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1
Chipaux, M., L. Toraille, C. Larat, L. Morvan, S. Pezzagna, Jan Berend Meijer, and T. Debuisschert. "Wide bandwidth instantaneous radio frequency spectrum analyzer based on nitrogen vacancy centers in diamond." AIP Publishing, 2015. https://ul.qucosa.de/id/qucosa%3A31236.
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We propose an original analog method to perform instantaneous and quantitative spectral analysis
of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is
pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and
monitored by a digital camera. An incoming microwave signal is converted into a microwave field
in the area of the NV centers by a loop shaped antenna. The resonances induced by the magnetic
component of that field are detected through a decrease of the NV centers photoluminescence. A
magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information
into spatial information, which allows for the simultaneous analysis of the microwave
signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an
amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz, associated
to a frequency resolution of 7MHz , and a refresh rate of 4 ms. With such integration time, a field
of a few hundreds of lW can be detected. Since the optical properties of NV centers can be
maintained even in high magnetic field, we estimate that an optimized device could allow
frequency analysis in a range of 30 GHz, only limited by the amplitude of the magnetic field
gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the
microwave sensitivity and to a decrease of the minimum refresh rate down to a few ls.
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Soares, Vitor Miguel Melo. "Handled RF spectrum analyser using Arduino." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12813.
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Mestrado em Engenharia Eletrónica e TelecomunicaçõesRadio frequency term refers to the electromagnetic spectrum bandwidth used to transmission of electromagnetic signals trough free space. The human knowledge about this phenomena turns possible to set wireless communications between electronic devices. The analysis of that spectrum is demanding in order to achieve proper communications between those devices. Whit spectrum analysers is possible to observe some physical characteristics of the communication. The aim of this document is to furnish information about the project, design and implementation of a spectrum analyser using open source digital control technology, Arduino.
Rádio-frequência é o termo utilizado para designar a gama de frequêcias utilizadas na transmissão de sinais eletromagnéticos, através do meio livre. O domínio deste fenómeno possibilita a que dispositivos eletrónicos possam comunicar sem fios. A análise do espectro eletromagnético utilizado pelos diferentes dispositivos que coabitam no dia a dia, é essencial para possibilitar o correcto funcionamento de todos. Para tal, são utilizados analisadores de espectro, que com os quais se pode monitorizar algumas das características físicas das comunicações sem fios. O objetivo deste trabalho é documentar o projeto, implementação e testes de validação de um analisador de espectros portátil para rádio-frequência utilizando tecnologia de controlo digital opensource, Arduino.
3
Ramazanali, Hawar. "Characterization and evaluation of ZigBee modules." Thesis, Linköping University, Department of Science and Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-6508.
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This thesis work started with an extensive literature study in several areas, ZigBee, instruments and measuring methods. The knowledge was implemented in use with the ZigBee modules from the two manufacturers ITN and Chipcon along with ZigBee Software Stack. Measuring methods were developed and software in ZigBee software Stack was developed to use in the ZigBee modules for the measurements. Developing measurement methods and performing measurements was an iterative process for the different measurements. The aim was to characterize the ZigBee modules in the most important areas during the extent of this master thesis work.
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Pragasam, Ravi L. "The MC68701 based spectrum analyzer." Thesis, Kansas State University, 1985. http://hdl.handle.net/2097/9872.
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Sivarajan, Kumar N. McEliece Robert J. McEliece Robert J. "Spectrum efficient frequency assignment for cellular radio /." Diss., Pasadena, Calif. : California Institute of Technology, 1990. http://resolver.caltech.edu/CaltechETD:etd-11082007-105043.
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Wang, Jun. "Multitaper spectrum based detection for spectrum sensing in cognitive radio networks /." access full-text access abstract and table of contents, 2009. http://libweb.cityu.edu.hk/cgi-bin/ezdb/thesis.pl?mphil-ee-b23750480f.pdf.
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Thesis (M.Phil.)--City University of Hong Kong, 2009."Submitted to Department of Electronic Engineering in partial fulfillment of the requirements for the degree of Master of Philosophy." Includes bibliographical references (leaves 66-74)
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Jia, Juncheng. "Cognitive radio networks for dynamic spectrum management /." View abstract or full-text, 2009. http://library.ust.hk/cgi/db/thesis.pl?CSED%202009%20JIA.
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Colice, Christopher Max. "Transformations in optics for radio-frequency spectrum analysis." Connect to online resource, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3256393.
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Nolan, Andrew John. "Frequency assignment and spectrum trading for radio services." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.403978.
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Gurr, J. Richard, Anthony Auvil, and Jim Rizzo. "WIDE-BAND RADIO FREQUENCY (RF) SOURCE SURVEILLANCE." International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/607394.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaReduction in available radio frequency (RF) spectrum for use in aircraft testing has steadily increased the probability of interference. The increase in users and required bandwidth generates requirements for increased monitoring and active management of the RF spectrum. The detection of background RF emissions and monitoring of authorized users will be used by future range test engineers to make decisions on when and where to conduct test missions to minimize the probability of interference. The detection of authorized users exceeding their allotted RF spectrum as well as unknown emitters should include: the general geographic area of potential interference, and times of transmission. This paper outlines the development of a complete system for wide-band RF monitoring to identify and locate active emissions. The RF surveillance system proposed must be inexpensive, easy to maintain, support large area coverage, and monitor wide bandwidths at long range. The system should contain software for emitter identification, which will determine where the current background and authorized RF transmissions occur and how they might effect authorized transmissions, and specialized software to alert spectrum managers of potential interference scenarios in real time based upon the daily schedule.
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Rockliff, Simon C. "Frequency hopping techniques for digital mobile radio /." Title page, contents and abstract only, 1990. http://web4.library.adelaide.edu.au/theses/09PH/09phr683.pdf.
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Kataria, Amit. "Cognitive radios spectrum sensing issues /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/5047.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 28, 2008) Includes bibliographical references.
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Petrin, Allen John. "Maximizing the Utility of Radio Spectrum: Broadband Spectrum Measurements and Occupancy Model for Use by Cognitive Radio." Diss., Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-07152005-135311/.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2006.Dr. Stevenson J. Kenney, Committee Member ; Dr. Paul G. Steffes, Committee Chair ; Dr. Gregory D. Durgin, Committee Member ; Dr. Aaron D. Lanterman, Committee Member ; Dr. Robert G. Roper, Committee Member.
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Cruickshank, David G. M. "Spread spectrum for a high frequency dispersed radio alarm scheme." Thesis, University of Edinburgh, 1992. http://hdl.handle.net/1842/13503.
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Alarm schemes for the elderly that are currently available are expensive. The vast majority of these schemes use a portable trigger worn by the client to transmit to a receiver unit within the client's home. This receiver unit then calls for help through the public telephone network. A large proportion of the overall cost of this type of scheme is the cost of providing each client with a receiver unit and a modem. In this thesis we look at the possibility of transmitting a high frequency alarm signal directly to a service centre from a portable transmitter worn by the client. This method should be much cheaper than a conventional telephone based system, as a receiver and modem for each client is not required. To obtain the required range, we sacrifice the speech link between the client and the service centre and use spread spectrum techniques to reduce the equivalent noise bandwidth of the system. There is a channel reserved exclusively for elderly alarm schemes, this channel in the high frequency radio band. In the high frequency radio band, the background noise is often dominated by man-made components and is therefore impulsive. The distribution of the impulsive noise in these channels is non-stationary and unknown to the system designer. An analysis of the performance of a direct sequence spread spectrum system using matched filter reception is developed. This analysis concentrates on providing a guaranteed minimum performance from a limited precision digital matched filter, regardless of the noise distribution. The performance of a non-linear clipping device preceding the matched filter is analysed and is shown to improve performance in impulsive noise. Finally, we study the design of a practical alarm scheme based on direct sequence spread spectrum.
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Laycock, S. C. "Very steep spectrum radio sources and clusters of galaxies." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233300.
