The expectations and visions of the mobile phone in a development context is vast. International development institutions such as the World Bank, World Summit of the Information Society and International Telecommunication Union together with business conglomerates Google and Facebook have all invested their perspectives and visions of how the information and technology community should unfold in Uganda. How do their perspectives merge, interfere and contrast with the perspectives and visions of actors in Uganda?   The research objective is to explore the feminist and postcolonial technoscientific practices of the mobile phone in a Ugandan context. In my exploration I use ethnographic, participatory and narrative methods to study the imaginations and real-time uses of the mobile phone among actors in the ICT community.   I ask how actors in technology hubs in a low-income country relate to local innovations and design processes. Using a diffractive method for analysis I discuss how stories of corruption and responsibility are entangled with the development of mobile applications for the local context and the relation of designers and users.   I ask how the mobile phone is changing the socio-technical relations of gender, technology and development. Using diffraction, intersectionality and figuration as cartographic nodes for discussion I examine how the initiatives Girl Geek Kampala and Women in Technology Uganda renegotiate and reconstitute the understandings of gender and technology.   I ask how the mobile phone is creating and changing the infrastructuring in Uganda. I address the situatedness of the mobile infrastructuring by departing in the generic properties of an infrastructure by Star and Ruhleder (1996). The mobile phone is being used for entertainment purposes, developmental goals and marketing strategies and cannot be singled out as a device that represents a uniform vision of the information society. The examination of situatedness suggests that the strength of understanding the mobile infrastructure lies in the ambiguity of sustaining and transforming relations simultaneously, or better yet, a posthumanist performativity where human and non-human forms of agency are taken into account.    The entanglements of postcolonial information and communication technologies, feminist technoscience and design form the basis for a discussion on how we invite collaborations between policy makers, business entrepreneurs and civil society organizations that engage and shape the futures we are responsible for. My ambition is to develop ways of re-thinking social innovation and technology development, which interfere with linear economic development and raises the participatory paradigm in science and technology policy.

The increasing usage of numerous mobile applications can cause impairments in cellular network performance. Such impairments result in performance degradation that can reduce the satisfaction level of subscribers. Consequently, subscribers may switch between different network operators to get good user experience. Thus the success of any network operator will primarily depend on the ability to ensure quality of experience (QoE), where QoE is a measure of the subscriber’s satisfaction level and is closely related to the performance of networks. Our work aims to identify the key performance indicators (KPI)which in turn can comprehensively model the QoE. Since the popularity of web browsing and video streaming applications continues to increase rapidly, analyzing the KPI of such applications will help to identify the parameters which degrade network performance the most. The analyzed KPIs are tested with different user equipments and different network load. This thesis work also includes tuning the Radio Network Controller (RNC) parameters to analyze the variation in user experience. Important performance metrics of webbrowsing and video streaming applications have been considered to measure the QoE. Atest environment for QoE estimation was developed using real Radio Network Controller(RNC) and simulatable models of the Core Network(CN) and User Equipments (UEs). Simulations with this test set up and subsequent analyses help to identify some of the RNC parameters which influence the QoE. Furthermore, simulatable models of widely used UEssuch as iPhone 6 and iPhone 3 were included in the test environment to assess their relative performance for web browsing and video streaming applications. Our simulation results confirm the superior performance of iPhone 6 which reinforces the reliability of our testbed. Finally, the simulations also helped to illustrate the degradation in QoE caused by the increase in RNC load.

No description available.

