272 research outputs found

    Exploring Dimensions of Mobile Information Technology Dependence

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    The breakthrough idea of technology dependence is developed from mass communication theory as an enhancement to the evolving literature on IS Continuance. Unlike prominent constructs in the continuance literature, dependency as adapted for use here involves conscious user recognition of the benefits from and motivations for technology use, which stands in contrast to typical continuance constructs that presume routinized and nonconscious usage patterns. This study develops, tests and explains emerging dimensions of technology dependency in the context of mobile 3G handset users in a university workplace community. Results provide the basis for development of measures and hypothetical relationships with related variables for future research, and provide a valuable new variable for inclusion in the IS Continuance literature stream

    Characterisation and Modelling of Measured Massive MIMO Channels

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    Empirical Research on the Impact of Personalized Recommendation Diversity

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    Personalized recommendation has important implications in raising online shopping efficiency and increasing product sales. There has been wide interest in finding ways to provide more efficient personalized recommendations. Most existing studies focus on how to improve the accuracy of the recommendation algorithms, or are more concerned on ways to increase consumer satisfaction. Unlike these studies, our study focuses on the process of decision-making, using long tail theory as a basis, to reveal the mechanisms involved in consumers’ adoption of recommendations. This paper analyzes the effect of personalized recommendations from two angles: product sales and ratings, and tries to point out differences in consumer preferences between mainstream products and niche products, high rating products and low rating products, search products and experience products. The study verifies that consumers demand diversity in the recommended content, and also provides suggestions on how to better plan and operate a personalized recommendation system

    Towards environmental RF-EMF assessment of mmwave high-node density complex heterogeneous environments

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    The densification of multiple wireless communication systems that coexist nowadays, as well as the 5G new generation cellular systems advent towards the millimeter wave (mmWave) frequency range, give rise to complex context-aware scenarios with high-node density heterogeneous networks. In this work, a radiofrequency electromagnetic field (RF-EMF) exposure assessment from an empirical and modeling approach for a large, complex indoor setting with high node density and traffic is presented. For that purpose, an intensive and comprehensive in-depth RF-EMF E-field characterization study is provided in a public library study case, considering dense personal mobile communications (5G FR2 @28 GHz) and wireless 802.11ay (@60 GHz) data access services on the mmWave frequency range. By means of an enhanced in-house deterministic 3D ray launching (3D-RL) simulation tool for RF-EMF exposure assessment, different complex heterogenous scenarios of high complexity are assessed in realistic operation conditions, considering different user distributions and densities. The use of directive antennas and MIMO beamforming techniques, as well as all the corresponding features in terms of radio wave propagation, such as the body shielding effect, dispersive material properties of obstacles, the impact of the distribution of scatterers and the associated electromagnetic propagation phenomena, are considered for simulation. Discussion regarding the contribution and impact of the coexistence of multiple heterogeneous networks and services is presented, verifying compliance with the current established international regulation limits with exposure levels far below the aforementioned limits. Finally, the proposed simulation technique is validated with a complete empirical campaign of measurements, showing good agreement. In consequence, the obtained datasets and simulation estimations, along with the proposed RF-EMF simulation tool, could be a reference approach for the design, deployment and exposure assessment of the current and future wireless communication technologies on the mmWave spectrum, where massive high-node density heterogeneous networks are expected.Project RTI2018-095499-B-C31 was funded by the Ministerio de Ciencia, Innovación y Universidades, Gobierno de España (MCIU/AEI/FEDER, UE). This project received funding from Universidad Carlos III de Madrid and the European Union's Horizon 2020 research and innovation programme under Marie Sklodowska-Curie Grant 801538

    A Consolidated View of Context for Intelligent Systems

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    This paper's main objective is to consolidate the knowledge on context in the realm of intelligent systems, systems that are aware of their context and can adapt their behavior accordingly. We provide an overview and analysis of 36 context models that are heterogeneous and scattered throughout multiple fields of research. In our analysis, we identify five shared context categories: social context, location, time, physical context, and user context. In addition, we compare the context models with the context elements considered in the discourse on intelligent systems and find that the models do not properly represent the identified set of 3,741 unique context elements. As a result, we propose a consolidation of the findings from the 36 context models and the 3,741 unique context elements. The analysis reveals that there is a long tail of context categories that are considered only sporadically in context models. However, particularly these context elements in the long tail may be necessary for improving intelligent systems' context awareness

    Revolutionizing the supermarket experience : the effect of real time promotions on coupon conversion and brand equity

