Energy efficiency of some non-cooperative, cooperative and hybrid communication schemes in multi-relay WSNs

In this paper we analyze the energy efficiency of single-hop, multi-hop, cooperative selective decode-and-forward, cooperative incremental decode-and-forward, and even the combination of cooperative and non-cooperative schemes, in wireless sensor networks composed of several nodes. We assume that, as the sensor nodes can experience either non line-of-sight or some line-of-sight conditions, the Nakagami-m fading distribution is used to model the wireless environment. The energy efficiency analysis is constrained by a target outage probability and an end-to-end throughput. Our results show that in most scenarios cooperative incremental schemes are more energy efficient than the other methods

Downlink Energy Efficiency Analysis of Some Multiple Antenna Systems

In this paper we compare the energy efficiency of different multiple antenna transmission schemes for long-range wireless networks, assuming a realistic power consumption model. We consider the downlink, between a base station and a mobile station, in which the Alamouti scheme, transmit beamforming, receive diversity, spatial multiplexing, and transmit antenna selection are compared. Our analysis shows that, for different types of base stations, outage probability requirements and spectral efficiencies, the transmit antenna selection scheme is in general the most energy efficient option. Although antenna selection is not the best in terms of outage probability, it becomes the most efficient in terms of overall power consumption as it requires a single radio-frequency chain to obtain spatial diversity

Competition, research and extension: the three approaches to the popularization of small satellites in the Alto Paraopeba region in Brazil

There are several approaches to the diffusion of the space technologies, three of them are in this work: competition, research, and extension. Thus, the objective of this work is to focus on presenting the results of the Brazilian nanosatellite team called NoizOrbita, and also to qualify quantitatively the impact of using these approaches in popularizing the topic of small satellites for space educational purposes. The team was founded on September 29, 2020, by three people: an alumni of Telecommunications Engineering at Federal University of São João del- Rei (UFSJ), Alto Paraopeba Campus (CAP), currently pursuing his Ph.D. in CubeSat Antennas at UFSC; a student currently in the 6th period of the Telecommunications Engineering undergraduate course (class of 2019); and a professor in the Department of Telecommunications and Mechatronics Engineering (DETEM). This initiative is intended to be a gateway to the space/satellite technologies in the institution and is based on three main pillars: Competitions, Research, and Extension in Nanosatellites. The team aims to obtain and develop small satellite technologies involving CAP undergraduate and graduate students, which enables them to learn the concepts of Space Engineering with the methodology of "learning by doing", covering the entire lifecycle of a spacecraft, even in a less complex way, through Systems Engineering approach. It also encourages the students to carry out scientific studies, prepare and publish papers, participate in conferences, and through extension, spread all the knowledge acquired in the various layers of society in the Alto Paraopeba region. Team members are all undergraduate and graduate students. Considering that one of the main characteristics of the team is its multidisciplinary nature, it leads to the advantage that students from all courses offered at CAP can join the group. This is reflected a lot by the concept of satellite engineering, since professionals from various areas of knowledge are sought for working with satellites and small satellites. Thus, in this work the main numbers related to the team were gathered, collected and presented in order to assess the impact and/or reach of the activities in its first year of existence. Data were extracted from databases, histories, and records on the various knowledge and information dissemination platforms. Regarding the research approach, the team obtained a significant number of scientific productions; regarding extension, presentations with satellite subjects were performed; and a great achievement with the competition aspect was obtained, which shows the effectiveness of these three approaches

Energy and Cost Analysis of Cellular Networks Under Co-Channel Interference

In this paper we carry out an energy efficiency and economic cost analysis of different cellular network designs. Our system model considers the co-channel interference, different amounts of available bandwidths and also the reuse of frequencies. The energy efficiency analysis employs a realistic power consumption model, while the economic analysis focus on infrastructure, spectrum licenses, and energy costs. Our results show that from an economic point of view the bandwidth cost and the number of employed base stations can be the most relevant factors to be balanced, while from an energy efficiency analysis it is more interesting to employ larger bandwidths and to balance the reuse of frequencies and the number of base stations. Moreover, although the system design under these two different points of view can be rather different, we also look into scenarios when the most energy efficient system design may also lead to the best economic option

