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United States Government Accountability Office: 
GAO: 

Report to Congressional Committees: 

February 2013: 

Spectrum Management: 

Further Consideration of Options to Improve Receiver Performance 
Needed: 

GAO-13-265: 

GAO Highlights: 

Highlights of GAO-13-265, a report to congressional committees. 

Why GAO Did This Study: 

The growth of commercial wireless-broadband services and government 
missions, including public safety and defense, has increased demand 
for radio-frequency spectrum. FCC and NTIA attempt to meet this demand 
while protecting existing users from harmful interference that can 
arise as new services and users come on line. To manage harmful 
interference, FCC and NTIA have historically focused on transmitters—
the equipment that emits signals. But, receivers also play a role. 
Congress and others are considering if further action to improve 
receiver performance to reduce harmful interference could help enhance 
spectrum efficiency and meet the growing demand for spectrum. 

The Middle Class Tax Relief and Job Creation Act of 2012 directed GAO 
to study spectrum efficiency and receiver performance; GAO studied 
four areas related to improving receiver performance, including (1) 
actions taken by manufacturers and commercial licensees, (2) actions 
taken by the federal government, (3) challenges, and (4) options 
identified by stakeholders. GAO reviewed federal regulations and 
reports prepared by FCC, NTIA, industry stakeholders, and other 
researchers, and interviewed spectrum users, industry associations, 
and other stakeholders. 

What GAO Found: 

Manufacturers and commercial licensees have taken a variety of actions 
to improve receiver performance. For some services, industry 
associations—-comprised of manufacturers, commercial licensees, and 
others-—have developed voluntary standards that are often used to 
design and procure receivers, such as those in cell phones and 
televisions, and to help improve receiver performance. Stakeholders 
also reported privately negotiating to resolve interference problems 
and sharing of information as having helped improve receiver 
performance. 

The federal government has used standards and taken other actions to 
improve receiver performance. Some federal spectrum users, like the 
Coast Guard and Department of Transportation, have specified or 
mandated use of industry standards for receivers using certain agency 
spectrum-based services. The National Telecommunications and 
Information Administration (NTIA), which manages the federal government’
s use of spectrum, has also mandated receiver standards for many 
federal spectrum assignments, such as those for land mobile radios 
used by emergency responders and radar systems. The Federal 
Communications Commission (FCC), which manages commercial and other 
nonfederal spectrum use, believes it lacks general authority to impose 
receiver standards and rather relies on the marketplace to improve 
receiver performance. In specific cases, FCC has provided incentives 
for nonfederal spectrum users to improve receivers. Both NTIA and FCC 
have taken additional actions to improve receiver performance, like 
undertaking studies and hosting public workshops. 

Although industry and government have taken actions, stakeholders 
identified three challenges to improving receiver performance: 

* Lack of coordination across industries when developing voluntary 
standards: Standards are often developed for a single industry and not 
coordinated with those using adjacent spectrum. 

* Lack of incentives for manufacturers or spectrum users to incur 
costs associated with using more robust receivers: The benefits of 
improved receiver performance, namely freed-up spectrum for new 
services and users, often accrue to others and not those incurring the 
costs to improve receivers. 

* Difficulty accommodating a changing spectrum environment: When 
spectrum is repurposed for a new use, upgrading or replacing receivers 
currently in use to mitigate interference can be difficult and take 
considerable time. 

In addition to greater use of voluntary industry standards, 
stakeholders GAO interviewed identified several other options to 
improve receiver performance. For example, interference limits would 
explicitly set a level of interfering signals that a receiver must 
tolerate before a user could seek government action to resolve 
interference problems. Each option entails trade-offs, and many 
stakeholders noted that a one-size-fits-all solution is likely not 
desirable or possible. Further, some options, such as interference 
limits, have not been implemented, and others, such as mandatory 
standards, have only been implemented for a limited number of users, 
primarily federal users. Therefore, the practical effects of these 
options—-that is, what would happen if these options were individually 
or collectively implemented-—are not well known, particularly for 
nonfederal users. 

What GAO Recommends: 

FCC should consider collecting information on the practical effects of 
options to improve receiver performance. FCC replied that it had 
initiated such a fact-gathering process; GAO believes FCC’s process to 
date may not provide information on the practical effects of these 
options. 

