From Smart Dust to Reliable Wireless Sensor Networks

At this ISA Expo 2008 this past October in Houston, Texas, I had the chance to catch Dr. Kris Pister‘s keynote presentation, From Smart Dust to Smart Plants: The Evolution of Wireless Sensor Networking. Kris is the Founder and chief technology officer for Dust Networks, which began operations in 2002.

Beginning in the early 1990s, Kris saw the impact of Moore’s Law on sensing, computation and communications technologies–ever falling costs and increasing power. He believed wireless sensor technology’s size, power, and cost would also follow these trends and committed his energies to this pursuit.

His research led to the vision for “smart dust” in the late 1990s. The components included passive communications, sensing, thick-film battery, solar cell recharging, power capacitance, analog I/O with digital signal processing (DSP) and laser diode communications–mostly built with Microelectromechanical systems (MEMS) technologies. In his research at University of California at Berkeley, he and his research team had a working prototype by the end of the 1990s.

The team’s work over the next several years was in the areas of ultra-low power and radio frequency (RF) communications. I had a great quote from his keynote in my notes, “RF is challenging. It’s robust today because the team saw so many failures a decade ago.”

The basis for the smart dust vision was cheap, easy, off the shelf RF systems. It had a wide cross-section of possible uses in academic, military, and industrial applications. Kris shared an example of an earthquake engineering research center where wired, seismic testing cost $5000 per node for real-time data acquisition. The cost per node with wireless seismic sensors was $200 per node. They had similar successes with temperature sensors in an HVAC application on the UC Berkeley campus, deploying 50 wireless sensors in 3 hours and reducing the cost per node from $800 (wired) to $100 (wireless).

For industrial applications, the team looked at research into the primary barriers for adoption of wireless sensor technology. The top four in order of concern were reliability, being standards-based, ease-of-use, and power consumption.

Recognizing the need for industry standards for broad adoption of new technologies, they are participating in several:

Dust Networks currently has leadership positions in several industry groups, including: the Wireless HART working Group (HART Foundation), the Internet Engineering Task Force (IETF), ISA’s SP100.11 working group (ISA SP100) and the Wireless Industrial Networking Alliance (WINA).

Specific to the WirelessHART standard:

Dust Networks joined the HART Communications Foundation (HCF) in October 2005. Since then, Dust contributed its Time Synchronized Mesh Networking (TSMP) protocols and technology and collaborated with the HART Foundation and its member companies to develop the industrial automation market’s first wireless standard for sensors.

In an earlier post, I discussed some of the diversity techniques used in the WirelessHART standard to achieve greater than 99.9% reliability to address this top concern among process manufacturers in the adoption of wireless sensors.

Kris also discussed their work on minimizing power consumption. Again turning back to my notes I captured this thought from the keynote, “Power- turning radios off is easy. Turning it on is hard… that’s why time synchronized is so important. If all nodes in a mesh are within 0.1 msec, than A will wake up and listen for that length of time. A sends ACK to B. Keeps networks synchronized to 100 microseconds or so.”

Nice, elegant design… let every device in a self-organizing network get their sleep to conserve power and make sure they wake together in a window of time to communicate and re-synchronize before their next nap.

A steady stream of news shows that Kris and the team’s work on the vision of smart dust has paved the way for rapid adoption of self-organizing wireless networks across many industries and world areas.

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