Portland, Ore. -- What with the Bluetooth headset crowd wandering the streets talking to the air, you might have thought the final tether to land lines had already been cut. You would be wrong. At least two vital functions have yet to be loosed: network routers, which must always be on and thus cannot be battery-powered, and the chargers for all those batteries powering the world's wireless network nodes, cell phones and laptops.
Now developers and researchers are getting out the wire cutters. With half a dozen companies already touting battery-powered mesh networks as replacements for dedicated, wired routers in industrial and field environments, observers predict the technology will work its way into the mainstream. And researchers at the Massachusetts Institute of Technology are perfecting a technology that they say could recharge batteries wirelessly--and perhaps eliminate batteries altogether--by harnessing omnidirectional wireless power beacons (see story, page 40).
"Right now, battery-powered mesh technologies are eliminating the need for wired routers in niche areas that have very stringent requirements or that have extreme operational difficulties, [such as] remote areas, extreme environments, military applications and the like," said Peter Middleton, a principal research analyst at Gartner Dataquest. "But even mainstream applications could take advantage of wireless battery recharging.
"One example I like is the wireless electronic picture frame, where the images are communicated to it wirelessly. Now, if you could wirelessly power it, too, that would be a very attractive technology."
Wireless technologies already pervade the telephone market, as consumers prove ever more willing to abandon the land line. Likewise, office networks, factory floors and field locations worldwide are increasingly going wireless. The wireless market for manufacturing alone is growing at about 26 percent per year and is predicted to balloon from $326 million in 2005 to more than $1 billion by 2010, according to a study by the ARC Advisory Group.
The companies duking it out to slake the thirst for wireless sensor networks in manufacturing include Arch Rock, Coronis Systems, Dust Networks, Ember, Millennial Net, Sensicast Systems and Texas Instruments' Chipcon unit. All offer solutions that eliminate the need for dedicated routers by using daisychained mesh topologies to pass packets among wireless nodes.
"The other radio technologies, like Bluetooth and ZigBee, don't allow you to build whole networks that can run off batteries for years," said Harry Forbes, a senior analyst at the ARC Advisory Group. "ZigBee uses a hierarchy of devices where its routers have to be powered all the time, but any battery-powered node in a mesh network can act as a router."
Manufacturing is pioneering wireless sensor networks because adding a new wired sensor in the factory or the field can cost thousands of dollars, compared with hundreds for the wireless alternative, Forbes said. For the wired solution, the installation cost of the wiring alone is five to 10 times the cost of the sensor. "With wireless sensor nets, you are spending less money for more information," said Forbes.
The wireless market for manufacturing is growing at about 26 percent per year.
Dust Networks Inc. underscored the point at the Electronica show in Munich, Germany, last week when it rolled out a system-on-chip (SoC) that lets OEMs build instant networks that Dust said would cost 10 times less to install and use five times less power than ZigBee solutions. Such nets could run for years on a single battery, the company said.
"A lot of the movement by Dust Networks' competitors is up the value chain--integrating more and more devices," said Forbes. "But Dust's SoC is a move down the value chain, which is almost unique in this market."
Dust Networks customer Emerson Process Management says its wireless sensor nets, built with Dust mesh technology, could end up saving customers billions over the networks' lifetime. "Mesh networking is one of the most exciting innovations to come along in the process industry in over 30 years," said Steve Sonnenberg, president of Emerson's Rosemount division.
Emerson beta site British Petroleum has begun widespread deployment of wireless sensor networks built with Dust mesh protocols. The deployments are not only retrofits of existing, wired nets but also new installations that put sensors in spots where it had not been economical to do so in the past, said Rob Conant, Dust's co-founder and vice president of marketing and business development.
"In one BP wireless network, within 30 minutes of deployment the temperature data they collected revealed the source of a maintenance problem that had been dogging them to the tune of $100,000 per year," Conant said. "Now BP says wireless sensor technology could have a multibillion-dollar impact on their bottom line."
Numbers like that explain why mesh networks are so attractive, but they have a dirty downside: The thousands of batteries needed to power them will one day have to be disposed of. As wireless nodes spread, so will the trash problem, observed Jim Tully, vice president and distinguished analyst at Gartner Dataquest.
If MIT's wireless power beacons turn out to work as well as claimed, however, disposable batteries could be replaced by longer-lived rechargeable ones, or high-efficiency capacitors could even eliminate the need for batteries of any kind. MIT's solution, nonradiative resonant-energy transfer, is claimed to harness omnidirectional energy beacons without wasting energy and without requiring a clear line of sight. Power from such energy beacons would pass harmlessly through everything but the intended targets, by virtue of resonant-power antennas that would be tuned to the power beacon's frequency in a lock-and-key approach.
"The idea of scavenging power from the environment is a more sustainable approach than powering thousands of devices with batteries that will eventually have to be discarded," said Tully. "Also, these mesh-networking applications are eventually going to find their way into our bodies, and there the ability to wirelessly power devices would be a very attractive idea, since you definitely don't want to have to replace any batteries inside your body."
"It is still convenient to have a battery as backup for some applications, but it's not necessary," said MIT professor Marin Soljacic, inventor of the technique. "Even today, there are experimental buses in China that have a huge capacitor that charges at every station, with just enough charge to take them to the next station."
Simulations of the nonradiative energy transfer technique at MIT have shown the approach holds promise for successful transfer within a range of 12 feet. That would make wireless power beacons viable for various consumer applications. "There are many items in the home that could take advantage of wireless power delivery," said Tully. "For example, if you could power all your remote controls wirelessly, then you would never have to change the batteries in them."
"People would like to operate their home stereo speakers and other electronic devices without wires, but that still leaves the power lines wired," said Stanley Bruederle, research vice president at Gartner Dataquest. "If that power could be delivered wirelessly too, then that could be the start of a very successful technology."
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