Perfecting Wireless Sensor Networks

By Eric Griffith

September 22, 2005

Wireless without the people: low power, low data-rate mesh networks residing in all electronics are the future for tracking -- and controlling -- just about everything.

It's a long way from the days of X10 for simple home controls such as using a remote to shut off your lights. Wireless Sensor Networks (WSN) are the future for not only monitoring systems as complicated as a computer and as simple as light bulbs, but also controlling those items as well.

This isn't radio frequency ID (RFID), says Mark Pacelle, vice president of marketing at Millennial Net, a company that designs WSN software and systems for use by OEMs and system integrators.

"We view RFID as a little different," Pacelle says. "It's more of a point-to-point passive link... typically, a device has to pass within close proximity of a reader" for RFID to work. At worst, he says, RFID is complementary to WSNs.

With WSNs, the connections are ongoing and constant, via a mesh networking topology. If one node/item goes dark, the path for data moves around it. Pacelle says all the data eventually gets passed back to a central gateway.

The data is also different. It's temperature, humidity, vibration, or moisture, to name a few things.

If all this sounds like Zigbee, or Zensys' Z-Wave, well, that's what they do as well. The difference is that Z-Wave concentrates on the home control market (witness their recent partner win with Logitech making a Z-Wave-capable Harmony remote control). Other WSN vendors plan to focus on the industrial sector. ZigBee, as Pacelle puts it, "isn't there yet." He claims his company is about five years ahead of where ZigBee will be when products using the protocol running on top of the 802.15.4 standard are readily available. Millennial Net's own proprietary network protocol, part of its MeshScape 4.0 system, runs on top of 802.15.4 chipsets, the same as ZigBee.

Is simple monitoring enough in such industrial setups? Not according to Tendril, a company which took the wraps off its WSN control platform at this week's DEMOfall show. Tim Enwall, CEO of Tendril, compares what his company does for WSN to what a company like Roving Planet does for large-scale 802.11 networks: "We sit on the networks and provide services to regular programmers," he says.

To this point, he says programmers wanting to communicate with nodes on a WSN had to program right down to the micro-controller level, and not across all devices. By providing a platform for programmers, he says, Tendril can give companies control over their WSN nodes, not just basic monitoring. He uses the term "service broker" to describe what Tendril provides.

"If you only have inbound data, that's less than half the solution. When you can interact: wow," says Enwall.

Again, he stresses that his company is not a ZigBee or Z-Wave company. In fact, he believes that IPv6 over low power wireless Personal Area Networks (AKA IPv6-loWPAN) will give ZigBee and Z-Wave a run for their money as an 802.15.4 protocol.

Whether just monitoring or fully controlling, WSNs seem to be on the rise. Tendril likes to point to a statement by Harbor Research that says by 2010 there will be trillions of users on the Internet, most of which will not be human beings. Millennial Net did a survey of 1,500 companies that indicated an interest in WSN, and 85 percent of them had a WSN or planned to put one in. The survey was meant to measure just how many customers would look to engage "professional services" with outside expertise to install their WSN -- 73 percent of respondents interested in WSN said they would.

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