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Favorable propagation (FP) and channel hardening are desired properties in massive multiple-input and multiple-output (MIMO) systems, where nearly optimal performance is achieved with linear processing techniques, such as maximal-ratio combining. To date, these properties have primarily been analyzed for statistical channel models, or ray-based models with very specific angular parameters and dist
The performance of linear multi-user multiple-input multiple-output (MU-MIMO) systems has been extensively studied for classical statistical channel models. In contrast, there is little analysis for ray-based models, which are physically motivated, feature prominently in standards and have been experimentally validated. Thus, we present a novel analysis framework for zero forcing (ZF) and maximal
Phase shifter-based hybrid beamforming has received a lot of attention at millimeter-wave frequencies for cellular communications. Nevertheless, the implementation complexity of such beamformers is rather high due to the complexities involved in designing and fabricating the required radio-frequency (RF) circuits. In contrast, lens-based RF beamformers significantly reduce the implementation compl
Multi-cell wireless systems usually encounter both intra-cell and inter-cell interference, which can be mitigated via coordinated multipoint (CoMP) transmission. Previous works on multi-cell analysis in the microwave band generally consider fully digital beamforming, requiring a complete radio-frequency chain behind each antenna. This is practically infeasible for millimeter-wave (mmWave) systems
This work demonstrates the sensitivity of lens antenna arrays operating at millimeter-wave (mmWave) frequencies. Considering a Rotman lens array in receive mode, our investigation focuses on its most imperative defect: aberration of electromagnetic (EM) energy. Aberration leads to spillover of electric fields to neighboring ports, reducing the lens' ability to focus the EM energy to a desired port
Massive multiple-input multiple-output (MIMO) is now making its way to the standardization exercise of future 5G networks. Yet, there are still fundamental questions pertaining to the robustness of massive MIMO against physically detrimental propagation conditions. On these grounds, we identify scenarios under which massive MIMO can potentially fail in Ricean channels, and characterize them physic
Lens–based massive multiple–input multiple–output (MIMO) systems have considerable potential to reduce signal processing cost at millimeter–wave frequencies. As a result, they are able to lower the effective channel dimension via beam selection, realized with a network of radio–frequency (RF) switches. However, lens arrays suffer from the inherent quantization of the beamspace, as well as errors d
What is a digital platform economy and what are its key policy implications? This report on Developing Platform Economies collects four chapters from researchers in the fields of economy, media and law to define, scrutinize and draw empirically based policy-recommendations for a European context, particularly in comparison to the US.What is a digital platform economy and what are its key policy implications? This report on Developing Platform Economies collects four chapters from researchers in the fields of economy, media and law to define, scrutinize and draw empirically based policy-recommendations for a European context, particularly in comparison to the US.
A search for charged Higgs bosons heavier than the top quark and decaying via H± → tb is presented. The data analysed corresponds to 36.1 fb−1 of pp collisions at s=13 TeV and was recorded with the ATLAS detector at the LHC in 2015 and 2016. The production of a charged Higgs boson in association with a top quark and a bottom quark, pp → tbH±, is explored in the mass range from mH± = 200 to 2000 Ge
Sustainability science is a wide and integrative scientific field. It embraces both complementary and contradictory approaches and perspectives for dealing with newer sustainability challenges in the context of old and persistent social problems. In this article we suggest a combined approach called social fields and natural systems. It builds on field theory and systems thinking and can assist su
Objective To evaluate the psychometric properties of the Fatigue Severity Scale (FSS), the Fatigue Impact Scale (FIS), and the Multidimensional Fatigue Inventory (MFI-20) in persons with late effects of polio (LEoP). More specifically, we explored the data completeness, scaling assumptions, targeting, reliability, and convergent validity. Methods A postal survey including FSS, FIS, and MFI-20 was
Introduction: Arterial stiffness is recognized as an intermediate phenotype and predictor of cardiovascular disease. Arterial stiffness is complex in origin with contributions from lifestyle and genetic factors. However, the association between single nucleotide polymorphisms (SNPs) and arterial stiffness remains unclear. Objective: The aim is to assess whether a multilocus genetic risk score (GRS
Objective: To study association between relevant cardiovascular pharmacotherapy and incident congestive heart failure (CHF) in patients with atrial fibrillation treated in primary health care. Methods: Study population included all adults (n=7975) aged 45 years and older diagnosed with atrial fibrillation at 75 primary care centers in Sweden between 2001 and 2007. Outcome was defined as a first di
Although natural terrestrial ecosystems have sequestered ∼25% of anthropogenic CO2 emissions, the long-term sustainability of this key ecosystem service is under question. Forests have traditionally been viewed as robust carbon (C) sinks; however, extreme heat-waves, drought and wildfire have increased tree mortality, particularly in widespread semi-arid regions, which account for ∼41% of Earth's
Although treaty abuse is an increasingly occurring element in international legal arguments, especially in the sphere of international economic law, the concept is still viewed by many lawyers as suspicious, for several reasons. First, lawyers have doubts about the legal status of the treaty abuse doctrine. Second, as many lawyers would seem to believe, the concept of treaty abuse is imprecise-it
Neuropsychological test-based norms are vital for accurate assessment of older adults’ level of cognition. Hence, it is important that these scores are not conflated with birth cohort effects. With data drawn from the Swedish Good Ageing in Skåne (GÅS) population study, this study examined birth cohort effects on test scores measuring several cognitive domains. A time-lag design with three distinc
