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New frontier for wireless: Sensor networks

By , Network World
June 07, 2004 11:47 AM ET

Network World - Wireless sensors finally are moving from starry-eyed predictions to hard-eyed but limited production.

As a result, network executives eventually can expect to see whole new classes of objects on their networks: pipe heaters, air conditioners, electric pumps and even grapes.

Wired sensor networks have been around for decades, with an array of gauges measuring temperature, fluid levels, humidity and other attributes on pipelines, pumps, generators and manufacturing lines. Many of these run as separate wired networks, sometimes linked to a computer but often to a control panel that flashes lights or sounds an alarm when a temperature rises too high or a machine vibrates too much. Also wired in are actuators, which let the control panel slow down a pump or turn on a heater or a fan in response to the sensor data.

Now advances in silicon radio chips, coupled with cleverly crafted routing algorithms and network software are promising to eliminate those wires, and their installation and maintenance costs (see graphic). Mesh network topologies will let these wireless networks route around nodes that fail or whose radio signal is hammered by interference from heavy equipment. A gateway will create a two-way link with legacy control systems, hosts, wired LANs or the Internet.

This combination of sensors and low-power wireless networking "give inanimate things an identity," says Ian McPherson, president of Wireless Data Research. "You can ascribe things like attributes, location and a history to an object." Wireless sensors will slash the costs of collecting this data, analyzing it and acting on it, he says.

These networks can use several different wireless technologies, including IEEE 802.11 wireless LANs, Bluetooth and radio frequency identification (RFID). But right now most of the action is with low-power radios that have a range of about 30 to 200 feet and data rates of up to around 300K bit/sec. Most of these, with their accompanying network software and APIs, are proprietary products.

But the IEEE last year approved the 802.15.4 low-rate standard for a simple, short-range wireless network whose radio components could run several years on a single battery. The ZigBee Association, a group of vendors, anticipates finalizing by year-end an industry specification for the network software that will run on the 802.15.4 radio chips.

"Over the next 12 months, the wireless trials will move to limited deployments, and they'll be in areas like environmental condition monitoring and meter reading," McPherson says.

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