View [hyperlink, http://www.gao.gov/products/GAO-13-265]. For more 
information, contact Mark Goldstein at (202) 512-2834 or 
goldsteinm@gao.gov. 

[End of section] 

Contents: 

Letter: 

Background: 

Selected Manufacturers and Commercial Licensees Have Taken a Variety 
of Actions to Improve Receiver Performance: 

The Federal Government Has Used Standards, Procurement, and Other 
Actions to Improve Receiver Performance: 

Several Challenges Impede Further Improvements to Receiver Performance: 

Stakeholders and Reports Identified Standards, Interference Limits, 
and Other Options to Improve Receiver Performance: 

Conclusions: 

Recommendation for Executive Action: 

Agency Comments and Our Evaluation: 

Appendix I: Objectives, Scope, and Methodology: 

Appendix II: Comments from the Department of Commerce: 

Appendix III: Comments from the Federal Communications Commission: 

Appendix IV: GAO Contact and Staff Acknowledgments: 

Tables: 

Table 1: Options Identified by Stakeholders and Reports to Improve 
Receiver Performance: 

Table 2: Organizations and Individuals Interviewed: 

Figures: 

Figure 1: Examples of Services by Frequency Band: 

Figure 2: Components of a Communications System: 

Figure 3: Classification of Interference: 

Figure 4: Types of Adjacent Band Interference: 

Figure 5: Perfect and Imperfect Filtering: 

Abbreviations: 

ANSI: American National Standards Institute: 

APCO: Association of Public-Safety Communications Officials: 

ATSC: Advanced Television Systems Committee: 

AWS: Advanced Wireless Services: 

CAP: Compliance Assessment Program: 

CSMAC: Commerce Spectrum Management Advisory Committee: 

DOD: Department of Defense: 

FAA: Federal Aviation Administration: 

FCC: Federal Communications Commission: 

GHz: gigahertz: 

GPS: Global Positioning System: 

IRAC: Interdepartment Radio Advisory Committee: 

ITS: Institute for Telecommunication Sciences: 

ITU: International Telecommunication Union: 

kHz: kilohertz: 

MHz: megahertz: 

NASA: National Aeronautics and Space Administration: 

NOAA: National Oceanic and Atmospheric Administration: 

NTIA: National Telecommunications and Information Administration: 

OMB: Office of Management and Budget: 

OOBE: out-of-band emissions: 

PCAST: President's Council of Advisors on Science and Technology: 

PSWN: Public Safety Wireless Network: 

RTCM: Radio Technical Commission for Maritime Services: 

SDARS: Satellite Digital Audio Radio Service: 

TAC: Technological Advisory Council: 

TIA: Telecommunications Industry Association: 

TSO: Technical Standard Order: 

WCS: Wireless Communications Service: 

[End of section] 

United States Government Accountability Office: 
Washington, DC 20548: 

February 22, 2013: 

The Honorable John D. Rockefeller IV: 
Chairman: 
The Honorable John Thune: 
Ranking Member: 
Committee on Commerce, Science, and Transportation: 
United States Senate: 

The Honorable Fred Upton: 
Chairman: 
The Honorable Henry A. Waxman: 
Ranking Member: 
Committee on Energy and Commerce: 
House of Representatives: 

Radio frequency spectrum is a natural resource used to provide an 
array of wireless communications services that are critical to the 
U.S. economy and a variety of government functions, such as national 
defense, air traffic control, weather forecasting, and public safety. 
[Footnote 1] As new spectrum-dependent technologies and services are 
brought to market in the private sector and government users develop 
new mission needs, the demand for spectrum continues to increase. A 
primary driver of the increased demand for spectrum has been the 
significant growth in commercial wireless-broadband services, 
including third and fourth generation technologies that are 
increasingly used with smart phones and tablet computers. Yet, much of 
the usable spectrum has already been allocated and assigned. 
Accommodating commercial wireless broadband and unanticipated future 
services and users, while protecting existing services and users, has 
proven challenging for the nation's spectrum management agencies--the 
Federal Communications Commission (FCC) and the National 
Telecommunications and Information Administration (NTIA).[Footnote 2] 
For example, LightSquared LLC proposed a nationwide, wireless 
broadband network that would employ both terrestrial and satellite-
based technology. However, NTIA and others identified problems with 
LightSquared's proposal, including potential interference with Global 
Positioning System (GPS) receivers which are deployed in a variety of 
applications, including navigation for commercial and military 
aircraft.[Footnote 3] 

