A University of Illinois researcher proposes using interference to improve radio communications
A University of Illinois researcher is trying the wireless equivalent of making a silk purse out of a sow’s ear.
The National Science Foundation has awarded Daniela Tuninetti a five-year, $400,000 grant to explore ways of using radio interference to improve wireless communications. Tuninetti is an assistant professor of electrical and computer engineering at the university’s Chicago campus. She talked this week with Network World about her research.
“I remember my first course in communications,” Tuninetti says. “We called it ‘noise’ because we didn’t know what to do with that.”
But interference is not in fact a random phenomenon. “What I’m saying is that it is indeed a communication [between two radios], with a structure. And it can be exploited,” Tuninetti says.
To illustrate, she uses the metaphor of people talking among themselves at a party. Person A says something to Person B, but because of the sound level, B can’t understand it. A third person, standing between them, however, does understand what A said, and then repeats it for B.
This concept, applied to wireless, is now being called “collaborative communications” – a group of client devices cooperatively monitor the radio environment and share power, signal strength, signal processing and other resources to enable and support optimal communications. “You take advantage of the fact that everyone can ‘listen’ to everyone else, and then share things like a better signal quality to help others,” Tuninetti says.
“Interference, which is [in fact] a message, can be decoded to facilitate this communication,” she says.
One promising area for collaborative communications, which has been emerging as a hot research area over the past few years, is multi-antenna designs, such as those used in phased-array antennas and more recently in multiple input, multiple output (MIMO) radios. MIMO is the basis of the emerging 802.11n high-throughput wireless LAN standard, which will boost data throughput to well over 100Mbps and sustain high rates over much longer distances.
Tuninetti foresees handheld devices forming peer-to-peer, meshed networks; individual antennas could form a much larger, virtual multi-antenna system, achieving some of the same benefits as MIMO on an individual device.
“I think in future, we’ll go more to peer-to-peer,” Tuninetti says. “These devices will need to organize themselves when they switch on. So every device will have intelligence for discovery, routing, and relaying information for others [in the network].”
One of the main obstacles to achieving such collaboration has nothing to do with communications theory or practice. It’s the limited battery life of client handhelds. Today, Tuninetti says, cell phones shift into sleep mode to minimize battery use when they have nothing to send or receive. They won’t be able to do that in a Tuninetti network.
“What I propose is that everyone should be awake and aware and listening to what’s going on, in order to be able to help others,” she says. “You need to be monitoring what’s going on around you, and making available your resources.”
The research project is intended to deliver several results, including new coding and signal techniques to improve the overall capacity of a wireless system, and designing distributed multi-access and routing protocols.
Tuninetti says her interest was sparked by a March 2003 paper, “Cooperative Communications in Wireless Systems” by Professor Elza Erkip, with Polytechnic University, presented at Rutgers University’s Center for Discrete Mathematics and Theoretical Computer Science.
A native of Italy, Dr. Tuninetti received her Master of Science in Telecommunications Engineering in 1998 from Politecnico di Torino in Torino, Italy, where she graduated summa cum laude. Her doctorate was awarded in 2002 from Telecom Paris. She has been with the University of Illinois at Chicago since May 2002.
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