Dissertations / Theses on the topic 'Communications Technologies'

This thesis investigates the feasibility of deploying mobile communication networks at the THz frequency range. Three areas were identified as the major issues on the way towards realising a functional THz mobile communication system: the high atmospheric attenuation levels and obstacle shadowing at the THz range, the deficiency in THz devices suitable for mobile telecommunications and the availability of reliable models for the analysis and design of THz radio networks.

There is currently a glaring absence of critical discourse surrounding the integration of information communications technologies in schools. Despite a growing body of literature showing that technology has both advantages and disadvantages, schools are incorporating ICT as if it were a panacea for educational and societal ills. This deification of ICT is based on utilitarian concerns and spiritual yearnings. The first chapter situates the author and outlines how the larger technology metanarrative has a mythic status. Chapter two situates the appeal to utilitarian and spiritual values in the wider culture. The final chapter examines how these issues are played out in the school system. The author concludes with a summary and raises areas for further investigation, along with suggestions for change.

Ces travaux de recherches s'inscrivent dans le cadre du projet COMMINDOR, qui porte sur l'étude de communications millimétriques courte portée à 60 GHz. L'antenne étant un élément-clé dans ces systèmes, plusieurs filières technologiques sont examinées pour mettre en évidence les qualités et les faiblesses propres à chacune d'elles, en terme de performances, d'intégration et de coût. Une technologie de circuit imprimé est mise en oeuvre pour la réalisation d'antennes planaires à bas coût sur un substrat duroi͏̈d. Pour remédier à la faible bande passante et au rayonnement parasite de la ligne, un nouveau mode d'alimentation par guide d'ondes est développé, conférant à l'antenne une adaptation large bande avec peu de pertes. Grâce à une modélisation électromagnétique globale, des antennes actives intégrées sont également conçues dans une filière MMIC et caractérisées sous pointes. Après le report de la puce et l'intégration à proximité des éléments de découplage, le bénéfice du concept actif sur le gain d'antenne et la bande passante est validé lors des mesures de rayonnement.

The concept of interactivity continuously enhances our day-to-day living, allowing us to experience a more convenient and enjoyable life style. Existing analogue technologies such as the internet, mobile phone and satellite have now entered their digital phase, making it possible to increase their capacity for interactivity. The technologies which provide this increased interactivity, namely the internet, mobile and television, are classed as interactive technologies. Television has been successful at marketing, having launched an interactivity interface known as iTV which initially offered superior commercial prospects. However, after a decade, the iTV industry is still quite young and has not reached its full potential. This thesis adopts a range of research methodology with which to forecast the future of interactive technologies, especially interactive TV (iTV). The uptake of new interactive technologies depends on many factors, notably the existing infrastructure in the country of adoption, cultural attitudes to new technology, the radicalism of the technology, social influences and interactions and ease of use, quality and cost. Beyond these, many other significant factors influence the acceptance of interactive technologies, the focus of this thesis is to ascertain the importance of those factors mentioned on technology adoption. This study has adopted technological and judgemental forecasting techniques to predict the future of interactive technologies, following which Cross- Cultural and Technology Acceptance studies were carried out to investigate interactive technology adoption. In the Cross-Cultural study, survey data were collected from the UK, Hong Kong and Pakistan so as to examine cultural factors pertaining to the likelihood of adoption, while Growth Curves were used to model and forecast future levels of adoption. Then technology trends in different countries were collected from the global marketing database Euromonitor. The Growth Curves, applied to a selection of interactive technologies, were evaluated and compared to identify the most useful model with which to forecast the future of interactive technologies. The findings identified the Bass Model, Simple Logistic Model and Gompertz Model as the most suitable models for the purpose, with different models identified as best for different cultures. The Judgemental study established that WWW will be the dominant service provider for financial services such as banking or financial products, while iTV will be the dominant service provider for entertainment. WWW will in fact be the dominant provider for most of the services, followed by iTV and then WAP. It is most likely that WWW, WAP and iTV will exhibit technology convergence in 20 years' time and in all probability will converge into WWW. Further to this the Cross-Cultural study confirmed that there are significant differences between cultures regarding the acceptance of interactive technologies, as it is affected by demographic and social interactions and influences. In addition, the study showed that each interactive technology has its own significant elements which influence its acceptance. Overall, the key elements identified as influencing acceptance of interactive technologies were Knowledge and Confidence, followed by the number of hours the individual spends with his or her family. The Technology Acceptance study identified a technology acceptance model for each interactive technology: WWW, WAP and iTV, which established the factors expected to influence the future growth of the technology. Managing these significant elements will assist further in promoting the growth of interactive technologies

The past few years have seen a major change in cellular networks, as explosive growth in data demands requires more and more network capacity and backhaul capability. New wireless technologies have been proposed to tackle these challenges. One of the emerging technologies is device-to-device (D2D) communications. It enables two cellular user equipment (UEs) in proximity to communicate with each other directly reusing cellular radio resources. In this case, D2D is able to offload data traffic from central base stations (BSs) and significantly improve the spectrum efficiency of a cellular network, and thus is one of the key technologies for the next generation cellular systems. Radio resource management (RRM) for D2D communications and how to effectively exploit the potential benefits of D2D are two paramount challenges to D2D communications underlaying cellular networks. In this thesis, we focus on four problems related to these two challenges. In Chapter 2, we utilise the mixed integer non-linear programming (MINLP) to model and solve the RRM optimisation problems for D2D communications. Firstly we consider the RRM optimisation problem for D2D communications underlaying the single carrier frequency division multiple access (SC-FDMA) system and devise a heuristic sub-optimal solution to it. Then we propose an optimised RRM mechanism for multi-hop D2D communications with network coding (NC). NC has been proven as an efficient technique to improve the throughput of ad-hoc networks and thus we apply it to multi-hop D2D communications. We devise an optimal solution to the RRM optimisation problem for multi-hop D2D communications with NC. In Chapter 3, we investigate how the location of the D2D transmitter in a cell may affect the RRM mechanism and the performance of D2D communications. We propose two optimised location-based RRM mechanisms for D2D, which maximise the throughput and the energy efficiency of D2D, respectively. We show that, by considering the location information of the D2D transmitter, the MINLP problem of RRM for D2D communications can be transformed into a convex optimisation problem, which can be efficiently solved by the method of Lagrangian multipliers. In Chapter 4, we propose a D2D-based P2P le sharing system, which is called Iunius. The Iunius system features: 1) a wireless P2P protocol based on Bittorrent protocol in the application layer; 2) a simple centralised routing mechanism for multi-hop D2D communications; 3) an interference cancellation technique for conventional cellular (CC) uplink communications; and 4) a radio resource management scheme to mitigate the interference between CC and D2D communications that share the cellular uplink radio resources while maximising the throughput of D2D communications. We show that with the properly designed application layer protocol and the optimised RRM for D2D communications, Iunius can significantly improve the quality of experience (QoE) of users and offload local traffic from the base station. In Chapter 5, we combine LTE-unlicensed with D2D communications. We utilise LTE-unlicensed to enable the operation of D2D in unlicensed bands. We show that not only can this improve the throughput of D2D communications, but also allow D2D to work in the cell central area, which normally regarded as a “forbidden area” for D2D in existing works. We achieve these results mainly through numerical optimisation and simulations. We utilise a wide range of numerical optimisation theories in our works. Instead of utilising the general numerical optimisation algorithms to solve the optimisation problems, we modify them to be suitable for the specific problems, thereby reducing the computational complexity. Finally, we evaluate our proposed algorithms and systems through sophisticated numerical simulations. We have developed a complete system-level simulation framework for D2D communications and we open-source it in Github: https://github.com/mathwuyue/py- wireless-sys-sim.

