A precoding aided space domain index modulation scheme for downlink multiuser MIMO systems

In this correspondence, we propose a space domain index modulation (IM) scheme for the downlink of multiuser multiple-input multiple-output (MU-MIMO) systems. Instead of the most common approach where spatial bits select active receiver antennas, in the presented scheme the spatial information is mapped onto the transmitter side. This allows IM to better exploit large dimensional antenna settings which are typically easier to deploy at the base station. In order to mitigate inter-user interference and allow single user detection, a precoder is adopted at the BS. Furthermore, two alternative enhanced signal construction methods are proposed for minimizing the transmitted power or enable an implementation with a reduced number of RF chains. Simulation results for different scenarios show that the proposed approach can be an attractive alternative to conventional precoded MU-MIMO.info:eu-repo/semantics/acceptedVersio

Frequency domain equalization for single and multiuser generalized spatial modulation systems in time dispersive channels

In this letter, a low-complexity iterative detector with frequency domain equalization is proposed for generalized spatial modulation (GSM) aided single carrier (SC) transmissions operating in frequency selective channels. The detector comprises three main separate tasks namely, multiple-input multiple-output (MIMO) equalization, active antenna detection per user and symbol wise demodulation. This approach makes the detector suitable for a broad range of MIMO configurations, which includes single-user and multiuser scenarios, as well as arbitrary signal constellations. Simulation results show that the receiver can cope with the intersymbol interference induced by severe time dispersive channels and operate in difficult underdetermined scenarios.info:eu-repo/semantics/acceptedVersio

Evaluation of the optical switching characteristics of erbium-doped fibres for the development of a fibre Bragg grating sensor interrogator

A polling topology that employs optical switching based on the properties of erbium-doped fibres (EDFs) is used to interrogate an array of FBGs. The properties of the EDF are investigated in its pumped and un-pumped states and the EDFs’ switching properties are evaluated by comparing them with a high performance electronically controlled MEM optical switch. Potential advantages of the proposed technique are discussed. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

An energy-aware resource design model for constrained networks

The Internet of Things is expected to incorporate objects and sensor networks of all kinds, and in particular, constrained sensor networks where energy consumption is a critical issue. In order to increase the lifetime of such networks, intelligent and standard-based solutions should be used. Here, we address this challenge through the use of CoRE interfaces for the resource design. These interfaces allow the server side to compose/organize resources and the client side to discover and determine how to consume such resources, besides allowing decisions to be easily integrated into the operation of the network. An energy-aware resource design model is proposed, based on CoRE interfaces, for the design of resources matching client needs. Based on this model, we develop an algorithm that proved to be energy efficient

Interference-aware iterative block decision feedback equalizer for single-carrier transmission

The deployment of increasingly dense heterogeneous mobile networks can create high levels of interference among users that, combined with severely time-dispersive channels, can result in substantial performance degradation. To cope with both effects, in this paper, we propose an iterative block decision feedback equalizer (IBDFE) for single carrier (SC) transmissions that makes use of the correlation between the interference in the receiving antennas and minimizes the mean squared error (MSE) of the detected symbols. Our analytic and simulated performance results show that the proposed receiver can clearly outperform the conventional IBDFE and the linear interference rejection combining (IRC) detector in severely time-dispersive channels with strong cochannel interference.info:eu-repo/semantics/acceptedVersio

One step greener: reducing 5G and beyond networks’ carbon footprint by 2-tiering energy efficiency with CO2 offsetting

Fifth generation (5G) and Beyond-5G (B5G) will be characterized by highly dense deployments, both on network plane and user plane. Internet of Things, massive sensor deployments and base stations will drive even more energy consumption. User behavior towards mobile service usage is witnessing a paradigm shift with heavy capacity, demanding services resulting in an increase of both screen time and data transfers, which leads to additional power consumption. Mobile network operators will face additional energetic challenges, mainly related to power consumption and network sustainability, starting right in the planning phase with concepts like energy efficiency and greenness by design coming into play. The main contribution of this work is a two-tier method to address such challenges leading to positively-offset carbon dioxide emissions related to mobile networks using a novel approach. The first tier contributes to overall power reduction and optimization based on energy efficient methods applied to 5G and B5G networks. The second tier aims to offset the remaining operational power usage by completely offsetting its carbon footprint through geosequestration. This way, we show that the objective of minimizing overall networks’ carbon footprint is achievable. Conclusions are drawn and it is shown that carbon sequestration initiatives or program adherence represent a negligible cost impact on overall network cost, with the added value of greener and more environmentally friendly network operation. This can also relieve the pressure on mobile network operators in order to maximize compliance with environmentally neutral activity.info:eu-repo/semantics/publishedVersio