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The topics covered in this dissertation are all areas of study involving observations at low radio frequencies. There are three main subject areas: a study of the twin-tailed radio galaxy 3C3.1; a study of both an old and a new sample of radio sources that exhibit very steep radio spectra at low frequency; the design and construction of a new radio telescope operating at low radio frequency together with the making of a new radio source survey. 3C3.1 has been studied by other authors but new high angular resolution, high sensitivity observations at low radio frequency have allowed further progress to be made in understanding the behaviour of this source. It has been thought that 3C3.1 type sources would be responsible for most (if not all) of the very steep spectrum radio sources. 3C3.1 is relatively close, hence easy to study. A model has been developed which explains the previously not understood brightness distribution along the long luminous jets. In order to quantify the predicted behaviour more precisely a set of simple numerical simulations was performed. Very steep spectrum radio sources are by their nature easier to detect at low radio frequencies. In the past, it has been shown that most, if not all, very steep spectrum sources are associated with clusters of galaxies. Both optical and further radio observations of a sample of sources prepared by the author, and a sample prepared by other workers were undertaken. The optical observations of high sensitivity have greatly strengthened the hypothesis that all of such sources are indeed associated with clusters of galaxies. The radio observations, both performed at high and low radio frequencies, have shown that such sources seem to have in general evolved from conventional sources with both 'tailed' and 'double' radio structure. A serious limitation for further work at low radio frequencies is the availibility of high sensitivity, high resolution instruments. A twenty five element interferometer with a one mile baseline operating at 38 MHz was designed and constructed. This allowed an appraisal of the operating conditions at such low frequency. A deep radio survey of the north pole was performed and a new sample of very steep spectrum constructed.
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Recio, Adolfo Leon. "Spectrum-Aware Orthogonal Frequency Division Multiplexing." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/30193.
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Reconfigurable computing architectures are well suited for the dynamic data flow processing requirements of software-defined radio. The software radio concept has quickly evolved to include spectrum sensing, awareness, and cognitive algorithms for machine learning resulting in the cognitive radio model.
This work explores the application of reconfigurable hardware to the physical layer of cognitive radios using non-contiguous multi-carrier radio techniques. The practical tasks of spectrum sensing, frame detection, synchronization, channel estimation, and mutual interference mitigation are challenges in the communications and the computing fields that are addressed to optimally utilize the capacity of opportunistically allocated spectrum bands.
FPGA implementations of parameterizable OFDM and filter bank multi-carrier (FBMC) radio prototypes with spectrum awareness and non-contiguous sub-carrier allocation were completed and tested over-the-air. Sub-carrier sparseness assumptions were validated under practical implementation and performance considerations. A novel algorithm for frame detection and synchronization with mutual interference rejection applicable to the FBMC case was proposed and tested.Ph. D.
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SoÌ, nmezer Volkan. "Cooperative wideband spectrum sensing and localization using radio frequency sensor networks." Thesis, Monterey, California: Naval Postgraduate School, 2009. http://hdl.handle.net/10945/4612.
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Approved for public release, distribution unlimitedThis thesis implements spectrum sensing and localization tasks using a radio frequency sensor network and analyzes the performance of this implementation through simulation. A sensor network based cooperative wideband spectrum sensing and localization scheme is proposed for the implementation of the tasks. In the proposed scheme, wavelet-based multi-resolution spectrum sensing and received signal strengthbased localization methods, which were originally proposed for cognitive radio applications, are adapted to radio frequency sensor networks. For cooperation of the nodes in the proposed scheme, a new three-bit hard combination technique is developed. A simulation model is created in MATLAB programming language to implement the proposed scheme and to analyze its simulation performance. The results of the simulation show that the proposed sensor network based cooperative wideband spectrum sensing and localization scheme is appropriate for radio frequency sensor networks and the proposed three-bit hard combination scheme is superior to the traditional hard combination schemes in terms of false alarm reduction.
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Sönmezer, Volkan. "Cooperative wideband spectrum sensing and localization using radio frequency sensor networks." Monterey, California : Naval Postgraduate School, 2009. http://edocs.nps.edu/npspubs/scholarly/theses/2009/Sep/09Sep%5FSonmezer.pdf.
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Thesis (M.S. in Electronic Warfare Systems Engineering and M.S. in Electrical Engineering)--Naval Postgraduate School, September 2009.Thesis Advisor(s): Tummala, Murali ; Jenn, David. "September 2009." Description based on title screen as viewed on November 6, 2009. Author(s) subject terms: Cooperative Spectrum Sensing, Source Localization, Multi-Resolution Spectrum Sensing, Three-Bit Hard Combination, RSS-Based Localization, Cognitive Radio, Wireless Sensor Networks, Electronic Warfare. Includes bibliographical references (p. 87-90). Also available in print.
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Valenta, Václav. "Frequency synthesis for cognitive multi-radio." Phd thesis, Université Paris-Est, 2010. http://tel.archives-ouvertes.fr/tel-00597461.
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This doctoral thesis deals with design aspects of a reconfigurable frequency synthesizer for flexible radio transceivers in future cognitive multi-radios. The frequency bandwidth to be covered by this multi-radio synthesizer corresponds to the frequency bands of the most diffused wireless communication standards in the frequency band 800 MHz to 6 GHz. Since multi-standard operation is required, the synthesizer must fulfil the most stringent and sometimes conflicting requirements. Given these requirements, a novel approach for multi-mode frequency synthesis has been conceived. A hybrid phase locked loop based frequency synthesizer has been proposed and a novel switching protocol has been presented and validated on an experimental evaluation board. This approach combines fractional-N and integer-N modes of operation with switched loop filter topology. Compared to standard PLL techniques, the hybrid configuration provides a great flexibility in terms of reconfiguration and moreover, it offers relatively low circuit complexity and low power consumption. This architecture provides reconfiguration of the loop bandwidth, frequency resolution, phase noise and settling time performance and hence, it can adapt itself to diverse requirements given by the concerned wireless communication standards. Corresponding analyses, simulations and measurements have been carried out in order to verify the performance and functionality of the proposed solution. A part from the design of the multiband frequency synthesizer, a set of regional measurements of the radio spectrum utilization has been carried out in the framework of this dissertation research. These measurements are based on the energy detection principle and provide a close look at the degree of radio spectrum utilization in different regions, namely in the city of Brno in the Czech Republic and in the city of Paris and one of its suburbs in France. The goal of the experimental measurement campaign has been to estimate the degree of radio spectrum usage in a particular environment and to point out the fact that a new approach for radio spectrum management is inevitable
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Bhadane, Kunal. "A Cognitive Radio Application through Opportunistic Spectrum Access." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc984265/.
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In wireless communication systems, one of the most important resources being focused on all the researchers is spectrum. A cognitive radio (CR) system is one of the efficient ways to access the radio spectrum opportunistically, and efficiently use the available underutilized licensed spectrum. Spectrum utilization can be significantly enhanced by developing more applications with adopting CR technology. CR systems are implemented using a radio technology called software-defined radios (SDR). SDR provides a flexible and cost-effective solution to fulfil the requirements of end users. We can see a lot of innovations in Internet of Things (IoT) and increasing number of smart devices. Hence, a CR system application involving an IoT device is studied in this thesis. Opportunistic spectrum access involves two tasks of CR system: spectrum sensing and dynamic spectrum access. The functioning of the CR system is rest upon the spectrum sensing. There are different spectrum sensing techniques used to detect the spectrum holes and a few of them are discussed here in this thesis. The simplest and easiest to implement energy detection spectrum sensing technique is used here to implement the CR system. Dynamic spectrum access involves different models and strategies to access the spectrum. Amongst the available models, an interweave model is more challenging and is used in this thesis. Interweave model needs effective spectrum sensing before accessing the spectrum opportunistically. The system designed and simulated in this thesis is capable of transmitting an output from an IoT device using USRP and GNU radio through accessing the radio spectrum opportunistically.
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Goedde, Todd William. "Decoder Board Hardware/Software Development in Wireless Interactive Video Data Service System." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/35871.
