Subject: [NEXTEL-1] Improving Spectrum Usage Through Cognitive Radio Technology

From: [email-masked]
Date: Sat, 08 May 2004 18:35:23 -0400

Improving Spectrum Usage Through Cognitive Radio Technology

(Approved by the IEEE-USA
Board of Directors, 13 Nov. 2003)

IEEE-USA strongly encourages the Federal Communication Commission (FCC)
to continue the innovative thinking evidenced by its encouragement of
the development and implementation of Cognitive Radio (CR) technology,
which offers the possibility of making significantly more efficient use
of the finite radio spectrum resource.

A Cognitive Radio is a radio frequency transmitter/receiver that is
designed to intelligently detect whether a particular segment of the
radio spectrum is currently in use, and to jump into (and out of, as
necessary) the temporarily-unused spectrum very rapidly, without
interfering with the transmissions of other authorized users. CR is a
relatively new technology, so we recognize that both technical and
policy questions must be answered before full CR implementation can
proceed.

Given the increasing demand for radio spectrum -- a finite resource --
and the potential for CR technology to facilitate sharing of otherwise
unused spectrum (temporally and geographically), IEEE-USA strongly
recommends that the FCC, with the cooperation of other government
agencies and private sector entities:

Determine, through industry/government sharing studies, in which bands
CRs can be used with confidence, and validate the results of those
sharing studies through initial field trials.

Confirm the technical reliability and practicality of CR, by resolving
technical issues including:

- What suitable "behaviors" and minimal technical restrictions are
necessary to ensure CRs will operate without causing harmful
interference to licensed users?

- How can a licensed frequency user determine that any interference
received is actually the result of cognitive radio operation, rather
than from some other source?

- What is the cumulative effect of very large numbers of CR users?

Create a regulatory environment that permits CR technology
implementation, while providing a method of redress and resolution for
instances where interference might occur.

This statement was developed by the IEEE-USA Committee on Communications
and Information Policy and represents the considered judgment of a group
of IEEE-USA members with expertise in the subject field. IEEE-USA is an
organizational unit of The Institute of Electrical and Electronics
Engineers, Inc., created in 1973 to advance the public good, while
promoting the careers and public-policy interests of the more than
235,000 electrical, electronics, computer and software engineers who are
U.S.  members of the IEEE. The IEEE is the world's largest technical
professional society. For more information, go to
http://www.ieeeusa.org.

BACKGROUND

In May 2003, the Federal Communications Commission (FCC) sponsored a
Cognitive Radio (CR) Technology Workshop to discuss the potential for
more efficient use of the ratio spectrum, based on emerging CR
technology, and how to best apply CR for better spectrum usage.

Studies have indicated that much of the available spectrum lies fallow
much of the time, on geographic, time and frequency bases. CRs can
utilize spectrum that is not already in use. They can also potentially
use lower power than required to reach from point A to point Z, by
sending lower-power (or even different frequency) signals to other CRs
at points B, C, D, and so on, between points A and Z.

In the past, radio transmitters and receivers have been hardware-based.
Once built, devices were only usable for the purposes for which they
were designed. Now, however, "software defined radio" (SDR) has been
developed, by which a given radio transmitter or receiver can be
dramatically updated and modified -- on the basis of changes only to the
software installed within the device.

CRs are "smart" in that they can "learn" about current use of spectrum
in their operating area, make intelligent decisions on that basis, and
react to immediate changes in the use of spectrum by other authorized or
CR users.
Thus, any radio spectrum can, in principle, be opportunistically used by
CRs on a non-interfering basis. CR technology offers the opportunity for
efficient use -- without interference to authorized/licensed users -- of
currently unused or underutilized spectrum.

The question of primary users' rights and obligations are raised, since
many licensed users' perceive they have exclusive control of the
spectrum that corresponds to their licenses, whether the license was
issued by comparative hearings or bought at auction. The Commission
needs to address these issues.

