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Wireless nets get SoC
By R. Colin Johnson
Courtesy of EE Times
(11/14/2006 3:59 AM EST)
PORTLAND Ore. — Dust Networks Inc. (Hayward, Calif.) unveiled the world's first system-on-chip (SoC) for wireless sensor networks at Electronica. By integrating all the hardware and software functions for creating distributed sensor networks onto a single chip—called its mote-on-chip—Dust Networks claims five-fold lower power consumption than Zigbee, the elimination of the need for wired routers, and a 10-fold reduction in the overall price of adding new sensors to an existing network.
"Our ASIC uses 80 percent less power than using an 802.15.4 radio [the standard used by Zigbee]," said Rob Conant, an electrical engineer and co-founder of Dust Networks. "We have designed our SoC to be easier for device designers to use, because we take responsibility for the performance of the network, so that the EEs designing products don't have to rewrite all the software for the networking and communications functions of a wireless sensor network."
Wireless sensor networks enable industrial users with distributed process control problems to quickly deploy new sensors without having to run cables to them, reducing their overall cost from thousands to hundreds of dollars. Their initial users are using that 10-fold cost reduction to deploy more sensors than they could afford to before. For instance, Emerson Process Management has launched a family of low-power wireless sensor networking systems that use of Dust Networks' Time Synchronized Mesh Protocol (TSMP) including temperature sensors, pressure sensors, fluid level sensors, and fluid flow sensors. British Petroleum (BP), Emerson's beta-tester, now says that going wireless has reduced the cost of adding new sensors by 10-fold, enabling them to deploy many more sensors than they could afford to have in the past.
How's it Work?
The other co-founder of Dust Networks, Chris Pister—a professor at the University of California-Berkeley and chief technology officer at Dust Networks, coined the phrase "smart dust" back in the mid-1990s. Since then, he has perfected the TSMP networking protocols—a mesh architecture that eliminates dedicated routers in favor of a daisy-chain style of communicating packets from wireless node to wireless node until they reach the central control computer. Consequently the two primary advantages of mesh networks are redundancy, since data can travel of multiple alternative paths, and extremely long range. Up until the SoC announcement, Dust Networks has been selling small circuit boards that use an off-the-shelf 802.15.4 radio from another company, but now the company has integrated all the mesh protocols onto two versions of a SoC—one for 900MHz or 2.4 GHz—that allows original equipment manufacturers (OEMs) to embed TSMP onto a board with their own sensors.
"Our SoC reduced power consumption 80 percent by taking a system-level approach to the radio design. Every one of our chips comes network ready with the TSMP protocol embedded—there is no user software to be written. All the user does is pass the chip packets—allowing us to optimize our chip for sensors that have to stay in the field unattended for five or more years." More than a dozen companies representing more than 90 percent of the market for wireless sensor networks, according to Dust Networks, have now demonstrated interoperable wireless devices all based on TSMP, including Emerson, Honeywell, ABB, Siemens and Yokogowa.
