The objective of this dissertation is to propose circuit architectures and techniques for built-in test and calibration of phase-locked loops. The design of phase-locked loops is first investigated to achieve a robust performance over process, temperature, voltage corners with minimum overhead. Different design techniques including adding loop programmability, increasing area efficiency, reducing noise immunity, and increasing frequency coverage are discussed. Secondly, built-in testing of phase-lock loops using sensors are proposed for loop dynamic parameters and reference spur. An integrator is designed to extract the subtle response from the system so that target parameters can be predicted. Different testing methodologies are applied different specification testing as well. Finally, an on chip phase-locked loop design is implemented for reference spur calibration. The phase-locked loop is designed with a programmable reference spur range. A static phase offset detector is included to identify the optimal setting of reference spur in the feedback system. The integrated jitter performance is improved by the calibration mechanism. The results of this thesis serve as an on-chip built-in self-test and self-calibration solution for embedded phase-locked loops in a high integration system.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Information Technology, Durban University of Technology, Durban, South Africa, 2015. / This thesis focuses on the development of an enhanced innovative secure mobile Internet voting system architecture that offers desirable security requirements to theoretically mitigate some of the intrinsic administrative and logistical challenges of voting, inter alia lack of mobility support for voters, voter inconvenience, election misconduct, and possible voter coercion often associated with the conventional poll-site voting system. Systems in existence have tended to revolve around the need to provide ubiquitous voting, but lack adequate control mechanism to address, in particular, the important security requirement of controlling possible coercion in ubiquitous voting. The research work reported in this thesis improves upon a well-developed Sensus reference architecture. It does so by leveraging the auto-coupling capability of near field communication, as well as the intrinsic merits of global positioning system, voice biometric authentication, and computational intelligence techniques. The leveraging of the combination of these features provides a theoretical mitigation of some of the security challenges inherent in electoral systems previously alluded to. This leveraging also offers a more pragmatic approach to ensuring high level, secure, mobile Internet voting such as voter authentication. Experiments were performed using spectral features for realising the voice biometric based authentication of the system architecture developed. The spectral features investigated include Mel-frequency Cepstral Coefficients (MFCC), Mel-frequency Discrete Wavelet Coefficients (MFDWC), Linear Predictive Cepstral Coefficients (LPCC), and Spectral Histogram of Oriented Gradients (SHOG). The MFCC, MFDWC and LPCC usually have higher dimensions that oftentimes lead to high computational complexity of the pattern matching algorithms in automatic speaker authentication systems. In this study, higher dimensions of each of the features were reduced per speaker using Histogram of Oriented Gradients (HOG) algorithm, while neural network ensemble was utilised as the pattern-matching algorithm. Out of the four spectral features investigated, the LPCC-HOG gave the best statistical results with an R statistic of 0.9257 and Mean Square Error of 0.0361. These compact LPCC-HOG features are highly promising for implementing the authentication module of the secure mobile Internet voting system architecture reported in this thesis. / D

Submitted by SBI Biblioteca Digital (sbi.bibliotecadigital@puc-campinas.edu.br) on 2017-02-01T12:51:11Z No. of bitstreams: 1 Ricardo FialhoTafas Junior.pdf: 1902411 bytes, checksum: fc7842d9f339a60c5d0842dad71af8e3 (MD5) / Made available in DSpace on 2017-02-01T12:51:11Z (GMT). No. of bitstreams: 1 Ricardo FialhoTafas Junior.pdf: 1902411 bytes, checksum: fc7842d9f339a60c5d0842dad71af8e3 (MD5) Previous issue date: 2016-12-16 / Pontif?cia Universidade Cat?lica de Campinas ? PUC Campinas / There is a growing need to ensure information security in telecommunications systems. However, currently, most cryptographic techniques protect only the message and do not prevent the capture of the transmitted symbols, which could compromise the security of the information. Therefore, a new cryptographic technique is proposed in this work which obfuscates the signal in the physical layer, making eavesdropping more difficult. First of all, prior to transmission, a change of basis operation is applied on the signal and, then, an obfuscation operation is performed on the base-changed signal. Afterwards, the obfuscated signal is returned to the initial base and it is ready for transmission. On the receiver side, a basis change is performed again and the de-obfuscation operation is applied, followed by an operation to return the signal to its original base. This work evaluated the bit error rate due to wrong key application and the maximum code breaking time to assess the technique. In addition, to the application in data communication and information security systems, the technique can be applied to data buses to prevent product cloning. / Existe uma necessidade crescente em garantir a seguran?a da informa??o em sistemas de telecomunica??es. Contudo, atualmente, a maioria das t?cnicas de criptografia protege apenas a mensagem, n?o impedindo a captura do sinal correspondente aos s?mbolos transmitidos, o que pode comprometer a seguran?a da informa??o. Em fun??o disso, neste trabalho, prop?e-se uma nova t?cnica criptogr?fica, que promove o ofuscamento dos sinais na camada f?sica, dificultando a??es de espionagem. Primeiramente, antes da transmiss?o, aplica-se uma opera??o de mudan?a de base sobre o sinal e, em seguida, uma opera??o de ofusca??o sobre o sinal modificado. Na sequ?ncia, retorna-se ? base inicial e o sinal ofuscado est? pronto para transmiss?o. Na detec??o, executa-se novamente a mudan?a de base, aplica-se a opera??o de desofusca??o, seguida da opera??o para retornar ? descri??o do sinal ? base original. Este trabalho estimou a taxa de erro de bit por uso de chave errada e o tempo m?ximo de quebra do c?digo para avaliar a t?cnica. Al?m da aplica??o em sistemas de telecomunica??es, a t?cnica pode ser aplicada em barramentos de dados, para evitar roubo de software ou firmware, prevenindo clonagem de produtos.

