17 research outputs found

    Outage Probability for Directional Beamforming in High Density Wireless Networks

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    partially supported by the projects CoSHARE (LISBOA-01-0145-FEDER0307095 - PTDC/EEI-TEL/30709/2017), and UIDB/50008/2020.In this paper, we derive the outage probability in directional millimeter-wave communications, capturing the effect of beamforming. In the proposed scenario, multiple transmitters are spatially distributed according to a spatial Poisson Point Process, which can cause interference to a pair of transmitter/receiver communicating nodes. The analysis considers a general distance-based path loss with Rayleigh and Rician fading channels and a sectored antenna model. Assuming that nodes are uniformly distributed over a circular or annular area centered at the receiver, we derive the outage probability due to the aggregate interference caused by multiple transmitters. The outage probability is based on the Signal-to-interference-plus-noise ratio (SINR) derived for the transmitter/receiver pair. Several simulations confirm the effectiveness of the derived results for different wireless channels and beamwidth values, highlighting the effect of directional communications on the outage probability.authorsversionpublishe

    MOOC on "Ultra-dense networks for 5G and its evolution": challenges and lessons learned

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    Proceeding of: 31st Annual Conference of the European Association for Education in Electrical and Information Engineering (EAEEIE 2022), Coimbra, Portugal, 26 June-1 July 2022Many of the new mobile communication devices will be things that power and monitor our homes, city infrastructure and transport. Controlling drones thousands of miles away, performing remote surgeries or being immersed in video with no latency will also be a huge game changer. Those are some of the few things that make the fifth generation (5G) a revolution expected to be a thrust to the economy. To that end, the design and density of deployment of new networks is also changing becoming more dense, what introduces new challenges into play. What else will it add to previous generations? The MOOC about Ultra-dense networks for 5G and its evolution has been prepared by the researchers of an European MSCA ITN, named TeamUp5G, and introduces the most important technologies that support 5G mobile communications, with an emphasis on increasing capacity and reducing power. The content spans from aspects of communication technologies to use cases, prototyping and the future ahead, not forgetting issues like interference management, energy efficiency or spectrum management. The aim of the MOOC is to fill the gap in graduation and post-graduation learning on content related to emerging 5G technologies and its applications, including the future 6G. The target audience involves engineers, researchers, practitioners and students. This paper describes the content and the learning outcomes of the MOOC, the main tasks and resources involved in its creation, the joint contributions from the academic and non-academic sector, and aspects like copyright compliance, quality assurance, testing and details on communication and enrollment, followed by the discussion of the lessons learned.This work has received funding from the European Union Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie ETN TeamUp5G, grant agreement No. 813391

    Inovação no Desenvolvimento do Curso Online Acessível a Todos (MOOC) sobre “Redes Ultra-densas 5G e sua Evolução”

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    Muitos dos novos dispositivos de comunicações móveis serão aparelhos que alimentam e monitorizam as nossas casas, infraestruturas urbanas e transportes. Controlar drones a milhares de quilómetros de distância, realizar cirurgias remotas ou estar imerso em vídeo com latência reduzida transformará certamente o acesso às tecnologias de informação e comunicação digitais. Estes são alguns dos aspetos que tornarão a quinta geração das comunicações móveis (5G) uma revolução, um impulso para a economia, e o foco de todos os intervenientes atuais na área das telecomunicações. Com este intuito, o planeamento e a crescente densidade de implantação destas novas redes introduzem novos desafios de otimização. Que elementos serão adicionados em relação às gerações anteriores? Baseados num Curso Online Acessível a Todos (MOOC) anteriormente desenvolvido na UC3M (UC3M Staff, 2022), o MOOC sobre redes ultra-densas 5G e sua evolução foi elaborado pelos investigadores da Marie Skłodowska-Curie Actions (MSCA) ITN/ETN Europeia (teamUp5G Reserachers, 2022), denominada TeamUp5G (Teamup5G, 2022; Pérez Leal et al., 2020) e apresenta as tecnologias mais importantes que suportam comunicações móveis 5G, com ênfase no aumento de capacidade e redução de energia, que facilitam o desenvolvimento de redes com pequenas células. Os conteúdos abrangem aspectos desde tecnologias de comunicação até casos de utilização, prototipagem e o futuro próximo, sem esquecer questões como a gestão de interferência, eficiência energética ou gestão de espectro. O objetivo do MOOC (TeamUp5G, 2022) é preencher a lacuna na aprendizagem ao nível dos estudos de graduação e pós-graduação, em conteúdos relacionados com tecnologias 5G emergentes e suas aplicações, incluindo a 6G futura. O público-alvo envolve engenheiros, investigadores, profissionais e estudantes. O artigo descreve o conteúdo e os resultados de aprendizagem do MOOC, as principais tarefas e recursos envolvidos na sua criação, as contribuições conjuntas do setor académico e não académico, e aspectos como a conformidade relativamente aos direitos de autor, garantia de qualidade, testes e detalhes sobre comunicação e inscrição, seguidos da discussão das lições extraídas.Este trabalho foi financiado pelo programa de investigação e inovação Horizonte 2020 da União Europeia através da Rede Europeia de Estágios (ETN) Marie Skłodowska-Curie TeamUp5G, acordo de bolsa N.º 813391, pela SNF Scientific Exchange - AISpectrum (projecto 205842) e UIDB/50008/2020. Os autores agradecem as contribuições da equipa audiovisual da UC3M responsáveis pela edição do MOOC, e da equipa responsável pelos direitos de autor e pela gravação na plataforma edX.info:eu-repo/semantics/acceptedVersio

    Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

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    Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10 years; 78.2% included were male with a median age of 37 years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

    5g ağlarında OFDM sistemleri için NOMA çoklu numerolojisi ve koruma bandı azaltım yöntemleri

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    Non-orthogonal multiple access (NOMA) is a promising technique which outperforms the traditional multiple access schemes in many aspects. It uses superposition coding (SC) to share the available resources among the users and adopts successive interference cancellation (SIC) for multiuser detection (MUD). Detection is performed in the power domain where fairness can be supported through appropriate power allocation. Since power domain NOMA utilizes SC at the transmitter and SIC at the receiver, users cannot achieve equal rates and experience higher interference. In this thesis, a novel NOMA scheme is proposed for multi-numerology (NR) orthogonal frequency division multiplexing (OFDM) system, i.e., different subcarrier spacings (SCSs). The scheme uses the nature of mixed NR systems to reduce the constraints associated with the MUD operation. This scheme not only enhances the fairness among the users but it improves the bit error rate performance as well. Although the proposed scheme is less spectrally efficient than conventional NOMA schemes, it is still more spectrally efficient than orthogonal multiple access schemes. As another contribution, we propose a novel frame structure for fifth generation (5G) networks. Such the structure aims to increase the capability of adopting the NR in 5G networks. In particular, a common cyclic prefix is appended to multiple OFDM symbols. Therefore, adopting large SCSs or short OFDM symbols becomes more flexible and applicable.Dikgen olmayan çoklu erişim (NOMA) yöntemi, birçok yönden geleneksel çoklu erişim (MA) tekniklerini geride bırakan ve gelecekte kullanılması beklenen tekniklerden biridir. Kullanıma açık kaynakları kullanıcılar arasında paylaşmak için süper-pozisyon kodlaması (SC) kullanır ve çok kullanıcılı algılama (MUD) için ardışık girişim giderim (SIC) yöntemi kullanır. Sinyallerin tespiti ise adil olarak uygun güç tahsisi (PA) yöntemi ile güç uzayında gerçekleştirilir. NOMA güç alanı, alıcıda (RX) SC, vericide (TX) ise SIC kullanılması sebebiyle kullanıcılar eşit hızlara ulaşamaz ve daha yüksek bir girişim yaşayamaz. Bu tezde ise ¸coklu numeroloji (NR) dikgen frekans bölmeli ¸coğullama (OFDM) sistemi, yani farklı alt taşıyıcı aralıkları (SCS' ler) için yeni bir NOMA şeması önerilmiştir. Önerilen şema, MUD işlemiyle ilişkili kısıtlamaları azaltmak için karışık NR sistemlerinin doğal özelliklerini kullanır. Bu şema sadece kullanıcılar arasındaki adil uygulama oranını arttırmakla kalmaz, aynı zamanda bit hata oranı performansını da (BER) geliştirir. Önerilen plan geleneksel NOMA yöntemlerinden spektrum verimliliğin açısından daha az olsa da Dikgen çoklu erişim (OMA) şemalarından spektrum verimliliği açısından daha zengindir. Bu olumlu yönlere ek başka bir katkı da OFDM sistemlerinde gereken koruma ekleri, örneğin döngüsel öneki (CP) azaltmak için yeni bir alıcı verici tasarımı önermekteyiz. Bir dizi OFDM sembolü TX' de bir CP' ye eklenir. RX' de, genişletilmiş hızlı bir Fourier dönüşümü (FFT) çalışması, uzunluğun CP ile çıkartılmış sinyale eşittir. Sonuç olarak, dikgen olarak iletilen semboller yapıcı bir eklenti olarak eklenir. Bu matematiksel olarak kanıtlanmıştır. Sonuç olarak, çogullanmış sembolleri ayırmak için iki yaklaşım benimsenmiştir