Concern about interference, such as the potential interference between 
LightSquared's planned network and GPS receivers, has been a factor in 
managing spectrum. Historically, FCC and NTIA have used guard bands--
idle spectrum that serves as a buffer between systems--and focused on 
transmitters--the equipment that emits signals, such as television and 
radio broadcasting--to manage interference between users in adjacent 
spectrum. However, guard bands occupy valuable spectrum that could be 
allocated for current and future services and users and transmitters 
represent only half of a transmission system. The other half of a 
transmission system is the receiver, and receiver performance, such as 
a receiver's ability to filter out signals from undesired 
transmitters, can also affect interference and spectrum efficiency. 
For example, if receivers, such as receivers in cell phones, do not 
filter out signals from transmitters in adjacent spectrum, the 
receivers can be vulnerable to interference, which can inhibit use of 
adjacent spectrum or require a guard band. Therefore, improved 
receiver performance can reduce the risk of interference and allow for 
more intensive and efficient use of spectrum. As a result, Congress 
and others are considering whether additional federal or industry 
action to improve receiver performance could help aid spectrum 
efficiency, among other efforts to make more efficient use of 
spectrum. In July 2012, the President's Council of Advisors on Science 
and Technology (PCAST) made several spectrum management findings and 
recommendations, including that NTIA, in collaboration with FCC, 
establish spectrum management methodologies that consider both 
transmitter and receiver characteristics, stating that receiver 
characteristics increasingly constrain effective and efficient 
spectrum use.[Footnote 4] 

The Middle Class Tax Relief and Job Creation Act of 2012 required that 
we conduct a study of efforts to ensure that transmission systems are 
designed and operated so as to not compromise reasonable use of 
adjacent spectrum, with a focus on receiver performance as it relates 
to increasing the efficient use of spectrum.[Footnote 5] Consequently, 
we examined the following questions: (1) What actions have selected 
manufacturers and commercial licensees taken to improve receiver 
performance? (2) What actions has the federal government taken to 
improve receiver performance? (3) What are the challenges, if any, to 
improving receiver performance? (4) What options have stakeholders and 
reports identified to improve receiver performance? 

To address these questions, we reviewed relevant statutes, 
regulations, and FCC and NTIA guidance and reports. We also analyzed 
literature on receiver performance, standards, and interference from 
academic journals as well as workshop proceedings conducted by FCC, 
NTIA, and university-affiliated organizations, such as the Silicon 
Flatirons Center. We interviewed FCC and NTIA officials to learn about 
actions the spectrum management agencies have taken to improve 
receiver performance and members of NTIA's Interdepartment Radio 
Advisory Committee (IRAC)[Footnote 6] and officials from the National 
Oceanic and Atmospheric Administration (NOAA) to learn about actions 
taken by federal spectrum users to improve receiver performance. In 
addition, we interviewed officials from industry associations 
representing various spectrum users; commercial licensees and 
manufacturers; and academics and representatives from research 
organizations that have participated in proceedings on receiver 
performance, among other criteria. Through these interviews, we 
discussed the advantages and disadvantages of improving receiver 
performance to increase spectrum efficiency; actions taken by 
commercial licensees, manufacturers, and the federal government--both 
federal spectrum users and spectrum management agencies--to improve 
receiver performance; and actions that could be taken to improve 
receiver performance. Finally, we analyzed the actions taken by 
commercial licensees, manufacturers, and the federal government for a 
judgmental sample of cases of interference wherein receiver 
performance played or could play a role. These cases involved (1) 
interference between cellular and public safety services in the 800 
MHz band, (2) potential interference between satellite radio and 
wireless communication in the 2.3 GHz band, and (3) potential and 
realized interference with radar systems. We selected these cases to 
ensure variation in application or use (e.g., cellular telephone, 
navigation), federal and nonfederal users, and existence of receiver 
standards, among other characteristics. For more information on our 
scope and methodology, see appendix I. 