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The Interactive Video Data Service (IVDS) system allows consumers to browse the Internet, request information on products or services, make purchases, indicate preferences, and perform other interactive applications. To provide this service, the IVDS system has three subsystems: Consumer Control (CC), Cell Repeater (CR), and Host subsystem.
In the CC subsystem, an IVDS transceiver box is placed near a television set. Once the consumer sends a command to the transceiver box using a standard television/VCR/Cable remote control, the transceiver box receives information embedded in the television audio, and then transmits the information to the CR subsystem as a radio frequency (RF) spread spectrum message.
The CR subsystem decodes the spread spectrum message and forwards it to the Host subsystem for processing. Located in the CR subsystem, a custom designed circuit board, called the decoder board, uses surface mounted components to decode and packetize the spread spectrum message for transfer to the CR main processor.
This paper provides a functional description of the hardware components on the decoder board, and describes the hardware/software developed for interfacing the decoder board to the radio receiver and to the CR main processor. Hardware modifications were needed to correct timing problems between components. Software was developed to initialize the components for downconverting, despreading, and demodulating spread spectrum messages, and to packetize them for transfer to the CR main processor. This paper also discusses the tests used to verify both the performance of the decoder board software and the operation of the hardware components.Master of Science
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Arigong, Bayaner. "Space and Spectrum Engineered High Frequency Components and Circuits." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc801923/.
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With the increasing demand on wireless and portable devices, the radio frequency front end blocks are required to feature properties such as wideband, high frequency, multiple operating frequencies, low cost and compact size. However, the current radio frequency system blocks are designed by combining several individual frequency band blocks into one functional block, which increase the cost and size of devices. To address these issues, it is important to develop novel approaches to further advance the current design methodologies in both space and spectrum domains. In recent years, the concept of artificial materials has been proposed and studied intensively in RF/Microwave, Terahertz, and optical frequency range. It is a combination of conventional materials such as air, wood, metal and plastic. It can achieve the material properties that have not been found in nature. Therefore, the artificial material (i.e. meta-materials) provides design freedoms to control both the spectrum performance and geometrical structures of radio frequency front end blocks and other high frequency systems. In this dissertation, several artificial materials are proposed and designed by different methods, and their applications to different high frequency components and circuits are studied. First, quasi-conformal mapping (QCM) method is applied to design plasmonic wave-adapters and couplers working at the optical frequency range. Second, inverse QCM method is proposed to implement flattened Luneburg lens antennas and parabolic antennas in the microwave range. Third, a dual-band compact directional coupler is realized by applying artificial transmission lines. In addition, a fully symmetrical coupler with artificial lumped element structure is also implemented. Finally, a tunable on-chip inductor, compact CMOS transmission lines, and metamaterial-based interconnects are proposed using artificial metal structures. All the proposed designs are simulated in full-wave 3D electromagnetic solvers, and the measurement results agree well with the simulation results. These artificial material-based novel design methodologies pave the way toward next generation high frequency circuit, component, and system design.
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Shin, Hong-Sup. "Analysis of the probability of error in frequency hopping multiple access system /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5868.
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Phoshoko, Silas M. "Radio frequency spectrum monitoring : Officers' acceptance of minitoring technologies such as fixed direction finders. /." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_7879_1256198977.
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The research focuses on the acceptance of new technologies within the telecommunications industry. The study examines three models namely Innovation theory, Theory of Reason Action (TRA), and Technology Acceptance Model (TAM). This study explores the technology acceptance models in order to explain why certain monitoring officers at ICASA would prefer specific technologies over others. Models of interest could be the innovation theory, TRA and TAM. After reviewing both models, the author will examine the TAM in detail as a model of interest in this study. In turn, this model is expected to assist us to understand why monitoring officer's at ICASA would prefer a particular frequency monitoring technology over the other.
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Cui, Xian. "Efficient radio frequency power amplifiers for wireless communications." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195652135.
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Mortazavi, S. H. "Frequency hopping spread spectrum characteristics and its application in a multi-cellular mobile radio environment." Thesis, University of Bristol, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.299807.
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Feng, Zhenhua. "Cross-Layer Optimization and Distributed Algorithm Design for Frequency-Agile Radio Networks." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/37207.
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Recent advancements in frequency-agile radio technology and dynamic spectrum access network
have created a huge space for improving the utilization efficiency of wireless spectrum.
Existing algorithms and protocols, however, have not taken full advantage of the new
technologies due to obsolete network design ideologies inherited from conventional network
design, such as static spectrum access and static channelization. In this dissertation, we
propose new resource management models and algorithms that capitalize on the frequencyagility
of next generation radios and the dynamic spectrum access concepts to increase the
utilization efficiency of wireless spectrum.
We first propose a new analytical model for Dynamic Spectrum Access (DSA) networks.
Compared to previous models, the new model is able to include essential DSA mechanisms
such as spectrum sensing and primary interference avoidance into solid mathematical representation
and thus drastically increase the accuracy of our model. The subsequent numerical
study conforms well with existing empirical studies and provides fundamental insights on
the design of future DSA networks.
We then take advantage of partially overlapped channel in frequency-agile radio networks
and propose simple joint channel scheduling and flow routing optimization algorithm that
maximizes network throughput. The model quantifies the impact of fundamental network
settings, such as node density and traffic load, on the performance of partially overlapped
channel based networks.
We then propose a cross-layer radio resource allocation algorithm JSSRC (Joint Spectrum
Sharing and end-to-end data Rate Control) that iteratively adapts a frequency-agile radio
network to optimum with regard to aggregate network spectrum utilization. Subsequently,
we extend JSSRC to include routing and present TRSS (joint Transport, Routing and Spectrum
Sharing) to solve the much more complex joint transport, routing and spectrum sharing
optimization problem. Both JSSRC and TRSS enjoy theoretical convergence and achieve
optimum with appropriate scheduling algorithms.
The works together strive to improve efficiency of spectrum utilization in frequency-agile
radio networks. Numerical and simulation studies show the effectiveness of our designs to
reduce the so-called spectrum shortage problem.Ph. D.
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Sen, Indranil. "Bandwidth Efficient Reduced-Complexity MT-DS-SS via Reduced Subcarrier Frequency Spacing." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1091107331.
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Rohatgi, Anil. "Implementation and Applications of an Anti-Collision Differential-Offset Spread Spectrum RFID System." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/13946.
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This report documents the design, construction, and implementation of a differential-offset spread spectrum RFID system, to avoid the problem of anti-collision interference from multiple RFID tags. Currently in industry, this problem is handled by establishing a two way communication link between the tags and the interrogator. The proposed system eliminates the need for the excessive hardware use to create this link, and therefore drastically reduces the cost of each tag. Not only is this system cheaper to implement but it is faster, requires less power, and by the nature of the design contains an inherent encryption scheme for the data being transmitted.
Specialized RFID tags were designed and fabricated in order to produce a pseudo random code unique to each tag. The design presented in this document allowed simultaneous interrogation of up to 255 tags within one sensing environment. Once queried, the tags then modulate the incoming signal from the interrogator with their own sequence, and reflect the signal back to the interrogator. What the interrogator then receives is a combination of backscatter from all of the tags within the sensing environment. Specialized software written in Matlab and LabView uses these unique sequences to isolate the data from a desired tag away from the sea of information being transmitted from every tag. Using this system, numerous applications for experiments and measurements can be devised.
One such application this thesis focuses on is the use of this system to simultaneously measure signal strengths from multiple diversity antennas in order to optimize their position and orientation. Currently, the majority of antenna diversity measurements are taken by measuring the signal strength of a given configuration one antenna at a time. By using the anti-collision RFID system proposed above, the signal strength produced by both antennas can be measured and recorded simultaneously to provide a true representation of their combined performance. This measurement can be used to find the optimal configuration for multiple antennas.
This thesis will fully explore the theories and procedures behind creating this system, and will provide the results and analysis of its performance.
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Delvecchio, Matthew David. "Enhancing Communications Aware Evasion Attacks on RFML Spectrum Sensing Systems." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99792.
