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Articles 1 - 15 of 15
Full-Text Articles in Physical Sciences and Mathematics
Dynamic Network Formation Using Ant Colony Optimization, Steven C. Oimoen
Dynamic Network Formation Using Ant Colony Optimization, Steven C. Oimoen
Theses and Dissertations
Military and industry are moving toward every device being network enabled and connected for reliable availability of communication and information. To make this type of system a reality, the devices must be capable of forming a network topology on their own in a dynamic environment to ensure that the correct information reaches a desired location and on-time. This research presents three contributions for solving highly dynamic (i.e. drastic change within the network) Multi-commodity Capacitated Network Design Problems (MCNDPs) resulting in a distributed multi-agent network design algorithm. The first contribution incorporates an Ant Colony Optimization (ACO) algorithm Ant Colony System (ACS) …
Application Of Optimization Techniques To Spectrally Modulated, Spectrally Encoded Waveform Design, Todd W. Beard
Application Of Optimization Techniques To Spectrally Modulated, Spectrally Encoded Waveform Design, Todd W. Beard
Theses and Dissertations
A design process is demonstrated for a coexistent scenario containing Spectrally Modulated, Spectrally Encoded (SMSE) and Direct Sequence Spread Spectrum (DSSS) signals. Coexistent SMSE-DSSS designs are addressed under both perfect and imperfect DSSS code tracking conditions using a non-coherent delay-lock loop (DLL). Under both conditions, the number of SMSE subcarriers and subcarrier spacing are the optimization variables of interest. For perfect DLL code tracking conditions, the GA and RSM optimization processes are considered independently with the objective function being end-to-end DSSS bit error rate. A hybrid GA-RSM optimization process is used under more realistic imperfect DLL code tracking conditions. In …
A Novel Communications Protocol Using Geographic Routing For Swarming Uavs Performing A Search Mission, Robert L. Lidowski
A Novel Communications Protocol Using Geographic Routing For Swarming Uavs Performing A Search Mission, Robert L. Lidowski
Theses and Dissertations
This research develops the UAV Search Mission Protocol (USMP) for swarming UAVs and determines the protocol's effect on search mission performance. It is hypothesized that geographically routing USMP messages improves search performance by providing geography-dependent data to locations where it impacts search decisions. It is also proposed that the swarm can use data collected by the geographic routing protocol to accurately determine UAV locations and avoid sending explicit location updates. The hypothesis is tested by developing several USMP designs that are combined with the Greedy Perimeter Stateless Routing (GPSR) protocol and a search mission swarm logic into a single network …
Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner
Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner
Theses and Dissertations
Information and Networked Communications play a vital role in the everyday operations of the United States Armed Forces. This research establishes a comparative analysis of the unique network characteristics and requirements introduced by the Topology Control Problem (also known as the Network Design Problem). Previous research has focused on the development of Mixed-Integer Linear Program (MILP) formulations, simple heuristics, and Genetic Algorithm (GA) strategies for solving this problem. Principal concerns with these techniques include runtime and solution quality. To reduce runtime, new strategies have been developed based on the concept of flow networks using the novel combination of three well-known …
On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham
On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham
Theses and Dissertations
Mobile ad-hoc networks offer dynamic portable communication with little or no infrastructure. While this has many benefits, there are additional shortcomings specific to wireless communication that must be addressed. This research proposes gossip-based on-demand key distribution as a means to provide data encryption for mobile ad-hoc networks. This technique uses message keys to avoid encrypting and decrypting a message at every node. Other optimizations used include secure channel caching and joint rekey messages. The use of gossip makes the scheme robust to node failure. Experimental results show only a 15% increase in end-to-end delay with a node failure rate of …
Factors Impacting Key Management Effectiveness In Secured Wireless Networks, Yongjoo Shin
Factors Impacting Key Management Effectiveness In Secured Wireless Networks, Yongjoo Shin
Theses and Dissertations
The use of a Public Key Infrastructure (PKI) offers a cryptographic solution that can overcome many, but not all, of the MANET security problems. One of the most critical aspects of a PKI system is how well it implements Key Management. Key Management deals with key generation, key storage, key distribution, key updating, key revocation, and certificate service in accordance with security policies over the lifecycle of the cryptography. The approach supported by traditional PKI works well in fixed wired networks, but it may not appropriate for MANET due to the lack of fixed infrastructure to support the PKI. This …
Cryptanalysis Of Pseudorandom Number Generators In Wireless Sensor Networks, Kevin M. Finnigin
Cryptanalysis Of Pseudorandom Number Generators In Wireless Sensor Networks, Kevin M. Finnigin
Theses and Dissertations
This work presents a brute-force attack on an elliptic curve cryptosystem implemented on UC Berkley's TinyOS operating system for wireless sensor networks. The attack exploits the short period of the pseudorandom number generator (PRNG) used by the cryptosystem to generate private keys. The attack assumes a laptop is listening promiscuously to network traffic for key messages and requires only the sensor node?s public key and network address to discover the private key. Experimental results show that roughly 50% of the address space leads to a private key compromise in 25 minutes on average. Furthermore, approximately 32% of the address space …
A Real-Time Wireless Sensor Media Access Control (Mac) Protocol, Barry W. Park
A Real-Time Wireless Sensor Media Access Control (Mac) Protocol, Barry W. Park
Theses and Dissertations
