This dissertation is concerned with Computer Supported Cooperative Work (CSCW) and in particular with ways in which insights from ethnomethodology can be melded into the design of CSCW systems—a relationship that has been labelled technomethodology. The dissertation outlines a number of possible ways in which system design can learn from ethnomethodology and concentrates on one particular aspect—namely that CSCW should look closely at its foundational assumptions and, if necessary, re-specify any concepts which appear problematic in their formulation.

How to communicate ?Human beings use the voice or gestures to give shape to their ideas. In digital communications, a modulation scheme is used to give shape to bits of information, i.e. to convert zeros and ones into an analog waveform. The question of an ideal modulation scheme is discussed in this thesis and we study the one that seems the most promising to us. The orthogonal frequency division multiplexing (OFDM) modulation is the most popular multicarrier modulation scheme nowadays. The main advantage of OFDM is its simplicity. However, due to the rectangular pulse shaping of the Fast Fourier transform filters, OFDM systems exhibit very high frequency leakage and poor stopband attenuation. In the light of these limitations, the offset-QAM-based filterbank multicarrier (FBMC-OQAM) modulation has recently received increasing attention. Rather than using a rectangular pulse, FBMC-OQAM uses a pulse shape which is more spread out in time, which results in a much better frequency localization. This in turn translates into higher spectral efficiency and much more flexibility for spectrum allocation. The main objective of this thesis is to investigate the applicability of the FBMC-OQAM modulation for next generations of communication systems. More specifically, we focus on two main directions. The first direction studies advanced equalization algorithms for multiple-antenna wireless systems characterized by highly frequency and/or time selective channels. The second direction studies two main linear impairments in optical fiber systems, namely, phase noise and chromatic dispersion. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

Shannon demonstrated that the channel capacity depends of the ratio of the received signal power to interference plus noise power (SINR). Inter-cell interference caused by neighbouring base stations (BSs) has been identified as one of the most severe problem towards the deployment of LTE technology as it can significantly deteriorate the performance of cellside User Equipment (UE). However, because of regulatory and radiation restrictions as well as operational costs, signal power may only be increased only up to a certain limit to reduce the interference. The other common radio propagation impairment is multipath. Multipath refers to a scenario where multiple copies of a signal propagate to a receiver using different paths. The paths can be created due to signal reflection, scattering and diffraction. As will be discussed later the effects of multipath contribute little to intercell interference because multipath characteristics such as delay spread are compensated for using cyclic prefixes. In this work, we will limit our scope to interference as it has been identified as the main cause of performance degradation for cell edge users due to the full frequency reuse technique used in LTE. To mitigate interference 3GPP devised options of increasing the capacity in LTEAdvanced Release 12 which include the use of spectral aggregation, employing Multiple Input and Multiple Output (MIMO) Antenna techniques, deploying more base stations and micro and femto cells, increasing the degree of sectorisation and Coordinated Multipoint (CoMP). We are primarily interested in evaluating performance improvements introduced when uplink (UL) and downlink (DL) coordinated/cooperative multipoint (CoMP) is enabled in LTE Advanced Release 12 as a way of reducing interference among sites. The CoMP option of reducing interference does not require deployment of new equipment compared to the other options mentioned above hence network deployment costs are minimal. CoMP in theory is known to reduce interference especially for cell edge users and therefore improves network fairness. With CoMP, multiple points coordinate with each other such that transmission of signals to and from other points do not incur serious interference or the interference can even be exploited as a meaningful signal. In September 2011 work on specifications for CoMP support was started in 3GPP LTEAdvanced as one of the core features in LTE-Advanced Release 11 to improve cell edge user throughput as well as the average network throughput. We set to do field measurements in the evaluation of the effectiveness of CoMP in LTE. 3GPP LTE Release 12 was used and cell edge users' performance was the focus. The network operates in 2330 - 2350 MHz band (Channel 40). From the field measurements, it was demonstrated that the CoMP (Scenario 2) feature indeed effective in improving service quality/user experience/fairness for cell edge users. CoMP inherently improves network capacity. A seven (7) percent throughput was noticed.