We conducted this performance audit from July 2012 to February 2013 in 
accordance with generally accepted government auditing standards. 
Those standards require that we plan and perform the audit to obtain 
sufficient, appropriate evidence to provide a reasonable basis for our 
findings and conclusions based on our audit objectives. We believe 
that the evidence obtained provides a reasonable basis for our 
findings and conclusions based on our audit objectives. 

Background: 

In the United States, responsibility for spectrum management is shared 
between two federal agencies: FCC, an independent agency, and NTIA, an 
administration within the Department of Commerce. FCC manages spectrum 
use for nonfederal users, including commercial, private, and state and 
local government users. NTIA manages spectrum for federal government 
users and acts for the President with respect to spectrum management 
issues. FCC and NTIA, with direction from Congress and the President, 
jointly determine the amount of spectrum allocated to federal and 
nonfederal users, including the amount to be shared by federal and 
nonfederal users.[Footnote 7] FCC and NTIA manage the radio frequency 
spectrum in the United States through allocation and assignment: 

* Allocation involves segmenting the radio spectrum into bands of 
frequencies that are designated for use by particular types of radio 
services or classes of users. (Figure 1 illustrates examples of 
services by frequency band.) In addition, spectrum managers specify 
service rules, which include the technical and operating 
characteristics of equipment. 

* Assignment, which occurs after spectrum has been allocated for 
particular types of services or classes of users, involves providing 
users, such as commercial entities or government agencies, with a 
license or authorization to use a specific portion of spectrum. FCC 
assigns licenses within frequency bands to commercial enterprises, 
state and local governments, and other entities, while NTIA authorizes 
spectrum use through frequency assignments to federal agencies. 

Figure 1: Examples of Services by Frequency Band: 

[Refer to PDF for image: illustration] 

Examples of allocated use: 

Maritime navigation signals: 
Frequency: 3 kHz-30 kHz. 

Navigational aids: 
Frequency: 30 kHz-300 kHz. 

AM radio, Maritime radio: 
Frequency: 300 kHz-3MHz. 

Shortwave radio: 
Frequency: 3 MHz-30 MHz. 

Broadcast television, FM radio: 
Frequency: 30 MHz-300 MHz. 

Broadcast television, Cellular telephone; 
Frequency: 300 MHz-3GHz. 

Space and satellite communications, Microwave systems: 
Frequency: 3 GHZ-30 GHZ. 

Radio astronomy: 
Frequency: 30 GHZ-300 GHz. 

Source: GAO. 

[End of figure] 

There are several entities that advise FCC and NTIA in their spectrum 
management activities. 

* FCC's Technological Advisory Council (TAC) consists of approximately 
50 telecommunications experts that provide technical advice to FCC and 
make recommendations on the issues and questions presented to it by 
FCC. TAC is a federal advisory committee organized under the Federal 
Advisory Committee Act.[Footnote 8] TAC is currently focused on key 
issues affecting the deployment of new broadband technologies and 
services, seeking to spur opportunities for innovation, greater 
efficiencies, and job creation. 

* The Commerce Spectrum Management Advisory Committee (CSMAC)--also 
organized under the Federal Advisory Committee Act--provides advice 
and recommendations to NTIA on a broad range of issues regarding 
spectrum management. CSMAC consists of approximately 25 private sector 
spectrum policy experts that offer insight and perspective on reforms, 
including long-range spectrum planning. Members are selected based on 
their technical background and expertise as well as to ensure 
diversity and balanced viewpoints. 

* NTIA's IRAC--an interagency advisory committee--comprised of 
representatives from 19 federal agencies that use spectrum, was 
established in 1922 to coordinate federal use of spectrum and provide 
policy advice on spectrum issues. It was originally organized by 
federal agencies that were seeking a way to resolve issues related to 
federal spectrum use in a cooperative manner. IRAC and its 
subcommittees assist NTIA in assigning frequencies for federal 
spectrum users and developing and executing policies, programs, 
procedures, and technical criteria pertaining to the allocation, 
management, and use of spectrum. 

The purpose of a communications system using spectrum is to relay 
information--audio, visual, and data--from a transmitter to a receiver 
(see figure 2). A variety of technical methods exist to encode 
information such that it can be transmitted as electromagnetic 
radiation. Antennas are components of both transmitters and receivers 
used to emit and admit, respectively, electromagnetic radiation-
carrying signals. 

