From Connectivity to Advanced Internet Services: A Comprehensive Review of Small Satellites Communications and Networks

Recently the availability of innovative and affordable COTS (Commercial Off The Shelf) technological solutions and the ever improving results of microelectronics and microsystems technologies have enabled the design of ever smaller yet ever more powerful satellites. The emergence of very capable small satellites heralds an era of new opportunities in the commercial space market. Initially applied only to scientific missions, earth observation and remote sensing, small satellites are now being deployed to support telecommunications services. This review paper examines the operational features of small satellites that contribute to their success. An overview of recent advances and development trends in the field of small satellites is provided, with a special focus on telecommunication aspects such as the use of higher frequency bands, optical communications, new protocols, and advanced architectures

Multi-Operator Spectrum Sharing for Energy Efficient Heterogeneous Cellular Networks

Next generation cellular networks will be characterized by a very high density of heterogeneous base stations with strong consequences on operational expenditures and energy costs. In this paper a multiobjective optimization framework is proposed which is aimed at minimizing the power consumption of heterogeneous networks owned by rival mobile network operators: in particular, resource sharing is shown to guarantee the provided quality of service (QoS) and to achieve remarkable energy savings

L'expérimentation urbaine : nécessité malaisée

Englander Jean-Loup. L'expérimentation urbaine : nécessité malaisée. In: Villes en parallèle, n°17-18, avril 1991. Acteurs et chercheurs dans la ville. pp. 166-167

Contrasting effects of tree origin and urbanization on invertebrate abundance and tree phenology

The ongoing wide-scale introduction of nonnative plants across the world may negatively influence native invertebrate fauna, due to a lack of coevolved traits related to the novel plants, e.g., unique phytochemicals or shifted phenology. Nonnative plants, specifically trees, are common in urban environments, areas that already pose novel habitats to plants and wildlife through a wide array of anthropogenic factors. For example, impervious surfaces contribute to increased ambient temperatures, the so-called urban heat island effect (UHI), which can affect local plant phenology. Yet, few studies have simultaneously studied the effects of urbanization and tree species origin on urban invertebrate communities. We measured the city-level UHI and phenology of nine native and seven nonnative tree species in five city-center parks in southern Sweden, as well as four common native species in a rural control forest. We quantified the abundance of invertebrates on a subset of native and nonnative tree species through shake sampling, sticky traps, and frass collection. In the urban environment, nonnative trees hosted significantly fewer invertebrates compared to native trees. Furthermore, the nonnative trees had a delayed phenology compared to native species, while the peak of caterpillars associated with the subset of trees surveyed for this measure was significantly earlier compared to that of the native species studied. The effect of tree species origin on urban invertebrate abundance was of a greater magnitude (effect size) than the effect of urbanization on invertebrate abundance in native tree hosts. Hence, the results indicate that the impact of nonnative vegetation may be a stronger driver of invertebrate declines in urban areas than other factors. As the effect of species origin on tree phenology was at a level comparable to the urban effect, increasing prevalence of nonnative vegetation can potentially obscure effects of urbanization on phenology in large-scale studies, as well as induce mismatches to invertebrate populations. Since parks harbor a large proportion of urban biodiversity, native trees play a crucial role in such habitats and should not be considered replaceable by nonnative species in terms of conservation value

Satellite Assisted Delivery of Alerts: A Standardization Activity Within ETSI

International audienceThe fast and efficient delivery of alerts to citizens in case of natural or manmade disasters is a crucial element in the crisis reaction chain. Current procedures and practices are however inhomogeneous and rely partially on outdated technologies. The increasing availability of new information channels suggests that the exploitation of available communications technologies can provide a consistent improvement in the alerting process. These considerations have led the ETSI Working Group SES/SatEC (Satellite Earth Stations and Systems/Satellite Emergency Communications) to initiate a standardization activity in order to define a multi-technology alert encapsulation protocol called MAMES (Multiple Alert Message Encapsulation over Satellite). This paper reports on the motivations and the approach followed within SES/SatEC in the definition of MAMES

Performance of wireless body area networks for health:ETSI SmartBAN or Bluetooth?

Abstract This paper deals with a comparative analysis of the performances of two different communications standards for wireless body area networks (WBAN): ETSI SmartBAN and Bluetooth low energy (BLE). The performance comparison is carried out in additive white Gaussian noise (AWGN) channel as well as in multipath fading channel. Aggregate interference is also taken into account to show which technology tolerates interference better. Both SmartBAN and BLE are possible wireless solutions to implement services like delivering individual’s health-related data. The results show that the SmartBAN can outperform BLE in both AWGN and fading channel, in particular, when interference is present, since SmartBAN can take advantage of BCH and repetition features