Les enjeux majeurs des dispositifs hyperfréquences utilisés dans les systèmes de télécommunication modernes sont la montée en fréquence de fonctionnement, la miniaturisation des circuits et l’intégrabilité des composants.Grâce à l’émergence des métamatériaux et à la maîtrise des propriétés des ferrites, il est possible de développer nouveaux dispositifs répondant à ces nouvelles exigences de l’électronique embarquée.Cette thèse développe, à partir d’une ligne métamatériau HIW coplanaire basée sur un substrat de ferrite, un nouveau dispositif hyperfréquence non réciproque de faible encombrement, opérant à des fréquences situées entre 13 et 15 GHz.Les prototypes fabriqués et caractérisés sous de faibles valeurs de champ magnétique, présentent les performances caractéristiques d’un isolateur bande étroite: isolation supérieure à 30 dB, pertes d’insertion inférieures à 1 dB. / The main challenges of microwave devices used in modern telecommunication systems are the increase of the operating frequency, the circuit’s miniaturization and the integration of components.Thanks to the emergence of metamaterials and the control of the properties of ferrites, it is possible to develop new circuits that meet these new requirements for embedded electronics.This thesis investigates, from a coplanar HIW metamaterial line based on a ferrite substrate, a new non-reciprocal microwave device, operating in frequency range between 13 and 15 GHz.Prototypes were fabricated and characterized under low magnetic field. They achieved the characteristic performances of a narrow band isolator: isolation over 30 dB and insertion losses of less than 1 dB.

The enabling technologies and the issues of next-generation millimeter-wave wireless access network and 100G long-haul optical transport network were developed and identified. To develop a simple and cost-effective millimeter-wave optical-wireless system, all-round research on the technical challenges of optical millimeter-wave generation, transmission impairments compensation, and simple base station design were discussed. Several radio-over-fiber systems were designed to simultaneously deliver multi-band wireless services on a single optical infrastructure, enabling converged system control and quality maintenance in central office. For the 100G optical transport network, the issues related to successful implementations of transmitter, fiber link, and receiver of a 112-Gb/s polarization-division multiplexing-quadrature phase shift keying (PDM-QPSK) system were comprehensively explored. The experimental results based on the constructed 112-Gb/s testbed indicated that careful dispersion management can effectively increase nonlinearity tolerance. Furthermore, the special emphasis on the two impairments of the 100G network with reconfigurable optical add-drop multiplexers: passband narrowing and in-band crosstalk, was studied. The results demonstrated that these impairments can be readily predicted with proper experimental and simulation efforts.

The Community Broadband Investment Act, introduced in the Georgia legislature in 2012 and 2013 is a reflection of a broader national debate over the role of government investment in broadband infrastructure. The bill would limit local governments' ability to invest in broadband infrastructure for their communities because of arguments that government entry into the telecommunications sector crowds-out private competition, does not serve the public adequately, and lacks a comprehensive business model or best practices. A closer look at the history of utility regulation and various economic perspectives on the proper government role in utility provision reveals that government has had an extensive historical role in utility infrastructure investment and regulation, and several economic doctrines support the conclusion that government can be helpful in facilitating effective broadband service to their communities. Case studies of different models of municipal broadband networks in Georgia reveal that government entry can facilitate private sector competition, often provides quality service, and has a set of best practices. The success of municipal broadband reveals an evolution in the approach to telecommunications regulation from a regulated monopoly approach to a public-private cooperation approach which considers public participation with private entities on a dynamic scale. Government-entry into the broadband market was a rational decision for several Georgia communities due to their unique set of circumstances, and while municipal broadband may not be the answer to many communities' problems with meeting public demand, communities should be allowed to maintain flexibility in their decision-making about how to best serve their residents, effectively allowing them to decide which combination of public and private advantages they can leverage to meet the demand of their communities in relation to their unique local characteristics.

