Computing Science

Research Profile: Wireless Sensors

Today we have much more data than ever before. Five, ten years ago, even if you had that amount of data, you would not have enough space to store it and not enough CPU power to process it. Now we can store it, process it, and communicate wirelessly much faster.

- Dr. Mario Nascimento, Associate Professor of Computing Science, University of Alberta


You’re driving your usual route to work one morning when your cell phone starts beeping. You glance at its screen and see this message:

“Accident on Fox Drive. Take Groat Road.”

Right now this scenario doesn’t exist in reality—you have to listen to the radio to find out where the accidents are during rush hour. But messages like this one could be popping up on your cell phone in the not-too-far-off future, says Dr. Mario Nascimento, a professor of computing science at the University of Alberta (U of A).

“Your cell phone can be tracked all the time,” says Nascimento. “So in theory, your cell phone provider can know where you are all the time.”

If your cell phone provider were to analyze its data about where and when you use your cell phone, it could get a pretty good idea of what your travel habits are, such as when you drive to work and what route you take. And, if a car accident were to block your route, your provider could notify you to stay clear of the accident.

Data about where and when things occur is called spatio-temporal data, and it’s one of the topics in Nascimento’s research area, database systems.

“Spatio-temporal data has always existed, but it’s much more common nowadays,” he says. And databases and other supporting technology are still catching up—currently, there are no commercially available databases designed to work with spatio-temporal data.

Nascimento and other researchers are working on ways to convert spatio-temporal data into formats that can be handled by existing databases such as Oracle.

Enter the wireless sensor


In addition to the cell phone, another plentiful producer of spatio-temporal data is the wireless sensor. In the next decade or two, it’s likely that many of the places where we live, work, and play will be enmeshed by networks of wireless sensors.

Like spatio-temporal data, sensors are nothing new. “A traditional sensor is a bulky piece of equipment connected through wires to a computer or some monitoring site,” says Alex Coman, who recently completed his PhD under the supervision of Nascimento.

“They just collected information, and that’s it. But because of technology advances, we can put more things on a small piece of hardware, so now there is a new breed of sensor that is wireless and has a processor and memory.”

This means that networks of wireless sensors can “think” for themselves rather than send their data to a central processor. And because they’re wireless, they’re easy to install—some researchers envision dropping batches of sensors from planes, for example.

Wireless sensor networks are just beginning to enter the real world, but researchers have already dreamt up all kinds of applications for them.

One possible use: wartime reconnaissance. Sensors could be dropped from a plane into a battlefield. “A satellite can look at the ground and see some things,” says Coman, “but it cannot see something under a tree or measure the humidity.”

Researchers at the University of California, Berkeley, have already used wireless sensors to study how California redwood trees affect their environment.

“Because redwoods are very tall (often over 100 metres), you can’t measure too many things from the ground. And it’s very costly to install wires,” says Coman. But by installing wireless sensors at different heights in a single tree, the researchers were able to efficiently gather data about the micro-environment created by the redwood.

“That’s a very good advantage that researchers so far did not have access to,” says Coman.

While the possible applications for wireless sensor networks are plenty, there are also plenty of practical problems that need to be solved so that wireless sensor networks can function smoothly.

One of these problems is energy efficiency. Wireless sensors need their own selfcontained energy source: batteries. And since no battery lasts forever, it’s important that wireless sensors do their work—data collection and processing—without wasting energy.

“The work I’m doing,” says Coman, “is trying to make the in-network processing as efficient as possible… The reason is that you’re trying to extend the lifetime of the sensor networks in order to be cost-effective. You want to install a network once and operate it as long as possible.”

Little Brothers?

As wireless technology envelops our world, making it possible for cell phones, wireless sensors, and other devices to monitor us at nearly every moment in our lives, it’s bound to remind some people of the oppressive Big Brother surveillance that George Orwell writes about in his novel 1984.

Nascimento points out that we are already being watched quite extensively, and so far we haven’t lost our freedom. “Do you have a credit card? A Safeway card? People already know where you are and what you’re buying and about how much you make.

“Am I worried? Not really. If you’re doing some research in biology, are you not going to study some bacteria because it could be used for biological weapons? No, I think you should. You just don’t use it for that. You use it for good.”

Article and photos by Erin Ottosen, 2007.