Densely deployed small cell networks will address the growing demand for broadband mobile connectivity, by increasing access network capacity and coverage. However, most potential small cell base station (SCBS) locations do not have existing telecommunication infrastructure. Providing backhaul connectivity to core networks is therefore a challenge. Millimeter wave (mmW) technologies operated at 30-90GHz are currently being considered to provide low-cost, flexible, high-capacity and reliable backhaul solutions using existing roof-mounted backhaul aggregation sites. Using intelligent mmW radio devices and massive multiple-input multiple-output (MIMO), for enabling point-to-multipoint (PtMP) operation, is considered in this research. The core aim of this research is to develop an architecture of an intelligent non-line-sight (NLOS) small cell backhaul (SCB) system based on mmW and massive MIMO technologies, and supporting intelligent algorithms to facilitate reliable NLOS street-to-rooftop NLOS SCB connectivity. In the proposed architecture, diffraction points are used as signal anchor points between backhaul radio devices. In the new architecture the integration of these technologies is considered. This involves the design of efficient artificial intelligence algorithms to enable backhaul radio devices to autonomously select suitable NLOS propagation paths, find an optimal number of links that meet the backhaul performance requirements and determine an optimal number of diffractions points capable of covering predetermined SCB locations. Throughout the thesis, a number of algorithms are developed and simulated using the MATLAB application. This thesis mainly investigates three key issues: First, a novel intelligent NLOS SCB architecture, termed the cognitive NLOS SCB (CNSCB) system is proposed to enable street-to-rooftop NLOS connectivity using predetermined diffraction points located on roof edges. Second, an algorithm to enable the autonomous creation of multiple-paths, evaluate the performance of each link and determine an optimal number of possible paths per backhaul link is developed. Third, an algorithm to determine the optimal number of diffraction points that can cover an identified SCBS location is also developed. Also, another investigated issue related to the operation of the proposed architecture is its energy efficiency, and its performance is compared to that of a point-to-point (PtP) architecture. The proposed solutions were examined using analytical models, simulations and experimental work to determine the strength of the street-to-rooftop backhaul links and their ability to meet current and future SCB requirements. The results obtained showed that reliable multiple NLOS links can be achieved using device intelligence to guide radio signals along the propagation path. Furthermore, the PtMP architecture is found to be more energy efficient than the PtP architecture. The proposed architecture and algorithms offer a novel backhaul solution for outdoor urban small cells. Finally, this research shows that traditional techniques of addressing the demand for connectivity, which consisted of improving or evolving existing solutions, may nolonger be applicable in emerging communication technologies. There is therefore need to consider new ways of solving the emerging challenges.