Wireless sensor networks are rapidly becoming a platform for applications such as battlefield monitoring, intelligence gathering, environmental monitoring, and emergency response. Inherent in these applications is a priority and urgency of the information or messages. This means the messages must be delivered in a timely manner for them to be useful. This research assigns a message priority level and provides high-priority messages quicker access to the channel. Using MICA2 sensors and a modified Media Access Control (MAC) layer, real-time message End-to-End (ETE) delay was reduced by 50 percent. Coupled with this decrease in delay, these same real-time messages also had …
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
An Adaptable Energy-Efficient Medium Access Control Protocol For Wireless Sensor Networks, Justin T. Kautz
Theses and Dissertations
Wireless networks have become ubiquitous recently and therefore their usefulness has also become more extensive. Wireless sensor networks (WSN) detect environmental information with sensors in remote settings. One problem facing WSNs is the inability to resupply power to these energy-constrained devices due to their remoteness. Therefore to extend a WSN's effectiveness, the lifetime of the network must be increased by making them as energy efficient as possible. An energy efficient medium access control (MAC) can boost a WSN's lifetime. This research creates a MAC protocol called Adaptive sensor Medium Access Control (AMAC) which is based on Sensor Medium Access Control …
Evaluation Of The Ad Hoc On-Demand Distance Vector Routing Protocol For Mobile Ad Hoc Networks, Amber J. Rickmon
Evaluation Of The Ad Hoc On-Demand Distance Vector Routing Protocol For Mobile Ad Hoc Networks, Amber J. Rickmon
Theses and Dissertations
Routing protocols designed for wired networks cannot be used in mobile ad hoc networks (MANETs) due to the dynamic topology, limited throughput, and energy constraints. New routing protocols have been designed for use in MANETs, but have not been thoroughly tested under realistic conditions such as node movement, number of sources, the presence of obstacles, and node speed. This research evaluates the performance of ad hoc on-demand distance vector routing with respect to throughput, goodput ratio, end-to-end (ETE) delay, node pair packet delivery rate, and node pair end-to-end delay. It shows these performance metrics vary significantly according to the choice …
Improving Tcp Performance By Estimating Errors In A Long Delay, High Error Rate Environment, Stephanie E. Carroll
Improving Tcp Performance By Estimating Errors In A Long Delay, High Error Rate Environment, Stephanie E. Carroll
Theses and Dissertations
Interest in finding methods of improving TCP performance over satellite and wireless networks is high. This has been an active area of research within the networking community. This research develops an algorithm, CETEN-R for TCP to determine if a particular packet is lost due to congestion or corruption and react accordingly. An analysis of the performance of CETEN-R under a variety of conditions is studied and then compared to TCP Reno and TCP New Reno. When delay is high and the error rate is high CETEN-R showed a 77.5% increase in goodput over TCP New Reno and a 33.8% increase …
Packet Analysis Of Unmodified Bluetooth Communication Devices, Neal A. Watts
Packet Analysis Of Unmodified Bluetooth Communication Devices, Neal A. Watts
Theses and Dissertations
Bluetooth technology has potential for widespread use within the Department of Defense and the Air Force. An office environment using Bluetooth technology can wirelessly connect computers, printers, and other office equipment in order to share information over short distances. The clutter and annoyance of cables connecting equipment can be eliminated. Bluetooth provides a standard interface for connection, as opposed to many different proprietary cables. The research is conducted indoors in a climate controlled environment, with minimal obstructions, to closely follow free-space signal propagation. Four different antenna orientations are used. The factors varied are the distance between devices, and the antenna …
Performance Evaluation And Analysis Of Effective Range And Data Throughput For Unmodified Bluetooth Communication Devices, Timothy F. Kneeland
Performance Evaluation And Analysis Of Effective Range And Data Throughput For Unmodified Bluetooth Communication Devices, Timothy F. Kneeland
Theses and Dissertations
The DoD and the Air Force continually seek to incorporate new technology in an effort to improve communication, work effectiveness, and efficiency. Office devices utilizing Bluetooth technology simplify device configuration and communication. They provide a means to communicate wirelessly over short distances thereby eliminating the need for different vendor specific cables and interfaces. One of the key concerns involved in incorporating new communication technology is security; the fundamental security concern of wireless communication is interception. Studies focusing on IEEE 802.11b have shown vulnerability zones around many DoD installations that reflect the ranges at which wireless communications using the 802.11b standard …
Adjusting Sensing Range To Maximize Throughput On Ad-Hoc Multi-Hop Wireless Networks, Christopher K. Roberts
Adjusting Sensing Range To Maximize Throughput On Ad-Hoc Multi-Hop Wireless Networks, Christopher K. Roberts
Theses and Dissertations
The use of ad-hoc wireless networks is becoming common within the United States Air Force. Such networks are able to be implemented where traditional wired networks are either impractical or too expensive. As the miniaturization of communication devices continues, it is becoming increasingly common for mobile devices to communicate directly with each other, eliminating the need for center access points. Such a network is referred to as a multi-hop ad-hoc network, or simply a multi-hop network. Most multi-hop network protocols use some form of carrier sensing to determine if the wireless channel is in use. A large sensing range can …
The Simulation, Modeling And Analysis Of Wireless Local Area Networks Supporting The Ieee 802.11 Standard, Jaikwan Joo
The Simulation, Modeling And Analysis Of Wireless Local Area Networks Supporting The Ieee 802.11 Standard, Jaikwan Joo
Theses and Dissertations
Research to improve the performance of the IEEE 802.11 has been ongoing since 1990. The focus of this research has investigated the use of the MAC and Physical layers for improving throughput. An adaptive MAC protocol, CATER (Code Adapts To Enhance Reliability) is based on the proposed MAC standard for wireless local area networks (WLAN)-802. 11. IEEE 802.11 uses a fixed Pseudo-Noise (PN) code for spreading the information signal, implying a fixed process gain at the receiver. When the channel degrades, IEEE 802.11 offers only retransmissions at the MAC layer to contend with the corrupted medium. However, CATER allows communicating …