Paris — A new, media-independent control-networking technology that has trained its sights on an eventual role in the low-cost wireless-sensor network market could pose a challenge to ZigBee, the open wireless standard based on IEEE 802.15.4 radio.

LonWorks control-networking platform creator Echelon Corp. today will unveil a "light" platform called Pyxos. With the first IC measuring 5 x 5 mm, "Pyxos networks are intended to be integrated inside a sensor or actuator," said Michael Tennefoss, vice president of marketing.

Echelon sees Pyxos' endgame as building pervasive sensor networks, Tennefoss said. "Many sensors are integrated in machines today, and yet the sensed data is usually trapped inside the machine. Our job is to take that information out of the device, process it locally and send it somewhere so that people can take action on it."

The company's LonWorks technology can work over power lines, twisted-pair wire and coaxial cable. The Pyxos platform initially will be implemented over twisted-pair, but Echelon confirmed that the company is quietly working to take it wireless. "Pyxos networks are media-independent," said Tennefoss, whereas "Zigbee only supports RF."

But with Echelon having yet to release a timetable or tech details for Pyxos' RF implementation, it's difficult to assess how great a threat it might pose to ZigBee or other embedded control-network solutions.

Market watcher Harbor Research Inc. estimates that 30 million devices will be connected this year in the industrial, building and power-utility markets. Of that 30 million, about 15 percent, or 4.5 million, will be wireless.

Echelon spent the past 12 to 18 months assessing "the available wireless solutions for the embedded control market" and determined that neither ZigBee nor Z-Wave "plays reliable radio," said Tennefoss. The issue with ZigBee, he said, is that "it's not suited for use in metal devices or in environments like factory floors, with lots of metal equipment and building material."

Harry Forbes, senior analyst at manufacturing and supply chain consultancy ARC Advisory Group Inc., agreed. "We have found that ZigBee 1.0 has some issues when applied to factory and plant environments," said Forbes, who recently completed an ARC report on ZigBee.

In his report, he wrote, "Most significant [of ZigBee's weaknesses] is the choice of a single RF channel for each ZigBee network and the restriction of channel selection to the ZigBee coordinator. Industrial wireless applications prefer to use a radio technology that will continue to perform in extremely noisy RF environments and with changing multipath interference patterns." Most industrial wireless applications, he added, use "frequency-hopping spread-spectrum radio technology for this reason."

While Forbes wrote that he believes "the ZigBee Alliance will be working on changes to improve this performance," he adds that it remains an issue for now.

Still, some sources expressed skepticism last week about Echelon's plan to go wireless with Pyxos.

The ZigBee Alliance, in particular, is wary of yet another proprietary technology for embedded controls. "ZigBee is unlike any control and sensing technology ever created. Never before has an open standards body like the IEEE created a simple, exceedingly robust while simultaneously very cost-effective, lightweight wireless-data protocol," said Jon Adams, director for wireless technology and strategy at Freescale Semiconductor Inc., a member of the alliance that developed the open specification to take advantage of the wireless protocol.

Jim Lindop, CEO of Jennic, a supplier of wireless microcontrollers based on the IEEE 802.15.4 standard, took a similar stance, saying that Pyxos' proprietary status and Echelon's lack of experience in developing a wireless protocol pose questions. Noting that the Jennic technology is agnostic in the higher layers and that it does not directly compete with either the Echelon or the ZigBee stack, Lindop urged Echelon to build the Pyxos protocol on top of the 802.15.4 standard in a manner similar to ZigBee.

Reliability issue
It's doubtful that Echelon will take that advice any time soon. A solution based on the IEEE 802.15.4 radio cannot achieve the 99.7 percent reliability Echelon customers demand, Tennefoss said.

But "while it is possible to build a wireless communications system with the reliability of NASA's Deep Space Network," countered Freescale's Adams, doing so is "impractical and cost-prohibitive for 99.999 percent of applications."

"While Zigbee developers and implementations are minuscule in number compared with those for Ethernet TCP/IP, there are multiple providers for chips, stacks and related products," commented Harbor Research director Mark Knebusch. "If there's a reliability problem, there's a good chance the developer and user community will solve it."

Echelon's goal in launching Pyxos is to address the embedded control-network market more effectively than it could with LonWorks, introduced in the late 1980s. The NeuronChip used in LonWorks is too expensive and too big to accommodate the tiny sensors and actuators essential to embedded controls. While LonWorks is built to connect everyday devices to one another and to the Internet, Pyxos is designed to go deeper into the devices themselves, according to Echelon.