Doutoramento em Engenharia Física
Hoje em dia, a tecnologia de fibra óptica está a ser amplamente usada nas áreas de telecomunicações e sensores. Historicamente, as qualidades das fibras ópticas poliméricas (POFs) têm sido menosprezadas devido à popularidade das fibras óticas de vidro. Tal facto advém maioritariamente da sua elevada atenuação. No entanto, os materiais que compõem as POFs têm vindo a melhorar significativamente nestes últimos anos. Nesse sentido, a emergência de novas técnicas e dispositivos têm vindo a ser demonstradas/os. Considerando o campo das telecomunicações, as POFs estão a crescer rapidamente em aplicações de redes de acesso. Além disso, o advento da operação monomodo e das redes de Bragg em POF estão a ser amplamente explorados em aplicações de sensores e portanto, este tipo de tecnologia tenderá a ser uma realidade num futuro próximo. Devido à necessidade de criar uma conexão de baixa perda entre fibra óptica de vidro e polimérica, será demonstrada uma nova técnica capaz de produzir terminais de POF de alta qualidade, num processo rápido, fácil e semiautomático. A conectorização destes tipos de fibras será também analisada nesta dissertação. No seguimento desta tese serão desenvolvidos dois sistemas de gravação de redes de Bragg em POF. Num dos sistemas será usado o tradicional laser de HeCd com operação nos 325 nm, sendo que noutro será usado o laser de KrF com operação nos 248 nm. Os resultados mostrarão a capacidade de gravar redes de Bragg em POF em apenas alguns segundos, contrariamente às várias dezenas de minutos necessários com o laser de 325 nm. Com base no sucesso dos resultados, o sistema de gravação que opera nos 248 nm será usado para fabricar redes de Bragg noutros tipos de fibras, incluindo as de índice em degrau, micro-estruturadas e sem bainha. A gravação de redes de Bragg de excelente qualidade em POFs de elevada birrefringência também será apresentada. A separação entre picos de ressonância irá ser usada para estimar a birrefringência de fase, que será então comparada com a obtida por simulações numéricas e com recurso ao método de varredura de comprimento de onda. As redes de Bragg produzidas pelos métodos anteriores serão então caracterizadas à deformação, temperatura, pressão, humidade e índice de refracção. Os resultados serão comparados com a literatura e com aqueles encontrados teoricamente. Um dispositivo de interferência multimodal feito pela conexão de duas fibras ópticas monomodo de vidro a uma fibra óptica multimodo de polímero, será usado para demonstrar a medição de deformação e temperatura. As capacidades de absorção de água, oferecidas pelo material à base de polimetilmetacrilato serão usadas para medir humidade. No final desta dissertação, um sensor híbrido composto por um dispositivo de interferência multimodal, baseado em POF e contendo uma rede de Bragg, demonstrará a capacidade de medir deformação, temperatura e índice de refracção. A propriedades de baixa absorção de água por parte do material que compõe a fibra polimérica será usada para demonstrar insensibilidade à humidade por parte do sensor.
Nowadays, fiber optic technology is being widely employed in communication and sensing areas. Historically, the qualities of polymer optical fibers (POFs) have been overwhelmed by the popularity of the silica optical fibers. This has been mainly due to the POFs higher transmission loss. However, in last years, POF materials are improving their performance. Therefore, the emergence of new devices and techniques have been demonstrated. Considering the communications field, POFs are growing rapidly in fiber to the home applications. Additionally, the advent of single mode operation and fiber Bragg gratings in POFs are being widely explored in several sensing applications. Consequently, this technology will tend to be a reality in a near future. Due to the need of a low loss connection between silica and polymer optical fibers, it will be demonstrated a new technique capable to produce POF terminals of high quality in an easy, fast and semi-automated process. The connectorization of these types of fibers will be then analysed in this dissertation. The development of two Bragg grating inscription systems for POFs will also be explored in this thesis. One of the systems will employ the traditional HeCd laser operating at 325 nm, while the other will use the KrF laser operating at 248 nm. Results will show the capability to write Bragg gratings in a POF in few seconds, contrary to the several tens of minutes reported for the 325 nm radiation. Based on the success of the results, the 248 nm inscription setup will be used to inscribe Bragg gratings in other types of POFs, including step-index, microstructured, and unclad POFs. The inscription of a high quality Bragg grating in a high-birefringence POF will also be presented and the phase birefringence arising from the Bragg peak separation will be compared with the numerical simulations togheter with the wavelength scanning method. The fiber Bragg gratings produced through the previous methods will be characterized to strain temperature, pressure, humidity and refractive index. Results will be compared with literature and with the ones found theoretically. A multimode interference device made by sandwiching a multimode POF between two single mode silica fibers will be used to demonstrate the ability to measure strain and temperature. The water absorption capabilities offered by the polymethylmethacrylate material will be used to measure humidity. At the end of this dissertation, a hybrid sensor composed of a POF based multimode interference device, comprising a fiber Bragg grating, will demonstrate the capability to measure strain, temperature and refractive index. The low water absorption properties of the material that composes the POF will be used to demonstrate a POF sensor with humidity insensitiveness.

Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Electrical Engineering, 2008.
Includes bibliographical references.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, Sept. 2004.
Thesis advisor(s): Rex Buddenberg. Includes bibliographical references (p. 103-105). Also available online.

Smart grid technologies are starting to be the future of electric power systems. These systems are giving the utilities detailed information about their systems in real time. One of the most challenging things of implementing smart grid applications is employing the communications into the systems. Understanding the available communications can help ease the transition to these smart grid applications. Many of the utility personnel are spending too much time trying to figure out which communication is better for their application or applications. So this thesis presents the different communication types available with discussing the different attributes in which these communication types are going to offer to the utility. Then these communication types are looked such that utilities can quickly understand how to approach the difficult task of obtaining the information from the different smart grid applications by the use of different communication options.

This dissertation claims that the reciprocal exchange of voice—an element for constructing community and strengthening political recognition—may be fostered in small-scale farming communities by (1) the appropriation and transformation of information and communications technologies, (2) artistic intervention, and (3) cross-community research. This study contributes to participatory research methodologies, particularly those that seek to tackle the diverse challenges faced by small-scale farmers from a broad, complex perspective. The main issue identified in this dissertation is as follows: The hegemony of economic behaviors, which stands as a cornerstone of neoliberal capitalism, constitutes the latest stage of a historical process in which the voices of small-scale farmers seem to have been progressively and systematically silenced, their traditional practices largely invalidated, and their reciprocal forms of social, political, and economic organization marginalized. The purpose of this study was to explore whether an open-ended, sociotechnical methodology could be designed and applied in small-scale farming communities with the aim of strengthening their reciprocal practices while amplifying the voices of their members. The author's research addressed the question of how the role of information and communications technologies can contribute to the creation of enabling environments in which subsistence farmers may exercise their own values and make their voices heard. Another goal was to study whether the reciprocal exchange of voice could relate to the construction and dissemination of a knowledge commons and improve the resilience of small-scale farmers in the context of complex and pressing challenges such as anthropogenic climate change. Consequently, the ERV (Enabling Reciprocal Voice) Methodology was developed and applied in small-scale farming communities in order to respond to the questions of this study. The ERV Methodology sought to redefine the modes of usage of information and communications technologies in order to help communities establish a shared communicational praxis and strengthen their reciprocal relations. The ERV Methodology stands in contrast with the technological determinism found in the purely solutionist, short-term initiatives that are generally implemented in small-scale farming communities. Instead of offering rapid solutions to isolated problems, the ERV Methodology sought to consolidate the social networks of farmers through online and offline interaction. The case studies examined in this dissertation were carried out in two small-scale farming communities in Tanzania and Mexico. Following the ERV Methodology, mobile phones and the Internet were used by farmers in those communities as tools for the collaborative creation of a knowledge commons focused on local agriculture. It was found that the ERV Methodology, carried out as artistic intervention, may encourage technological appropriation, induce reciprocity, and amplify voice under certain sociotechnical conditions. These findings suggest that such a methodology might benefit farmers by becoming a significant aid to increase their resilience and their capacity to face complex challenges in the longer term. However, another conclusion was that the ERV Methodology should be applied carefully, with a strong awareness of the local context, and that greater efforts must be made in order to integrate other communities, such as local authorities and scientific researchers, into the reciprocal dynamics enabled by the methodology.