Figure 2: Components of a Communications System: 

[Refer to PDF for image: illustration] 

Transmitter: Signal broadcast; 
Signal; 
Receiver: Signal received. 

Source: GAO. 

[End of figure] 

A variety of factors influence the ability of a receiver to properly 
capture the transmitted signal and decode the information for use, 
including the terrain, distance, and atmospheric conditions between 
the transmitter and the receiver. For instance, buildings, mountains, 
and foliage can prevent a transmitted signal from being properly 
received for some types of communications systems. In other instances, 
the receiver may be located too far away from the transmitter. In 
addition, communications systems must operate in environments where a 
variety of natural and man-made electromagnetic radiation is present. 
Such undesired radiation could impede a communications system's 
transmissions from reaching its intended recipients, and such an 
occurrence is called interference. It is impossible to eliminate all 
interference from communications systems and not all interference will 
prevent the proper functioning of a communications system. However, in 
some cases, the interference is considered harmful, meaning that it 
"endangers the functioning of a radionavigation service or of other 
safety services or seriously degrades, obstructs, or repeatedly 
interrupts a radiocommunication service."[Footnote 9] 

Harmful interference can occur when two communications systems use the 
same or adjacent frequencies in the same geographic area (see fig. 3). 
In the first case, co-channel interference occurs when two 
communications systems operate on the same frequency assignment in the 
same geographic area. In the second case, adjacent band interference 
occurs between two communication systems operating on different, but 
adjacent, frequency assignments in the same geographic area. Adjacent 
band interference, the focus of this report,[Footnote 10] has two main 
causes (see figure 4): 

* Transmitters emit undesired emissions into adjacent frequencies that 
can cause interference to receivers operating on those assigned 
frequencies. This is generally known as out-of-band emissions. 

* Receivers admit undesired emissions from transmitters in adjacent 
frequencies, causing those receivers to experience interference. In 
other words, the receiver cannot reject this undesired energy, 
impairing its use. 

Figure 3: Classification of Interference: 

[Refer to PDF for image: illustration] 

Types of interference: 

Co-channel: 
Operators in the same frequencies in the same geographic area. 

Adjacent band: 
Operators in adjacent frequencies in the same geographic area: 
* Transmitter's energy outside transmitter's assignment (out-of-band 
emissions): Managed by limits on transmitter's authorized bandwidth; 
* Receiver admits energy outside receiver's assignment: Managed by 
receiver performance. 

Source: GAO analysis of PCAST information. 

[End of figure] 

Figure 4: Types of Adjacent Band Interference: 

[Refer to PDF for image: 3 illustrations] 

1) No interference: The transmitters and receivers are correctly 
calibrated: 

Band A transmitter: 
Signal from Band A; 
Band A receiver: Band A signal received; 

Neighboring band transmitter: 
Neighboring band signal; 
Neighboring band receiver: Neighboring band signal received. 

2) Interference attributable to transmitter: For example, out-of-band 
emissions (OOBE) from neighboring band spill into a Band A, causing 
interference: 

Band A transmitter: Signal from Band A; 
Neighboring band transmitter: Neighboring band transmitter causes 
disruption by broadcasting OOBE; 
Band A receiver: Band A reception disrupted; 
Neighboring band receiver: Neighboring band signal received. 

3) Interference attributable to Receiver: For example, Band A receiver 
allows signal outside the assigned frequency band, resulting in 
interference: 

Band A transmitter: Signal from Band A; 
Neighboring band transmitter: Neighboring band signal; 
Band A receiver: Band A reception interference: The receiver fails to 
reject signal from a neighboring band, allowing them to interfere with 
reception of Band A; 
Neighboring band receiver: Neighboring band signal received. 

Source: GAO. 

[End of figure] 

Concerns about harmful interference are a factor in FCC and NTIA 
spectrum management decisions. To prevent harmful interference, FCC 
and NTIA have primarily focused on setting emission limits on 
transmitters and establishing guard bands--spectrum that is left 
unused between different radio services. For instance, FCC and NTIA 
often place limits on the out-of-band emissions of transmitters to 
prevent adjacent band interference. In cases where out-of-band 
emissions cannot be sufficiently lowered, FCC or NTIA establishes 
guard bands to separate the assigned frequencies of adjacent 
communications systems. When a spectrum user experiences interference, 
it can make a claim of harmful interference to the relevant agency--
FCC or NTIA--which will investigate and work to resolve the problem. 
According to FCC, applying the definition of harmful interference 
often requires case-by-case consideration, as the definition does not 
provide objective guidance on what level of service degradation or 
interruption meets the "harmful" threshold and because several 
factors, including the type and purpose of the service, must be taken 
into account. 