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Recent innovations in machine learning have paved the way for new capabilities in the field of radio frequency (RF) communications. Machine learning techniques such as reinforcement learning and deep neural networks (DNN) can be leveraged to improve upon traditional wireless communications methods so that they no longer require expertly-defined features. Simultaneously, cybersecurity and electronic warfare are growing areas of focus and concern in an increasingly technology-driven world. Privacy and confidentiality of communication links are both more important and more difficult than ever in the current high threat environment. RF machine learning (RFML) systems contribute to this threat as they have been shown to be successful in gleaning information from intercepted signals, through the use of learning-enabled eavesdroppers. This thesis focuses on a method of defense against such communications threats termed an adversarial evasion attack in which intelligently crafted perturbations of the RF signal are used to fool a DNN-enabled classifier, therefore securing the communications channel.
One often overlooked aspect of evasion attacks is the concept of maintaining intended use. In other words, while an adversarial signal, or more generally an adversarial example, should fool the DNN it is attacking, this should not come at the detriment to it's primary application. In RF communications, this manifests in the idea that the communications link must be successfully maintained with friendly receivers, even when executing an evasion attack against malicious receivers. This is a difficult scenario, made even more so by the nature of channel effects present in
over-the-air (OTA) communications, as is assumed in this work.
Previous work in this field has introduced a form of evasion attack for RFML systems called a communications aware attack that explicitly addresses the reliable communications aspect of the attack by training a separate DNN to craft adversarial signals; however, this work did not utilize the full RF processing chain and left residual indicators of the attack that could be leveraged for defensive capabilities. First, this thesis focuses on implementing forward error correction (FEC), an aspect present in most communications systems, in the training process of the attack. It is shown that introducing this into the training stage allows the communications aware attack to implicitly use the structure of the coding to create smarter and more efficient adversarial signals. Secondly, this thesis then addresses the fact that in previous work, the resulting adversarial signal exhibiting significant out-of-band frequency content, a limitation that can be used to render the attack ineffective if preprocessing at the attacked DNN is assumed. This thesis presents two novel approaches to solve this problem and eliminate the majority of side content in the attack. By doing so, the communications aware attack is more readily applicable to real-world scenarios.Master of Science
Deep learning has started infiltrating many aspects of society from the military, to academia, to commercial vendors. Additionally, with the recent deployment of 5G technology, connectivity is more readily accessible than ever and an increasingly large number of systems will communicate with one another across the globe. However, cybersecurity and electronic warfare call into question the very notion of privacy and confidentiality of data and communication streams. Deep learning has further improved these intercepting capabilities. However, these deep learning systems have also been shown to be vulnerable to attack. This thesis exists at the nexus of these two problems, both machine learning and communication security. This work expands upon adversarial evasion attacks meant to help elude signal classification at a deep learning-enabled eavesdropper while still providing reliable communications to a friendly receiver. By doing so, this work both provides a new methodology that can be used to conceal communication information from unwanted parties while also highlighting the glaring vulnerabilities present in machine learning systems.
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Pediaditaki, Sofia. "Interference-aware adaptive spectrum management for wireless networks using unlicensed frequency bands." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/11725.
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The growing demand for ubiquitous broadband network connectivity and continuously falling prices in hardware operating on the unlicensed bands have put Wi-Fi technology in a position to lead the way in rapid innovation towards high performance wireless for the future. The success story of Wi-Fi contributed to the development of widespread variety of options for unlicensed access (e.g., Bluetooth, Zigbee) and has even sparked regulatory bodies in several countries to permit access to unlicensed devices in portions of the spectrum initially licensed to TV services. In this thesis we present novel spectrum management algorithms for networks employing 802.11 and TV white spaces broadly aimed at efficient use of spectrum under consideration, lower contention (interference) and high performance. One of the target scenarios of this thesis is neighbourhood or citywide wireless access. For this, we propose the use of IEEE 802.11-based multi-radio wireless mesh network using omnidirectional antennae. We develop a novel scalable protocol termed LCAP for efficient and adaptive distributed multi-radio channel allocation. In LCAP, nodes autonomously learn their channel allocation based on neighbourhood and channel usage information. This information is obtained via a novel neighbour discovery protocol, which is effective even when nodes do not share a common channel. Extensive simulation-based evaluation of LCAP relative to the state-of-the-art Asynchronous Distributed Colouring (ADC) protocol demonstrates that LCAP is able to achieve its stated objectives. These objectives include efficient channel utilisation across diverse traffic patterns, protocol scalability and adaptivity to factors such as external interference. Motivated by the non-stationary nature of the network scenario and the resulting difficulty of establishing convergence of LCAP, we consider a deterministic alternative. This approach employs a novel distributed priority-based mechanism where nodes decide on their channel allocations based on only local information. Key enabler of this approach is our neighbour discovery mechanism. We show via simulations that this mechanism exhibits similar performance to LCAP. Another application scenario considered in this thesis is broadband access to rural areas. For such scenarios, we consider the use of long-distance 802.11 mesh networks and present a novel mechanism to address the channel allocation problem in a traffic-aware manner. The proposed approach employs a multi-radio architecture using directional antennae. Under this architecture, we exploit the capability of the 802.11 hardware to use different channel widths and assign widths to links based on their relative traffic volume such that side-lobe interference is mitigated. We show that this problem is NP-complete and propose a polynomial time, greedy channel allocation algorithm that guarantees valid channel allocations for each node. Evaluation of the proposed algorithm via simulations of real network topologies shows that it consistently outperforms fixed width allocation due to its ability to adapt to spatio-temporal variations in traffic demands. Finally, we consider the use of TV-white-spaces to increase throughput for in-home wireless networking and relieve the already congested unlicensed bands. To the best of our knowledge, our work is the first to develop a scalable micro auctioning mechanism for sharing of TV white space spectrum through a geolocation database. The goal of our approach is to minimise contention among secondary users, while not interfering with primary users of TV white space spectrum (TV receivers and microphone users). It enables interference-free and dynamic sharing of TVWS among home networks with heterogeneous spectrum demands, while resulting in revenue generation for database and broadband providers. Using white space availability maps from the UK, we validate our approach in real rural, urban and dense-urban residential scenarios. Our results show that our mechanism is able to achieve its stated objectives of attractiveness to both the database provider and spectrum requesters, scalability and efficiency for dynamic spectrum distribution in an interference-free manner.
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Banks, Paul Russell. "Characterisation of the radio noise environment in New Zealand." Click here to access this resource online, 2009. http://hdl.handle.net/10292/787.
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A methodology for the measurement of the radio frequency environment close to the radio noise floor is presented for urban, suburban and rural areas within New Zealand for the purposes of characterisation and trend monitoring by radio spectrum managers. Flux density measurements in bands within a range of frequencies from 80 MHz to 8 GHz have been made in urban, suburban and rural areas of New Zealand during 2007 and 2008. An analysis of the band occupancy is presented in summary form. These summaries are intended as a starting point for radio spectrum usage and can be used as a reference for any future measurements. A description of the computer directories and charts resulting from these measurements, using 20 MHz bandwidths have also been included. All the results for the work have been collated in a set of computer directories named “NZRFI Directories 2007 2008”, which are intended as a reference for use in the determination of local activity in particular frequency ranges. A disc with the full range measurement spectral density charts and channel occupancy charts accompanies this work. Also included on the disc are sets of 20 MHz band charts for some urban, suburban and rural location measurements.
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Graf, Patrick Anthony. "Efficient bit encoding in backscatter wireless systems." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33946.
