WCA September 2012

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Wire & Cable ASIA – September/October 2012 67
From theamericas
Mr Chen: The wireless operators contend that they need not
just better-managed spectrum but additional spectrum, and
they want the government to clear their access to it.
Mr Cooper: How can 20 per cent more spectrum – which
is as much as they’re ever going to get, in their wildest
dreams – solve the problem when the need is for 20 times
more spectrum? It can’t. They’ve got to push harder on
technology. They’re not using technology that exists today
and was demonstrated 10 years ago.
Mr Chen: Where do we stand now on technology that
makes more efficient use of spectrum?
Mr Cooper: The technology that senses whether some
free radio spectrum is available at that location is known
as cognitive radio. This is still in the early stages of
development but could be available in five to 10 years.
The technology that allows cellular radios to use any of
a large number of channels is called software-defined
radio, or frequency-agile radio. All radios today are
software-defined, but their agility is not yet adequate. That
will take five years or longer.
The technology that lets many people use the same
radio channel at the same time is called smart antenna
technology or adaptive array technology or interference
mitigation. This uses computer processors to take the
signals from multiple antennas at each location and sorts
the various signals out so they don’t interfere with one
another.
Smart antenna technology has been available for almost 20
years but is not yet used by cellular operators.
Mr Chen: The presidential committee’s report concludes
that the radio spectrum could be used as much as 40,000
times as efficiently as it is now. That sounds dramatic. Is it
feasible?
Mr Cooper: Cognitive radio, Smart antennas, and the
other techniques all require computer processors. As the
processors get more powerful they are capable of more
spectrally efficient techniques. It’s a continuum. You add
technologies, you improve the processing, you introduce a
new technique, you get incremental improvement.
Doubling every two and a half years is Cooper’s Law. You
don’t have to double very much to get to 40,000. When
they say 40,000 times, that’s a million times more spectrum.
It’s going to take 20 years. Each time you put in new
technology you get a big jump.
Dorothy Fabian
Features Editor