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  Partner: UNT Libraries
 Degree Discipline: Computer Science
 Collection: UNT Theses and Dissertations
Bounded Dynamic Source Routing in Mobile Ad Hoc Networks

Bounded Dynamic Source Routing in Mobile Ad Hoc Networks

Access: Use of this item is restricted to the UNT Community.
Date: August 2003
Creator: George, Glyco
Description: A mobile ad hoc network (MANET) is a collection of mobile platforms or nodes that come together to form a network capable of communicating with each other, without the help of a central controller. To avail the maximum potential of a MANET, it is of great importance to devise a routing scheme, which will optimize upon the performance of a MANET, given the high rate of random mobility of the nodes. In a MANET individual nodes perform the routing functions like route discovery, route maintenance and delivery of packets from one node to the other. Existing routing protocols flood the network with broadcasts of route discovery messages, while attempting to establish a route. This characteristic is instrumental in deteriorating the performance of a MANET, as resource overhead triggered by broadcasts is directly proportional to the size of the network. Bounded-dynamic source routing (B-DSR), is proposed to curb this multitude of superfluous broadcasts, thus enabling to reserve valuable resources like bandwidth and battery power. B-DSR establishes a bounded region in the network, only within which, transmissions of route discovery messages are processed and validated for establishing a route. All route discovery messages reaching outside of this bounded region are dropped, thus ...
Contributing Partner: UNT Libraries
Building an Intelligent Filtering System Using Idea Indexing

Building an Intelligent Filtering System Using Idea Indexing

Date: August 2003
Creator: Yang, Li
Description: The widely used vector model maintains its popularity because of its simplicity, fast speed, and the appeal of using spatial proximity for semantic proximity. However, this model faces a disadvantage that is associated with the vagueness from keywords overlapping. Efforts have been made to improve the vector model. The research on improving document representation has been focused on four areas, namely, statistical co-occurrence of related items, forming term phrases, grouping of related words, and representing the content of documents. In this thesis, we propose the idea-indexing model to improve document representation for the filtering task in IR. The idea-indexing model matches document terms with the ideas they express and indexes the document with these ideas. This indexing scheme represents the document with its semantics instead of sets of independent terms. We show in this thesis that indexing with ideas leads to better performance.
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Modeling Complex Forest Ecology in a Parallel Computing Infrastructure

Modeling Complex Forest Ecology in a Parallel Computing Infrastructure

Date: August 2003
Creator: Mayes, John
Description: Effective stewardship of forest ecosystems make it imperative to measure, monitor, and predict the dynamic changes of forest ecology. Measuring and monitoring provides us a picture of a forest's current state and the necessary data to formulate models for prediction. However, societal and natural events alter the course of a forest's development. A simulation environment that takes into account these events will facilitate forest management. In this thesis, we describe an efficient parallel implementation of a land cover use model, Mosaic, and discuss the development efforts to incorporate spatial interaction and succession dynamics into the model. To evaluate the performance of our implementation, an extensive set of simulation experiments was carried out using a dataset representing the H.J. Andrews Forest in the Oregon Cascades. Results indicate that a significant reduction in the simulation execution time of our parallel model can be achieved as compared to uni-processor simulations.
Contributing Partner: UNT Libraries
Performance Analysis of Wireless Networks with QoS Adaptations

Performance Analysis of Wireless Networks with QoS Adaptations

Date: August 2003
Creator: Dash, Trivikram
Description: The explosive demand for multimedia and fast transmission of continuous media on wireless networks means the simultaneous existence of traffic requiring different qualities of service (QoS). In this thesis, several efficient algorithms have been developed which offer several QoS to the end-user. We first look at a request TDMA/CDMA protocol for supporting wireless multimedia traffic, where CDMA is laid over TDMA. Then we look at a hybrid push-pull algorithm for wireless networks, and present a generalized performance analysis of the proposed protocol. Some of the QoS factors considered include customer retrial rates due to user impatience and system timeouts and different levels of priority and weights for mobile hosts. We have also looked at how customer impatience and system timeouts affect the QoS provided by several queuing and scheduling schemes such as FIFO, priority, weighted fair queuing, and the application of the stretch-optimal algorithm to scheduling.
Contributing Partner: UNT Libraries
Resource Allocation in Mobile and Wireless Networks

Resource Allocation in Mobile and Wireless Networks

Access: Use of this item is restricted to the UNT Community.
Date: August 2003
Creator: Owens II, Harold
Description: The resources (memory, power and bandwidth) are limited in wireless and mobile networks. Previous research has shown that the quality of service (QoS) of the mobile client can be improved through efficient resources management. This thesis contains two areas of research that are strongly interrelated. In the first area of research, we extended the MoSync Algorithm, a network application layer media synchronization algorithm, to allow play-out of multimedia packets by the base station upon the mobile client in a First-In-First-Out (FIFO), Highest-Priority-First (PQ), Weighted Fair-Queuing (WFQ) and Round-Robin (RR) order. In the second area of research, we make modifications to the DSR and TORA routing algorithms to make them energy aware routing protocols. Our research shows that the QoS of the mobile client can be drastically improved through effective resource allocation.
Contributing Partner: UNT Libraries
Routing Optimization in Wireless Ad Hoc and Wireless Sensor Networks

