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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Platforma pro mobilní agenty v bezdrátových senzorových sítích / Platform for Mobile Agents in Wireless Sensor Networks

Horáček, Jan January 2009 (has links)
This work deals with implementation of an agent platform, which is able to run agent code in wireless sensor networks. Implementation has been done for MICAz platform, which uses TinyOS operating system for developing applications. This work contains list of chosen TinyOS parts and illustrates, how such a platform can be used for our purposes. We will describe main features of ALLL language and we will also demonstrate some examples of agents.
92

Positioning System for Rescuing Missions in Underground Facilities : Wireless Network Implementation

Martínez Olivo, Alejandro January 2019 (has links)
In the case of an emergency in an underground facility, the harsh environment make the rescue missions a difficult and taxing task for the first responders. Disorientation, stress and lack of communication are fatal in that territory. In order to overcome all this difficulties and provide a system to coordinate and help locate emergency responders, a new Indoor Positioning System (IPS) is proposed. The system shall be scalable so it can expand its coverage over the site, it would adapt and remain reliable in the harsh conditions of the environment. The main goal of this project is to present an analysis of the current wireless technologies, their advantages and disadvantages and a comparison between them. Build a new solution and present the results of the performance of the network. The tests recreate the characteristics of the underground territory and present a good analysis of the system. This thesis project report the process, to build a scalable, adaptable and reliable wireless network to be used as the framework of a positioning system. The system is constructed using the ZigBee protocol stack and the nRF52840 hardware. A graphical user interface is developed to facilitate the configuration of the network. At the end the results gives proof that the system can be used in the underground facilities as long as the network is deployed carefully. / Vid en nödsituation i en underjordisk anläggning, på grund av den svåra miljön, räddningsuppdragen blir en svår och beskattande uppgift för de första svararna. Desorientering, stress och brist på kommunikation är dödliga inom det området. För att övervinna alla dessa svårigheter och tillhandahålla ett system för att samordna och hjälpa till att hitta nödlägen, föreslås ett nytt inomhuspositioneringssystem (IPS). Systemet ska vara skalbart så att det kan utöka sin täckning över webbplatsen, det skulle anpassa sig och förbli tillförlitligt under de svåra miljöerna. Detta arbete har huvudmål att presentera en analys av den nuvarande trådlösa tekniken, deras fördelar och nackdelar och en jämförelse mellan dem samtidigt bygga en ny lösning och presentera resultaten av nätverkets prestanda. Testen modellerar egenskaperna hos det underjordiska territoriet och presenterar en bra analys av systemet. Detta arbete rapporterar processen för att bygga ett skalbart, anpassningsbart och pålitligt trådlöst nätverk som ska användas som ett ramverk för ett positioneringssystem. Systemet är konstruerat med ZigBee-protokollstacken och hårdvaran nRF52840. Ett grafiskt användargränssnitt utvecklas för att underlätta konfigurationen av nätverket. Resultatet bevisar att systemet kan användas vid de underjordiska anläggningarna så länge nätverket distribueras noggrant.
93

Development and Analysis of a Model for Assessing Perceived Security Threats and Characteristics of Innovating for Wireless Networks

Schmidt, Mark Bradley 13 May 2006 (has links)
This dissertation employed a two prong approach, whereby the survey and case study methods were used to investigate security issues regarding wireless networks. The survey portion draws together two previously unrelated research streams. Given the recent increased concern for security in the computing milieu, Innovation Diffusion Theory and security factor constructs were merged and synthesized to form a new instrument. This instrument is useful in an effort to understand what role security concerns play in the adoption and diffusion of technology. In development of the new instrument, 481 usable surveys were collected and analyzed. Factor analysis revealed favorable factor loadings in the data. Further analysis was then conducted utilizing multiple regression analysis. This analysis led to the discovery that the constructs of Susceptibility and Severity of Threat, Improvement Potential, and Visibility are significant predictors in regard to level of concern when using wireless networks. Case studies were conducted with a goal to gain a deep knowledge of IT professionals? concerns, attitudes, and best practices toward wireless security. To this end, seven IT professionals were personally interviewed regarding their perceptions and attitudes toward wireless security. In an effort to compare IT professional and end user opinions, 30 IT professionals also completed a paper based survey regarding their perceptions about security. Findings indicate that security professionals are very optimistic for the future of wireless computing. However, that optimism is tempered by a realization that there are a myriad of potential threats that might exploit weakness in wireless security. To determine differences and similarities between users? perspectives and managers? perspectives regarding wireless network security, the results from the survey and case study were synthesized. Most IT professionals (76.19%) reported that, all factors considered, they prefer to use wired networks as opposed to wireless networks; whereas, substantially fewer (44.86%) of the end user respondents reported that they preferred wired over wireless networks. Overall, results suggest that IT professionals are more concerned about security than are end users. However, a challenge remains to make administrators and users aware of the full effect of security threats present in the wireless computing paradigm.
94

