So far, nothing major has gone wrong. But engineers at T-Systems International GmbH, which is operating the huge transmission network carrying high-definition signals from 12 stadiums hosting the World Cup soccer tournament in Germany, aren't kicking back because, as the saying goes, "the game isn't over until it's over."

T-Systems, a unit of German telco Deutsche Telekom, is in charge of a highly robust and reliable network that carries standard TV and HDTV (high-definition television) signals for what media experts say is the most viewed sports events in the world.

For sure, with billions of viewers glued to their tubes, the company's reputation could be quickly ruined by a technical glitch, like a loss of transmission during a decisive game. Not surprisingly, T-Systems has built one of the biggest, most reliable and secure private broadcast transmission networks ever to operate in Germany, let alone Europe.

The fiber optic network uses dedicated WDM (wavelength division multiplexer) at the lowest level, SDH (Synchronous Digital Hierarchy ) in the middle and IP (Internet Protocol) on top of the stack.

"What we have, essentially, is a packet over SDH network, which provides point-to-point IP connections," said Carsten Winterberg, head engineer of the FIFA World Cup broadcast project at T-Systems. "We need this type of connectivity to provide uncompressed signals."

Host Broadcast Services (HBS), which has been hired by the World Cup tournament organizer Federation Internationale de Football Association (FIFA) to provide production services, has required all signals to be delivered in an uncompressed format. Uncompressed HDTV signals require transmission connections of around 1.5G bps (bits per second), according to Winterberg.

To play it safe, T-Systems has two fiber optic cables running into the stadiums, each capable of transmitting data at speeds up to 20G bps. A satellite link is held in reserve, should both cable connections fail.

The stadium cables connect to a meshed backbone, boasting 480G bps of capacity.

"HDTV puts special demands on data transmission, such as packet delivery times and packet loss," said Walter Zornek, head of the FIFA World Cup engineering project at T-Systems. "We've had to design the network to meet these broadcast-specific demands."

All cables, nodes and other network components are monitored by an advanced network monitoring system.

The network is tough, if not almost impossible, for hackers to crack, according to Winterberg. "It's totally self-contained; the signals are completely separated from all other networks," he said. "I suppose you could try to cut a cable somewhere, but even that won't bring the network down because we have a lot of redundancy built into it."

For the World Cup, T-Systems has also amassed a satellite farm, consisting of 25 dishes to beam signals around the globe.

"The World Cup has helped us learn how to work with HDTV on a very large scale," Zornek said. "We'll be able to put this experience to good use for the German professional soccer league where HDTV is to play a big role in future."