The startups will duel with the HomePlug Powerline Alliance, which is using a rival technology from Intellon Corp. (Ocala, Fla.). Executives of both U.K. companies are skeptical that the group will succeed globally, despite backing from such powerful chip and systems companies as 3Com, Cisco, Intel and Motorola. That's because HomePlug's technology is geared to work in the North American regulatory environment, which the two companies describe as lax compared with the rest of the world.

Analog links over power cables have been in use for several years, but the shift to digital communications has been stymied by the noisy electrical environment, scant standards and persistently high costs. Now the pace of introductions is increasing as rival camps try to eke out a position in the technology.

Executives at nSine (Reading, England) claim the company's nPlug technology eventually could scale up to 40 Mbits/s. But Cyan (Cambridge, England) is aiming at command-and-control networks for domestic appliances because it believes home power wiring's trees and rings are too noisy for high-data-rate communications.

NSine said it has hit first silicon on a mixed-signal modem and a digital baseband that implement nPlug, developed over three years by a team now numbering 30 engineers. The two chips, fabricated in 0.35-micron technology at Taiwan Semiconductor Manufacturing Co., will sell for $5 in volume when mounted on a board with about 15 passive components, said Peter Norman, president and chief executive officer of nSine.

"Even at low volume, it will be just $7 or $8" for the board, which will be available late this year, Norman said.

Low-cost trigger

To keep costs low, a single capacitor rather than a typical isolation transformer provides power isolation. "Low cost drives ubiquity in consumer markets, and low cost is the trigger for technologies to move from niche markets to the mainstream consumer sector," said Norman.

NPlug uses a proprietary protocol with bit-wise arbitration and simple 16-bit cyclical redundancy checking for error correction, rather than a more complex, forward error-correcting scheme. For modulation, nPlug uses Gaussian frequency-shift keying on four carrier frequencies, between 10 and 30 MHz, as recommended by the European Telecommunications Standards Institute. Those carriers, in turn, are modulated onto the sinusoidal mains voltage at low injected-power levels.

The use of multiple frequencies, each capable of transporting 2.5 Mbits/s, is a form of redundancy intended to cope with the vagaries of power-line attenuation. "Although each channel carries 2.5 Mbits/s, the payload is about 1.5 Mbits/s, and we find that one of the four frequencies can always be detected," said Norman.

By using more carrier frequencies it should be possible to scale the nPlug technology to 40 Mbits/s, yet the modulation and proprietary protocol are simple and low in cost, he added.

To market its nPlug technology to consumer electronics companies in Japan, nSine has formed a joint venture with Softbank Networks Inc. (Tokyo) called nSine Powernet Japan.

"Softbank Networks is enthusiastic about establishing a de facto standard for home networking with Japan's powerful consumer electronics industry," said Yutaka Shinto, president and chief executive officer of Softbank Networks. "I expect the restrictions on availability of higher bandwidths in Japan will be deregulated as early as next year to make this smart technology spread."

In the United States, Intellon Corp. claims its PowerPacket technology, used by the HomePlug Powerline Alliance, enables speeds of up to 14 Mbits/s. It uses orthogonal frequency-division modulation with up to 84 carrier frequencies. The access method is CSMA/CA, and the technology is said to meet FCC Part 15 emission standards.

"It's overly complex, it's overly costly and it's not anywhere yet," nSine's Norman said of the PowerPacket-based HomePlug approach, arguing that the North American attempts at power-line communications are PC-centric and favor higher data rates and higher costs.

Norman said he thinks the Intellon offering will struggle to compete globally because it will not meet the stricter CISPR-22 electromagnetic-compatibility regulations adhered to outside the United States and Canada. "The FCC emission regulations are 100 times less rigorous than CISPR-22," he said. "And we are demonstrating systems now."

Changing environment

But what will be acceptable in different countries remains an open question, and the regulatory environment is still changing in Europe, argued Paul Brown, chief executive at White Box Solutions Ltd. (Kendal, England), a consultancy that specializes in power-line communications.

"There is a lot of work being done on the interpretation of CISPR-22," Brown said. "There is a move to soften Europe's stance. The electrical utilities want to put more frequencies over their wires. Correlating between the differential signal injected and the propensity to common-mode interference and radiated interference is not well-defined. Below 30 MHz there is little radiated interference; it's mainly conducted."

Chris Davies, chief technology officer of Cyan Technology, agreed with Norman about the significance of CISPR-22. And like nSine, Cyan is using TSMC to manufacture its silicon. But the similarities mainly end there.

While nSine is pursuing data communications, Cyan is pursuing only very low data rates. "If we can get 2.4 kbaud, that would be fine," said Davies.

Cyan, a spin-off from Cambridge Consultants Ltd., has a 16-bit microcontroller licensed from CCL that is its main technology and product. "Cyan is based on the technology that was XAP," said Davies. "It's a 16-bit microcontroller optimized for embedded applications and particularly for wired communications."

CCL developed the XAP core in the early 1990s. It was an extremely lean microcontroller that did its 16-bit work with just 8,000 gates or so.

Cyan has renamed the core eCOG-1 and extensively modified it. "We found we could get vastly improved performance if we surrounded the core with timers, buffers and autonomous engines for serial-protocol communications," said Davies. "We've also added structures to make programming easier.

"We expect eCOG silicon in June, and we have about four products that can benefit from a 16-bit microcontroller. One of those is a mains-borne communications product."

Cyan is not revealing technical details yet. But Davies did say, "I don't believe that your fridge needs to talk to your toaster and everything needs to able to handle Internet Protocol and support a browser. Most of these things are simply on or off — the light bulb being the best and simplest example — and people want to control them remotely. But the additional cost needs to be very small."

Real-world difficulties

Davies acknowledged that "companies have tried to put high data rates down the mains." But he argued that while the approach "may work in the laboratory, in the noisy real world it doesn't."

Cyan has already partnered with Amino Communications Ltd. (Cambridge) to develop a device that combines Amino's interprocess communications standard, called IntAct, alongside Cyan's eCOG architecture. The partnership is expected to result in the Cyan chip's being used for embedded communications in a range of products that Amino is developing with customers. Those products are expected to enter the consumer market in the fourth quarter.