June 13, 2006 4:00 AM PDT
HDTV--the clincher in war between cable and phone?
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AT&T, which plans to officially begin offering commercial TV service this summer, has taken a different approach to building its network. It has put fiber further into neighborhoods and is using a technology called Very High Speed Digital Subscriber Line, or VDSL, to deliver up to 25Mbps of bandwidth into homes over its existing copper lines.
But when doing the math, it's easy to see that AT&T's initial service plans will have it bumping up against its bandwidth ceiling. The carrier has said it will provide one HDTV channel, which eats up about 8Mbps each stream, using MPEG-4 compression technology. But on top of this, it is promising up to three standard-definition channels (roughly 2Mbps to 3Mbps of bandwidth per stream) plus at least 6Mbps of high-speed Internet access, for every home. If a household is consuming all these services at full capacity, it is using up 23Mbps.
AT&T executives say they are confident that the carrier will have enough bandwidth to serve plenty of HDTV content in the 15 to 20 U.S. markets it plans to reach with TV service this year. They also argue that most people won't use all kinds of services at the same time, and that when more bandwidth is needed, the company will upgrade its network to newer DSL technology. Still, the company is not offering HDTV in its controlled release of the service in San Antonio.
"I can deliver HDTV today, no problem," said Christopher Rice, executive vice president at AT&T. "Even if you assume that people will go to 3 HDTVs, we can double capacity to 45Mbps and 50Mbps by using VDSL2+ bonding technology."
AT&T won't be the only company that needs to upgrade its network to keep pace with HDTV demand. Cable operators will also have to do some building. These companies broadcast TV signals across their networks to all subscribers, and when people click on a channel, it tunes that particular stream of video. With higher-capacity HDTV streams traveling over this network alongside analog streams, cable networks are nearly tapped out.
But Cox's Esser said cable companies have several options for tapping deeper into their existing infrastructure to increase the volume.
Esser said that his company, which offers nine HDTV channels today, is upgrading and re-spacing electronics on its network to increase bandwidth. Cox and other cable operators are also trying to encourage customers to switch to digital cable from analog TV, which eats significantly more capacity, he said.
And finally, cable companies are also looking into a technology called "switched digital," which mimics Internet Protocol. Instead of broadcasting every TV signal throughout the entire network, "switched digital" allows only the channels currently being watched to be sent to customers' homes along the coaxial cable.
"We've known for a long time that we are going to need more capacity on the network," he said. "And we've already been planning for it for a long time."
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