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As the size and power consumption of microelectronic circuits continues to decrease, passively-powered sensors promise to come to the forefront of commercial electronics. One of the most promising technologies that could realize this goal is backscatter sensing. Backscatter sensors could harvest power from and modulate data onto an impinging carrier waveform. Currently radio frequency identification (RFID) technology passively powers itself and transmits statically stored data. However, this technology has two major weaknesses: lack of resiliency against narrowband interference and slow data rates. Both of these issues could be detrimental in sensing applications. This thesis will lay out a method for addressing both of these weaknesses through a unique application of spread spectrum encoding. Instead of spread spectrum being viewed as the multiplication of an already encoded data sequence with a periodic pseudorandom sequence, each sequence could be viewed in an aperiodic manner, where a single period of a pseudorandom sequence represents a data symbol. In this manner, backscatter sensors not only benefit from the increased resiliency that spread spectrum provides, but also can have higher data rates, since multiple bits can be encoded on a single symbol and multiple nodes can be read simultaneously, using spread spectrum multiple access techniques. In this thesis, 63-chip and 255-chip Kasami sequences, as well as 127-chip Gold sequences, will be analyzed for their use in various aperiodic direct sequence spread spectrum/multiple access system configurations (systems that have up to three nodes and use up to four different aperiodic sequences per node to represent different symbols). For each different configuration, near-"ideal" code configurations/rotations will be determined for use in the system.
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Borrego, José Pedro Mateiro Matias. "Impact of the transient behavior of radio communication systems on spectrum management." Doctoral thesis, Universidade de Aveiro, 2015. http://hdl.handle.net/10773/14243.
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Doutoramento em Engenharia EletrotécnicaThis PhD Thesis falls within the domain of spectrum engineering and spectrum management, and intends to address current and concrete problems, with which, regulators have to deal. Particularly, the definition of technical conditions to be met by radio systems, which will operate in specific bands, selected to introduce novel concepts such as flexibility and technological neutrality. The Block Edge Mask approach was adopted to define technical conditions of operation, in those bands. However, this model, based on spectral masks, which are defined in the frequency domain, do not take into account the transient behavior or time-varying characteristics of signals used by emerging radio communication systems. Furthermore, measurement methodologies developed for validation of technical parameters associated to these models, which are recommended by international bodies, potentially lead to practical issues that must be scrutinized. Thus, alternative time-frequency mixed domain signal processing techniques are explored, in this thesis, to be used for assessing the compliance of radio systems operating under such constraints.
Esta Tese de Doutoramento insere-se nos domínios da engenharia do espectro e da gestão do espectro radioelétrico, e pretende abordar problemas atuais e concretos com que os reguladores se deparam. Em particular, a definição de condições técnicas a serem cumpridas pelos sistemas rádio que irão operar em determinadas faixas de frequências, selecionadas para a introdução de abordagens de gestão do espectro mais flexíveis e tecnologicamente neutras. O modelo de Máscara Delimitadora de Bloco (Block Edge Mask) foi adotado, a nível europeu, como estratégia de definição de condições técnicas de operação, nessas faixas. Contudo, este modelo, que recorre a restrições que são apenas estabelecidas no domínio da frequência, não entra em linha de conta com comportamentos transitórios ou com a variabilidade temporal de sinais inerentes aos sistemas de radiocomunicações atuais. Para além disso, a medição e validação de parâmetros técnicos associados a estes modelos, conforme definidas nas recomendações internacionais aplicáveis, levantam problemas práticos que importa escalpelizar. Nesse sentido, são exploradas, nesta tese, técnicas alternativas de processamento de sinal no domínio misto tempo-frequência, tendo em vista a sua utilização na avaliação de conformidade dos sistemas rádio em face das restrições aplicáveis.
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Chen, Bosi. "Spectrum Regrowth for OFDM-based LTE and WIMAX Systems." PDXScholar, 2013. https://pdxscholar.library.pdx.edu/open_access_etds/601.
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An abstract of the thesis of Bosi Chen for the Master of Science in Electrical and Computer Engineering presented Aug 1st, 2012. Title: Spectrum Regrowth for OFDM-based LTE and WiMAX Systems. In OFDM-based (Orthogonal Frequency Dimension Multiplexing) LTE (Long Term Evolution) and WiMAX (Worldwide Interoperability for Microwave Access) Systems, one of the critical components is the RF power amplifier. With current technologies, RF power amplifiers are not perfectly linear. The nonlinearity of an RF power amplifier is one of the main concerns in RF power amplifier design. The nonlinearity control is described by the out-of-band power emission levels, and the nonlinearity of an RF power amplifier is usually described by IP3 (the third-order intercept point). However, there is need of a clear relationship or expression between the out-of-band power emission level and IP3 for LTE and WiMAX Systems, which helps the RF designers to choose components. This thesis presents the analysis of the nonlinear effect of an RF amplifier in LTE and WiMAX Systems, and the derivation of the expressions for the estimated out-of-band emission levels for LTE and WiMAX signals in terms of IP3 and the power level of the signal. The result will be helpful for RF engineers in the design and test of RF power amplifiers in LTE and WiMAX Systems.
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Moore, Megan O. 'Neal. "One Size Does Not Fit All: Optimizing Sequence Length with Recurrent Neural Networks for Spectrum Sensing." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/104050.
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With the increase in spectrum congestion, intelligent spectrum sensing systems have become more important than ever before. In the field of Radio Frequency Machine Learning (RFML), techniques like deep neural networks and reinforcement learning have been used to develop more complex spectrum sensing systems that are not reliant on expert features. Architectures like Convolutional Neural Networks (CNN) and Recurrent Neural Networks (RNN) have shown great promise for applications like automated modulation classification, signal detection, and specific emitter ID. Research in these areas has primarily focused on "one size fits all" networks that assume a fixed signal length in both training and inference. However, since some signals are more complex than others, due to channel conditions, transmitter/receiver effects, etc., being able to dynamically utilize just enough of the received symbols to make a reliable decision allows for more efficient decision making in applications such as electronic warfare and dynamic spectrum sharing. Additionally, the operator may want to get to the quickest possible decision.
Recurrent neural networks have been shown to outperform other architectures when processing temporally correlated data, such as from wireless communication signals. However, compared to other architectures, such as CNNs, RNNs can suffer from drastically longer training and evaluation times due to their inherent sample-by-sample data processing. While traditional usage of both of these architectures typically assumes a fixed observation interval during both training and testing, the sample-by-sample processing capabilities of recurrent neural networks opens the door for "decoupling" these intervals. This is invaluable in real-world applications due to the relaxation of the typical requirement of a fixed time duration of the signals of interest. This work illustrates the benefits and considerations needed when "decoupling" these observation intervals for spectrum sensing applications. In particular, this work shows that, intuitively, recurrent neural networks can be leveraged to process less data (i.e. shorter observation intervals) for simpler inputs (less complicated signal types or channel conditions). Less intuitively, this works shows that the "decoupling" is dependent on appropriate training to avoid bias and insure generalization.Master of Science
With the increase in spectrum congestion, intelligent spectrum sensing systems have become more important than ever before. In the field of Radio Frequency Machine Learning (RFML), techniques like deep neural networks and reinforcement learning have been used to develop more complex spectrum sensing systems that are not reliant on expert features. Architectures like Convolutional Neural Networks (CNN) and Recurrent Neural Networks (RNN) have shown great promise for applications like automated modulation classification, signal detection, and specific emitter ID. Research in these areas has primarily focused on "one size fits all" networks that assume a fixed signal length in both training and inference. However, since some signals are more complex than others, due to channel conditions, transmitter/receiver effects, etc., being able to dynamically utilize just enough of the received symbols to make a reliable decision allows for more efficient decision making in applications such as electronic warfare and dynamic spectrum sharing. Additionally, the operator may want to get to the quickest possible decision. Recurrent neural networks have been shown to outperform other architectures when processing temporally correlated data, such as from wireless communication signals. However, compared to other architectures, such as CNNs, RNNs can suffer from drastically longer training and evaluation times due to their inherent sample-by-sample data processing. While traditional usage of both of these architectures typically assumes a fixed observation interval during both training and testing, the sample-by-sample processing capabilities of recurrent neural networks opens the door for "decoupling" these intervals. This is invaluable in real-world applications due to the relaxation of the typical requirement of a fixed time duration of the signals of interest. This work illustrates the benefits and considerations needed when "decoupling" these observation intervals for spectrum sensing applications. In particular, this work shows that, intuitively, recurrent neural networks can be leveraged to process less data (i.e. shorter observation intervals) for simpler inputs (less complicated signal types or channel conditions). Less intuitively, this works shows that the "decoupling" is dependent on appropriate training to avoid bias and insure generalization.
