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Both the EUTELSAT (http://www.eutelsat.org) and ASTRA (http://www.astra.lu) satellite operators are offering new multimedia satellite platforms for Europe, North Africa, and the Middle East. These new platforms are based on the open architectures of the DVB and MPEG-2 digital standards and feature high-speed Internet access at data rates of up to 2 Mb/s per individual user (see Figure 8-3) or 40 Mb/s for delivery of data broadcast services (see Figure 8-4).Europe’s DVB Group has selected the MPEG-2 DSM-CC (Digital Storage Media-Command and Control) specification to serve as the heart of the DVB Data Broadcasting Standard in conjunction with DVB-SI (Service Information). This DVB data broadcasting specification is based on a series of four Profiles, with each Profile corresponding to a particular application area for DVB-compliant broadcast networks.The Data Piping Profile is for the simple, end-to-end delivery of anonymous, nonsynchronous digital bitstreams. The Data Streaming Profile is for the end-to-end transport of asynchronous, synchronous, or synchronized bitstreams. The Multiprotocol Encapsulation Profile permits the use of the DVB transport mechanism for different communications services that require the transmission of communication protocol datagrams. The Data Carousel Profile supports the periodic transmission of comprehensive data modules. In addition to these four Profiles, an object carousel specification has been added in order to support data broadcast services that require the broadcasting of objects as defined in the DVB Network Independent Protocols specification. The equipment required consists of a satellite dish and a DVB/MPEG-2 adapter card for the computer. Antennas that already receive digital TV services from the EUTELSAT and ASTRA satellite constellations also can be used to receive high-speed multimedia services. The return link consists of an ordinary modem connected to a telephone line or an ISDN line.Each multimedia service provider has a Network Control Center (NCC) that acts as a DVB broadcast station. The NCC consists of modulators, multiplexers, encoders, and a system controller as well as a conditional access and subscriber management system. The DVB platform connects to a multimedia platform consisting of satellite servers/routers and a data gateway using TCP/IP (Transmission Control Protocol/Internet Protocol). TCP/IP is a suite of protocols that allows communications between groups of dissimilar computer systems
from a variety of vendors. The IP part of TCP/IP is the protocol used to route a data packet, called a “datagram,” from its source to its destination over the Internet. The platform performs the elementary tasks of a server and distributes IP datagrams as an MPEG-2 data structure in the DVB-compliant MPEG-2 digital bitstream.