80 research outputs found

    Broadcasting in 4G mobile broadband networks and its evolution towards 5G

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    One of the challenges of the mobile industry is to cope with the growth of mobile traffic demand expected for the next years, primarily driven by the increasing usage of mobile video services. Indeed, the existence of increasingly powerful terminals is encouraging the consumption of high-quality video content. Usually, video services are identified with linear Television (TV) and scheduled broadcast (point-to-multipoint (p-t-m)) distribution. However, the consumption of video content over mobile networks is different from traditional fixed TV because contents are mainly consumed on-demand with unicast point-to-point (p-t-p) connections. Then, the convergence of linear TV and on-demand content delivery represents a challenge that requires a combined broadcast/unicast transmission model. This dissertation addresses the use of broadcasting technologies for the provision of mobile multimedia services in Fourth Generation (4G) mobile broadband networks and beyond. Specifically, the dissertation focuses on the broadcast technology included in 4G Long Term Evolution (LTE) and LTE Advanced (LTE-A) networks, known as Enhanced Multicast Broadcast Multimedia Services (eMBMS). It analyses the benefits of the eMBMS physical layer aspects regarding Multimedia Broadcast Multicast Services over a Single Frequency Network (MBSFN) deployments and identifies the current limitations of eMBMS at physical layer by comparing with the broadcast technology of the other 4G mobile system, the Institute of Electrical and Electronics Engineers (IEEE) 802.16m standard. Those limitations are the use of a dedicated carrier and Multiple-Input Multiple-Output (MIMO) techniques for broadcast transmissions. Our investigations employ a complete simulation platform including link-level and system-level simulations to evaluate the performance of broadcast transmissions in these real technologies. The research on eMBMS services is aimed at finding the optimum delivery of streaming and file download services focusing on the Radio Resource Management (RRM) problem and trade-off between Physical layer – Forward Error Correction (PHY-FEC) and Application Layer - Forward Error Correction (AL-FEC). Concerning streaming services, results show that the use of AL-FEC increases the coverage level and, then, the maximum service data rate. The gain due to AL-FEC is greater in scenarios with high mobility users, although, this gain is limited if low zapping times are desired. Regarding file delivery services, this dissertation analyses the duration of the transmission required to guarantee the correct file reception and the reduction in the mean throughput of unicast users with different delivery modes. They are the unicast delivery, the eMBMS delivery and a hybrid approach, which combines a first eMBMS delivery with a postdelivery error repair phase with unicast transmissions. Our results show that the hybrid delivery is the most efficient configuration in terms of file download time, although it further reduces unicast performance.Calabuig Gaspar, J. (2015). Broadcasting in 4G mobile broadband networks and its evolution towards 5G [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/48561TESI

    Del Mat-Builging a la ciudad en el espacio

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    [Resumen] Mat-building es un tipo de edificio de baja altura y gran densidad característico de la arquitectura europea de los años 60 y 70. El término es acuñado por Alison Smithson y su paradigma es la Freie Universität en Berlín de Candilis, Josic y Woods. Basado en un riguroso orden interno y una indeterminación en la forma, el proyecto del mat-building es una cuestión de combinatoria. En España, Rafael Leoz y Ricardo Bofill demuestran la utilidad de este modo de proyectar para la edificación en altura. Este artículo estudia cómo estas experiencias prefiguran algunos aspectos clave de la arquitectura contemporánea.[Abstract] Mat-building is a low-rise, high-density construction which characterizes European architecture of the 1960s and 1970s. The term is coined by Alison Smithson and its paradigm is the Free University in Berlin by Candilis, Josic and Woods. Based on a strong internal order and indeterminacy in form, mat-buildings’ design is a combinatory method. In Spain, Rafael Leoz and Ricardo Bofill demonstrate the utility of this way of designing to conceive high-rise works. This paper addresses how these proposals anticipate some important aspects of contemporary architecture

    On the Integration of Grassmannian Constellations into LTE Networks: a Link-level Performance Study

