Radio Standard Gets Small
The IEEE's 802.15.4 standard, which was ratified in September 2003, defines the physical (PHY) and media access control (MAC)layers of low-power radio standard that can operate in the public 2.4GHz band transfering data at a few hundred bits per second at a range of around 15 meters to 20 meters (see IEEE Approves 802.15.4). The ZigBee Alliance has taken the IEEE's radio work and developed a software stack and upper layers to create the ZigBee spec, which was ratified in December 2004 (see ZigBee Ready to Buzz?).
What 802.15.4 and ZigBee have over other similar technologies like 802.11 and Bluetooth is that 802.15.4 radios require a teeny, tiny amount of power to operate. This means that battery-powered devices can maintain wireless connectivity for months or maybe even years without requiring any maintenance (see ZigBee, the Wireless Dormouse).
Now 802.15.4/ZigBee has started to emerge as a radio standard for wireless mesh sensors. Such networks rely on hundreds or thousands of tiny battery-powered sensors to monitor things like pressure and heat levels in warehouses, factories, oil rigs, and many other industrial applications.
Startups like Dust Networks and Ember Corp. have unwired these sensors and developed mesh networking hardware and software that allows each to operate as a tiny wireless routers, passing data around the network.
Dust, which has so far scored VC funding to the tune of $30 million, has just announced its first 802.15.4 product. Interestingly, the firm doesn't like to call it a ZigBee product, because it feels that ZigBee is focused on consumer devices. Although Rob Conant, VP of marketing at the firm, says that the Dust product will interoperate with ZigBee radios.
Meanwhile, Ember, which so far has $52 million in funding under its belt, gladly embraces the ZigBee label and claims that 120 customers are already using its products to build wireless sensors for a variety of purposes.
— Dan Jones, Site Editor, Unstrung