Methods and Tools for Battery-free Wireless Networks

Geißdörfer, Kai 15 November 2022 (has links)
Embedding small wireless sensors into the environment allows for monitoring physical processes with high spatio-temporal resolutions. Today, these devices are equipped with a battery to supply them with power. Despite technological advances, the high maintenance cost and environmental impact of batteries prevent the widespread adoption of wireless sensors. Battery-free devices that store energy harvested from light, vibrations, and other ambient sources in a capacitor promise to overcome the drawbacks of (rechargeable) batteries, such as bulkiness, wear-out and toxicity. Because of low energy input and low storage capacity, battery-free devices operate intermittently; they are forced to remain inactive for most of the time charging their capacitor before being able to operate for a short time. While it is known how to deal with intermittency on a single device, the coordination and communication among groups of multiple battery-free devices remain largely unexplored. For the first time, the present thesis addresses this problem by proposing new methods and tools to investigate and overcome several fundamental challenges.
95

Network Selection Algorithm for Satisfying Multiple User Constraints Under Uncertainty in a Heterogeneous Wireless Scenario

Mahadevan, Srisudha 20 September 2011 (has links)
No description available.
96

Clock synchronization and dominating set construction in ad hoc wireless networks

Zhou, Dong 22 November 2005 (has links)
No description available.
97

Opportunistic Computing in Wireless Networks

Yang, Zhimin 23 August 2010 (has links)
No description available.
98

An Economic Model of Subscriber Offloading Between Mobile Network Operators and a WLAN Operator

Patterson, Cameron Webster 03 November 2014 (has links)
With increasing mobile data demand there is a push towards heterogeneous networks. Small-scale operators (SSOs) of WLANs are becoming more prevalent, while Mobile Network Operators (MNOs) seek an outlet for their customers' data usage. These conditions prompt the need for an effective relationship between the two parties for the purpose of offloading cellular data traffic to WLANs in a way that is economically beneficial to all involved. This thesis presents a model of such a relationship, in which the SSO sets a strategic offloading price per subscriber and several MNOs can choose how many subscribers they want to offload in order to minimize their costs. We determine the optimal offloading price, identify how the SSO incorporates its own network's quality of service (QoS) into its price decision, and examine the way in which the MNOs' cost structures affect their ability to offload. This model can be applied by both MNOs and SSOs to make informed network deployment decisions, even before engaging in an offloading relationship. / Master of Science
99

Analyzing Wireless LAN Security Overhead

McCarter, Harold Lars 16 May 2006 (has links)
Wireless local area networks (WLAN) are beginning to play a much larger role in corporate network environments and are already very popular for home networking applications. This increase in accessibility has created large security holes for hackers and thieves to abuse, which is finally being addressed by stronger security methods such as advanced encryption algorithms and efficient authentication processes. However, these security methods often hamper network performance unbeknownst to engineers and users. This research examines the effects of Wired Equivalent Privacy (WEP), Temporal Key Integrity Protocol (TKIP), and Counter Mode/CBC-MAC Protocol (CCMP) encryption algorithms on throughput rates for IEEE 802.11 networks as well as the authentication times for Lightweight Extensible Authentication Protocol (LEAP) and Protected Extensible Authentication Protocol (PEAP). The research shows that today's wireless hardware is capable of reducing overhead of even the most advanced encryption schemes to less than five percent of the total bandwidth. / Master of Science
100

On Design and Analysis of Energy Efficient Wireless Networks with QoS

Vankayala, Satya Kumar January 2017 (has links) (PDF)
We consider optimal power allocation policies for a single server, multiuser wireless communication system. The transmission channel may experience multipath fading. We obtain very efficient, low computational complexity algorithms which minimize power and ensure stability of the data queues. We also obtain policies when the users may have mean delay constraints. If the power required is a linear function of rate then we exploit linearity and obtain linear programs with low complexity. We also provide closed-form optimal power policies when there is a hard deadline delay constraint. Later on, we also extend single hop results to multihop networks. First we consider the case, when the transmission rate is a linear function of power. We provide low complexity algorithms for joint routing, scheduling and power control which ensure stability of the queues, certain minimum rates, end-to-end hard deadlines, and/or upper bounds on the end-to-end mean delays. Further we extend these results to the multihop networks where the power is a general monotonically increasing function of rate. For our algorithms, we also provide rates of convergence to the stationary distributions for the queue length process and also approximate end-to-end mean delays. Finally, we provide computationally efficient algorithms that minimize the total power when there is a end-to-end hard deadline delay constraint.

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