Abstact 1 - Over the past few years, mobile broadband technologies and speeds have greatly increased in the European Union, reaching an ever larger share of broadband consumers. These changes have implications for broadband market competition. In the past, mobile services offered slow but mobile internet whereas fixed services offered faster but fixed internet. Fixed and mobile broad-band were therefore obviously complementary services. While mobile broadband speeds have significantly increased over the latest years, fixed broadband is remaining rather a fixed technol-ogy. Consequently, if mobile broadband becomes fast enough considering some consumers’ needs, we believe that the same consumers will choose to use only the mobile broadband tech-nology (who by itself offers high-speed and mobility) instead of both fixed and mobile broad-band technologies. As a result, we may observe an increasing trend towards fixed to mobile substitution. Our study investigates empirically this trend. More specifically, it analyzes the im-pact of mobile broadband technology evolution - through 4G adoption - on fixed to mobile sub-stitution in the 28 European countries from 2009 until 2015. The few studies examining this sub-ject show that fixed to mobile substitution exists although none of these studies analyze the evo-lution of this substitution. The results confirm a significant existence of a fixed to mobile substi-tution in the EU, and show that this substitution is more than doubled when a country adopts 4G. The growing competitive pressure from mobile operators also provides fixed operators with incentives to acquire – or merge with – mobile operators. This fact should be a concern for policy makers as it could have harmful consequences for competition and investment on the broad-band market. / Abstract 2 - Whereas open science – i.e. publishing articles in scientific journals – had been largely studied on the academic side, there is still a need to explore the subject on the industry side. This study spe-cifically analyzes the role of academic institutions in firms’ scientific publications and uses a novel approach to explore the subject. Publications issued from collaborations with academic institutions are indeed differentiated from other publications. The first type of publications is considered as an indicator of firms’ collaborative activities with academic institutions whereas the second type of publications is considered as the result of firms’ strategies and/or firms’ capa-bilities to publish. This study provides evidence that industry publications are a valuable signal to attract academic partners. In addition, this study provides evidence that potential academic partners are more willing to team up with firms’ researchers who have proven their ability to achieve high-quality research/publications without the help of academic partners. Finally, the study provides evidence that past successful collaborations with academic partners lead the firm to reiterate such collaborations in the short term (2 years max.). / Abstract 3 - The objective of this study is twofold. First, it provides further knowledge on the subject of prof-itability of industry science/publications as it is not clear yet whether industry sci-ence/publications are profitable to firms. Second, it considers the central role of academic part-ners in the profitability of firms’ scientific publications as previous empirical studies do not con-sider such role. To investigate the subject, we perform several regressions with firms profits as dependent variable. The results provide evidence that the publication of scientific articles is not a profitable activity in itself (as it was demonstrated in two previous studies). Collaborations with academic institutions are the real basis of profitable results; the production of scientific publica-tions is only one of the consequences of these collaborations. This study also shows that not all collaborations are profitable, only collaborations in high-tech sectors that lead to high-quality publications lead to larger profits. Indeed, in their quest for survival and profitability, companies competing in high-tech sectors often need the help of academic partners to exploit scientific knowledge. On average, a rise of about 7% in successful collaborations (leading to high-quality publications) raises the profit of high-tech firms by about 1%. - / Abstract 4 - This chapter analyzes the factors influencing the quality of the output of I-A collaborations ap-proximated by the quality of the I-A co-publications. More specifically it analyzes two subjects that are typically complicated to study empirically because of a lack of available data: (1) it compares US and EU I-A partnerships and (2) it discusses if and how internet is a useful tool in I-A collaborations. The results empirically confirm that EU universities are less efficient partners than US universities when collaborating with the private sector. This study also demonstrates a much larger gap between EU and US academic partners in high-tech sectors. Finally, the results provide evidence that broadband is a useful tool for international I-A collaborations although broadband is less important in the success of I-A international collaborations in high-tech sectors compared to lower-tech sectors. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

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.

Thesis (M.S.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / The satellite industry has experienced amazing growth incorporate television transmissions over the last decade, as well as in use by educators and government. Further expansion seems assured as conferencing systems improve and costs decrease. But there is no training ground to guarantee a high level of professional performance in this rapidly expanding field. This study was designed to assess the needs of telecommunications networks, project growth and create a model program to meet future training requirements. Telecommunications technology is developing so fast that literature older than three years is generally out of date and current material is scanty. Thus, interview and questionnaire were the main tools of this research. In addition to a questionnaire on hiring and training practices sent to a random sample corporate users of satellite networks, the researcher relied heavily on extensive interviews with leaders in the field. Results showed an urgent need for academic training and, more challenging, a need for extensive research to weed out and/or update outmoded communications theory and provide a sound basis on which to base this training. To date the telecommunications industry (and satellite teleconferencing in particular) has been vendor driven with little thought given to exploring non-traditional approaches. There is clear indication that many traditional methods no longer serve in this new age of instantaneous, face-to-face communications with global reach. We are just beginning to see creative applications of new mediums such as the use of videoconferencing as a selling and marketing tool. And as technology continues to improve, we can expect more innovative uses that warrant careful study. This research suggests that a model program to meet academic needs should be built around an institute or "high tech center" with a strong, industry-oriented research arm. Students--undergraduate as well as master's and doctoral candidates--should be imbued with a thorough knowledge of the principles of telecommunications theory as well as a working knowledge of state-of-the-art equipment. Internships with industry and government would be vital. Publication of research and interaction with college communication departments throughout the country should be encouraged. / 2999-01-01

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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

Thesis (M.S.)--Kutztown University of Pennsylvania, 1993. / Source: Masters Abstracts International, Volume: 45-06, page: 2805. Abstract precedes thesis as 2 preliminary leaves. Typescript. Includes bibliographical references (leaves 48-51).