International Telemetering Conference Proceedings / October 25-28, 1993 / Riviera Hotel and Convention Center, Las Vegas, Nevada
This paper addresses the creation of a large virtual-range environment whereby multiple, geographically dispersed, test ranges may operate in concert to support test operations. The most significant benefit of the virtual range environment is the time-sharing of costly processing resources. Other benefits include improved reliability and responsiveness of inter-range data transfer. This paper will focus on existing and near-term technology that may be applied to create a virtual-range and will address the technological and economic advantages and disadvantages of TDM vs. ATM approaches.

Approved for public release; distribution is unlimited.
This research evaluates the IEEE 802.16 standards and technologies that are currently being developed in the commercial sector. The robust capability of this standard lends itself potentially to numerous military applications. This research explores how this technology might address the shortcomings of existing military radio and data systems; specifically, with respect to the issues surrounding the Ship to Objective Maneuver (STOM) communications. The intent of this research is to provide recommendations on the necessary 'adapt from COTS' changes for this technology to address STOM networking requirements. This research includes discussions on the military requirements for an IEEE 802.16 adapted waveform. The requirements are for the IEEE 802.16 'adapt from COTS' are derived from researched on the Concept of Employment for STOM operations and the specification of the Joint Tactical Radio Systems (JTRS) Wideband Networking Waveform (WNW). These discussions offer an illustration of the complex networking demands the COTS adapted systems would need to address. Through detailed exploration of the current IEEE 802.16 standards and implementation testing with pre-standard IEEE 802.16a equipment, we were able to make recommendations on the COTS adaptations necessary to make IEEE 802.16 suitable as a complimentary technology within the STOM scenario.
Captain, United States Marine Corps

CHDS State/Local
This thesis explores the impact of rapidly evolving emerging technologies on public safety communications centers. It is intended to further the discussion on whether the public safety community is prepared for these new technologies, which will likely become commonplace over the next several years, and how to prepare to integrate those technologies into existing structures. Through the use of a nominal group technique and cross-impact analysis, this thesis utilized a pre-collected data set concerning the risks, structure, governance, policy and external influences associated with public safety communications centers in light of emerging technological advancements to determine what trends and events were of the greatest concerns to those actively involved in the leadership of public safety communications centers, development of emerging technologies, and implementation of governance models used by the various agencies. Those findings were analyzed and strategies were identified to allow for successful mitigation of the most statistically significant risks. Ultimately, this thesis determined that through visionary leadership, effective strategic planning and mitigation of risk, public safety agencies could position themselves for successful implementation of emerging technologies with their communications centers.

A new high-level language is sought after for implementing and mocking functional-ity on the Axis Communications platform. We analyze what impact the Node.js run-time environment has regarding performance and its ability to perform functionality.The performance refers to metrics on CPU, memory, free disk space and responsetimes and what effect an added Node.js runtime has on the platform. The functional-ity is based on Axis’ ideas about having Node.js run high-level services. A test planvalidates the functionality of a JavaScript service implemented as an API with JSONobjects as a POST and GET methods. To test the performance a test suite that sam-ples the data on a device and saves it like log files on a client. The variable is threedifferent stages, where the current device serves as the baseline. Secondly, to findout what impact Node.js itself has the second stage is with Node.js present and thethird stage represents a device where Node.js and the JavaScript service is put underload. The results show that it is possible to implement a JavaScript service runningunder Node.js since the test plan with its assertions passed on all tests. Regardingperformance and response time we did see a decrease in CPU idle time and memoryand an increase in the response time compared to the baseline.

The levels of organizational performance (OP) achievable from a dollar investment in information and communications technologies (ICT) remains elusive. A consensus exits among scholars and organizational leaders that effective use of ICT improves OP yet managers continue to struggle to justify investments in ICT. The purpose of this quantitative study was to explore and explain how investments in ICT related with OP. The study built on the resource-based view of the firm theoretical framework. A key question in the study was whether there existed a consistent, positive correlation between ICT investments, decision-making performance, and OP, and if so, explain the interdependence among the predictor and outcome variables. The sampling frame for the research was the major nonprofit organizations in Kenya. Data were collected using a tested and validated measurement instrument, and analyzed using SPSS software. Correlation, analysis of variance, and multiple regression analyses were used for data analysis and interpretation. Results revealed that not all investments in ICT correlate positively with OP. In fact, investments in some ICT systems did not correlate at all with OP. This study has implications for positive social change, it facilitates informed decision making that saves resources and thus improves social good. The study is expected to contribute to the body of knowledge on the effect of investments in ICT on the effectiveness of decision making and OP.

Large scale data centers (DC) and high performance computing (HPC) systems require more and more computing power at higher energy efficiency. They are already consuming megawatts of power, and a linear extrapolation of trends reveals that they may eventually lead to unrealistic power consumption scenarios in order to satisfy future requirements (e.g., Exascale computing). Conventional complementary metal oxide semiconductor (CMOS)-based electronic interconnects are not expected to keep up with the envisioned future board-to-board and chip-to-chip (within multi-chip-modules) interconnect requirements because of bandwidth-density and power-consumption limitations. However, low-power and high-speed optics-based interconnects are emerging as alternatives for DC and HPC communications; they offer unique opportunities for continued energy-efficiency and bandwidth-density improvements, although cost is a challenge at the shortest length scales. Plasmonics-based interconnects on the other hand, due to their extremely small size, offer another interesting solution for further scaling operational speed and energy efficiency. At the device-level, CMOS compatibility is also an important issue, since ultimately photonics or plasmonics will have to be co-integrated with electronics. In this paper, we survey the available literature and compare the aforementioned interconnect technologies, with respect to their suitability for high-speed and energy-efficient on-chip and offchip communications. This paper refers to relatively short links with potential applications in the following interconnect distance hierarchy: local group of racks, board to board, module to module, chip to chip, and on chip connections. We compare different interconnect device modules, including low-energy output devices (such as lasers, modulators, and LEDs), photodetectors, passive devices (i.e., waveguides and couplers) and electrical circuitry (such as laserdiode drivers, modulator drivers, transimpedance, and limiting amplifiers). We show that photonic technologies have the potential to meet the requirements for selected HPC and DC applications in a shorter term. We also present that plasmonic interconnect modules could offer ultra-compact active areas, leading to high integration bandwidth densities, and low device capacitances allowing for ultra-high bandwidth operation that would satisfy the application requirements further into the future.

Thesis (M.S. in Electrical Engineering)--Naval Postgraduate School, December 2004.
Thesis advisor(s): David C. Jenn, Siew Yam Yeo. Includes bibliographical references (p. 63-64). Also available online.