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Panasenko, Dmitriy. "Single-shot detection of ultrashort laser pulses with applications to nonlinear propagation in transparent dielectrics and radio-frequency spectrum analysis /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2004. http://wwwlib.umi.com/cr/ucsd/fullcit?p3144315.
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Yoon, Seungil. "Cross-layer dynamic spectrum management framework for the coexistence of white space applications." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/44787.
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The objective of this dissertation is to propose the cross-layer spectrum management architecture for white space applications that improves the performance the main functions of the spectrum management. In the proposed cross-layer architecture, white space network devices such as white space devices and the spectrum map server cooperate to support the extended spectrum map, the inter-cell transmit power adaptation (ITPA), and the frequency-domain coexistence beacon (FCB). Upon the cross-layer architecture, firstly, white space devices (WSDs) achieve a faster search and higher accuracy in spectrum sensing with the extended spectrum map, the extended DHCP (Dynamic Host Configuration Protocol), and the FCB. Secondly, WSDs achieve the precise selection of their operating channel in spectrum decision with the extended spectrum map and the ITPA. In spectrum sharing, thirdly, the collaboration- based spectrum sharing with the ITPA achieve more accommodation of WSDs by increasing the number of channels shared between WSDs. Finally, WSDs with the FCB and the extended spectrum achieve effective spectrum mobility by obtaining the occupancy-status of channels precisely.
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Leclercq, Indy. "The local radio sky : high frequency-resolution single-dish studies of polarised Galactic synchrotron emission around 1.4 GHz." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/the-local-radio-sky-high-frequencyresolution-singledish-studies-of-polarised-galactic-synchrotron-emission-around-14-ghz(ea6e9f26-1a23-42c7-8d90-1d47b0297ad4).html.
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Polarised synchrotron emission from the Milky Way is of interest for its role as a foreground to the polarised CMB and as a probe of the interstellar medium. The Galactic ALFA Continuum Transit Survey (GALFACTS) and the Global Magneto-Ionic Medium Survey (GMIMS) are two ongoing surveys of the diffuse polarised emission around 1.4 GHz, with wide bandwidths and high frequency-resolution. In this thesis, I use early data from GALFACTS to investigate the behaviour of polarised, diffuse Galactic synchrotron emission. I also analyse GMIMS total intensity data. I derive a rotation measure (RM) map of the GALFACTS sky using a combination of RM-synthesis and linear angle fitting, commenting on the structure of the maps in general and on specific regions in particular. Overall I find that the maps are rich in features, and probe the RM structure of the extended Galactic emission with reasonable accuracy. I also derive the Angular Power Spectrum (APS) of the polarised emission for thirty-one 15 by 15 degree subregions across the GALFACTS data. I compute the E- and B-modes (E+B) and the scalar APS of the polarised emission (PI). I parametrise the APS by fitting a power law to the data. Comparing the E+B APS to the PI APS shows that E+B is consistently steeper across the sky. The APS data is also used to estimate the level of foreground contamination of the CMB B-mode by the synchrotron emission. I find that the slope of the APS averaged over high-latitude, low-emission subregions agrees exactly with that of the Planck 30 GHz polarised emission, thus setting an upper limit to the synchrotron contamination of CMB B-modes. Finally, I evaluate the spurious, systematic, temperature zero-level offset and associated uncertainty in preliminary GMIMS total intensity maps, finding a lower limit of ±0.26 K. I also make spectral index maps made using the GMIMS data and the Haslam et al. (1982) 408 MHz map, improving upon previous spectral index maps in the literature.
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Yang, Xianzhen. "Power Spectrum Prediction of Amplified Dual-Band LTE-Advanced Signals." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4351.
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In wireless communication, the nonlinearity of a radio frequency (RF) power amplifier is an important issue for power amplifier designers. Since the nonlinearity is generated by the properties of physical components, it is hard to avoid it in producing power amplifiers. Power amplifier designers should know about the nonlinearity in order to compensate for it.
A two-tone test is a relatively widely used method to measure the nonlinearity of a power amplifier, which means the third order intercept point (IP3) can be measured from the two-tone test. Through the two-tone test, researchers have proposed some formulae to present what the amplified Code Division Multiple Access (CDMA) signal is like. They derived formulae in terms of output power, bandwidth, IP3, and IP5 to express the amplified CDMA signal and further to Orthogonal Frequency Division Multiplexing (OFDM) signals. With the development of wireless communication, researchers put their interest increasingly in Multiple Input Multiple Output (MIMO) systems. A formula expressing amplified dual two-tone signals has been proposed. In their research, they discussed what the expressions of intermodulation and cross modulation are and what their locations are.
In this research, dual band LTE-Advanced signals, whose modulation is OFDM are utilized, which means this research proposes a formula expression about the power spectrum of dual-band LTE-Advanced signals. Intermodulation and cross modulation caused by nonlinearity of power amplifiers are then specially discussed. This study will help RF designers to continuously compensate for them.
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Valente, Pedro Brigas. "WiFi radio resource management." Master's thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/23484.
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Mestrado em Engenharia Electrónica e TelecomunicaçõesPassive optical networks have been subject of research in recent years, standing out from the other distribution networks not only by the speed and distribution of multiple services, including video, data and voice, but also by the absence of active equipment between the central and terminal devices, not requiring the use of electricity. Also the progress made in mobile and "smart" equipment led to the increase of its popularity and personal use. The increase of mobile devices, as well as their features, were boosted by the evolution of WiFi technologies, mostly fueled by passive optical networks, favoring the connection of several devices through radio waves. There has been several improvements in wireless communications, especially in WiFi technology, in order to keep up with the speed increase in optical distribution networks. However the limitations in the frequency spectrum and the vast implementation of the technology itself became an obstacle to the development of WiFi networks. The main goal of this dissertation is the development of processes dedicated to the frequency spectrum management in WiFi networks within environments congestedbymultipleradiosignaltransmitters. Thisworkisdevelopedaround a gateway under development by Altice Labs combining optical network terminal and access point features, and presents a solution to the equipment transmission power management and the frequency channel selection.
As redes ópticas passivas têm sido alvo de grande investigação nos últimos anosdestacando-sedasoutrasredesdedistribuiçãonãosópelavelocidadee distribuição de multiplos serviços, incluindo video, dados e voz, mas também pela ausência de equipamentos activos entre a central local e o equipamento terminal, não sendo necessário o uso de energia eléctrica. Também o avanço que se tem verificado no desenvolvimento de equipamentos móveis e "inteligentes" tem levado a sua popularidade e utilização a crescer de forma constante. Por sua vez, este aumento do número de dispositivos móveis, bem como das respectivas características, foi impulsionado pela evolução da tecnologia WiFi, em grande parte alimentada pelas redes ópticas passivas, facilitando a conexão de múltiplos dispositivos através de ondas de rádio. Têm sido várias as melhorias nas comunicações sem fios, especialmente na tecnologia WiFi, no sentido de acompanhar o aumento da velocidade das redes de distribuição ópticas. No entanto as limitações ao nível do espectro de frequência e a vasta implementação da própria tecnologia têm-se revelado obstáculos ao desenvolvimento das redes WiFi. Esta dissertação tem como objectivo o desenvolvimento de soluções para a gestão do espectro de frequência das rede WiFi em ambientes congestionados pela presença de múltiplos transmissores de sinal rádio. Este trabalho é desenvolvido sob um gateway em desenvolvimento pela Altice Labs que combina as funcionalidades de um terminal de redes ópticas e de um access point, e apresenta uma solução para a gestão da potência de transmissão do equipamento e para a escolha do canal de frequência a utilizar.
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Rodesten, Stephan. "Program för frekvensanalys." Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-58157.
