Distributed Computing: Motes

In the first of a series of blogs about my top 6 areas of technology for 2005, I'll explain what motes are, and who some of the players are.

What is a mote? A mote is a battery-powered wireless sensor device, which can connect to neighbouring motes in an ad-hoc mesh network. Sensors can monitor parameters such as temperature, pressure, moisture, light, sound, or magnetism. Data from the sensors is transferred across the mesh in a peer to peer manner potentially to a centralised server. In this way, large networks of sensors can be built without the need for extensive cabling infrastructure. As each mote is within a short distance of a neighbour, low-power short range wireless can be used, allowing the devices to work from battery power. Radios are typically only turned on for short periods of time to enable the transmission or relay of information from one mote to another.

I believe they were originally envisioned as a battlefield technology in the US. The concept used here is to be able to distribute thousands of tiny smart dust sensors across a battlefield, or along a national border. The sensors would then be able to detect the passing of a person or tank, and relay this info through the wireless network back to commanders on the other side of the battlefield.

Government IT contractor Science Applications International Corporation (SAIC) is developing this technology for the US Defence and Homeland Security departments. It is adopting sensor networks to create electronic perimeter systems for defence and intelligence customers. Thomas J. Sereno Jr., manager for the SAIC monitoring systems division, said tests found the technology can use small magnetometers to detect whether someone is carrying a gun. SAIC plans to use microphones to search for "acoustic signatures" of vehicles, moving groups of people and such. Sereno said it also will build in cameras of the sort used in mobile phones.

While much research is now ongoing in the field of MEMS based dust-scale sensors, real motes available today are somewhat larger in size, perhaps using a pair of AA batteries, costing around $100. Researchers and analysts claim the devices can sometimes operate for up to three years on a pair of double-A batteries. Developments in miniaturisation and integration over the next few years are expected to lower this to $10, making them more suitable for wider deployment.

BP is using the technology to cut the cost of monitoring at a Washington state oil refinery. HP is experimenting with using motes, combined with imaging and RFID sensors to manage the flow of goods through a warehouse in Memphis. Others are working on the use of the sensors for building automation - for monitoring and controlling heat and light settings.

Bechtel Group may soon start testing sensor nets that use a new standard IEE 802.15.4, that lets motes self-assemble into a network without having to pre-define the route data takes to get through the network. Bechtel has used wireless sensors in projects such as the London Underground, and expects the technology to have use in smart buildings, defence contracts, and chemical plants.

You could also envisage deploying motes along the side of motorways, or even within the tarmac, to allow communications about traffic density or accidents along the road. A receiver built into each car could receive this information, perhaps relaying information to the driver about a problem ahead.

One of the earliest startups in the area is called Dust Networks, which is based on research originally carried out at the University of California at Berkeley, funded by Darpa.

Another is Ember, a startup based on work at MIT, with backing from Bob Metcalfe (3Com founder). Ember are working with Zigbee wireless network technology for the local links. Ember have an office in Cambridge.

Crossbow Networks is currently selling a small mote device based on a couple of AA batteries.

Motes are here now, with perhaps 200,000 in use today. By 2008 there could be up to 100 million wireless sensors in use. The worldwide market for wireless sensors will grow from $100m this year, to more than 10 times that by 2009 (Harbor Research).

Sources: [Much of this article is from my knowledge of the space, however I've used a recent offline Computing article, and some other resources on the net for some of the facts] [Washington Post]

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