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Past Winner
2002 NSERC Doctoral Prize

Mathini Sellathurai

Electrical and Computer Engineering

McMaster University

Mathini Sellathurai doesn't use a cell phone. She says she doesn't have the time for wireless chit chat. She's been too busy developing the technology that could soon provide laptops with high-speed wireless connections.

It's world-leading research for which the recently graduated McMaster University student is being awarded a 2002 Natural Sciences and Engineering Council Doctoral Prize — one of Canada's premier graduate student awards.

Until the mid-1990s it was commonly thought that the only way to increase wireless capacity was to increase bandwidth and power.

But in 1996, Jerry Foschini at Lucent Technology's Bell-Labs in New Jersey opened a new realm of wireless research when he experimentally demonstrated a novel way to increase capacity that he dubbed BLAST (Bell-Labs Layered Space-Time) architecture.

Rather than increase bandwidth, the BLAST system uses multiple antennas at both the sending and receiving ends of a wireless system. Multiple signals are sent in parallel (thus the use of space and time), at the same frequency, and with the standard transmitter power divided between them.

"The major challenge with this approach is that when you use the same bandwidth to send different signals, how do you extract the signals at the receiving end?" notes Dr. Sellathurai.

In 1999, she and her PhD supervisor McMaster's Dr. Simon Haykin visited the Bell-Labs. Dr. Sellathurai was impressed with the cutting-edge BLAST technology.

But she also thought that she could make it better.

Enter Turbo-BLAST. The doctoral researcher applied her research in a type of wireless communications coding principle called turbo to design a new BLAST system.

Rather than rely on a single decoding process for the complex multiple signals being received, Turbo-BLAST uses an iterative, or repetitive, decoding process. The turbo approach uses two decoders to break each problem in half and maximize the decoding by sending information back and forth between the decoders.

Having developed the concept theoretically, Sellathurai wanted to put it to the test.

"In January 2000, I told to professor Haykin that I wanted to test my algorithms in Bell-Labs real-life BLAST test-bed. I was with Bell-Lab's BLAST group by September 2000 to test our algorithm. It was a rare opportunity to collaborate with the group responsible for the BLAST test-bed at Holmdel, New Jersey," she says.

Not only did the Turbo-BLAST technology perform seamlessly, but during work with BLAST-system inventor Jerry Foschini, the pair created another new, patented system to increase wireless capacity.

Turbo-BLAST now represents one of the leading approaches to increasing wireless capacity. Devices such as laptops and palm pilots could one day be equipped with multiple antennae and receivers and thus be able to operate at high-speed through local area networks.

Dr. Sellathurai, currently a research scientist with the Communications Research Centre in Ottawa, is extending her research in ways to increase information transmission capacity in both satellite and wireless communications systems.