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Denna rapport täcker arbetsprocessen bakom att skapa en spektrumanalysator. Läsaren kommer att få läsa om den valda metoden men även alternativa metoder. Utöver detta kommer även de teoretiska delarna bakom varje moment att undersökas samt jämföras med potentiella alternativa lösningar. Projektet har utförts på uppdrag av KA Automation. Syftet med projektet var att skapa en basplattform för analys av ljudfrekvenser. Målet med detta var att kunna identifiera ljudegenskaper i form av frekvenserna hos exempelvis servomotorer i vattenpumpar. Tanken var att i ett senare utvecklingsskede kunna identifiera om och när nya frekvenser dykt upp i ljudprofilen vilket i sådana fall kan resultera i att motorn är i behov av service. Basplattformen är uppbyggd med hjälp av C# och ljudbehandlingsbiblioteket NAudio. Från resultatet kan slutsatsen dras att detta program kan analysera ljud och visa de olika frekvensernas styrka och därmed är en lämplig basplattform för vidareutveckling.This report will cover the work process behind creating a spectrum analyzer. The reader will be able to read about the chosen method but also the alternative methods. Apart from this the theoretical parts behind every moment will also be covered and compared to potential alternative solutions. The project has been carried out on behalf of KA Automation. The purpose of the project was to create a base for analyzing sound frequencies. The goal was to be able to identify sound properties in the form of frequencies in servo motors in for example water pumps. The idea was to be able to in a later development stage be able to identify when new frequencies have entered the audio profile which might result in the motor to be in need of service. The base is created with the help of C# and the sound library NAudio. From the result one can conclude that this program can analyze sound and display the magnitude of its frequency components and is therefore a suitable base for future development.
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Saldanha, Nancy. "Modeling, design and fabrication of orthogonal and psuedo-orthogonal frequency coded SAW wireless spread spectrum RFID sensor tags." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5025.
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Surface acoustic wave (SAW) sensors offer a wireless, passive sensor solution for use in numerous environments where wired sensing can be expensive and infeasible. Single carrier frequency SAW sensor embodiments such as delay lines, and resonators have been used in single sensor environments where sensor identification is not a necessity. The orthogonal frequency coded (OFC) SAW sensor tag embodiment developed at UCF uses a spread spectrum approach that allows interrogation in a multi-sensor environment and provides simultaneous sensing and sensor identification. The SAW device is encoded via proper design of multiple Bragg reflectors at differing frequencies. To enable accurate device design, a model to predict reflectivity over a wide range of electrode metallization ratios and metal thicknesses has been developed and implemented in a coupling of modes (COM) model. The high coupling coefficient, reflectivity and temperature coefficient of delay (TCD) of YZ LiNbO[sub3] makes it an ideal substrate material for a temperature sensor, and the reflectivity model has been developed and verified for this substrate. A new concept of pseudo-orthogonal frequency coded (POFC) SAW sensor tags has been investigated, and with proper design, the POFC SAW reduces device insertion loss and fractional bandwidth compared to OFC. OFC and POFC sensor devices have been fabricated at 250 MHz and 915 MHz using fundamental operation, and 500 MHz and 1.6 GHz using second harmonic operation. Measured device results are shown and compared with the COM simulations using the enhanced reflectivity model. Additionally, the first OFC devices at 1.05 GHz were fabricated on 128[superscript o] YX LiNbO[sub3] to explore feasibility of the material for future use in OFC sensor applications. Devices at 915 MHz have been fabricated on YZ LiNbO[sub3] and integrated with an antenna, and have then been used in a transceiver system built by Mnemonics, Inc. to wirelessly sense temperature.; The first experimental wireless POFC SAW sensor device results and predictions will be presented.ID: 029809657; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 148-152).
Ph.D.
Doctorate
Electrical Engineering and Computer Science
Engineering and Computer Science
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Bolas, Eduardo José Ludovico. "Broadband VHF maritime communications based on cognitive radio." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/16285.
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Doutoramento em Engenharia EletrotécnicaTraditionally, maritime business is associated to transportation, which represents about 90% of global trade, and fishery, but new activities at sea, opened up by technological innovations, are transforming economical context of maritime services and resources. In the future, the massive use of technology to support endurance and ranging of maritime operations, namely in intelligent transport systems and autonomous vehicles areas, would lead to federations of maritime based embedded computing devices. Nevertheless, existing systems are not prepared to support such paradigm change. Currently, stovepiped systems rely on narrowband communications systems, where voice and low data rate are the most common used services, and specific broadband applications, such as Internet access, are supported by satellite communications (SATCOM). Unfortunately, UMTS/LTE networks do not provide consistent solutions, due their limited sea coverage, so there is a need for an additional capacity that can provide acceptable performances at low cost, which might act as a complement or even an alternative to satellite. We propose a Cognitive Radio based Broadband VHF (CR-B-VHF) communications solution to provide appropriate connectivity to support current information exchange requirements and enable future developments on maritime services and applications, thus avoiding SATCOM inconveniences. This CR-BVHF network would operate in a context of spectrum scarcity, within hierarchical spectrum access model, and use cognitive radio based concepts to implement a dynamic system that can activate and deactivated subcarriers, according to spectrum opportunities, ensuring an adequate interference level at incumbent's live services. The main contribution of this thesis work is the proposed CR-B-VHF framework and the demonstration of its suitability, feasibility and deployability. The presented relevancy analysis provides an overview of the state of the art on maritime business and its associated support communications and information systems, and prospects future requirements and applications for low-cost broadband access. The developed solutions for detection and exploitation of multiple non-contiguous narrowband spectrum opportunities in maritime VHF band, within a hierarchical spectrum access context, and their envisage performances, provide good indications regarding attainability of opportunistic BVHF systems and their future deployment. Finally, the discussion on regulatory and standardization issues intend to contribute for a shared problem solving, providing an end user perspective of hierarchical spectrum access. Despite the fact that technical aspects are nor the main issues on opportunistic systems deployment, novel proposed Spectrum Coherences Detector and its experimental demonstrated performances might be an important enabler and an additional argument to convince maritime communications stakeholders.
Tradicionalmente, a economia do mar está associada ao transporte marítimo, que representa cerca de 90% do comércio mundial, e à pesca, mas as novas atividades associadas à inovação tecnológica estão a transformar o contexto económico dos serviços e aplicações marítimas. No futuro, a utilização massiva de tecnologia no suporte às atividades desenvolvidas no mar, nomeadamente em transportes marítimos inteligentes e sistemas autónomos, conduzirá a uma federação de sistemas marítimos integrados. Contudo, as comunicações marítimas existentes não estão preparadas para dar suporte a esta alteração de paradigma. Atualmente, os sistemas dedicados baseiam-se em comunicações de banda estreita, onde a telefonia e a transmissão de dados de baixo débito são os serviços mais comuns, e aplicações de banda larga específicas, como o acesso a Internet, são disponibilizados através de comunicações por satélite (SATCOM). Infelizmente, as redes UMTS/LTE não providenciam soluções consistentes, devido à fraca cobertura sobre o mar. Por conseguinte, existe uma clara necessidade de capacidade adicional que possa disponibilizar desempenhos adequados a baixo custo e que possa constituir um complemento, ou mesmo uma alternativa, ao satélite. Nesta tese é proposta uma solução de comunicações de banda larga em VHF, baseada em rádio cognitivo (CR-B-VHF), que permite disponibilizar uma adequada conectividade de suporte aos requisitos atuais de troca de informação e a futuros desenvolvimentos nos serviços e aplicações marítimas, evitando as desvantagens da utilização do satélite. Esta rede foi concebida para operar num contexto de escassez de espectro, assumindo um modelo de acesso hierárquico, e utiliza conceitos de rádio cognitivo para implementar um sistema dinâmico que possa ativar e desativar sub-portadoras, de acordo com as oportunidades para transmitir, garantindo um adequado nível de interferência com os serviços dos incumbentes. O principal contributo deste trabalho é a proposta de um conceito de CR-B-VHF e a demonstração da sua adequabilidade, exequibilidade e aceitabilidade. A análise de relevância apresentada, proporciona uma perspetiva do estado da arte das atividades marítimas associadas à economia do mar e dos sistemas de informação e comunicação que lhes dão suporte, bem como uma perspetiva dos requisitos futuros e as aplicações para acessos de banda larga a baixo custo. As soluções desenvolvidas para a deteção e exploração de múltiplas e nãocontíguas oportunidades de banda estreita na banda marítima de VHF, e as suas previsíveis prestações, abrem boas perspetivas relativamente ao potencial dos sistemas oportunísticos na banda de VHF e a sua futura implementação. Finalmente, é apresentada uma discussão sobre questões regulatórias e de normalização, cujo objetivo é contribuir para a solução do problema da utilização partilhada do espectro, providenciando uma perspetiva de utilizador final, num modelo de acesso hierárquico ao espectro.