Despite the growing importance of information and communication technologies (ICTs), their use in the field of program evaluation has been, to date, understudied. Using a mixed-method approach and a conceptual framework informed by social interdependence theory, this thesis sought to contribute to this area of research by exploring how evaluation practitioners engage with ICTs, and if and how this influences evaluation use. The comprised two parts are in a cascade design: a qualitative study relied on interviews with practitioners, followed by a quantitative study utilizing a survey instrument to obtain findings from a larger cohort of practitioner respondents. The findings from both studies revealed that ICTs’ value is greater for the use of evaluative results (findings use) than for benefits arising from evaluation processes (process use), and that these tools support evaluation activities by aiding background and foreground processes. When used in the background, ICTs can help evaluators by offering flexibility, improving speed, and efficiency. In contrast, ICTs used for foreground processes help foster communication with and engagement of stakeholders. Together, this makes the use of ICTs a valuable extension to existing evaluator skillsets, especially when the tools are mindfully incorporated to fit a project’s contextual complexity. The findings also point to a number of barriers – at both the individual and organizational levels - that inhibit further integration of technology into evaluation practice. A conceptual framework developed as a result of the findings visually depicts this process, and it represents a significant contribution of the thesis. Given the growing proliferation of ICTs in all aspects of life, further insight through systematic inquiry is much needed to keep abreast of these rapidly changing trends. The provision of such has implications not only for evaluation practitioners, client organizations and professional evaluation associations, but for the ongoing development of empirical inquiry in the area.

Peu de travaux se sont centrés sur l'analyse des fusions technologiques, en vue de créer une innovation conjointe, c'est-à-dire, la création d'une nouvelle ressource fondée sur la mise en commun du savoir-faire spécifique des entreprises. L'objet de cette recherche est de comprendre comment et pourquoi, évolue un processus d'intégration post-fusion dans le secteur des TIC, en vue de créer une innovation conjointe. Pour ce faire, il a été choisi une démarche qualitative reposant sur l'étude d'un cas unique d'une fusion. La démarche proposée met en évidence deux éléments fondamentaux jusqu'ici négligés par les recherches recensées : la dynamique du modèle d'intégration et le choix du mode d'intégration le plus approprié à la réalisation d'une innovation. Le premier souligne le possible passage entre différentes politiques d'intégration au cours d'une même opération de fusion. Le second suggère un processus d'apprentissage lent et progressif, processus permis par une co-construction du changement. Cette recherche apporte une contribution majeure par rapport au courant processuel, en permettant d'améliorer la conception et le pilotage des processus d'intégration répondant à un objectif d'innovation
Few works were specifically centred on the analysis of technological mergers, in order to create a joint innovation i. E. , the creation of a new resource based on the pooling of the specific know-how of the companies. The object of this research is to understand how and why, evolves a process of integration post-merger in the sector of the TIC, in order to create a technological innovation. With this intention, it was selected a qualitative step resting on the study of a single case of a merger. The step suggested highlights two fundamental elements neglected up to now by research listed: the dynamics of the model of integration and the choice of the mode of integration more appropriate to the realization of an innovation. The first underlines the possible passage between various policies of integration during the same operation of merger. The second suggests a process of slow and progressive training, processes permitted by a co-construction of the change. This research contributes a major share compared to the process current, while making it possible to improve the design and piloting of the process of integration meeting an aim of innovation

This thesis investigates the degree to which our everyday conceptions of 'place' have changed in contemporary society, especially in relation to the use of information and communications technologies (ICTs). The empirical evidence is a case study of 20 low-income families who live in Santiago, Chile. These families had just moved to a new social housing estate from the shantytowns and/or situations of extreme overcrowding. The first section of the thesis examines how their conceptions of 'place' have changed as a result of the move. On the one hand, it is difficult for them to perceive the housing estate as a 'place' with the same characteristics as their former home environments (close social networks, common history, etc.) due to a difficult and still incomplete adaptation. On the other hand, their social exclusion, especially demonstrated in terms of their limited spatial mobility, means that their everyday life still unfolds in a limited and relatively static number of places. In these circumstances they develop a minimal concept of place based not on an emotional attachment to a space, but rather on particular practices located in certain time and space. This concept of place is labelled here as 'localities of practices'. The second part of the thesis examines how these 'localities of practices' are becoming increasingly 'mediated,' or the increasing degree to which the use of ICTs permeates the conceptions of place of the members of these families through an analysis of practices related to the use of three particular technologies. The first study shows how the home is a project that has to be constructed in a constant competitive interplay with the place created by television use. The second analyses how the noise produced by hi-fi technologies at very high volumes is used to redefine the spaces of the housing estate against the background of their quite limited material surroundings. The third shows how the use of mobile phones, and the 'media space' created by them, reconstitutes and gives a new meaning to the limitations that these families face when moving through the urban environment of Santiago. As a result of these continual processes of mediation the thesis concludes that along with the physical environment of the housing estate, the spatial environments created by the use of media technologies are key to the construction of 'place' to such a degree that is almost impossible to consider one without the other. They, together, are their "machines for living in"; the setting in which their everyday lives unfold.

Optical packet switching (OPS) is the most prominent candidate transport solution that can seamlessly integrate electrical and optical layers by transferring certain switching functionality from electronics to optics, thus alleviating unnecessarily slow and expensive optical-electrical-optical conversions and signal processing at the switching node. Optical Label Switching (OLS) is an important aspect of the optical packet switched network that enables very low-latency forwarding of ultra-high bit-rate, protocol-independent packets entirely in the optical domain. The objective of the proposed research is to develop novel, efficient techniques to realize several key enabling technologies such as optical label generation and encoding, optical label swapping, all-optical buffering, and spectral efficient transmission system for optical label switched based OPS networks. A novel scheme of generating optical label at the ingress node using optical carrier suppression and separation (OCSS) technique is proposed. This scheme does not suffer from any unavoidable interference, limited extinction ratio or strict synchronization requirements between payload and label as observed by the currently available other label generation methods. One of the primary challenges to realize optical label swapping at the core node of scalable OLS network is the insertion of new optical labels without any wavelength conversion for same wavelength packet routing. A novel mechanism to realize same wavelength packet switching without using any conventional wavelength converter in the OLS network carrying differential phase-shift keying (DPSK) modulated payload and on-off keying (OOK) modulated optical label is demonstrated. Also a new dense wavelength division multiplexing (DWDM) optical buffer architecture using optical fiber delay lines that can provide wavelength selective reconfigurable variable delays is proposed. Optical packet switching provides automated, reconfigurable, and faster provision of both wavelength and bandwidth with finer granularity in the optical layer. However, a newer, cost-effective, and spectrally efficient optical transmission technology is essential to support the explosive bandwidth demand expected by the future optical packet switched networks. To meet this challenge, a spectrally efficient solution for transporting 40 Gbps per channel data over 50 GHz spaced DWDM system is developed by exploiting optical carrier suppression and separation technique and optical duobinary modulation.

Beginning with an understanding of the aesthetic and idealism of modern design, this thesis discusses the interrelationship between culture, technology and graphic design since mid-century. A review of the rise of postmodern critique, particularly as expressed through digital technologies, demonstrates how cultural shifts and developing communications technologies work in tandem to influence the emergence of visual systems. By revealing several underlying premises of modernity, it is shown that the linearity of modern design is a biased and limited theory of vision. This argument is reinforced by contrasting the modern conception of direct communication with alternative design practices that encourage readers to play a more active role in the interpretation of a message. However, the thesis ultimately returns to the fundamental principles of modernism to suggest that certain tenets of modernist thought should not be jettisoned so quickly, simply because digitization encourages open-ended viewing experiences.

The aim at the start of this thesis was to examine the use of broadband technologies in education, particularly focusing on the GEMISIS 2000 Schools Project. I use it now to open up discussion about the implementation and subsequent use of Information and Communications Technology (ICT) in education. The GEMISIS 2000 project began as a partnership initiative between Salford City Council, The University of Salford and Cable and Wireless (formerly Nynex).

