Subject: [NEXTEL-1] The ARRL says the FCC's proposed "interference temperature" concept is "highly premature and should not go forward" at this time.

From: [email-masked]
Date: Sun, 11 Apr 2004 20:15:58 -0400

From The ARRL Letter
Vol. 23, No. 14

April 9, 2004

The ARRL says the FCC's proposed "interference temperature" concept is
"highly premature and should not go forward" at this time.

In a Notice of Inquiry and Notice of Proposed Rule Making in ET Docket
03-237 last November, the FCC sought comment on the interference
temperature metric - or model - "for quantifying and managing
interference."

The FCC initially wants to implement the concept in two microwave bands.
It asserts that the new metric "could represent a fundamental paradigm
shift"
in its spectrum management approach by using a standard that takes into
account "the cumulative effects of all undesired RF energy" at a given
instant. The FCC suggests the interference temperature limit for a band
"would serve as an upper bound or 'cap' on the potential RF energy that
could be introduced into the band."

The ARRL contends, however, that the FCC doesn't have enough information
to put such a model into place, and it should not try to take a
shortcut.

"It is now rushing to judgment on a proposal to permit broadband over
unshielded power line systems in the high frequency and low-band VHF
spectrum," ARRL commented, "without first carefully studying the ability
of sensitive and geographically proximate fixed and especially mobile
radio systems to tolerate such interference." Instead of determining
what
a proper post-BPL RF environment should be, the League noted, the FCC
has suggested that amateurs orient their antennas away from the
interference
source.

"There can be no shortcuts in a conceptual shift to management of the RF
environment without disenfranchising incumbent licensees, which
themselves
provide valuable and sometimes indispensable services," the ARRL said.
"Whether by overlay or underlay of additional users, the Commission has
stumbled repeatedly by attempting shortcuts in the process."

The ARRL said the FCC should preserve the interference temperature
concept
as a "holistic method" of dynamic RF spectrum management--the
determination of compatibility in sharing of allocations. "However, the
concept is not yet mature, and there are no shortcuts in the
preparations
necessary to implement it."

The ARRL says localized noise studies in various bands are a
prerequisite
to putting an interference temperature metric into place, along with a
"comprehensive evaluation of the differences in receiver sensitivities
and
emission modes" across various services and bands. The League has been
conducting noise studies in different geographic environments, and it
proposed objective, formal studies to provide a basis for an
interference
temperature metric in the future.

The ARRL says it's also necessary to create a new management paradigm
for
unlicensed services, accompanied by "substantial change" in their
regulation. Otherwise, the League said, management of the RF environment
will be impossible.

An interference temperature metric also would not be appropriate for the
HF spectrum as well as certain other bands, including those used for
radio
astronomy, the ARRL commented. The variability of HF skywave propagation
and the extreme sensitivity of certain amateur and all radio astronomy
receivers coupled with very small signal levels make calculating an
interference temperature metric "impractical for these bands," the
League
added.

For the short term, the League said, other methods of improving spectrum
efficiency, such as dynamic frequency selection by cognitive radios in
certain bands, might have greater potential than adopting an
interference
temperature metric.

 ARRL Comments:

http://gullfoss2.fcc.gov/prod/ecfs/retrieve.cgi?native_or_pdf=pdf&id_document=6516086568

 http://www.arrl.org/arrlletter/04/0409/

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