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    This paper presents Grassmannian signaling as a transmission scheme that can be integrated in Long Term Evolution (LTE) to support higher user speeds and to increase the throughput achievable in the high Signal to Noise Ratio (SNR) regime. This signaling is compared, under realistic channel assumptions, with the diversity transmission modes standardized in LTE, in particular, Space-Frequency Block Coding and Frequency-Switched Transmit Diversity for two and four transmit antennas, respectively. In high-speed scenarios, and even with high antenna correlation, Grassmannian signaling outperforms the LTE diversity transmission modes starting from four transmit antennas. Furthermore, in the high SNR regime, Grassmannian signaling can increase the link data rate up to 10% and 15% for two and four antennas, respectively

    Wegener's granulomatosis : description of a case with oral manifestation

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    Wegener?s granulomatosis is a multisystemic granulomatous vasculitis that predominantly affects the airways and the kidneys, but may affect any organ. Otorhinolaryngological manifestations may be oral ulcers, gingival swelling or septal perforations that can cause saddle nose deformities, rhinitis, sinusitis and hearing loss. The oral ulcers usually occur when the disease is advanced. Renal involvement is characterized by focal and segmental glomerulosclerosis, and determines the evolution. The diagnosis is made by clinical symptoms and signs, the presence of c-ANCA and a positive biopsy. The anatomic pathology is characterized by vasculitis, granulomatous inflammation with multinuclear giant cells and necrosis. The prognosis has improved as a result of treatment with immunosuppressants associated with corticosteroids. We report a case of a 53-year-old patient with Wegener?s granulomatosis with oral manifestation, which began as chronic mastitis

    Femtosecond digital lensless holographic microscopy to image biological samples

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    The use of femtosecond laser radiation in digital lensless holographic microscopy (DLHM) to image biological samples is presented. A mode-locked Ti:Sa laser that emits ultrashort pulses of 12 fs intensity FWHM, with 800 nm mean wavelength, at 75 MHz repetition rate is used as a light source. For comparison purposes, the light from a light-emitting diode is also used. A section of the head of a drosophila melanogaster fly is studied with both light sources. The experimental results show very different effects of the pinhole size on the spatial resolution with DLHM. Unaware phenomena on the field of the DLHM are analyzed

    Multi-user non-coherent detection for downlink MIMO communication

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    © 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Current cellular technologies are based on the concept of coherent communication, in which the channel matrix used for demodulation is estimated via reference or pilot signals. Coherent systems, however, involve a significant increase of the signalling overhead, especially when the number of transmission points is increased or when the mobile channel changes rapidly, which motivates the use of non-coherent techniques. This letter extends the use of non-coherent communications to a multi-user (MU) multiple-input multiple-output (MIMO) framework by combining superposition coding with a reduced-complexity detection method. Numerical results confirm that our scheme achieves higher user rates than non-coherent MU transmission based on time multiplexing. In addition to the well-known sum-rate gain of MU systems, an extra performance gain given by downlink non-coherent MU communication is shown and qualitatively justified.This work was performed in the framework of the FP7 project ICT-317669 METIS, supported in part by the European Union. The authors would like to acknowledge the contributions of their colleagues in METIS, although the views expressed are those of the authors and do not necessarily represent the project. The associate editor coordinating the review of this manuscript and approving it for publication was Prof. Chandra Ramabhadra Murthy.Roger Varea, S.; Calabuig Soler, D.; Cabrejas Peñuelas, J.; Monserrat Del Río, JF. (2014). Multi-user non-coherent detection for downlink MIMO communication. IEEE Signal Processing Letters. 21(10):1225-1229. https://doi.org/10.1109/LSP.2014.2330854S12251229211

    Microconcrete with partial replacement of Portland cement by fly ash and hydrated lime addition