In the light of increasing promotion of new information and communications technologies (ICTs) as a tool for economic development, this thesis examines the relationship between ICTs, rural businesses and rural development among rural engineering and manufacturing firms in South Warwickshire and the Cotswolds. Despite high levels of general interest in this subject area, previous research has tended to concentrate on the technical (supply-side) issues of these new technologies; the human (demand-side) aspect has, so far, been largely overlooked. The devised theoretical framework distinguishes between influential factors internal and external to the firm. Empirical research draws upon humanistic behavioural concepts to investigate ICT adoption decision-making processes at the micro-level of individual sectors, enterprises and entrepreneurs in rural areas, and to evaluate the role of external agencies. Firms in the study area are diverse in terms of their ICT adoption and use, and entrepreneurial characteristic and linkages with other businesses and organizations are found to be major determinants of technology requirements and uptake. Two types of firms are identified: inwardly-oriented firms, with local buyer and supplier contacts, which make little use of technology; and outwardly-oriented firms, which use ICTs more intensively and have geographically dispersed networks of customers and suppliers. While notable levels of general awareness of ICTs exist among rural businesses, the initial financial outlay involved, coupled with a lack of knowledge of existing technological solutions and support, and a need for skills training, remain significant disincentives to ICT uptake among smaller firms. Agencies currently lag behind local businesses in terms of their ICT awareness and use, and understanding of the potential development implications of technology. In many cases there is a mis-match between agencies' perceptions of ICT use in rural firms and their response to this area of business support. Although there is a recognition amongst agencies that their client firms are applying new technologies in their business processes, ICTs are seen by the majority of agencies as a future component of business strategy. Thus, appropriate support for firms implementing ICTs is not yet widely accessible. Findings suggest that ICT implementation is not appropriate in all firms; requirements and applications vary widely and there is a need for a tailored approach by agencies and policy makers which takes account of the uniqueness of entrepreneur and firm characteristics.

The number of individuals facing vision loss as adults is increasing, and the need for these adults to have access to training and skills to aid in their adjustment process is prevalent. Guided by the tenets of connectivism, this phenomenological study examined current trends in social networking and the possibilities that are available to adults adjusting to low vision by using technology as a means for continued learning, social interaction, and professional connections. The main research question focused on the participants' perception of the adjustment process and their ability to learn and use technology. Data were collected through semi-structured interviews of 10 adults who had low vision and had attended some form of intervention. The experiences were recorded through the use of reflection that included memoing and inductive coding where themes emerged during the field process. NVivo software was utilized to clarify and present details about themes and patterns presented during the interview discussions. These themes detailed the participants' feelings of confidence and self expressed level of skills needed to use technology; the barriers to using technology, such as cost and time; and benefits of staying connected with technology. The findings from this study suggested that the ability to stay connected and to access information outweighed the barriers, although the participants expressed frustration with technological issues. The study contributed to an area of research that supports the benefits of continued training for adults adjusting to low vision. A process of training could be implemented that would involve general technology as well as assistive technology assisting individuals with continued success in their daily lives.

Le Canada figure parmi les rares pays à avoir une stratégie d'interdiction de facto de fusions entre grandes banques nationales. D'un côté, dans le contexte d'une crise financière cela semble un grand atout stratégique. Par contre, les banques canadiennes sont aussi moins compétitives ou moins agressives pour promouvoir l'entrepreneurship et par conséquent, cela freine le rythme de l'innovation (Groupe d'études stratégiques sur la concurrence, 2008). Ainsi, un tel environnement financier conservateur fait souvent l'objet de critiques envers les petites et moyennes entreprises, lesquelles considèrent que les banques canadiennes ne sont pas très relationnelles. Dernièrement, la crise fInancière américaine qui a dégénéré en crise mondiale a illustré 1) les désavantages de collaborer en écosystème ouvert dans le secteur financier et 2) l'importance de réglementer et d'établir des normes rigides. Cette crise semble donc a priori conforter le conservatisme et la réglementation. Or, l'industrie des technologies de l'information et des communications (TIC) semble illustrer le contraire. En effet, pour assurer le développement de cette industrie, certains facteurs doivent être considérés: 1) l'importance de fonctionner en écosystème ouvert pour démocratiser l'innovation (Von Hippel, 2005) et, en particulier, l'innovation non contractuelle (Olleros, 2007) et 2) d'établir des normes de collaboration ou des normes relationnelles (Macneil, 2000) pour une meilleure performance économique globale (Chesbrough, 2003). Il semble que la comparaison des deux secteurs (bancaire et TIC) permet de relever la problématique relationnelle dans des contextes différents tout en aboutissant aux constats suivants: davantage de conservatisme et de réglementation permettent probablement de protéger des industries bien établies, mais cela semble freiner l'entrepreneuriat et l'innovation qui sont une source de développement économique. Ainsi, bien que le conservatisme et la réglementation soient des solutions à court terme, elles ne procurent pas le dynamisme nécessaire pour relancer et donner confiance dans les échanges socioéconomiques. Cette thèse propose de puiser au coeur d'une problématique souvent effleurée, mais non réellement élaborée parce qu'elle remet en question le fondement des échanges économiques dans un système libéral: le système de valeurs. En effet, les acteurs socio-économiques ont besoin de fonctionner selon des normes relationnelles, plutôt que transactionnelles (Macneil, 2000; Ferguson, Paulin et Bergeron, 2005) pour une meilleure performance individuelle et globale de l'écosystème (Iansiti et Levien, 2004) et avoir ainsi une logique de confiance et d'engagement de long terme (Morgan et Hunt, 1994). Ces postulats répondent à la logique du marketing relationnel dont la définition est de plus en plus sociale et systémique (Gummesson, 1999, p. 24) et intègre depuis 2004, la logique à dominance service (LDS) qui focalise sur l'importance du service comme processus de cocréation de valeur (Vargo et Lusch, 2004; 2008a; 2008b). Comment donc appliquer le marketing relationnel ou sa dernière variante, la LDS dans une perspective plus large, plus systémique et qui reflète la complexité des dyades interactionnelles? Comment rétablir le credo (Je crois dans l'avenir, McCraw, 2007, p.6) dans l'économie pour que les différents acteurs socio-économiques accordent les crédits financiers, politiques et culturels nécessaires? L'incertitude étant un point central dans la théorie transactionnelle (Williamson, 1979), il est possible de la juguler avec des normes relationnelles (Ferguson et Paulin, 2009) qui s'étendent du coeur de métier de l'industrie aux dimensions périphériques de l'écosystème global. À travers une méthodologie par articles, cette thèse explore la dynamique relationnelle dans une perspective écosystémique. Cette perspective est originale et pertinente, car elle permet: (1) d'adopter une conceptualisation appropriée des relations (théorie ancrée) selon la métaphore de l'écosystème; (2) elle saisit la réalité dans sa complexité et en temps réel (étude qualitative longitudinale); et (3) elle explore les interactions, les réseaux et les relations selon une logique systémique de contenu (les dimensions explicatives) et de processus (évolution dans le temps). Deux industries stratégiques ont été analysées: le secteur bancaire et celui des technologies de l'information et des communications. La richesse, la pertinence et la complémentarité de leurs écosystèmes ont permis de développer une compréhension triangulée des relations au sein d'un écosystème, sur les meilleures pratiques managériales et les facteurs clés de succès. L'intégration du paradigme relationnel s'est faite à trois niveaux: coeur de métier, entreprise élargie et écosystémique (Moore, 1996, p. 26). Cet objectif à trois volets a beaucoup contribué au choix de procéder à une thèse par articles. Les trois perspectives gagnaient à être explorées séparément dans trois recherches spécifiques. (1) La première a visé le coeur de métier pour apprécier les processus organisationnels relationnels mis en place avec les clients internes (directeurs de compte). (2) La deuxième recherche a ciblé l'évaluation du paradigme relationnel dans la dyade entreprise/clients organisationnels (PME) selon une vision gagnant-gagnant organisation-clients-employés. (3) La troisième recherche a focalisé sur la dynamique relationnelle coopétitive animant les dyades complexes au niveau écosystémique. D'un point de vue théorique, cette thèse propose deux contributions majeures: 1) une revue de littérature intégrative pluridisciplinaire du marketing relationnel en lien avec les nouveaux paradigmes émergents dans les autres domaines et 2) le développement d'une nouvelle théorie de l'écosystème en lien avec les défis empiriques, théoriques et méthodologiques actuels. Cette thèse illustre également l'importance de retrouver le credo dans l'économie, non pas en limitant les crédits, mais en s'assurant de partager des valeurs relationnelles durables de confiance et d'engagement au profit de l'ensemble de l'écosystème. Elle propose donc une nouvelle théorie de l'écosystème, qui est une extension du marketing relationnel et de la logique à dominance service (Vargo et Lusch, 2004; 2008a; 2008b). La LDS dénonce les pratiques marketing ancrées dans la logique industrielle de production et qui ont transformé le concept de «servuction du client» (Langeard et Eiglier, 1987) en servitude du client (Paulin, 2009). La théorie de l'écosystème proposée vient donc endosser les postulats de la LDS et les enrichir de dimensions sociales, durables et éthiques applicables à l'ensemble de l'écosystème et non pas dans une logique dyadique microscopique. D'un point de vue méthodologique, l'innovation est substantielle en termes d'approche qualitative plurielle. La triangulation est multiple: théories, disciplines, sources, méthodes de collecte, d'analyse et stratégies de théorisations. Plusieurs chercheurs en marketing ou en management ont multiplié les méta-analyses, mais les recherches quantitatives se sont concentrées soit sur le niveau micro, mezzo ou macro d'une relation. Il semble qu'aucune recherche n'a, jusqu'à présent, entrepris dans un même temps une méthodologie à la fois dyadique, systémique, dynamique et processuelle sur deux ou trois niveaux écosystémiques ou appliqué la théorie ancrée (Glaser et Strauss, 1967) pour comprendre les questions relationnelles. D'un point de vue épistémologique, cette thèse a pour principale contribution, un positionnement post moderniste de réconciliation des paradigmes. Ce dernier a permis de relever plusieurs défis d'approches de la complexité et ensuite de théorisation qui auraient été difficilement réussis en suivant des paradigmes isolés. Le dialogue interparadigmes a permis de saisir les différentes facettes de l'iceberg et d'enrichir les descriptions et explications. D'un point de vue managérial, les contributions sont aussi importantes et se situent à trois niveaux: l) un niveau dyadique client interne/organisation; 2) un niveau dyadique client externe/organisation et enfin, 3) un niveau multidyadique entre divers partenaires et notamment les compétiteurs/coopérateurs (coopétiteurs, Brandenburger et Nalebuff, 1996, p. 2). La théorie de l'écosystème proposée dans cette thèse offre donc d'être un cadre théorique, un cadre méthodologique et un cadre empirique en symbiose avec la complexité relatiormelle des écosystèmes actuels.

