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Zheng compares the scheme to a driver’s reacting to what she sees other drivers doing. “If I’m in a traffic lane that is heavy, maybe it’s time for me to shift to another lane that is not so busy,” she says. When shifting lanes, however, a driver needs to follow rules that prevent her from bumping into others.
Zheng has demonstrated her approach in computer simulations and is working toward testing it on actual hardware. But putting spectrum-sharing theory into practice will take engineering work, from designing the right antennas to writing the software that will run the cognitive radios, Zheng acknowledges. “This is just a starting phase,” she says.
Nonetheless, cognitive radios are already making headway in the real world. Intel has plans to build reconfigurable chips that will use software to analyze their environments and select the best protocols and frequencies for data transmission. The FCC has made special allowances so that new types of wireless networks can test these ideas on unused television channels, and the Institute of Electrical and Electronics Engineers, which sets many of the technical standards that continue to drive the Internet revolution, has begun considering cognitive-radio standards.
It may be 10 years before all the issues get sorted out, Zheng says, but as the airwaves become more crowded, all wireless devices will need more-efficient ways to share the spectrum.
Bob Broderson – Advanced communication algorithms and low-power devices
University of California, Berkeley
John Chapin – Software-defined radios
Vanu, Cambridge, MA
Michael Honig – Pricing algorithm for spectrum sharing
Joseph Mitola III – Cognitive radios
Mitre, McLean, VA
Adam Wolisz – Protocols for communications networks
Technical University of Berlin, Germany
Home page image courtesy of Gregg Segal.