Extending 5G capacity planning through advanced subscriber behavior-centric clustering

his work focuses on providing enhanced capacity planning and resource management for 5G networks through bridging data science concepts with usual network planning processes. For this purpose, we propose using a subscriber-centric clustering approach, based on subscribers’ behavior, leading to the concept of intelligent 5G networks, ultimately resulting in relevant advantages and improvements to the cellular planning process. Such advanced data-science-related techniques provide powerful insights into subscribers’ characteristics that can be extremely useful for mobile network operators. We demonstrate the advantages of using such techniques, focusing on the particular case of subscribers’ behavior, which has not yet been the subject of relevant studies. In this sense, we extend previously developed work, contributing further by showing that by applying advanced clustering, two new behavioral clusters appear, whose traffic generation and capacity demand profiles are very relevant for network planning and resource management and, therefore, should be taken into account by mobile network operators. As far as we are aware, for network, capacity, and resource management planning processes, it is the first time that such groups have been considered. We also contribute by demonstrating that there are extensive advantages for both operators and subscribers by performing advanced subscriber clustering and analytics.info:eu-repo/semantics/publishedVersio

Teachers’ practices mediate the association between teachers’ ideas and children’s perceived participation in early childhood education

Participation is a fundamental right of all children. Its promotion is considered a key investment in children’s well-being, crucial to support high-quality early childhood education (ECE). In this study we aimed to investigate if ECE teachers’ ideas on children’s participation were associated with children’s perceived participation, analysing the mediating role of teachers’ practices and dimensions of process quality. Participants in this quantitative study were 336 children (163 boys) aged between 44 and 84 months, and 58 ECE teachers (all female) aged between 26 and 60 years old, from 24 randomly selected ECE centres in Lisbon metropolitan area. Using multilevel modelling, given the hierarchical structure of data, we found that ECE teachers’ ideas about participation do influence children’s perceived participation, through teachers’ perceived practices. Further, ECE teachers’ perceived participation practices were associated with children’s perceived participation, through observed participation practices and observed process quality. This study suggests the interdependence of the subjective and objective properties of ECE classrooms, and how both should inform our understanding of the conditions needed to promote children’s participation.info:eu-repo/semantics/publishedVersio

Classroom quality and children's social skills and problem behaviors: dosage and disability status as moderators

Multiple studies have reported associations between early childhood education (ECE) quality and dosage and children’s social and behavior development, with some suggesting that this association may be stronger for specific groups of children. In this study, we examined the association between classroom quality and children’s social skills and problem behaviors, as reported by ECE teachers, as well as the moderating effects of ECE dosage and children’s disability status. Participants were 222 children (Mage = 63.75, SD = 7.77), including 180 typically developing (90 boys) and 42 children with disabilities (29 boys), from 44 inclusive classrooms in the Metropolitan Area of Lisbon, Portugal. Our results indicated that children’s social skills and behavior problems were not directly associated with observed classroom quality domains. However, lower classroom organization predicted lower social skills and higher externalizing behavior at higher number of months with the lead teacher; and instructional support predicted increased social skills for children with disabilities. Days absent from school predicted lower social skills. Overall, our results suggest that diverse types of dosage influence teacher’s reports of social and behavioral outcomes in different ways.info:eu-repo/semantics/acceptedVersio

Caseous calcification of the mitral annulus: A multi-modality imaging perspective.

Mitral annulus calcification is a common echocardiographic finding, particularly in the elderly and in end-stage renal disease patients under chronic dialysis. Caseous calcification or liquefaction necrosis of mitral annulus calcification is a rare evolution of mitral annular calcification. Early recognition of this entity avoids an invasive diagnostic approach, since it is benign and, unlike intracardiac tumors and abscesses, has a favorable prognosis. The authors present the case of an 84-year-old woman with a suspicious large, echodense mass at the level of the posterior mitral leaflet with associated severe mitral regurgitation. Cardiac magnetic resonance imaging demonstrated a hypoperfused mass with strong peripheral enhancement 10 minutes after gadolinium administration. Multislice computed tomography showed the calcified nature of the mass. A multi-modality imaging approach confirmed the diagnosis of caseous calcification of the posterior mitral annulus. The patient refused surgical treatment