The state-of-art technologies keep generating new ways of improving on the performance of the old systems. Array antennas, one of the continuously improving technologies, brought many benefits to our life. The superiorities of array antennas remove the disadvantages of the old technology radars such as great sidelobes, vulnerability to the jammers, and degradation effect of the clutter. Array antennas find many applications on different areas. Today, unmanned aerial vehicles (UAVs) have begun to be seen in our life more often than before. UAVs prevent pilot loss of life. They carry out a variety of military and civilian missions such as surveillance and reconnaissance, target recognition, battle damage assessment, EW, search and rescue, and traffic monitoring. An important use of the UAVs is troop support, carrying out reconnaissance and surveillance missions, which requires maintaining a data-link with troops in order to send any data collected, such as video images, or audio. During operations it is necessary to continuously maintain a data and control link with the operator. This requires the ground station antenna to track the UAV so the antenna beam is pointed properly. The purpose of this research is to design and build an array to angle-track a UAV and, eventually, to accomplish the data transfer from the UAV to the ground station.

The unlicensed wireless spectrum offers exciting opportunities for developing innovative wireless applications. This has been true ever since the 2.4 GHz band and parts of the 5 GHz bands were first opened for unlicensed access worldwide. In recent years, the 5 GHz unlicensed bands have been one of the most coveted for launching new wireless services and applications due to their relatively superior propagation characteristics and the abundance of spectrum therein. However, the appetite for unlicensed spectrum seems to remain unsatiated; the demand for additional unlicensed bands has been never-ending. To meet this demand, regulators in the US and Europe have been considering unlicensed operations in the 5.9 GHz bands and in large parts of the 6 GHz bands. In the last two years alone, the Federal Communications Commission in the US has added more than 1.2 GHz of spectrum in the pool of unlicensed bands. Wi-Fi networks are likely to be the biggest beneficiaries of this spectrum. Such abundance of spectrum would allow massive improvements in the peak throughput and potentially allow a considerable reduction of latency, thereby enabling support for emerging wireless applications such as augmented and virtual reality, and mobile gaming using Wi-Fi over unlicensed bands. However, access to these bands comes with its challenges. Across the globe, a wide range of incumbent wireless technologies operate in the 5 GHz and 6 GHz bands. This includes weather and military radars, and vehicular communication systems in the 5 GHz bands, and fixed-service systems, satellite systems, and television pick-up stations in the 6 GHz bands. Furthermore, due to the development of several cellular-based unlicensed technologies (such as Licensed Assisted Access and New Radio Unlicensed, NR-U), the competition for channel access among unlicensed devices has also been increasing. Thus, coexistence across wireless technologies in the 5 GHz and 6 GHz bands has emerged as an extremely challenging and interesting research problem. In this dissertation, we first take a comprehensive look at the various coexistence scenarios that emerge in the 5 GHz and 6 GHz bands as a consequence of new regulatory decisions. These scenarios include coexistence between Wi-Fi and incumbent users (both in the 5 GHz and 6 GHz bands), coexistence of Wi-Fi and vehicular communication systems, coexistence across different vehicular communication technologies, and coexistence across different unlicensed systems. Since a vast majority of these technologies are fundamentally different from each other and serve diverse use-cases each coexistence problem is unique. Insights derived from an in-depth study of one coexistence problem do not help much when the coexisting technologies change. Thus, we study each scenario separately and in detail. In this process, we highlight the need for the design of novel coexistence mechanisms in several cases and outline potential research directions. Next, we shift our attention to coexistence between Wi-Fi and vehicular communication technologies designed to operate in the 5.9 GHz intelligent transportation systems (ITS) bands. Until the development of Cellular V2X (C-V2X), dedicated short range communications (DSRC) was the only major wireless technology that was designed for communication in high-speed and potentially dense vehicular settings. Since DSRC uses the IEEE 802.11p standard for its physical (PHY) and medium access control (MAC) layers, the manner in which DSRC and Wi-Fi devices try to gain access to the channel is fundamentally similar. Consequently, we show that spectrum sharing between these two technologies in the 5.9 GHz bands can be easily achieved by simple modifications to the Wi-Fi MAC layer. Since the design of C-V2X in 2017, however, the vehicular communication landscape has been fast evolving. Because DSRC systems were not widely deployed, automakers and regulators had an opportunity to look at the two technologies, consider their benefits and drawbacks and take a fresh look at the spectrum sharing scenario. Since Wi-Fi can now potentially share the spectrum with C-V2X at least in certain regions, we take an in-depth look at various Wi-Fi and C-V2X configurations and study whether C-V2X and Wi-Fi can harmoniously coexist with each other. We determine that because C-V2X is built atop cellular LTE, Wi-Fi and C-V2X systems are fundamentally incompatible with each other. If C-V2X and Wi-Fi devices are to share the spectrum, considerable modifications to the Wi-Fi MAC protocol would be required. Another equally interesting scenario arises in the 6 GHz bands, where 5G NR-U and Wi-Fi devices are likely to operate on a secondary shared basis. Since the 6 GHz bands were only recently considered for unlicensed access, these bands are free from Wi-Fi and NR-U devices. As a result, the greenfield 6 GHz bands provide a unique and rare opportunity to freshly evaluate the coexistence between Wi-Fi and cellular-based unlicensed wireless technologies. We study this coexistence problem by developing a stochastic geometry-based analytical model. We see that by disabling the listen before talk based legacy contention mechanism---which has been used by Wi-Fi devices ever since their conception---the performance of both Wi-Fi and NR-U systems can improve. This has important implications in the 6 GHz bands, where such legacy transmissions can indeed be disabled because Wi-Fi devices, for the first time since the design of IEEE 802.11a, can operate in the 6 GHz bands without any backward compatibility issues. In the course of studying the aforementioned coexistence problems, we identified several gaps in the literature on the performance analysis of C-V2X and IEEE 802.11ax---the upcoming Wi-Fi standard. We address three such gaps in this dissertation. First, we study the performance of C-V2X sidelink mode 4, which is the communication mode in C-V2X that allows direct vehicular communications (i.e., without assistance from the cellular infrastructure). Using our in-house standards-compliant network simulator-3 (ns-3) simulator, we perform simulations to evaluate the performance of C-V2X sidelink mode 4 in highway environments. In doing so, we identify that packet re-transmissions, which is a feature introduced in C-V2X to provide frequency and time diversity, thereby improving the system performance, can have the opposite effect if the vehicular density increases. In fact, packet re-transmissions are beneficial for C-V2X system performance only at low vehicular densities. Thus, if vehicles are statically configured to always use/disable re-transmissions, the maximum potential of this feature is not realized. Therefore, we propose a simple and effective, distributed re-transmission control mechanism named Channel Congestion Based Re-transmission Control (C2RC), which leverages the locally available channel sensing results to allow vehicles to autonomously decide when to switch on re-transmissions and when to switch them off. Second, we present a detailed analysis of the performance of Multi User Orthogonal Frequency Division Multiple Access (MU OFDMA)---a feature newly introduced in IEEE 802.11ax---in a wide range of deployment scenarios. We consider the performance of 802.11ax networks when the network comprises of only 802.11ax as well as a combination of 802.11ax and legacy stations. The latter is a practical scenario, especially during the initial phases of 802.11ax deployments. Simulation results, obtained from our ns-3 based simulator, give encouraging signs for 802.11ax performance in many real-world scenarios. That being said, there are some scenarios where naive usage of MU OFDMA by an 802.11ax-capable Wi-Fi AP can be detrimental to the overall system performance. Our results indicate that careful consideration of network dynamics is critical in exploiting the best performance, especially in a heterogeneous Wi-Fi network. Finally, we perform a comprehensive simulation study to characterize the performance of Multi Link Aggregation (MLA) in IEEE 802.11be. MLA is a novel feature that is likely to be introduced in next-generation Wi-Fi (i.e., Wi-Fi 7) devices and is aimed at reducing the worst-case latency experienced by Wi-Fi devices in dense traffic environments. We study the impact of different traffic densities on the 90 percentile latency of Wi-Fi packets and identify that the addition of a single link is sufficient to substantially bring down the 90 percentile latency in many practical scenarios. Furthermore, we show that while the addition of subsequent links is beneficial, the largest latency gain in most scenarios is experienced when the second link (i.e., one additional) link is added. Finally, we show that even in extremely dense traffic conditions, if a sufficient number of links are available at the MLA-capable transmitter and receiver, MLA can help Wi-Fi devices to meet the latency requirements of most real-time applications.
