New hardware could lead to wireless devices that identify
and exploit unused transmission frequencies, using radio spectrum much more
efficiently.
The way in which radio spectrum is currently allocated to
different wireless technologies can lead to gross inefficiencies. In some
regions, for instance, the frequencies used by cellphones can be desperately
congested, while large swaths of the broadcast-television spectrum stand idle.
One solution to that problem is the 15-year-old idea of
“cognitive radio,” in which wireless devices would scan their environments for
vacant frequencies and use these for transmissions. Different proposals for
cognitive radio place different emphases on hardware and software, but the
chief component of many hardware approaches is a bank of filters that can
isolate any frequency in a wide band.