Energy efficiency vs. economic cost of cellular networks under co-channel interference

In this paper we analyze the efficiency of cellular network designs, by taking into account the co-channel interference among cells, different amounts of available bandwidths, and frequency reuse. A realistic power consumption model is considered for the energy efficiency analysis, and for the economic analysis it is employed a model in which the total cost is composed by three factors: spectrum license, energy and infrastructure costs. Our results show that different conclusions can be obtained according to the focus of the network design: energy efficiency or total costs. Assuming an economic point of view, the most cost efficient solutions can be obtained when the number of base stations and the available bandwidth are the factors to be balanced, as the infrastructure cost and the spectrum license costs correspond to the most relevant fraction of the total costs. However, considering the energy efficiency anlysis, it can be more beneficial to employ a higher system bandwidth and balance the number of base stations and the reuse of frequencies in order to minimize the required transmit power

Development of a low-cost ground segment capable of receiving data from nanosatellites: a partnership between Brazil and Portugal

Two universities joined forces to develop a shared ground segment (Ground Stations and Mission Operation Centers) for satellite signals reception, capable of working together autonomously in a network to receive telemetry data and decode information. The main objective of this cooperation and network is to, firstly, give both universities an infrastructure capable of receiving signals in VHF and UHF. Secondly, and most importantly, it aims to create an exchange of experiences between students from these universities while also contributing to the regional development of each country in nanosatellite data reception technology. The ground segment itself provides mutual data collection on a private server, using two ground stations located in different hemispheres to expand global coverage and minimize revisit time, which also contributes to supplying the nanosatellite telemetries database, which is being built in Portugal. The server architecture allows both universities to schedule future passes of their chosen satellites, recording them in a log file that can be used in future studies, enabling research groups to gain experience in signal processing analysis. The modular system is developed entirely using Commercial Of-The-Shelf (COTS) components and 3D printed parts, including Antennas, Amplifiers, Filters and also SDRs (Software Defined Radio), leaving the door open to new integrations that can expand frequency coverage, or system performance improvements. The design supports a wide variety of missions, operating on amateur radio frequency in VHF (2 m band of 144-146 MHz) and UHF (70 cm band of 430-440 MHz), enabling remote access and remote control of the antennas and their recorded data. All the ground segment architecture, hardware, and software, as well as its operational procedures, are discussed in this paper and can be found in detail on our public repository in GitLab. As of March 21st, it has completed several observations for verification. The results are being processed on a low-cost computer (Raspberry Pi4) connected to an SDR which in turn connects to the antennas. The assembly of this interface intends to give a friendly user experience and, if desirable, an easy expansion of this system. The project developed can be easily replicated in other locations around the world, mainly because of its low price and ease of use

Temporal trends in morbidity and mortality for respiratory diseases in São Paulo, Brazil