For example, if the CR can detect "on frequency" use by incumbent users
that it should not interfere with, what is to prevent existing users
from just "keying up" when CR activity is detected (or even just
periodically as a "defensive measure") causing the CR to move? Would
this become illegal, and under what penalty? By definition, CRs should
be inherently non-interfering on a completely independent basis.
Therefore, incumbents should be prohibited from deliberately blocking CR
access to otherwise unused spectrum.

Of course, the full potential and practicality of CR technology has yet
to be fully demonstrated. IEEE-USA suggests that CRs first be proven
effective in spectrum that could be considered "low hanging fruit" (i.e.
spectrum that has a relatively low percentage of actual usage by the
authorized users, and for which the actual occurrence of limited amounts
of interference would not be catastrophic).

For example, some bands may not be currently in use. Or, some bands have
low average usage. And, some TV broadcast channels are not used at all
in geographic areas where CR could be tried.

Clearly, initial trials should not be implemented in spectrum that the
Department of Defense, law enforcement agencies or fire departments use.
In such cases, the spectrum is often used only a small amount of time on
average, but sometimes when it is needed, it is vitally important that
it be available, without interference. After significant trials and
experience, perhaps CRs could even be used in those spectrum ranges; but
surely not in its initial technology trials.

Even in the end, CRs should probably not use some spectrum bands, such
as spectrum used for the global positioning satellite (GPS), or spectrum
used by satellites for observing weather patterns. In such cases, the CR
would not likely detect any competing use of the spectrum, but could
interfere with its authorized use.

While at first glance unlicensed spectrum may appear to be a good
candidate for initial CR testing, it is necessary to consider the number
of consumer and industrial devices that may or do use that spectrum. In
fact, some of the unlicensed bands (e.g., 2.4 GHz) are already extremely
crowded with devices sharing the band. Thus, experiments with CR in the
unlicensed spectrum bands would not fully answer the issues of how CR
should be used in licensed/authorized spectrum bands. Such issues must
be addressed to take full advantage of CR potential to allow increased
sharing of otherwise unused spectrum.

Clearly, some technical issues must be answered before any large-scale
CR implementation can proceed, even though it limited trials showing CR
technology effectiveness have been demonstrated. However, the challenge
of creating a regulatory environment that permits CR technology
implementation, while providing a method of redress for instances where
harmful interference might occur, and providing for their resolution, is
just as important.

IEEE-USA strongly encourages the FCC and other government agencies, as
well as the private sector, to pursue CR technology development and
application as vigorously as possible. The goal is to relieve radio
spectrum overcrowding, which actually translates to a lack of access to
full radio spectrum utilization.

Although the FCC must surely recognize and address all of the pertinent
issues, IEEE-USA suggests that at this time, the FCC's major efforts,
should focus on the following major issues:

Deciding which bands would be available for initial CR trials, through
sound and equitable sharing studies conducted cooperatively between
industry and government agencies. Confirming the results of such sharing
studies through field trials would, open up other CR bands as the
technology proves effective, and further sharing studies and field
trials would confirm the CR ability to coexist in those other bands.

Defining the rights of the licensed spectrum band users where CR
technology is authorized. Certainly, licensed users should be protected
from CR interference (largely a technical issue). But if CR benefits are
to be realized, CRs should not be denied the right to operate on a truly
non-interfering basis. The FCC should not charge fees for such
non-interfering use, or employ active techniques to deliberately block
CR access to spectrum that would otherwise be unused temporally or
geographically.
Defining "harmful interference" within the authorized CR bands.

At least in the beginning, the FCC should not implement a complete set
of absolute rules as to how CR technology should be experimented with,
but put guidelines or policies in place that CR users and primary users
should follow in good faith.
Establishing a method for incumbent spectrum users to register evidence
of interference to their systems and achieve resolution.
In the interest of realizing the potentially significant benefits of CR
technology as rapidly as possible, the FCC should act as quickly as
possible to put guidelines/policies in place for trial and long-term CR
technology implementation.
Rapid implementation is important not only to solve problems of
inadequate access to unused or underutilized spectrum, but also to
enhance U.S. technological leadership in cognitive radio technology.

http://www.ieeeusa.org/forum/POSITIONS/cognitiveradio.html

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