In addition to regulatory actions, well-designed transmitters and 
receivers can also help prevent harmful interference. Electronic 
components called filters are used by transmitters and receivers to 
help ensure that a transmitter only emits electromagnetic signals in 
its assigned frequency and a receiver only admits electromagnetic 
signals from its assigned frequency. Ideally, filters would only allow 
desired signals to pass and block all undesired signals and hence, 
adjacent band interference would never occur. However, in practice, 
filters are not perfect, which leads to the potential for harmful 
adjacent-band interference (see fig. 5). 

Figure 5: Perfect and Imperfect Filtering: 

[Refer to PDF for image: illustrated vertical bar graph] 

Signal level after filter response plotted against Radio frequency 
spectrum. 

Depicted: 

"Wanted" signal in Channel A; 
Guard band; 
"Wanted" signal in Channel B; 
Ideal filter response; 
Typical filter response; 
Unwanted signal from out-of-bank leakage. 

Source: GAO analysis of The Technology Partnership and InterDigital 
information. 

[End of figure] 

The potential for improving receivers to prevent adjacent-band 
interference has been receiving increased attention by FCC and NTIA. 
One of the most recent and high-profile examples, as described 
earlier, is the potential interference between LightSquared's proposed 
wireless broadband network and GPS receivers. There have been a 
limited number of other cases where interference concerns involved 
receiver performance to date, including potential interference between 
mobile communications services and satellite radio, comprised of 
several proceedings over more than 10 years, and between television 
receivers and unlicensed devices seeking to use spectrum between 
channels.[Footnote 11] However, an FCC official stated in a recent 
testimony that receiver performance is becoming increasingly important 
as a limiting factor in repurposing spectrum for new uses and in 
packing services closer together.[Footnote 12] FCC, working with NTIA, 
continues its efforts to repurpose spectrum for new uses and 
technologies--that is, change its rules to reallocate a band of 
spectrum from an existing use to a new use--to accommodate the growing 
demand for spectrum.[Footnote 13] 

Selected Manufacturers and Commercial Licensees Have Taken a Variety 
of Actions to Improve Receiver Performance: 

To improve receiver performance, manufacturers and commercial 
licensees have developed voluntary standards that are used to design 
and procure receiver equipment for some services. Manufacturers and 
commercials licensees have also used private negotiation, improvements 
to technology, and information sharing between and among spectrum 
users to improve receiver performance. 

Voluntary Industry Standards: 

Some industry-led organizations have adopted voluntary standards for 
receivers.[Footnote 14] Standards can help guide receiver design to 
help prevent interference from adjacent spectrum users and can be 
either voluntary or mandatory. If voluntary, the specific industry 
members voluntarily agree to meet them, but are not legally required 
to do so. If mandatory, the standards would have been imposed by 
governmental action and industry members would be legally required to 
meet them. Features of receiver standards often include selectivity, 
the ability of a receiver to separate the wanted from unwanted signals 
in the adjacent frequency; sensitivity, the detection limit of the 
receiver to admit the weakest desired signal level; and dynamic range, 
the range of desired signal levels from the weakest to the strongest 
that a receiver can admit and function properly. Several industry 
representatives told us that voluntary standards for receivers adopted 
by industry-led organizations are working well to limit interference. 

Some industry organizations have developed voluntary standards for 
receivers, including those in the aviation, satellite, and broadcast 
industries. The processes these organizations use to develop standards 
are similar and generally include bringing together a diverse group of 
stakeholders (both commercial and government) for open discussions of 
specific issues and a transparent, consensus-based decision making 
process. 

