Search

Chapter 1 gives a brief introduction on the evolution of satellite communications and the services being envisaged to be provided by satellite systems. A discussion on different EU initiatives in supporting the development of satellite communications is also presented. The operating frequencies of and technical issues in satellite systems operations for network interconnection are also addressed. Finally, the objectives and activities under the COST Action 253 are described. [ABSTRACT FROM PUBLISHER]

Non-GEO satellite systems can help to meet the demand for information by providing global access to the telecommunications infrastructure, currently available only in advanced urban areas of the developed countries. Like GEO satellites, non-GEO satellites also provide a means of interconnecting LAN on a global basis. The main advantage of the deployment of non-GEO satellites is their relatively low altitudes in comparison with GEO satellites. This enables non-GEO satellites, especially LEO satellites, to provide services with delay which is compatible, or nearly compatible, with that introduced by the terrestrial networks. Because of their lower altitudes, lower power terminals are possible. This in turn has a positive effect in the size and cost of the terminals. The evolution from GEO to LEO satellites has resulted in a number of global satellite systems such as the Iridium, which is now in the sky, the Globalstar and ICO.

In the future, radio communication systems will offer different services through single user equipment; furthermore, it is expected that different radio communication systems will merge into one universal communication system. Today, there are two known concepts for providing wireless communication services: terrestrially based communication systems and satellite communication systems. Each concept has its specific characteristics, and consequently, advantages and disadvantages. The main disadvantages of terrestrially based systems are: poor radio channel quality, Rayleigh fading limits the cell radius and transmitted data rate and; and Terrain shadowing causes gaps in radio coverage.