Routing Optimization in Wireless Ad Hoc and Wireless Sensor Networks

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Date: August 2003
Creator: Joseph, Linus
Description: Wireless ad hoc networks are expected to play an important role in civilian and military settings where wireless access to wired backbone is either ineffective or impossible. Wireless sensor networks are effective in remote data acquisition. Congestion control and power consumption in wireless ad hoc networks have received a lot of attention in recent research. Several algorithms have been proposed to reduce congestion and power consumption in wireless ad hoc and sensor networks. In this thesis, we focus upon two schemes, which deal with congestion control and power consumption issues. This thesis consists of two parts. In the first part, we describe a randomization scheme for congestion control in dynamic source routing protocol, which we refer to as RDSR. We also study a randomization scheme for GDSR protocol, a GPS optimized variant of DSR. We discuss RDSR and RGDSR implementations and present extensive simulation experiments to study their performance. Our results indicate that both RGDSR and RDSR protocols outperform their non-randomized counterparts by decreasing the number of route query packets. Furthermore, a probabilistic congestion control scheme based on local tuning of routing protocol parameters is shown to be feasible. In the second part we present a simulation based performance study ...
Contributing Partner: UNT Libraries
Secret Key Agreement without Public-Key Cryptography

Secret Key Agreement without Public-Key Cryptography

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Date: August 2003
Creator: Surapaneni, Smitha
Description: Secure communication is the primary challenge in today's information network. In this project an efficient secret key agreement protocol is described and analyzed along with the other existing protocols. We focus primarily on Leighton and Micali's secret-key agreement without the use of public-key encryption techniques. The Leighton-Micali protocol is extremely efficient when implemented in software and has significant advantages over existing systems like Kerberos. In this method the secret keys are agreed upon using a trusted third party known as the trusted agent. The trusted agent generates the keys and writes them to a public directory before it goes offline. The communicating entities can retrieve the keys either from the online trusted agent or from the public directory service and agree upon a symmetric-key without any public-key procedures. The principal advantage of this method is that the user verifies the authenticity of the trusted agent before using the keys generated by it. The Leighton-Micali scheme is not vulnerable to the present day attacks like fabrication, modification or denial of service etc. The Leighton-Micali protocol can be employed in real-time systems like smart cards. In addition to the security properties and the simplicity of the protocol, our experiments show that in ...
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XML-Based Agent Scripts and Inference Mechanisms

XML-Based Agent Scripts and Inference Mechanisms

Date: August 2003
Creator: Sun, Guili
Description: Natural language understanding has been a persistent challenge to researchers in various computer science fields, in a number of applications ranging from user support systems to entertainment and online teaching. A long term goal of the Artificial Intelligence field is to implement mechanisms that enable computers to emulate human dialogue. The recently developed ALICEbots, virtual agents with underlying AIML scripts, by A.L.I.C.E. foundation, use AIML scripts - a subset of XML - as the underlying pattern database for question answering. Their goal is to enable pattern-based, stimulus-response knowledge content to be served, received and processed over the Web, or offline, in the manner similar to HTML and XML. In this thesis, we describe a system that converts the AIML scripts to Prolog clauses and reuses them as part of a knowledge processor. The inference mechanism developed in this thesis is able to successfully match the input pattern with our clauses database even if words are missing. We also emulate the pattern deduction algorithm of the original logic deduction mechanism. Our rules, compatible with Semantic Web standards, bring structure to the meaningful content of Web pages and support interactive content retrieval using natural language.
Contributing Partner: UNT Libraries
Agent extensions for peer-to-peer networks.

Agent extensions for peer-to-peer networks.

Date: December 2003
Creator: Valiveti, Kalyan
Description: Peer-to-Peer (P2P) networks have seen tremendous growth in development and usage in recent times. This attention has brought many developments as well as new challenges to these networks. We will show that agent extensions to P2P networks offer solutions to many problems faced by P2P networks. In this research, an attempt is made to bring together JXTA P2P infrastructure and Jinni, a Prolog based agent engine to form an agent based P2P network. On top of the JXTA, we define simple Java API providing P2P services for agent programming constructs. Jinni is deployed on this JXTA network using an automated code update mechanism. Experiments are conducted on this Jinni/JXTA platform to implement a simple agent communication and data exchange protocol.
Contributing Partner: UNT Libraries
An analysis of motivational cues in virtual environments.

An analysis of motivational cues in virtual environments.

Access: Use of this item is restricted to the UNT Community.
Date: December 2003
Creator: Voruganti, Lavanya
Description: Guiding navigation in virtual environments (VEs) is a challenging task. A key issue in the navigation of a virtual environment is to be able to strike a balance between the user's need to explore the environment freely and the designer's need to ensure that the user experiences all the important events in the VE. This thesis reports on a study aimed at comparing the effectiveness of various navigation cues that are used to motivate users towards a specific target location. The results of this study indicate some significant differences in how users responded to the various cues.
Contributing Partner: UNT Libraries