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Kilicoglu, Nezaket. "Construction Of An Experimental Radar System." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612760/index.pdf.
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In this thesis, an Experimental Radar System is designed and constructed for
use in experimental radar studies such as clutter measurement and target
detection, both in the laboratory and outdoor. COTS laboratory equipments are
utilized as hardware elements of the radar and MATLAB is used as signal
processing and user interface software tool. Vector signal generator (as
transmitter), spectrum analyzer with vector signal analysis (as receiver), a high
power amplifier, a low noise amplifier, horn antennas and a computer are the
hardware units of the system. Various transmit signals are generated and pulse
Doppler processing is performed at the receiver side. The system is controlled
through the user interface which runs on a PC.
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Bolívar, Díaz Nicolás. "Medium access control messaging scheme for cognitive radio networks." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/84098.
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Cognitive Radio (CR) is one possible option for mitigating the inefficient wireless spectrum distribution that occurs as a result of fixed spectrum allocation. The use of Dynamic Spectrum Access capabilities will potentially enable secondary users to utilize available and unoccupied frequency slots (channels) whenever the licensed users for those channels are absent. In Cognitive Radio Networks (CRNs), whenever users access the spectrum in an opportunistic manner, control messaging is a crucial issue to ensure that secondary users, i.e. Cognitive Radio Users (CRUs), do not interfere with the licensed users, i.e. Primary Users. In CRNs, where not all CRUs share the same set of channels, i.e. CRUs with Heterogeneous Frequency Devices (HFD), a set of channels must be chosen with care to allow all CRUs in the network to be able to transmit and receive control information. The thesis considers how Control Messaging Schemes (CMSs) can be used within CRNs and proposes a novel CMS for a CRN supporting HFDs. The thesis starts by classifying the CMSs; generating a new taxonomy and identifying the main characteristics for an efficient CRN with HFD. Then, different mathematical approaches for choosing the set of channels used for control information are presented. Next, a CMS for a CRN with HFDs model based upon the aforementioned characteristics and calculating the minimum number of channels for transmitting control information is proposed. Finally the thesis concludes with a number of CMS being presented and evaluated in terms of their impact upon transmission efficiency.
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Neji, Najett. "Etude de la compatibilité radioélectrique du futur système de communication aéronautique en bande L." Phd thesis, Supélec, 2011. http://tel.archives-ouvertes.fr/tel-00825251.
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Au début des années 2000, les instances aéronautiques ont exprimé le besoin de développer un nouveau système de radiocommunication aéronautique du fait de l'augmentation du trafic aérien et de la saturation croissante des capacités de communication radio entre les aéronefs et les stations de contrôle aérien. L'une des composantes de ce système, nommée L-DACS (" L-band Digital Aeronautical Communication System "), devrait opérer dans la bande L-aéronautique (960-1164 MHz), dans laquelle fonctionnent également de nombreux autres systèmes radioélectriques. La compatibilité radioélectrique (CRE) de L-DACS avec ces systèmes est un des facteurs principaux à prendre en considération dans le développement d'un tel système.L'objectif principal de cette thèse est d'identifier les principaux problèmes reliés à la CRE et d'en étudier les cas critiques. Ces travaux sont fondamentaux en aéronautique, puisque tout dysfonctionnement dans la communication ou dans les systèmes de radionavigation peut mettre en danger la sécurité du vol. Les conclusions de cette thèse contribueront à la normalisation du système L-DACS et à la finalisation de ses spécifications.Dans une première étape, on étudie l'état de l'art dans les communications aéronautiques et en CRE. On analyse en particulier les dernières spécifications des deux systèmes candidats L-DACS. Ensuite, on propose un algorithme de calcul de brouillage dans le but d'étudier la CRE dans le domaine fréquentiel, d'en identifier et d'en traiter les cas critiques. L'analyse fréquentielle étant insuffisante dans plusieurs cas, on propose alors une approche temporelle d'étude de CRE. Après en avoir présenté les avantages, on présente un exemple d'étude de l'effet d'un système L-DACS sur un récepteur DME (" Distance Measuring Equipment ") à l'aide d'un banc de test CRE aéronautique.Cette thèse a été réalisée en collaboration avec la Direction Générale de l'Aviation Civile (DGAC), qui est un acteur principal pour la réglementation des communications et un affectataire de fréquence pour le spectre aéronautique en France. La thèse contribue aux études menées par la DGAC à l'échelle nationale et internationale.Dans les perspectives, on propose la poursuite de cette étude par une approche temporelle plus générale pour étudier la CRE entre des systèmes radioélectriques quelconques en tenant compte de paramètres supplémentaires liés à la dynamique des systèmes et aux propriétés de leurs technologies.
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Andrén, Alexander. "Telekrig mot bandspridningsteknik." Thesis, Försvarshögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:fhs:diva-2680.
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I denna uppsats betraktas två olika bandspridningstekniker och vilken påverkan de har på telekrigsförmågan. Uppsatsen svarar på frågan: Vilka möjligheter finns att bedriva signalspaning och störning mot radiokommunikation som använder bandspridningsteknikerna frekvenshopp eller direktsekvens? Inledningsvis beskrivs en modell för telekrig mot radiokommunikation, ”telekrigcykeln”. Därefter beskrivs principer för ett radiosystem samt de två bandspridningsteknikerna frekvenshopp och direktsekvens. Slutligen analyseras bandspridningsteknikernas påverkan med hjälp av telekrigcykeln och resultaten diskuteras. Uppsatsen kommer fram till att båda signalerna går att spana mot, direktsekvens innebär större svårigheter för signalspaningen än frekvenshopp. Störning av båda signalerna görs bäst med störsändare som befinner sig nära radiomottagaren, dock är det svårt att placera störsändare nära motståndarens mottagare.This essay examines two spread-spectrum technologies and what their effects are on the electronic warfare ability. The essay seeks to answer this question: What are the possibilities for signals intelligence and communications jamming against radio communications using one of the two spread-spectrum technologies frequency-hopping and direct sequence? The essay initially describes a model for how electronic warfare against radio communication is conducted, “telekrigcykeln”. It then describes the principles of a radio system as well as the two spread-spectrum technologies frequency-hopping and direct sequence. Using the model “telekrigcykeln” the essay finally analyses and discusses the impact of the spread-spectrum technologies. The essay finds that it is possible to conduct signals intelligence towards both signals, however direct sequence pose bigger problems than frequency-hopping. Both signals are easiest to jam using a jammer in close proximity to the radio receiver. However, close-proximity jammers are harder to place close to the opponent’s receiver.
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Al-Sharari, Hamed. "An implementation of acquisition using transform domain/cycle code shift keying system on a multipath channel." Ohio : Ohio University, 1998. http://www.ohiolink.edu/etd/view.cgi?ohiou1177004799.
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Neužil, Jan. "Uživatelské rozhraní pro HP89410A." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217775.
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The aim of this thesis was to develop user interface in LabVIEW to make typical measurements with spectral analyzer HP89410A There is introduced the theory of operation of an analogue heterodyne and a digital FFT spectral analyzer. It is explained the background of the Fast Fourier Transform. There are discussed the key settings in measuring with FTT analyzer, like window function, bandwidth, number of frequency points, or the averaging. Further is described the program, which was developed for measuring frequency characteristic by white noise and by stepped measurement. It was also made a module for measuring Signal to Noise Ratio and module for Total Harmonic Distortion. In the last part of this thesis are shown the results of processed exemplar measurements.