    Massive Online Open Course (MOOC) on ‘Ultra-dense Networks for 5G and its Evolution’

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    Many of the new mobile communication devices will be things that power and monitor our homes, city infrastructure and transport. Controlling drones thousands of miles away, performing remote surgeries or being immersed in video with no latency will also be a huge game changer. Those are some ofthe few things that make the fifth generation (5G) a revolution expected to be a thrust to the economy. To that end, the design and density of deployment of new networks is also changing becoming more dense, what introduces new challenges into play. What else will it add to previous generations? The MOOC about Ultra-dense networks for 5G and its evolution has been prepared by the researchers of an European MSCA ITN, named TeamUp5G, and introduces the most important technologies that support 5G mobile communications, with an emphasis on increasing capacity and reducing power. The content spans from aspects of communication technologies to use cases, prototyping and the future ahead, not forgetting issues like interference man agement, energy efficiency or spectrum management. The aim of the MOOC is to fill the gap in graduation and post-graduation learning on content related to emerging 5G technologies and its applications, including the future 6G. The target audience involves engineers, researchers, practitioners and students. This paper describes the content and the learning outcomes of the MOOC, the main tasks and resources involved in its creation, the joint contributions from the academic and non-academic sector, and aspects like copyright compliance, quality assurance, testing and details on communication and enrollment, followed by the discussion of the lessons learned.info:eu-repo/semantics/acceptedVersio

    Global age-sex-specific mortality, life expectancy, and population estimates in 204 countries and territories and 811 subnational locations, 1950–2021, and the impact of the COVID-19 pandemic: a comprehensive demographic analysis for the Global Burden of Disease Study 2021

