• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 598
  • 80
  • 60
  • 25
  • 24
  • 13
  • 10
  • 10
  • 9
  • 9
  • 7
  • 7
  • 7
  • 7
  • 7
  • Tagged with
  • 1028
  • 1028
  • 311
  • 276
  • 178
  • 155
  • 150
  • 142
  • 124
  • 120
  • 104
  • 101
  • 101
  • 100
  • 85
  • 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.
121

Next Generation RFID Randomization Protocol

LaValley, Jason 06 December 2011 (has links)
Radio Frequency IDentification (RFID) is a wireless communications technology which allows companies to secure their assets and increase the portability of information. This research was motivated by the increased commercial use of RFID technology. Existing security protocols with high levels of security have high computation requirements, and less intensive protocols can allow a tag to be tracked. The techniques proposed in this thesis result in the increase of ciphertexts available without a significant increase in processing power or storage requirements. The addition of random inputs to the generation of ciphertexts will increase the number of possible results without requiring a more advanced encryption algorithm or an increased number of stored encryption keys. Four methods of altering the plaintext/ciphertext pair (random block, set pattern, random pattern, and indexed placement) are analyzed to determine the effectiveness of each method. The number of ciphertexts generated, generation time, and generation errors were recorded to determine which of the four proposed methods would be the most beneficial in a RFID system. The comparison of these method characteristics determined that the set pattern placement method provided the best solution. The thesis also discusses how RFID transmissions appear to attackers and explains how the random inputs reduce effectiveness of current system attacks. In addition to improving the anonymity of RFID tag transmissions, the concept of authenticating random inputs is also introduced in this thesis. These methods help prevent an adversary from easily associating a tag with its transmissions, thus increasing the security of the RFID system.
122

Communication in the presence of frequency offset /

Buetefuer, John Lawrence. Unknown Date (has links)
This thesis considers the problem of the demodulation of a digital, quadrature modulated carrier which has been subject to an unknown frequency shift introduced by the communications channel. In particular, this thesis investigates a multiple symbol detection (MSD) approach, with a focus on improving the bit error rate performance of traditional double differential phase shift keying (DDPSK) detection techniques. / Thesis (PhDTelecommunications)--University of South Australia, 2004.
123

Radio-Frequency Signal Strength Based Localisation in Unstructured Outdoor Environments

Kloos, Gerold January 2008 (has links)
Doctor of Philosophy (PhD) / This thesis addresses the issues arising in range-only localisation and tracking using Radio Frequency Received Signal Strength Indicator measurements. One of the key issues in Radio Frequency (RF) based localisation and tracking applications is to obtain an accurate sensor representation. Such a sensor model is one of the prerequisites to achieve high accuracy and precision in the localisation and tracking task. The sensor models used at present for this task are very simplistic, and as a consequence are unable to achieve highly accurate and precise localisation. While such an accurate sensor description is desirable it has not been presented for RF sensors. This thesis addresses the task of obtaining an accurate sensor model for RF sensors. The major drawbacks of the most commonly used model, the nth power model, are demonstrated. A new model to satisfy the necessary requirements for high accuracy localisation is developed. This model is based on theoretical considerations and experimental data. It depicts the real occurring behaviour of RF sensors more closely than the models used so far for RF based range-only localisation. The use of this better sensor representation offers the possibility of achieving more accurate localisation. The expected performance of the alternative sensor model is compared to the commonly used nth power model. Furthermore, the inherent properties of the new sensor model are presented and their ramifications with regards to the goal of achieving highly accurate localisation are discussed. In addition to the sensor model development, the well-known probabilistic filtering techniques Kalman Filter, Particle Filter and Histogram Filter are compared and used to implement 1-dimensional and 2-dimensional range-only trackers. The filtering techniques are evaluated with respect to their suitability for appropriately handling the new multi-modal sensor model and the resulting multi-modal state distributions, and to provide correct and conclusive localisation and tracking results. Results from experiments using real data obtained in outdoor environments with a prototype RF localisation system as well as results obtained from simulations are presented in this thesis to validate the theoretical findings and the newly developed sensor model.
124

Sequence design with applications to ultra-wideband communication systems

Wu, Di, January 2007 (has links)
Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 98-103).
125

A reliability study of the RFID technology

Ng, Ling Siew. January 2006 (has links) (PDF)
Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2006. / Thesis Advisor(s): Ha, Tri T. ; Su, Weilian. "December 2006." Description based on title screen as viewed on March 12, 2008. Includes bibliographical references (p. 55-56). Also available in print.
126

Broadband modeling of on-chip transformers for silicon RFICs /

Rapolu, Kavitha. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 91-97). Also available on the World Wide Web.
127

Photonic front-end and comparator processor for a sigma-delta modulator

Escobar, Kenny E. January 2008 (has links) (PDF)
Thesis (M.S. in Electrincal Engineering)--Naval Postgraduate School, September 2008. / Thesis Advisor(s): Pace, Phillip E. "September 2008." Description based on title screen as viewed on November 4, 2008. Includes bibliographical references (p. 65-66). Also available in print.
128

Efficient cardinality counting for large-scale RFID systems /

Qian, Chen. January 2008 (has links)
Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 68-72). Also available in electronic version.
129

The effect of conveyor speed, packaging materials, and product on the readability of radio frequency identification transponders

Falls, Jonathan Ryan Thomas. January 2006 (has links)
Thesis (M.S.)--Michigan State University. School of Packaging, 2006. / Title from PDF t.p. (viewed on Nov. 17, 2008) Includes bibliographical references (p. 219-223). Also issued in print.
130

A hybrid modulation for the VHF aeronautical channels

Akos, Dennis M. January 1992 (has links)
Thesis (M.S.)--Ohio University, November, 1992. / Title from PDF t.p.

Page generated in 0.0533 seconds