SAN JOSE, Calif. -- IPTV 2007 -- While coaxial cable would be the best medium for a home network, AT&T Inc. is happy with using the Home Phoneline Networking Alliance (HomePNA) specification as part of its U-verse IPTV service, AT&T Research Labs executive Vernon Reed said at the IPTV 2007 conference yesterday.

Reed, sans guitar, gave a presentation explaining the carrier's priorities for home networking, and how those led to the choice of HomePNA, announced in August. (See AT&T: Hold the MoCA.)

The choice was interesting given that Verizon Communications Inc. had placed an early bet on Multimedia over Coax Alliance (MOCA), a standard for networking over coax. (See Entropic, Verizon Serve Up MOCA.)

Coax is the best option for home networks, Reed said. It's shielded and unregulated, meaning just about any radio frequency (RF) signal can be sent on the cables without causing or receiving interference.

But AT&T wanted to apply one technology to all homes. "If you go into multidwelling facilities or apartment buildings, you don't always have access to coax," he said.

So AT&T sought a technology that would work on twisted-pair copper, and that ruled out MOCA. Reed said MOCA uses so much RF spectrum that it can't be run on twisted-pair -- at least, not without upsetting the Federal Communications Commission (FCC).

That made HomePNA a likely choice, but the kicker was the suite of diagnostic tools HomePNA was able to offer. AT&T can pinpoint the exact locations of interference or signal loss within a home, Reed said.

And while Reed didn't mention it, HomePNA 3.1 also happens to have the approval of the International Telecommunication Union (ITU), as the standards body announced yesterday. (See ITU Approves Home Standard.)

It all comes down to the idea of IPTV as a managed service, or an "assured" service, as Reed put it. Because IPTV targets a mainstream crowd, as opposed to early adopters who want to build home networks, AT&T and other carriers are starting to treat home networks as parts of their own networks. (See RBOCs Want Inside Your House.)

"We have to be very careful about selecting technologies that map themselves well into this assured services network," Reed said.

That's why Reed gives the thumbs-down to 802.11n wireless LANs as an option for U-verse. Wireless networks are subject to interference from uncontrollable sources, such as a neighbor's wireless network, Reed said. That unpredictability could translate into more service calls and more trips for technicians out to customers' homes -- the kinds of things any carrier is hoping to avoid.

"The feeling in the labs is, any wireless technology for moving video would have to be treated as an adjunct to the primary service. Dedicated wires are, for an 'assured service,' the mechanism of choice for the home network."

Still, AT&T evaluates every HomePNA competitor it's aware of, even the wireless ones, and Reed said he's also open to the idea of wannabe universal standards from the Digital Living Network Alliance, the Home Gateway Initiative (HGI), and the ITU's G.HN effort. But any home-networking standard AT&T accepts would have to match the diagnostic capabilities of HomePNA, he said.

— Craig Matsumoto, West Coast Editor, Light Reading