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    [EN] The reduction in Portland cement consumption means lower CO2 emissions. Partial replacement of Portland cement by pozzolans sucha as fly ash has its limitations due to the quantity of calcium hydroxide generated in the mix. In this work we have studied the contribution of the addition of hydrated lime to Portland cement + fly ash systems. We have also studied several levels of cement replacement, ranging from the 15% to 75%. The best mechanical results were obtained replacing 50% of Portland cement by the same amount of fly ash plus the addition of hydrated lime (20% respect to the amount of fly ash). In these systems, an acide-base self-neutralization of the matrix has occurred through a pozzolanic reaction of fly ash with portlandite liberated in the hydration of Portland cement and the added hydrated lime. It has been identified for these mixtures a significant amount of hydrated gehlenite, typical reaction product from rich-alumina pozzolans.Lorca, P.; Calabuig Pastor, R.; Benlloch Marco, J.; Soriano Martinez, L.; Paya Bernabeu, JJ. (2014). Microconcrete with partial replacement of Portland cement by fly ash and hydrated lime addition. Materials and Design. 64:535-541. doi:10.1016/jmatdes.2014.08.022S5355416

    Time-frequency Grassmannian signalling for MIMO multi-channel-frequency-flat systems

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    In this paper, we consider the application of non-coherent Grassmannian signalling in practical multi-channel-frequency-flat multiple-input multiple-output (MIMO) wireless communication systems. In these systems, Grassmannian signalling, originally developed for single-channel block-fading systems, is not readily applicable. In particular, in such systems, the channel coefficients are constant across time and frequency, which implies that spectrally-efficient signalling ought to be jointly structured over these domains. To approach this goal, we develop a concatenation technique that yields a spectrally-efficient time-frequency Grassmannian signalling scheme, which enables the channel coherence bandwidth to be regarded as an additional coherence time. This scheme is shown to achieve the high signal-to-noise ratio non-coherent capacity of MIMO channels when the fading coefficients are constant over a time-frequency block. This scheme is also applicable in fast fading systems with coherence bandwidth exceeding that of one subchannel. The proposed scheme is independent of the symbol duration, i.e., the channel use duration, and is thus compatible with the transmit filter designs in current systems.The work of the first and second authors is supported, in part, by the Natural Sciences and Engineering Research Council of Canada (NSERC). This work is also supported, in part, by Huawei Canada Co., Ltd., in part, by the Ontario Ministry of Economic Development and Innovation's ORF-RE (Ontario Research Fund-Research Excellence) program, and, in part, by the Ministerio de Ciencia e Innovacion (project number TEC2011-27723-C02-02). The associate editor coordinating the review of this paper and approving it for publication was Z. Wang.Fouad, YMM.; Gohary, RH.; Cabrejas Peñuelas, J.; Yanikomeroglu, H.; Calabuig Soler, D.; Roger Varea, S.; Monserrat Del Río, JF. (2015). Time-frequency Grassmannian signalling for MIMO multi-channel-frequency-flat systems. IEEE Communications Letters. 19(3):475-478. https://doi.org/10.1109/LCOMM.2014.2386873S47547819

    Bibliometric analysis of fitness equipment: How scientific focuses affect life-cycle approaches and sustainable ways of development

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    Research Question: Although fitness equipment is recognised worldwide as a tool for physical activities and a sustainable result in optimizing human movements within a wide range of environments, the state of the art and scientific advances have not been analysed from a bibliometric point of view. Research Methods: Using descriptive bibliometric software, this study examined the scientific production, and the most prolific authors, articles, and institutions. Bibliometric maps were used to visualise the content of published articles and to determine the most prolific terms, co-citation, and co-authorship. Results and Findings: A total of 678 original papers were retrieved from 447 journals in Web of Science®. The Journal of Strength and Conditioning Research had the highest number of articles (25), while the American Journal of Preventive Medicine the highest number of global citations (656). Citation and co-authorship networks were defined. Implications: Research on fitness equipment is still in an early maturation stage with 30 years of scientific development in its timeline. Fitness equipment and its related fields of application could represent a real step into a more sustainable balance between the economic, environmental, and social spheres
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