This research encompassed an investigation of high school learners using MXiT, and their attitudes towards mobile security guidelines. The research was conducted across thirteen schools in the Pinetown, ILembe and Umlazi districts of KwaZulu-Natal. The literature review has shown that the majority of security guidelines and their successful use depend on education and awareness of what these security measures are. Secure use of mobile social networking sites such as MXiT are best regulated by parental awareness and monitoring of children‟s online habits. This needs parents to be abreast of technology, its uses and benefits, the associated dangers, as well as how to encourage and monitor usage. The research was conducted by administering questionnaires to grades 8 to 11 inclusive in the three districts of KwaZulu-Natal. Out of the 1300 questionnaires handed out to learners, a total of 856 completed questionnaires (66%) were received and analysed. It was found from the study that 89,5% of under age users that participated in this research are using MXiT. Users are also not fully aware of the security features when using MXiT. It has also been found that African respondents as compared with non- African respondents are less aware of the possible dangers in using MXiT, less aware that criminals can use fake IDs and pretend to be someone they are not, and less aware that people can get addicted to MXiT. Learners are aware of the dangers that can be associated with MXiT; however they are prepared to talk to strangers and meet new people online, thus exposing themselves to these dangers. In conclusion, there is scope to improve the security measures for MXiT users, and there is a need to improve the levels of education around using these security features. / Thesis (M.Com.)-University of KwaZulu-Natal, Westville, 2011.

With rapid advances in semiconductor technologies and packaging schemes, wireless products have become more versatile, portable, inexpensive, and user friendly over last few decades. However, the ever-growing demand of consumers to share information efficiently at higher speeds requires higher data rates, increased functionality, lower cost, and more reliability. The 60-GHz-frequency band, with 7 GHz license-free bandwidth addresses, such demands, and promises a low-cost multi-Gbps wireless transmission with a power budget in the order of 100 mW. This dissertation presents the systematic development of key building blocks and integrated 60-GHz-receiver solutions. Two different approaches are investigated and implemented in this dissertation: (1) low-cost SiGe-based direct-conversion low-power receiver front-end utilizing gain-boosting techniques in the front-end low-noise amplifier, and (2) CMOS-based heterodyne receiver front-end suitable for high-performance single-chip 60 GHz transceiver solution. The ASK receiver chip, implemented using 0.18 ?m SiGe, presents a complete antenna-to-baseband multi-gigabit 60 GHz solution with the lowest reported power budget (25 pJ/bit) to date. The subharmonic direct conversion front-end, implemented using 0.18 ?m SiGe, presents excellent conversion properties with a 4 GHz DSB RF bandwidth. On the other hand, the CMOS heterodyne implementation of the 60 GHz front-end receiver, targeted towards a robust, single-chip, high-performance, low-power, and integrated 60 GHz transceiver solution, presents the most wideband receiver front-end reported to date. Finally, different multi-band and tunable millimeter-wave circuits are presented towards the future implementation of cognitive and multi-band millimeter-wave radio.

Timing jitter and phase noise are important design considerations in most electronic systems, particularly communication systems. The desire for faster transmission speeds and higher levels of integration, combined with lower signal levels and denser circuit boards has placed greater emphasis on managing problems related to phase noise, timing jitter, and timing distribution. This thesis reports original work on phase noise modelling in electronic systems. A new model is proposed which predicts the up-conversion of baseband noise to the carrier frequency in RF amplifiers. The new model is validated by comparing the predicted phase noise performance to experimental measurements as it applies to a common emitter (CE), bipolar junction transistor (BJT) amplifier. The results show that the proposed model correctly predicts the measured phase noise, including the shaping of the noise about the carrier frequency, and the dependence of phase noise on the amplifier parameters. In addition, new work relating to timing transfer in digital communication systems is presented. A new clock recovery algorithm is proposed for decoding timing information encoded using the synchronous residual time-stamp (SRTS) method. Again, theoretical analysis is verified by comparison with an experimental implementation. The results show that the new algorithm correctly recovers the source clock at the destination, and satisfies the jitter specification set out by the ITU-T for G.702 signals.

Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2003. / "January 2003" Includes bibliographical references (leaves 120-129).