The need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operat...

The exponential growth of World-Wide Web (WWW) requires efficient delivering mechanism. Web caching has shown to be a very economical way to scale WWW by reducing traffic in congested network links, decreasing latency to the clients, and reducing load in the origin servers. In this paper we study an emerging caching strategy called satellite caching distribution in which all ISP (i.e. Internet ...

A satellite communications system is based on antennas in a stable orbit above the earth. Satellites serve as relay stations in the sky. The basic idea of satellite communications is that two stations on earth discuss via one or more satellites. So a little bit of satellite-related terminology: 1. Earth station is an antenna on or near the surface of the earth. 2. Uplink is a transmission from ...

Optical communications can provide high-data-rate telemetry from deep-space probes with subsystems that have lower mass, consume less power, and are smaller than their radio frequency (RF) counterparts. However, because optical communication is more affected by weather than is RF communication, it requires groundstation site diversity to mitigate the adverse effects of inclement weather on the ...

Unmanned space servicing requires an ability to capture a free-floating satellite, replace a module and deploy the satellite using a robotic arm. As direct teleoperation from the ground is not possible due to limitations of the communication link (delay, bandwidth and intermittence) the servicers will therefore have to operate with a certain degree of autonomy. The need for autonomy is particul...

Satellite networking is different from wired or wireless networks. TCP/IP performance and behavior with respect to normal wireless network and wired networks are different from one another. As the architecture of TCP/IP protocol was not designed to perform well over high-latency or noisy channels and so its performance over satellite networks are totally different. The properties of satellite c...

The in vitro translation of tomato black ring virus genomic and satellite RNAs which had been treated with protease to remove the genome-linked protein was compared with that of untreated RNA. There were no differences in the amount or size distributions of the translation products and no differences in the proportions of added RNA which bound to ribosomes in wheat germ extracts. The genome-lin...

This paper deals with the analysis of advanced fade countermeasures for supporting DVB-S2 reception by mobile terminals mounted on high-speed trains. Recent market studies indicate this as a potential profitable market for satellite communications, provided that integration with wireless terrestrial networks can be implemented to bridge the satellite connectivity inside railway tunnels and larg...