Wireless access points on unmanned aerial vehicles (UAVs) are being considered for mobile service provisioning in commercial networks. To be able to efficiently use these devices in cellular networks it is necessary to first have a qualitative and quantitative understanding of how their design parameters reflect on the service quality experienced by the end user. In this paper we model a networ...

Unmanned aerial vehicles (UAVs) can be used as aerial wireless base stations when cellular networks are not operational due to natural disasters. They can also be used to supplement the ground base station in order to provide better coverage and higher data rates for the users. Prior studies on UAVbased wireless coverage typically consider an Air-to-Ground path loss model, which assumes that th...

The Communication Systems Simulation Laboratory (CSSL) at the NASA Johnson Space Center is tasked to perform spacecraft and ground network communication system simulations, design validation, and performance verification. The CSSL has developed simulation tools that model spacecraft communication systems and the space and ground environment in which the tools operate. In this paper, a spacecraf...

Terrestrial communication networks have experienced significant development in recent years by providing emerging services for ground users. However, one critical challenge raised is to provide full coverage (especially dense high-rise urban environments) users due scarce network resources and limited coverage. To meet this challenge, we propose a high altitude platform (HAP)-reserved ground-ai...

Autonomous communications systems often involve the use of separate solar cells and antennas, which necessitate a compromise in the utilization of the limited surface area available. These separate items may be combined,, provided that the antennas and solar cells are compatible. To show the compatibility of solar cells and antennas, the concept is used to create linearly polarized slot antenna...

Aims. We have analysed ground-based multi-colour Strömgren photometry and single-filter photometry from the star tracker on the  satellite of the δ Scuti star ǫ Cephei. Methods. The ground-based data set consists of 16 nights of data collected over 164 days, while the satellite data are nearly continuous coverage of the star during 14 days. The spectral window and noise level of the satelli...

Recently, earth observation system by using satellite network have attracted much attention due to their wide coverage and disaster resistance. Although the system is useful for collecting various data, which have an affect on a natural disaster, ecology and so forth, earth observation satellite hardly send the collected observation data to the ground station. This is because that the earth obs...

Cropping system level study is not only useful to understand to overall sustainability of agricultural system, but also it helps in generating many important parameters which are useful in climate change impact assessment. Considering its importance, Space Applications Centre, took up a project for mapping and characterizing major cropping systems of Indo-Gangetic Plains of India. The study are...

Conceived to combat widescale biodiversity erosion in farmland, agri-environment schemes have largely failed to deliver their promises despite massive financial support. While several common species have shown to react positively to existing measures, rare species have continued to decline in most European countries. Of particular concern is the status of insectivorous farmland birds that forag...

We analyze the ground states at boundaries of four-dimensional (full-dimensional) ground-state regions of the lattice-gas model on the infinite plane triangular lattice with nearest- and next-nearest-neighbor pairwise interactions and with additional interaction between three particles at the vertices of a nearest-neighbor triangle. In such a way we determine the ground states at fixed density ...