* The Telecommunications Industry Association (TIA) is a trade 
association representing the global-information and communications-
technology industry, including equipment manufacturers and commercial 
licensees, and is an American National Standards Institute (ANSI) 
accredited standards developing organization.[Footnote 15] Within TIA, 
there are committees that set standards for specific spectrum uses, 
such as the committee that sets standards for land mobile radios used 
by, among others, public safety agencies. According to TIA officials, 
developing a new standard includes the coming together of relevant 
industry stakeholders who have determined that the creation or 
amendment of standards is necessary, participation by industry and 
government stakeholders, and a documented, open process. Standards are 
typically created or amended within 1 to 3 years.[Footnote 16] 

* In the aviation industry, RTCA, Inc. develops minimum performance 
standards for aviation-related receivers.[Footnote 17] According to 
RTCA officials, these standards typically include requirements for 
rejecting signals from users in adjacent and other bands. Meetings are 
publicly announced and open to anyone with an interest in the topic or 
standard under consideration. The timelines for developing a standard 
can vary greatly, but typically take 3 to 5 years. 

* In the broadcast industry, the Advanced Television Systems Committee 
(ATSC) has established voluntary industry recommended practices for 
television receivers, which include requirements for rejecting signals 
from adjacent spectrum users. ATSC practices are created by a multi-
stakeholder group--representing the broadcast, broadcast equipment, 
motion picture, consumer electronics, computer, cable, satellite, and 
semiconductor industries--and usually take at least 1 to 2 years to 
achieve consensus. 

Once developed, voluntary industry standards may be used by 
manufacturers and commercial licensees to design and procure 
equipment. Representatives of the cellular industry told us that their 
industry relies on a voluntary approach to receiver standards and 
receiver performance, pointing out that voluntary industry standards 
are used on a daily basis between handset manufacturers and wireless 
companies. Officials at the National Public Safety Telecommunications 
Council said that the TIA standards for land mobile radios are 
commonly referenced by public safety agencies when procuring 
equipment, including receivers. Representatives of two different land 
mobile radio manufacturers told us that standards form a baseline for 
performance and that their receivers typically exceed the relevant 
performance standards. 

When procuring equipment, compliance and certification processes can 
be used to assure users that equipment meets the voluntary industry 
standards. In some cases, there is a general certification program 
that covers a particular service. For example, the National Institute 
of Standards and Technology--in partnership with other industry 
representatives, the public safety community, and other government 
agencies--has a testing process for public-safety land mobile 
radios.[Footnote 18] In other cases, compliance testing might be 
carried out by those purchasing the equipment. For example, TIA 
representatives told us that many of TIA's member companies are 
involved in testing equipment against standards, although TIA is not 
itself involved in the certification process. 

Negotiation, Improvements to Technology, and Information Sharing: 

Negotiation. In addition to developing and using voluntary industry 
standards, some manufacturers and commercial licensees privately 
negotiate interference concerns. Representatives of the cellular 
industry told us that their industry deals with interference on a 
daily basis, as interference problems are increasing and have become a 
regular part of doing business. Several industry representatives 
highlighted the cellular industry as a sector in which the wireless 
companies and manufacturers work in concert to maximize efficiency; 
these efforts often occur within the cellular spectrum bands and among 
like services. According to one industry representative, voluntary 
negotiations helped resolve interference to fixed microwave services 
that occurred in the past.[Footnote 19] The interference occurred when 
a new service began operating next to a microwave service in the 1.9 
GHz band, where the microwave receivers had been in operation for 30 
years. To resolve the interference, the parties discussed whether to 
add filters to the transmitters or the receivers and decided to add 
filters to the receivers. 

Improvements to Technology. Some manufacturers and commercial 
licensees also apply technological advancements to receivers and their 
components to improve the performance of receivers. For example, RTCA 
representatives told us that advances in filtering technology have 
been utilized in modern aviation equipment to reduce interference. One 
manufacturer of land mobile radios told us the company is continually 
making changes to equipment to improve performance and reduce 
interference. During the discussions to resolve interference to public 
safety operations using land mobile radios in the 800 MHz band, this 
manufacturer examined technical advances in receiver design that could 
help alleviate the interference. 

