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Technological Advisory Council (TAC) White Paper

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Released: April 22, 2013

PUBLIC NOTICE

Federal Communications Commission
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DA 13-801

April 22, 2013

OFFICE OF ENGINEERING AND TECHNOLOGY INVITES COMMENTS ON

TECHNOLOGICAL ADVISORY COUNCIL (TAC) WHITE PAPER AND

RECOMMENDATIONS FOR IMPROVING RECEIVER PERFORMANCE

ET Docket No. 13-101

Comment Date: June 21, 2013
Reply Comment Date: July 8, 2013

Early in 2012, Chairman Julius Genachowski tasked the FCC’s Technological Advisory Council (TAC)
to study the role of receivers in ensuring the efficient use of spectrum and to provide recommendations on
avoiding obstacles posed by receiver performance to making spectrum available for new services. Acting
on this request, the TAC working group on Receivers and Spectrum provided actionable
recommendations to the Chairman at the TAC’s December 2012 meeting1 and has recently formalized
these recommendations in a white paper for the Commission to consider, titled, Interference Limits Policy
– The use of harm claim thresholds to improve the interference tolerance of wireless systems
; at
http://transition.fcc.gov/bureaus/oet/tac/tacdocs/WhitePaperTACInterferenceLimitsv1.0.pdf (TAC white
paper). The FCC’s Office of Engineering and Technology (OET) invites comment on the TAC white
paper and its recommendations to help determine what next steps may be appropriate.
In addition to the work of the TAC, the Government Accountability Office (GAO) was tasked by
Congress in the Middle Class Tax Relief and Job Creation Act of 2012 to study spectrum efficiency and
receiver performance. The GAO report, Further Consideration of Options to Improve Receiver
Performance Needed
, at http://www.gao.gov/assets/660/652284.pdf, was recently published and makes
reference to the TAC white paper. The report recommends the Commission consider small-scale pilot
tests and other methods to collect information on the practical effects of various options for improving
receiver performance.
Also, in July 2012, the President’s Council of Advisors on Science and Technology (PCAST) published a
report, titled, Realizing the Full Potential of Government-Held Spectrum to Spur Economic Growth; at
http://www.whitehouse.gov/sites/default/files/microsites/ostp/pcast_spectrum_report_final_july_20_2012
.pdf. This report noted the important role of receivers in spectrum policy and regulation, and