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    Background: Estimates of demographic metrics are crucial to assess levels and trends of population health outcomes. The profound impact of the COVID-19 pandemic on populations worldwide has underscored the need for timely estimates to understand this unprecedented event within the context of long-term population health trends. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 provides new demographic estimates for 204 countries and territories and 811 additional subnational locations from 1950 to 2021, with a particular emphasis on changes in mortality and life expectancy that occurred during the 2020–21 COVID-19 pandemic period. Methods: 22 223 data sources from vital registration, sample registration, surveys, censuses, and other sources were used to estimate mortality, with a subset of these sources used exclusively to estimate excess mortality due to the COVID-19 pandemic. 2026 data sources were used for population estimation. Additional sources were used to estimate migration; the effects of the HIV epidemic; and demographic discontinuities due to conflicts, famines, natural disasters, and pandemics, which are used as inputs for estimating mortality and population. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate under-5 mortality rates, which synthesised 30 763 location-years of vital registration and sample registration data, 1365 surveys and censuses, and 80 other sources. ST-GPR was also used to estimate adult mortality (between ages 15 and 59 years) based on information from 31 642 location-years of vital registration and sample registration data, 355 surveys and censuses, and 24 other sources. Estimates of child and adult mortality rates were then used to generate life tables with a relational model life table system. For countries with large HIV epidemics, life tables were adjusted using independent estimates of HIV-specific mortality generated via an epidemiological analysis of HIV prevalence surveys, antenatal clinic serosurveillance, and other data sources. Excess mortality due to the COVID-19 pandemic in 2020 and 2021 was determined by subtracting observed all-cause mortality (adjusted for late registration and mortality anomalies) from the mortality expected in the absence of the pandemic. Expected mortality was calculated based on historical trends using an ensemble of models. In location-years where all-cause mortality data were unavailable, we estimated excess mortality rates using a regression model with covariates pertaining to the pandemic. Population size was computed using a Bayesian hierarchical cohort component model. Life expectancy was calculated using age-specific mortality rates and standard demographic methods. Uncertainty intervals (UIs) were calculated for every metric using the 25th and 975th ordered values from a 1000-draw posterior distribution. Findings: Global all-cause mortality followed two distinct patterns over the study period: age-standardised mortality rates declined between 1950 and 2019 (a 62·8% [95% UI 60·5–65·1] decline), and increased during the COVID-19 pandemic period (2020–21; 5·1% [0·9–9·6] increase). In contrast with the overall reverse in mortality trends during the pandemic period, child mortality continued to decline, with 4·66 million (3·98–5·50) global deaths in children younger than 5 years in 2021 compared with 5·21 million (4·50–6·01) in 2019. An estimated 131 million (126–137) people died globally from all causes in 2020 and 2021 combined, of which 15·9 million (14·7–17·2) were due to the COVID-19 pandemic (measured by excess mortality, which includes deaths directly due to SARS-CoV-2 infection and those indirectly due to other social, economic, or behavioural changes associated with the pandemic). Excess mortality rates exceeded 150 deaths per 100 000 population during at least one year of the pandemic in 80 countries and territories, whereas 20 nations had a negative excess mortality rate in 2020 or 2021, indicating that all-cause mortality in these countries was lower during the pandemic than expected based on historical trends. Between 1950 and 2021, global life expectancy at birth increased by 22·7 years (20·8–24·8), from 49·0 years (46·7–51·3) to 71·7 years (70·9–72·5). Global life expectancy at birth declined by 1·6 years (1·0–2·2) between 2019 and 2021, reversing historical trends. An increase in life expectancy was only observed in 32 (15·7%) of 204 countries and territories between 2019 and 2021. The global population reached 7·89 billion (7·67–8·13) people in 2021, by which time 56 of 204 countries and territories had peaked and subsequently populations have declined. The largest proportion of population growth between 2020 and 2021 was in sub-Saharan Africa (39·5% [28·4–52·7]) and south Asia (26·3% [9·0–44·7]). From 2000 to 2021, the ratio of the population aged 65 years and older to the population aged younger than 15 years increased in 188 (92·2%) of 204 nations. Interpretation: Global adult mortality rates markedly increased during the COVID-19 pandemic in 2020 and 2021, reversing past decreasing trends, while child mortality rates continued to decline, albeit more slowly than in earlier years. Although COVID-19 had a substantial impact on many demographic indicators during the first 2 years of the pandemic, overall global health progress over the 72 years evaluated has been profound, with considerable improvements in mortality and life expectancy. Additionally, we observed a deceleration of global population growth since 2017, despite steady or increasing growth in lower-income countries, combined with a continued global shift of population age structures towards older ages. These demographic changes will likely present future challenges to health systems, economies, and societies. The comprehensive demographic estimates reported here will enable researchers, policy makers, health practitioners, and other key stakeholders to better understand and address the profound changes that have occurred in the global health landscape following the first 2 years of the COVID-19 pandemic, and longer-term trends beyond the pandemic. Funding: Bill &amp; Melinda Gates Foundation.</p

    Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021

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    Background: Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations. Methods: The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model—a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates—with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality—which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds. Findings: The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2–100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1–290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1–211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4–48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3–37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7–9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles. Interpretation: Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere. Funding: Bill &amp; Melinda Gates Foundation.</p

    Global Burden of Cardiovascular Diseases and Risks, 1990-2022

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    Age-standardized CVD mortality rates by regionranged from 73.6 per 100,000 in High-income Asia Pacific to432.3 per 100,000 in Eastern Europe in 2022. Global CVDmortality decreased by 34.9% from 1990 to 2022. Ischemicheart disease had the highest global age-standardized DALYsof all diseases at 2,275.9 per 100,000. Intracerebralhemorrhage and ischemic stroke were the next highest CVDcauses for age-standardized DALYs. Age-standardized CVDprevalence ranged from 5,881.0 per 100,000 in South Asia to11,342.6 per 100,000 in Central Asia. High systolic bloodpressure accounted for the largest number of attributableage-standardized CVD DALYs at 2,564.9 per 100,000globally. Of all risks, household air pollution from solid fuelshad the largest change in attributable age-standardizedDALYs from 1990 to 2022 with a 65.1% decrease
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