Satellite Internet services using DVB/MPEG-2 and multicast Web caching

Communication satellites can be used to broadcast large volumes of data directly to extensive user groups. With the latest generation of high-powered direct broadcast satellites and the changing traffic and usage patterns in the Internet, new ways of using satellites for delivering data directly to the end user have become viable alternatives to terrestrial point-to-point networks. In this article the software architecture of a distributed system, which has been successfully implemented and which supports online and offline interactive multimedia services, is presented. It is based on a method of carrying Internet datagrams over DVB/MPEG-2 transport systems, intended for digital television. It relies on a configuration using a broadband forward channel and a separate, usually narrowband, return channel. The forward link is usually provided by a geostationary satellite, whereas the return channel uses a different network technology, such as dialup connection, a direct Ku-band return link, a LEO satellite network, or an LMDS local distribution system. A generic multicast system is presented which exploits the inherent capabilities of satellites to reach a large number of customers. The reliable multicast strategy chosen is shown to handle multiple applications, each with different reliability and timing requirements.