Future wireless communication systems will utilize the spatial properties of the wireless channel to improve the spectral efficiency and thus increase capacity. This is realized by deploying multiple antennas at both the transmitter and receiver. Utilizing the spatial properties of the channel demands channel models that properly reflect these characteristics. Due to the unpredictable nature of the wireless channel, a common approach is to model its effects in a statistical fashion. A few large world wide cooperations, like the 3GPP or WINNER projects, have developed channel models intended for reference and standardization use. These models are partly based on bulk parameters which describe the characteristics of the channel over larger areas of several wavelengths. These parameters include shadow fading, angle spread, and delay spread among others, and are within the WINNER project called large scale (LS) parameters. Considering the variations of these parameters, it is likely that they are correlated between closely located areas. Therefore it is of key interest to model their correlation properties instead of randomizing them independently for each new simulation. In multi-cell scenarios, when considering macro diversity or evaluation other properties such as interference and/or handover schemes, the intra site correlation of the shadow fading parameters should be taken into account for proper simulations. Neglecting this correlation the interference could be over/under estimated, hence the system capacity can be over/under estimated. Further, reliable estimations of the interference levels will increase the frequency reuse, and may even permit reuse within the same cell, on spatially separated links. The thesis focuses on modelling the statistics and variations of these parameters to increase accuracy of channel models. Previous studies have looked at the autocorrelation properties of the shadow fading in outdoor environments and found it to follow an exponential decay. This means that an first order autoregressive function would be sufficient to model this effect. Research of the angular spread parameter is more scarce, and therefor this issue is studied herein. In addition to the autocorrelation properties the intra-site correlation between the different large scale parameters is of interest. It is herein found that the shadow fading is negatively correlated with angle spreads, while the angle spread at the base station and the angle spread at the mobile show positive correlation. Finally, the inter site correlation between one mobile and multiple base stations is studied as a function of the angular separation between the links. For closely located base station, ie with small angular separation as seen from the mobile, substantial inter-site correlation is found. It is further seen that the correlation of the shadow fading is more prominent than the correlation of angle spread. / QC 20101109

Zugl.: Aachen, Techn. Hochsch., Diss., 2009.

Zugl.: Hamburg, Techn. Univ., Diss., 2008

Hybrid plasmonic (HP) waveguides, a multi-layer waveguide structure supporting a hybrid mode of surface plasmonics and Si photonics, is a compromise way to integrate plasmonic materials into Si or SOI platforms, which can guide optical waves of sub-wavelength size, and with relative low propagation loss. In this thesis, several HP waveguides and devices are developed for the purposes of optical communications and sensing. The single-slot HP ring resonator sensor with 2.6µm radius can give a quality factor (Q factor) of 1300 at the communication wavelength of 1.5µm with a device sensitivity of 102nm/RIU (refractive index unit). The Mach-Zehnder interferometer (MZI) with a 40µm double-slot HP waveguide has a device sensitivity around 474nm/RIU. The partly open silicon side-coupled double-slot HP ring resonator has a device sensitivity of 687.5nm/RIU, with a Q factor over 1000 after optimization. Further, an all-optical switching HP donut resonator with a photothermal plasmonic absorber is developed, utilizing the thermal expansion effect of silicon to shift the resonant peak of the HP resonator. The active area has a radius of 10µm to match the core size of a single-mode fiber. By applying 10mW power of the driving laser to the absorber, the resonator transmitted power can be changed by 15dB, with an average response time of 16µs. Using the same fabrication flow, and removing the oxide materials using hydrogen fluoride wet etching, a hollow HP waveguide is fabricated for liquid sensing applications. The experimentally demonstrated waveguide sensitivity is about 0.68, which is more than twice that of pure Si waveguide device. Microelectromechanical systems (MEMS) can also be integrated into vertical HP waveguides. By tuning the thickness of the air gap, over 20dB transmitted power change was experimentally demonstrated. This can be used for optical switching applications by either changing the absorption or phase of the HP devices. / <p>QC 20170427</p>

Zugl.: Köln, Universiẗat, Diss., 2007.

<p>VDL mode 4 is a digital data link operating in the VHF band, its mainly use is for the aviation industry.VDL4 can as an example provide with positioning data, speed information of aircrafts or vehicles equipped with a VDL4 transponder. A connection between the groundsystem and the airborne system is called a point to point connection, which can be used for various applications. This data link needs to be transferred between groundstations during flights in order maintain the connection, which is called handoff.</p><p>The handoff process needs to be quick enough to not drop the link and at the same time a low rate of handoffs is desirable. The data link is regarded as a narrow resource and link management data for handoff is considered as overhead.</p><p>This thesis studies how to make the handoff procedure optimal with respect to involved aspects. Previous research of handoff algorithms and models of the VHF-channel are treated. Standardized parameters and procedures in VDL4 and are explored in order to find an optimal solution for the handoff procedure in VDL4.</p><p>The studied topics are analyzed and it is concluded to suggest an algorithm based on an adaptive hysteresis including signal quality and positioning data provided in VDL4. Standardized parameters which could be useful in the handoff procedure are commented, since the VDL4 standards are under development.</p>

No description available.