Powerline adapters: Home networking without rewiring

Three major powerline networking technologies offer high-speed connections simply by plugging small devices into electrical outlets

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Deming said that a HomePlug AV system might, in an ideal environment, achieve 86Mbit/sec. to 90Mbit/sec., but that extensive testing showed that 35Mbit/sec. is a realistic expectation. However, he noted that 35Mbit/sec. is sufficient for high-definition video, which usually takes 20Mbit/sec. Aluminum house wiring (used three decades ago), halogen lights, long wiring runs and electric motors can also degrade a signal, he noted.

"The biggest problem is consumer education," added Lesley Kirchman, marketing director at ActionTec Electronics Inc. in Sunnyvale, Calif. "Many people don't understand how easy it is. Words like 'easy' and 'simple' are overused, and people tend to be jaded. And I think that a lot of people are afraid of networking."

UPA standard

UPA backers tout the fact that UPA got to the market first with 200Mbit/sec., as the first UPA adapters for home use began shipping in January 2005, and volume production began in April 2005, explained Brian Donnelly, president of the UPA Marketing Working Groupand vice president at Corinex Communications Corp. in Vancouver, British Columbia.

"There have been about a dozen firmware upgrades since then, and it's become pretty bulletproof," he said. The chief difference cited between UPA and the other two technologies is a feature that allows an adapter to be placed in a long wire run to boost the signal between one end and the other. Thirty-three adapters can be used in a home network, but some configurations are open-ended, he added. For encryption they use 168-bit DES. Throughput can reach 95Mbit/sec., he said.

Initially, most sales were in Europe, but retail acceptance ballooned last year in North American, with sales rising 800%, he said. He expects that 3.5 million devices will have shipped by year's end.

There are about 15 vendors shipping UPA products, one of which is Netgear Inc. in Santa Clara, Calif. "We chose UPA because of the quality and because UPA was there first. We were on the market a good six to eight months before HomePlug came out," said Jamie Ching, Netgear's powerline product manager. But Netgear also sells HomePlug units, he noted.

A powerline adapter from Netgear Inc. that uses the UPA standard.
A powerline adapter from Netgear Inc. that uses the UPA standard.

"Ninety percent of the time, you can just plug and play," Ching said. "The other 10% of the time, the house may have older wiring, or it may have added wiring that doesn't have good connectivity with the older wiring. But the technology is robust enough for most situations." Most appliances do not interfere, he added.

Panasonic HD-PLC

The third technology is Panasonic Corporation of North America's HD-PLC, based on proprietary technology including Panasonic chips, explained Mike Timar, product manager at Panasonic USA in Secaucus, N.J.

The theoretical speed of the units is 190Mbit/sec., and Timar said that users could expect a throughput of 40Mbit/sec. to 45Mbit/sec. for file transfers and up to 80Mbit/sec. for streaming, where lost bits are immaterial. He noted that, by comparison, DVDs output at 6Mbit/sec., and an uncompressed Blu Ray disc uses 33Mbit/sec.

One unit in an HD-PLC network is designated the master by setting a switch. The units use 128-bit AES encryption, and they can be set to use a new random key, without software, by pressing buttons on the master unit, he added. Sixteen adapters can take part in one network.

"We are looking to the time when you can plug your plasma TV into a power outlet, and no other connections are needed," Timar said. "In the meantime, we have come out with these adapters, and they are selling pretty well. But I think that the customers don't appreciate the benefits of higher speeds and security and robustness, since they have nothing to compare it with."

Panasonic has also promoted the concept of interoperability between the different powerline adapter technologies through its involvement in a consortium called the Consumer Electronics Powerline Communication Alliance (CEPCA). Panasonic has recently agreed to partner with the HomePlug Alliance and submit a joint specification to the IEEE P1901 Working Group, which is working to define an industrywide data-over-powerline technology. Future products using the proposed standard would be interoperable with existing HomePlug AV and Panasonic HD-PLC units, Panasonic and HomePlug jointly announced.

Donnelly said that the UPA has been collaborating with CEPCA on proposed interoperability specifications for the P1901 Working Group. No vote on a new specification is expected until next year, he indicated, and he questioned whether anyone today can predict future compatibility with a standard that remains to be finalized.

"There are multiple proposals, and there are likely to be mergers among the proposals -- this is just Stage 1," Donnelly said. But he foresaw continued involvement by the UPA, leaving open the possibility of three-way interoperability with a future specification.

Real-world testing

Interested in how well powerline networking devices work? See "Review: Using powerline adapters for home networking".

Lamont Wood is a freelance writer in San Antonio.

Copyright © 2007 IDG Communications, Inc.

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