1 TAC presentation; http://transition.fcc.gov/bureaus/oet/tac/tacdocs/meeting121012/TAC12-10-
12FinalPresentation.pdf

recommended receiver interference limits be defined to specify the level of radio interference that
receivers should be expected to tolerate without being able to make claims of harmful interference. The
TAC white paper focuses on this definition of “interference limits” in making its policy proposals.
The TAC white paper sets forth an interference limits policy approach, and suggests that steps should be
taken to define the radio environment in which receivers are expected to operate. According to the paper,
this approach would make it easier to determine which party bears responsibility for mitigating harmful
interference when it occurs, by specifying signal power levels called “harm claim thresholds” that a
service would be expected to tolerate from other services before a claim of harmful interference could be
made. The TAC white paper asserts this approach would avoid the need to mandate that receivers be
built, sold, or operated with specific performance characteristics. In addition, it could incentivize
incumbent spectrum users to improve receivers to more efficiently use spectrum without stifling
innovation and receiver design.
OET seeks specific comment on the TAC white paper, which recommends multiple actions the
Commission could take to implement an interference limits policy. We also seek comment on the overall
interference limits policy approach proposed in that white paper and information on the practical effects
of various options including the method used today relative to receiver standards and specifications, the
use of multi-stakeholder organizations in the development of interference thresholds, and the role of the
FCC.
Interference Limits Policy Approach –
Comments are requested on the viability of the overall interference limits policy approach presented in
the TAC white paper. In particular, we invite parties to comment on the viability of the use of an
interference limits policy approach among services operating in adjacent frequency bands. What are the
costs and benefits associated with this approach? Are there specific frequency bands or services that
would particularly benefit from this approach or where implementation is straightforward and would be
appropriate for a trial? We request comment on any areas where additional technical analysis may be
needed to implement an interference limits policy approach, such as the impact of various coding and
modulation schemes on interference thresholds, propagation models that should be used in determining
the interference thresholds, measurement methods for assessing compliance with the limits in cases of
interference, and methods for determining the performance characteristics of currently deployed receivers
and systems. In addition, we invite parties to discuss the key implementation issues of the proposed
approach that would need to be addressed as the Commission focuses on making additional spectrum
available for new mobile and fixed wireless broadband services. Would proactive attention to
establishing interference limits create more certainty in the marketplace for spectrum (re)allocations?
The TAC white paper makes note that an interference limits policy approach may not be appropriate in all
cases. Are there other policy approaches that should be considered? Moreover, the GAO report identifies
the lack of incentives for manufacturers or spectrum users to incur costs associated with using more
robust receivers, and the difficulty of accommodating a changing spectrum environment, such as when
spectrum is repurposed for a new use. Are the incentives in the TAC white paper recommendations for
improving receiver robustness to interference sufficient? Are there other incentives not mentioned in the
TAC white paper recommendations that should be considered? Should the Commission consider
circumstances unique to each service, such as the diversity of devices available, the cost of replacement
devices, typical replacement times, or sophistication of users that may impact the practicality, necessity,
or sufficiency of such an approach? How should the technological evolution of components and receiver
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design influence the timeframe and evolution of interference limits? In light of these issues, are there
other alternatives, or other options within an interference limits policy approach, that should be
considered for further analysis and/or small-scale pilot tests? What are the cost and benefit tradeoffs of
these alternatives?
Receiver Standards --
Industry standards for receiver performance exist for certain federal and non-federal wireless services and
technologies. There are also wireless services for which there are no industry guidelines or standards for
receiver performance. Where industry standards exist for receivers, what is the relationship between
these standards and the method for determining appropriate harm claim thresholds for receivers? How do
actual receivers perform in relation to existing performance standards? How are receivers evaluated in
meeting those industry standards? Where there are industry standards, how are such standards enforced?
To the extent standards are voluntary, how do users of receivers know whether equipment meets or
exceeds such standards? Where there are no industry standards for receiver performance, how should
acceptable thresholds of receiver performance be developed and validated? What are the technical and
performance issues among diverse wireless services that need to be understood and analyzed between
different stakeholder groups, especially the developers of wireless transmitters, receivers and
components? What are the cost and performance trends of key receiver components that determine
practical thresholds of system performance?
The TAC recommends that the FCC implement a web accessible repository (e.g., through the FCC
spectrum dashboard) of existing receiver standards, and a voluntary repository of receiver specifications
for existing receivers. This, the TAC contends, would facilitate technical information sharing among
diverse stakeholder groups of wireless system developers who need to know and understand the
specifications of systems other than their own. How effective would this method of information sharing
be for product developers? What are the source documents that would be appropriate for such a
repository? Are there additional and/or more effective methods, perhaps industry-led, to share receiver
technical standards and specifications between stakeholder groups that traditionally do not work together
in the same industry groups (e.g., standards organizations)? Given the increasing number of devices
developed for international use, would an industry-led approach be more effective than a US-specific
repository?
Multi-Stakeholder Organizations –
The TAC recommends that the Commission encourage the formation of one or more multi-stakeholder
groups to investigate interference limits policy at suitable high-value inter-service boundaries. We seek
comment on such a multi-stakeholder process and solicit interest from candidate participants. What
frequency bands would be most appropriate for considering the formation of a multi-stakeholder
organization to develop technical parameters and methods for implementing an interference limits policy?
Are there more effective methods of organizing a diverse group of stakeholders for developing such
technical parameters?
What is the best way to initiate the formation of a multi-stakeholder group? We invite comment and
recommendations on applicable governance, issue resolution, and enforcement methods, including but not
limited to how stakeholders can coordinate across industry segments, such as those where voluntary
standards are needed and/or developed. Also, recognizing that service boundaries and spectrum sharing
often involve both non-federal and federal spectrum users, we seek comment on the costs and benefits of
a comprehensive approach between the FCC and NTIA to incorporate receiver performance into spectrum
management practices. How should the FCC and NTIA coordinate with government agencies and other
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stakeholders to address situations where large numbers of users are impacted by changes to adjacent
spectrum licenses? Should the FCC and NTIA perform band assessments to determine where possible
future repurposing in a band might impact adjacent bands and develop plans and processes to ensure
proper protections?
Role of the FCC –
We seek general comment on whether and how the Commission should implement a policy that
incentivizes improved interference tolerance of wireless systems. Specifically, should the FCC adopt a
policy of employing interference limits in certain cases of neighboring bands and services? Should the
FCC adopt specific rules for establishing interference limits that are recommended by one or more multi-
stakeholder groups? Should the FCC develop a compliance model similar to the one used in the context
of CALEA,2 in which there is industry-led establishment of standards and solutions and the Commission
would get involved only via special petition? We envision that the FCC could be a facilitator in a non-
directive role with convening stakeholders. Also, the GAO recommends consideration of small-scale
pilot tests of options for improving receiver performance. What should be the scope of an appropriate
pilot test? What role should the FCC play in encouraging and initiating industry action? Are there
existing FCC proceedings where incentives to improve the interference tolerance of wireless systems
should be applied?
Comments. Pursuant to sections 1.415 and 1.419 of the Commission’s rules, 47 C.F.R. §§ 1.415, 1.419,
interested parties may file comments and reply comments on or before the dates indicated on the first
page of this document. Comments may be filed using the Commission’s Electronic Comment Filing
System (ECFS). See Electronic Filing of Documents in Rulemaking Proceedings, 63 FR 24121 (1998).

Electronic Filers: Comments may be filed electronically using the Internet by accessing the
ECFS: http://fjallfoss.fcc.gov/ecfs2/.

Paper Filers: Parties that choose to file by paper must file an original and one copy of each filing.
If more than one docket or rulemaking number appears in the caption of this proceeding, filers
must submit two additional copies for each additional docket or rulemaking number.
Filings can be sent by hand or messenger delivery, by commercial overnight courier, or by first-
class or overnight U.S. Postal Service mail. All filings must be addressed to the Commission’s
Secretary, Office of the Secretary, Federal Communications Commission.

All hand-delivered or messenger-delivered paper filings for the Commission’s Secretary
must be delivered to FCC Headquarters at 445 12th St., SW, Room TW-A325,
Washington, DC 20554. The filing hours are 8:00 a.m. to 7:00 p.m. All hand deliveries
must be held together with rubber bands or fasteners. Any envelopes must be disposed of
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Commercial overnight mail (other than U.S. Postal Service Express Mail and Priority
Mail) must be sent to 9300 East Hampton Drive, Capitol Heights, MD 20743.

U.S. Postal Service first-class, Express, and Priority mail must be addressed to 445 12th
Street, SW, Washington DC 20554.

2 The Communications Assistance for Law Enforcement Act (CALEA), Pub. L. No. 103-414
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For further information contact: Robert Pavlak at 202-418-0761 or via email at Robert.Pavlak@fcc.gov or
Ronald Repasi at 202-418-0768 or via email at Ronald.Repasi@fcc.gov
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