Trial runs broadband over power lines
Published: 15 Jul 2004 13:00 BST
AT&T and Pacific Gas and Electric on Wednesday announced a trial run of broadband sent over power lines, an emerging alternative to cable and DSL for delivering high-speed Internet access.
The company recruited about 100 residents as testers in Menlo Park, California, where the power grid is used to feed 13 megabits per second of Internet access to Wi-Fi repeaters on street lampposts. Homes then receive up to 3Mbps of wireless Net access. Participants were given Wi-Fi phones from Cisco Systems so that they can make phone calls over the broadband connection.
AT&T won't consider anything more than a trial of the technology until at least 2005, when chipmakers say they'll deliver the silicon upgrades needed for an even faster connection through the power grid. That will result in a much faster experience inside homes, said Irwin Gerszberg, AT&T director of local network technology.
"For a trial, three megs is no problem, but it's not going to hold when the networks get crowded conditions," he said.
The Internet signals are sent at high frequencies over the mains wires: as mains power is very low frequency the two can coexist on the same line without interference. Power lines are also an attractive broadband delivery system, because they are already in place and reach more homes than either cable systems or telephone lines.
Federal Communications Commission chairman Michael Powell attended a demonstration of the technology. He has said broadband over power line (BPL) technology makes it "theoretically possible to reach every power outlet in America with a broadband connection". The FCC is under pressure to substantially increase the number of US homes that have broadband, which now stands at about 29.2 million.
However, BPL has aroused controvery among existing radio users. The power lines act as aerials and transmit the data signals as radio, interfering with services already allocated the same frequency bands under international treaty. One trial by Alliant Energy in Cedar Rapids, Iowa, was abandoned last month after interference problems proved intractable. BPL also has significant limitations of speed and effective distance from substations: solving these problems may require more signal power and more radio frequency use, exacerbating the potential for interference.
AT&T and other local phone companies support the technology, because it doesn't rely on the local phone networks owned by regional Bell operating companies BellSouth, Verizon Communications, Qwest Communications International and SBC Communications.
Phone competition rules that set cheap rates elapsed last month, so the Bells are expected to charge more for access. Accordingly, alternative "last mile" connections into homes, such as BPL or wireless broadband, are getting more attention, AT&T executives said.
Current Communications Group and Cinergy Broadband, a subsidiary of a Midwestern utility with the same name, in March teamed up for one of the largest commercial rollouts of BPL. However, there are about two dozen ongoing trials of the technology throughout the United States, AT&T said.
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