Doctor of Philosophy
Wireless networks have become ubiquitous in our lives today. Whether it is cellular connectivity on our mobile phones or access to Wi-Fi hotspots on laptops, tablets, and smartphones, never before has wireless communication been as integral to our lives as it is today. In many wireless communication systems, wireless devices operate by sending signals to and receiving signals from a central entity that connects to the wired Internet infrastructure. In the case of cellular networks, this entity is the cell tower deployed by the operators (such as ATandT, Verizon, etc. in the US), while the Wi-Fi router deployed in homes and offices plays this role in Wi-Fi networks. There is also another class of wireless systems, where wireless devices communicate with each other without requiring to communicate with any central entity. An example of such a distributed communication system---which is fast gaining popularity---is vehicular communication networks. End-user devices (e.g. cellphone, laptop, tablet, or a vehicle) can communicate with each other or the central entity only if they are both tuned to the same frequency channel. This channel can lie anywhere within the radio frequency spectrum, but some frequency channels (the collection of channels is referred to as frequency bands) are more favorable—--in terms of how far the signal sent over these channels can reach—--than others. Another dimension to these frequency bands is the licensing mechanism. Not all frequency bands are free to use. In fact, most frequency bands in the US and other parts of the world are licensed by the regional regulatory agencies. The most well-known example of this licensing framework is the cellular network. Cellular operators spend large amounts of money (to the tune of billions of dollars) to gain the privileges of exclusively operating in a given frequency band. No other operator or wireless device is then allowed to operate in this band. Without any external interfering wireless device, cellular operators can guarantee a certain quality of service that is provided to its customers. Thus, the benefits of using licensed frequency bands are obvious but these bands and their associated benefits come at a high price. An alternative to licensed frequency bands are the unlicensed ones. As the name suggests, unlicensed frequency bands are those where any two or more wireless devices can communicate with each other (subject to certain rules) without having to pay any licensing fees. Unsurprisingly, because there is no limit to who or how many devices can communicate over these bands, wireless devices in these bands frequently experience external interference, which manifests to the end-user in terms of interruption of service. The best example of a wireless technology that uses unlicensed bands is Wi-Fi. One of the greatest advantages of Wi-Fi networks is that anyone can purchase a Wi-Fi router and deploy it within their homes or offices—--flexibility not afforded by licensed bands. However, this very flexibility and ease-of-use can sometimes contribute negatively to Wi-Fi performance. Arguably, we have all faced scenarios where the performance of Wi-Fi is poor. This is most likely to happen in scenarios where there are hundreds (or even thousands) of neighboring Wi-Fi devices, such as at stadiums, railway stations, concerts, etc. Based on our discussions above, it is clear as to why Wi-Fi performance suffers in such scenarios. Thus, although unlicensed bands are lucrative in terms of low-cost, and ease of use, there is no guarantee on how good a voice/video call or a video streaming session conducted over Wi-Fi will be. The above problem is well-known and well-researched. Regulators, researchers, and service providers actively seek solutions to offer better performance over unlicensed bands. An obvious solution is to make more unlicensed bands available; if all neighboring Wi-Fi users communicate with their respective routers on different channels, everyone could communicate interference-free. The problem, however, is that frequency bands are limited. Even more limited are those bands that support wireless communications over larger distances. Another solution is to improve the wireless technology—if a Wi-Fi device can more efficiently utilize the channel, its performance is likely to improve. This fact has driven the constant evolution of all wireless technologies. However, there are fundamental limits to how much a frequency channel can be exploited. Therefore, in recent years, stakeholders have turned to spectrum sharing. Even though a wireless network may possess an exclusive license to operate on a given frequency band, its users do not use the band everywhere and at all times. Then why not allow unlicensed wireless devices to operate in this band at such places and times? This is precisely the premise of spectrum sharing. In this dissertation, we look at the problem of coexistence between wireless technologies in the 5 GHz and 6 GHz bands. These two bands are extremely lucrative in terms of their relatively favorable propagation characteristics (i.e., their communication range) and the abundance of spectrum therein. Consequently, these bands have garnered considerable attention in recent years with the objective of opening these bands up for unlicensed services. However, the 5 GHz and 6 GHz bands are home to several licensed systems, and the performance of these systems cannot be compromised if unlicensed operations are allowed. Significant activity has taken place since 2013 concerning new technologies being developed, new spectrum sharing scenarios being proposed, and new rules being adopted in these two bands. We begin the dissertation by taking a comprehensive look at these issues, describing the various coexistence scenarios, surveying the existing literature, describing the major challenges, and providing directions for potential research. Next, we look at three coexistence problems in detail: (i) coexistence of dedicated short range communications (DSRC) and Wi-Fi, (ii) coexistence of cellular V2X (C-V2X) and Wi-Fi, and (iii) coexistence of 5G New Radio Unlicensed (5G NR-U) and Wi-Fi. The former two scenarios involve the coexistence of Wi-Fi with a vehicular communication technology (DSRC or C-V2X). These scenarios arose due to considerations in the US and Europe to allow Wi-Fi operations (on an unlicensed secondary basis) in the spectrum that was originally reserved for vehicular communications. Our work shows that because DSRC and Wi-Fi are built on top of fundamentally similar protocols, they are, to an extent, compatible with each other, and coexistence between these two technologies can be achieved by relatively simple modifications to the Wi-Fi protocol. However, C-V2X, owing to its inheritance from the cellular LTE, is not compatible with Wi-Fi. Consequently, significant research is required if the two technologies are to share the spectrum. On the other hand, in the coexistence of 5G NR-U and Wi-Fi, we focus on the operations of these two technologies in the 6 GHz bands. NR-U is a technology that is built atop the 5G cellular system, but is designed to operate in the unlicensed bands (in contrast to traditional cellular systems which only operate in licensed bands). Although these two technologies can coexist in the 5 GHz and 6 GHz bands, we restrict our attention in this dissertation to the 6 GHz bands. This is because the 6 GHz bands are unique in that the entire range of the 6 GHz bands were opened up for unlicensed access all at once recently, and no Wi-Fi or NR-U devices currently operate in these bands. As a result, we can learn from the mistakes made in the 5 GHz bands, where a vast majority of today's Wi-Fi networks operate. Our work shows that, indeed, we can take decisive steps---such as disabling certain Wi-Fi functions---in the 6 GHz bands, which can facilitate better coexistence in the 6 GHz bands. Finally, in the course of identifying and tackling the various coexistence scenarios in the 5 GHz and 6 GHz bands, we identify some open issues in the performance of new wireless technologies designed to operate in these bands. Specifically, we highlight the need to better understand and characterize the performance of Multi User Orthogonal Frequency Division Multiple Access (MU OFDMA), a feature common in cellular networks but newly introduced to Wi-Fi, in the upcoming Wi-Fi 6 generation of devices. We propose and evaluate an analytical model for the same. We also characterize the performance of Multi Link Aggregation---which a novel feature likely to be introduced in future Wi-Fi 7 devices---that is aimed at reducing the worst-case delay experienced by Wi-Fi devices in dense traffic conditions. Additionally, we identify an issue in the performance of the distributed operational mode of C-V2X. We show that packet re-transmissions, which is a feature aimed at improving the performance of C-V2X, can have a counter-productive effect and degrade the C-V2X performance in certain environments. We address this issue by proposing a simple, yet effective, re-transmission control mechanism.