Doenças respiratórias são importante causa de morbi-mortalidade em todas as faixas etárias, com considerável impacto econômico e social. Diversos autores vêm apontando um aumento nas hospitalizações e mortes por algumas causas respiratórias, porém em nosso meio, poucos estudosanalisaram estas tendências recentemente. No presente trabalho, dados de hospitalizações para o período de 1995 a 2000 e de mortalidade para 1991-2000 foram analisados através de tabelas e gráficos descritivos, testes de correlação e de tendência linear. Observou-se que houve decréscimo na taxa de internações por doenças respiratórias entre 1995-1997 e tendência de aumento de 1997-2000 em todas as idades. Tendência crescente foi também observada na mortalidade por doenças respiratórias entre 1991-2000. Padrões específicos para diferentes grupos de doenças respiratórias, diferentes faixas etárias e sexos foramobservados. Concluímos que no período estudado, houve participação importante na morbi-mortalidade respiratória de doenças agudas, como as pneumonias, mas com tendência a diminuir a sua participação, ao contrário de doenças crônicas como a DPOC. Estes resultados indicam uma mudança no perfil destas doenças, o que traz conseqüências imediatas para a formulação de políticas de saúde.Respiratory diseases are important causes of morbi-mortality in all agegroups, with considerable economic and social impacts. Several studies have been poiting out an increase inhospitalizations and deaths due to respiratory diseases. However, few studies have analysed such recent trends in Brazil. In the present study we analyzed hospitalizations occuring from 1995 to 2000 and mortality from 1991 to 2000 through descriptive tables and graphs, correlation analysis and trend tests. We observed a decrease in the rate of hospitalizations for respiratory diseases between 1995-1997 and an increase between 1997-2000 for all agegroups. Increasing trends were also observed for mortality between 1991-2000. Specific patterns for different causes of respiratory diseases, different agegroups and sexes were observed. We concluded that, in the period studied, acute respiratory diseases such as pneumonia had a greater contribution to the respiratory morbi-mortality but with a decreasing trend. Onthe other hand, chronic respiratory diseases have presented increasing trends in the period. These results point out to a changing pattern in the respiratory diseases morbi-mortality with direct consequences for public health policy making

Peritonite bacteriana espontânea causada por Listeria monocytogenes em pacientes com cirrose: primeiro relato de caso no Brasil

Two cases of spontaneous bacterial peritonitis (SBP) caused by Listeria monocytogenes in cirrhotic patients are reported. In one of the cases, the microorganism was isolated from pleural effusion and ascites. SBP is a serious and common complication of patients with ascites caused by hepatic cirrhosis and the culture of the ascitic fluid is an important tool for the diagnosis and for the more appropriate treatment. Although a third generation cephalosporin has usually been employed for empiric treatment of SBP, it does not provide adequate coverage against Listeria spp. In such cases the use of ampicillin (with or without sulbactam) or sulfamethoxazole-trimethoprim is recommended. The last one is used for secondary prophylaxis, instead of norfloxacin. To summarize, Listeria monocytogenes infection is a rare cause of SBP, whose treatment should be specific for the bacteria.Foram relatados dois casos de peritonite bacteriana espontânea (PBE) por Listeria monocytogenes em pacientes com cirrose. Em um dos casos isolamos também o agente no líquido pleural. A PBE é uma complicação comum e grave de pacientes com ascite por cirrose e a cultura do líquido ascítico é de grande importância para o diagnóstico e para o tratamento mais adequado. Embora uma cefalosporina de terceira geração seja geralmente utilizada para o tratamento empírico da PBE, ela não oferece cobertura adequada contra a Listeria spp. Nesses casos, recomenda-se o uso de ampicilina (com ou sem sulbactam) ou sulfametoxazol-trimetoprim. Para a profilaxia secundária indica-se o uso deste último, ao invés da norfloxacina. Em resumo, a infecção por Listeria monocytogenes é uma causa rara de PBE e o tratamento específico deve ser administrado

Energy and cost analysis of cellular networks under co-channel interference

In this paper we carry out an energy efficiency and economic cost analysis of different cellular network designs. Our system model considers the co-channel interference, different amounts of available bandwidths and also the reuse of frequencies. The energy efficiency analysis employs a realistic power consumption model, while the economic analysis focus on infrastructure, spectrum licenses, and energy costs. Our results show that from an economic point of view the bandwidth cost and the number of employed base stations can be the most relevant factors to be balanced, while from an energy efficiency analysis it is more interesting to employ larger bandwidths and to balance the reuse of frequencies and the number of base stations. Moreover, although the system design under these two different points of view can be rather different, we also look into scenarios when the most energy efficient system design may also lead to the best economic option