Gaps seen in ratified powerline standard

The IEEE 1901 committee has officially ratified its standard for broadband over powerline. The process has been difficult, lasting over four years. Those responsible for the standard say the move is another step toward broader use of powerline networks, but the area still embraces at least three incompatible approaches.

The difficulties the 1901 group faced also point to some of the dark sides of the formal standards process.

The final 1901 standard, to be published in February 2011, addresses multiple aspects of broadband over powerline. It consists of more than 1,500 pages approved by 81 percent of the committee which had representatives from 94 organizations, said Jean-Philippe Faure, chairman of IEEE 1901.

The most controversial aspect of the standard was its definition of a PHY and MAC for home networks. The group ultimately blessed two incompatible approaches—the technology of the HomePlug Powerline Alliance and that of the Panasonic-led HD-PLC group.

The 1901 spec also defines a co-existence mechanism so the two incompatible approaches at least do not interfere with each other if they are used in the same home. The separate ITU G.hn group has adopted the mechanism as optional for its specification which defines a separate technology for running data over powerlines, coax or phone lines.

Both the 1901 approaches and G.hn are expected to deliver physical layer data rates up to 500Mbit/s and actual throughput of about 200-230Mbit/s. Chips for HomePlug and HD-PLC nets have been available for some time, but the first G.hn chips are just beginning to emerge.

The 1901 group fought for two years over the home networking approach. Spain-based powerline vendor Diseno de Sistemas en Silicio SA (DS2), led opposition to the effort because it failed to define a single technology and effectively shut out its approach which was used by some European IPTV vendors.

But DS2 fell on hard times, losing major customers. The company went bankrupt earlier this year and its assets were purchased by Marvell. The move raised speculation rival Broadcom might buy a powerline startup.

With the final ratification of the IEEE spec, the HomePlug group has added 1901 compliance to its certification program which has approved 215 HomePlug AV products to date. The HD-PLC group is expected to make a similar move

"Finalization of this global standard is a major milestone for powerline networking and will help unify and stabilize the industry as did previous IEEE standards for networking," said the HomePlug group in a press statement.