L'interaction entre le droit commun de la concurrence et la régulation sectorielle est au centre de la problématique juridique dans l'ensemble des industries dites en réseau. Les rapports entre les deux ensembles normatifs et des autorités chargées de leur mise en œuvre, prennent pourtant une nouvelle dimension dans le secteur des communications électroniques, où un puissant dispositif sectoriel de nature préventive est mis en place par les instances communautaires en amont du droit de la concurrence, afin de contrôler le pouvoir de marché. La coexistence de la régulation sectorielle de dimension économique et du droit commun de la concurrence, est forte de conséquences sur l'évolution de chacun de deux volets du contrôle, ainsi que sur la configuration des marchés en cause, qui sont profondément marqués par l'intervention des autorités sectorielles. Or, une analyse attentive, d'une part de l'application des règles sectorielles et d'autre part de l'apport et du potentiel du droit commun, démontre qu'il n'est pas nécessaire d'édicter des nouvelles règles ou de perpétuer la réglementation spécifique en vue de contrôler le jeu concurrentièl dans les secteurs en question. Vu d'une manière globale, les règles du droit de la concurrence et les mécanismes d'analyse classiques utilisés dans les autres domaines économiques, sont suffisants pour faire face aux défis concurrentiels de « l'économie numérique », pourvu que les autorités de contrôle adaptent la mise en oeuvre des règles communes aux spécificités des marchés des nouvelles technologies.

Ces travaux de recherche portent sur les systèmes de communication radio-sur-fibre aux fréquences millimétriques supérieures à 60 GHz. Cette thèse s’articule autour de trois problématiques cruciales pour ces systèmes : la mesure du bruit de phase des signaux millimétriques instables générés par voie optique, la suppression de l’impact du bruit de phase sur les performances des systèmes de communications radio-sur-fibre par l’utilisation de techniques de conversion de fréquence non-cohérente, et enfin l’étude de l’impact du bruit d’intensité sur les performances des systèmes à détection non-cohérente. La première partie du travail présente une nouvelle technique de détection numérique du bruit de phase, capable de mesurer le bruit de phase à n’importe quelle fréquence millimétrique générée par voie optique et donc le plus souvent instable. Il est possible de mesurer le bruit de phase pour une large gamme de fréquences de décalage, allant de fréquence très proches de la porteuse à des bruits lointains grâce à l’adaptation de la résolution fréquentielle de la mesure. Cette mesure se fait de plus sans l’approximation des petits angles, très souvent utilisés. Dans la deuxième partie, un système de communication millimétrique basé sur une détection non-cohérente est étudié. L’étage de conversion de fréquences électrique permettant l’analyse des signaux est réalisé avec une détection d’enveloppe, ce qui permet de s’affranchir des variations de phase et de fréquence de la porteuse générée par voie optique. Pour terminer, des études théoriques et expérimentales sont menées sur l’impact du bruit d’amplitude sur les systèmes radio-sur-fibre utilisant ce type de détection non-cohérente. Les simulations, basées sur des modèles théoriques, sont capables de déterminer quel bruit est prédominant lors des mesures d’EVM parmi les bruits optiques et électriques. Cette technique s’appuie sur l’observation de l’évolution de l’EVM sur la puissance optique reçue
This Ph.D. investigates the radio over fiber communication systems at mm-wave frequencies higher than 60 GHz. The thesis elaborates on three crucial issues in these systems including:phase noise measurement of unstable optically generated mm-wave signals, elimination ofphase noise impact on performance of radio over fiber systems using non-coherent down conversion technique, and studying the amplitude noise impacts on performance of system based on these detectors. In the first part of this work, a new digital phase noise measurement technique is presented which is able to extract the phase noise of any unstable mm-waveoptically generated signal. This technique is able to measure the phase noise for a widerange of offset frequencies from close-in phase noise to far noise floor by adapting frequency resolution of measurement and without considering small angle approximation. In the second part, we present a radio over fiber system at mm-wave frequency based on non-coherent electrical frequency down conversion stage using an envelope detector which is robust against phase and frequency fluctuations of the optically generated carrier signal. Finally, a the oreticaland experimental study of amplitude noise impact on performance of radio over fiber systemsbased on non-coherent receivers is presented. In this study, a simulation technique based ontheory is developed which is able to determine, among different optical and electrical noise, the one which has the dominant effect on EVM results. This simulation technique is based onobserving the EVM evolution versus received optical power

Using the XO laptop as a case study, this project explores the tension, if any, between modernization and the diffusion of information and communication technologies in developing countries. Modernization, the diffusion of innovation, and Burniske's (2003) chain of doing serve as theoretical frameworks to examine new visions of development that One Laptop Per Child (OLPC) aims to introduce to impoverished people on a global scale, with poverty alleviation being their main goal. Employing a qualitative approach, namely document analysis and analysis of online discussions, this research concludes that modernization is still used in new visions of development.