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    Retailers face a complex task in designing promotional strategies in today’s business environment and, since Millennials will revolutionize consumer marketing, it is critical for companies to succeed in attracting them in order to thrive. As consumers shop while using their smartphone, there is an opportunity window for retailers to easily attract them, by sending push notifications with Real Time Promotions to their smartphones. Hence, the main purpose of this dissertation is to understand whether having Real Time Promotions, in the form of digital coupons, increases coupon redemption and retailer’s brand equity. It also aims to understand if the form in which the coupon is presented, either percentage or cents-off, influences its usage by consumers. Additionally, it will allow us to see if there is a specific consumer profile who will value the most these promotions. For this matter, an online experimental study and seven in-depth interviews were made to reach insightful information. The main conclusions taken from the present study indicate that RTP may increase coupon redemption since coupons are delivered in the store and available for a short time period, signalling time urgency. Regarding the coupon face value, being framed in percentage-off (vs. cents-off) increases coupon redemption for both low-priced and high-priced products, in a supermarket context. Moreover, the implementation of Real Time Promotions enhances retailer’s Brand Equity and these promotions were found to be more relevant for younger consumers.Os retalhistas enfrentam uma tarefa complexa ao desenvolver estratégias promocionais no atual ambiente de negócios e, uma vez que os Millennials irão revolucionar o marketing de consumo, é fundamental que as empresas consigam atraí-los para prosperar. Uma vez que os consumidores utilizam o telemóvel enquanto fazem compras, existe uma oportunidade para os retalhistas os atraírem facilmente enviando notificações com promoções em tempo real para os seus smartphones. Assim, o objetivo principal desta dissertação é perceber se as Promoções em Tempo Real, na forma de vales de desconto digitais, aumentam a redenção dos mesmos e a brand equity do retalhista. Este estudo pretende também investigar se a forma em que o cupão é apresentado, quer em percentagem ou dinheiro, influencia o seu uso pelos consumidores e se existe um perfil específico do consumidor que valorize mais estas promoções. Com este propósito, um questionário on-line e sete entrevistas foram feitas para obter informações mais detalhadas. As principais conclusões do presente estudo indicam que as Promoções em Tempo Real podem aumentar o uso de vales de desconto, uma vez que são entregues em loja e estão disponíveis por um período limitado de tempo, criando pressão no consumidor. Verificou-se também que os cupões em percentagem, em vez de euros, têm um resgate maior tanto para produtos mais baratos como para os produtos mais caros. Além disso, a implementação destas promoções aumenta a brand equity do retalhista e é mais relevante para os consumidores mais jovens

    Mobile Web Usage: A Network Perspective

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    With recent advances in mobile devices and network capabilities, Mobile Internet subscription has caught up to and in some markets even surpassed that of the traditional fixed-line Internet. Hence, in order to sustain future growth and improve their business model, there is a need for the stakeholders to understand the ever evolving Mobile Internet user behaviour. This thesis analysed data collected from a mobile cellular network in Finland during a week in 2010 using a modified version of the Tstat traffc classifier tool to capture HTTP header and network flow data. Since this was the first time this tool was used for the network measurements, the main aim of the thesis was to test the reliability of the data and then to create an analysis process to build in-depth understanding of the traffic usage patterns. Another goal was also to identify mobile handset devices using the new dataset available. First, a study of the traffic symmetry and diurnal pattern of the traffic flow was done, which showed downlink dominating the traffic with periods of high traffic during the evening hours. Comparison with the port-based classification showed that the Tstat traffic classifier was more capable in identifying modern Internet applications correctly. The results also found HTTP to be the dominant protocol in Mobile Internet. These information rich HTTP headers enabled detailed study of the HTTP traffic. The Operating System (OS) information available in the User-Agent (UA) header validated the fact that most traffic is indeed from PC based devices and thus enabled separate study for mobile handset based traffic. For identifying the handsets, the UA headers were mapped to the WURFL database. From this study, Nokia devices were found to have the highest traffic volume and flows followed by the iOS and Android OS platforms. However, there were lot of malformed and non-standard UAs, which means there is a need to further refine the handset identification methodology

    Super-Broadband Wireless Access Network

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    Study of multi-antenna terminals in the presence of close scatterers

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    Projecte final de carrera realitzat en col.laboració amb ENSTA ParisTechMulti-antenna technologies may offer significant increases in data throughput and link range without additional bandwidth or transmit power by using spatial diversity concept. However, the radiation proprieties and return loss of these antennas as well as the channel capacity may be modified by many factors such as close scatterers (human body), mutual coupling, PCB housing, etc. The goal of this study is to characterize the behavior of some multi-antenna prototypes in the presence of these perturbation sources. Most of the antennas are designed to work for 2.4/5.2/5.8 GHz WLAN bands and 2.5/3.5/5.5GHz WiMAX bands and are printed on PCBs of size 114x64 mm2 which follow the average dimensions of PDAs found in the market. Different antennas were designed, simulated and fabricated. In Chapter 4 the results for the circular monopole array antenna is widely detailed. In the Appendix, designs of other antennas simulated and/or fabricated are shown
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