tag readers with known location are used to estimate the physical location of an individual tag, with/without the help of few reference …

Characterization And Design Of High-Level Vhdl I/Q Frequency Downconverter Via Special Sampling Scheme, Jesse P. Somann

Theses and Dissertations

This study explores the characterization and implementation of a Special Sampling Scheme (SSS) for In-Phase and Quad-Phase (I/Q) down conversion utilizing top-level, portable design strategies. The SSS is an under-developed signal sampling methodology that can be used with military and industry receiver systems, specifically, United States Air Force (USAF) video receiver systems. The SSS processes a digital input signal-stream sampled at a specified sampling frequency, and down converts it into In-Phase (I) and Quad-Phase (Q) output signal-streams. Using the theory and application of the SSS, there are three main objectives that will be accomplished: characterization of the effects of input, …

Supplementing An Ad-Hoc Wireless Network Routing Protocol With Radio Frequency Identification (Rfid) Tags, Leroy S. Willemsen

Theses and Dissertations

Wireless sensor networks (WSNs) have a broad and varied range of applications, yet all of these are limited by the resources available to the sensor nodes that make up the WSN. The most significant resource is energy. A WSN may be deployed to an inhospitable or unreachable area, leaving it with a non-replenishable power source. This research examines a way of reducing energy consumption by augmenting the nodes with radio frequency identification (RFID) tags that contain routing information. It was expected that RFID tags would reduce the network throughput, the ad hoc on-demand distance vector (AODV) routing traffic sent, and …

Optimal Coverage Of Theater Targets With Small Satellite Constellations, Axel Rendon

Theses and Dissertations

The daylight passes of a low-Earth orbit satellite over a targeted latitude and longitude are optimized by varying the inclination and eccentricity of an orbit at different altitudes. This investigation extends the work by Emery et al, in which the optimal Right Ascension of the Ascending Node was determined for a circular, matched inclination orbit. The optimal values were determined by a numerical research method based on Emery et al's Matlab program. Results indicate that small increases in inclination raise the number of daylight passes up to 33%. These optimal inclinations depend on the satellite semi-major axis. Eccentricity increases also …

New Hybrid Automatic Repeat Request (Harq) Combining With Space Time Block Coding (Stbc) In Invariant And Variant Fading Channel, Guillem Ernest Malagarriga Vilella

Theses

Hybrid Automatic Repeat reQuest (HARQ) combining for space time block coding Multiple Input Multiple Output (MIMO) system consisting of N transmit antennas and M receive antennas (NxM) in a time invariant channel and in a time varying channel is proposed and its performance is analyzed. Based on the measured channel matrix, the receiver chooses the best retransmission order and communicated it to the transmitter.

The scheme, where this algorithm is performed, is a combination of a precombining HARQ scheme and the Multiple Alamouti Space-Time Block Coding (MASTBC), which is suitable for more than 2 transmit antennas. The combination of this …

On The Performance Evaluation Of High-Speed Transport Protocols, Bridget Hillyer

UNF Graduate Theses and Dissertations

As high-speed networks with large bandwidth delay products (BDP) become more common, high-speed transport protocols must be developed that perform well in these contexts. TCP has limitations in high BDP networks. A number of high-speed TCP proposals have emerged, including BIC TCP, High Speed TCP, and H-TCP. XCP is an intraprotocol communication mechanism that promises even greater performance by providing explicit feedback from routers about congestion. It requires changes to routers and end hosts, though, whereas the other experimental protocols only require changes to an end host. We evaluated the performance ofXCP against BIC TCP, High Speed TCP, H-TCP, and …

Free Roaming: A System For Ubiquitous Computing, Huanjin Liu

Theses Digitization Project

Based on the Umbilical Cord system, this project enriches the Ubiquitous Computing system with a Free Roaming system. This Free Roaming consists of a distributed authentication system, a data caching system and a communication system between them. It allows user to roam within this system and access his data everywhere. Together with the Umbilical Cord system, a Ubiquitous Computing system is functionally completed as a prototype, and is ready to be deployed into the Internet.

Linux Based Pda Gateway For Wireless Sensor Networks, Áine Mccarthy

Theses

Recent years have seen a dramatic increase in the development and deployment of intelligent sensors and their use with a plethora of networking protocol technologies. Wireless Sensor Networks (WSN) can be used to monitor the environment, objects in the environment and the interaction of these objects with each other. Examples include environment and habitat monitoring, structural monitoring, disaster management and emergency response. The deployment of such large-scale WSN possess many challenges, the most important being scalability, portability, fault tolerance, adaptability and ubiquitous connectivity. There also exist many challenges when trying to establish communication with WSN. WSN can function as a …

Analysis Of Relay-Based Cellular Systems, Ansuya Negi

Dissertations and Theses

Relays can be used in cellular systems to increase coverage as well as reduce the total power consumed by mobiles in a cell. This latter benefit is particularly useful for mobiles operating on a depleted battery. The relay can be a mobile, a car or any other device with the appropriate communication capabilities. In thesis we analyze the impact of using relays under different situations. We first consider the problem of reducing total power consumed in the system by employing relays intelligently. We find that in a simulated, fully random, mobile cellular network for CDMA (Code Division Multiple Access), significant …

Design Of Survivable Wdm Network Based On Pre-Configured Protection Cycle, Byungkyu Kang

Theses: Doctorates and Masters

Wavelength Division Multiplexing (WDM) is an important technique which allows the trans- port of large quantities of data over optical networks. All optical WDM-based networks have been used to improve overall communication capacity and provide an excellent choice for the design of backbone networks. However, due to the high traffic load that each link can carry in a WDM network, survivability against failures becomes very important. Survivability in this context is the ability of the network to maintain continuity of service against failures, since a failure can lead to huge data losses. In recent years, many survivability mechanisms have been …