Information Sharing. Some manufacturers and commercial licensees share 
information to help improve receiver performance. The creation of 
standards, discussed earlier, is one area where manufacturers and 
commercial licensees, as well as other stakeholders, share information 
for the purpose of improving receiver performance. One equipment 
manufacturer told us that bringing together different stakeholders 
brings forth the best ideas to solve problems. Another example of 
communication helping to improve receiver performance was the sharing 
of information by commercial licensees, manufacturers, and industry 
associations to create guidance in response to interference between 
cellular and public safety services in the 800 MHz band. In this 
instance, after reports of interference were made in a number of 
locations, representatives of the public safety community and the 
wireless company involved came together to help resolve the 
interference. An equipment manufacturer said that there was a lot of 
cooperation and coordination among the stakeholders as they wanted to 
quickly eliminate the interference adversely affecting the mission-
critical communications of public safety agencies using land mobile 
radios. As a result of this coordination and information sharing, a 
Best Practices Guide was created that contained information on how to 
prevent interference and mitigate existing interference.[Footnote 20] 

The Federal Government Has Used Standards, Procurement, and Other 
Actions to Improve Receiver Performance: 

To improve receiver performance, federal spectrum users have mandated 
use of industry standards for receivers, specified system requirements 
to procure equipment, and negotiated with other spectrum users to 
resolve interference concerns. NTIA has mandated the use of standards 
for many federal spectrum users while FCC has not done so for 
nonfederal spectrum users, but both spectrum management agencies have 
taken actions to resolve specific cases of interference and conducted 
research to improve receiver performance. 

Federal Spectrum User Actions: 

Some federal spectrum users have specified, and in some cases 
mandated, standards for receiver performance that are often based on 
industry-developed standards.[Footnote 21] Federal agencies use 
spectrum to operate systems both for internal use and for external use 
by other parties. For external systems, federal agencies can mandate 
standards that parties must meet to use the system. For example, the 
Department of Transportation uses ASTM International standards for 
emerging communication applications among vehicles and roadside 
equipment to enable safety, mobility, and environmental benefits. 
[Footnote 22] Similarly, the Federal Aviation Administration (FAA) 
publishes Technical Standard Orders (TSO) for communication and 
navigation systems that incorporate by reference RTCA standards for 
aviation receivers.[Footnote 23] According to RTCA officials, 
compliance with TSOs can be used as one basis for FAA certification of 
communications, navigation, and surveillance equipment. RTCA standards 
for receivers typically include requirements for rejecting signals 
from adjacent and other bands to limit interference. 

In addition to using existing industry-developed standards, federal 
spectrum users work with standards-setting bodies and other 
organizations to create standards in response to particular cases of 
or concerns about interference. For example, the Coast Guard worked 
with a standards-setting body--the Radio Technical Commission for 
Maritime Services (RTCM)--to create new standards for receivers when 
its marine radio system--used for applications such as distress calls 
and port navigation--experienced interference from neighboring 
services that were operating in compliance with federal rules for 
transmitters.[Footnote 24] According to one Coast Guard official, the 
standards were created in a few months and equipment manufacturers 
began producing receivers that met the new standards in 1 to 2 years. 
Similarly, the National Aeronautics and Space Administration (NASA) is 
currently working with other space-faring nations to create standards 
to help maintain the spectrum performance of highly sensitive 
satellite downlink receivers used to obtain data from interplanetary 
spacecraft missions (e.g., Mars exploration rovers). One NASA official 
said that adjacent band interference is a concern given the sensitive 
natures of these receivers and that both transmitter and receiver 
standards can help to address a majority of interference problems. 

When procuring equipment, federal spectrum users also specify system 
and component requirements, including those for receiver performance. 
The Department of Defense (DOD) uses acquisition guidance that 
emphasizes the need to address the potential for adjacent-channel and 
adjacent-band interference when designing and procuring equipment. As 
part of this guidance, DOD has established receiver performance 
requirements that apply to all procurements by military departments. 
[Footnote 25] NOAA also specifies system performance, including 
receiver performance, when procuring equipment. According to NOAA 
officials, the agency defines a system's expected availability--that 
is, the time that a system or equipment is capable of being used--when 
procuring equipment, which is then used to determine specifications 
for system components and subcomponents including receivers. 

Federal spectrum users also privately negotiate with other spectrum 
users, both federal and nonfederal, to resolve interference concerns 
between adjacent spectrum users. According to NTIA officials and IRAC 
members, interference cases are handled on a case-by-case basis, which 
can result in making changes to individual systems such as adding 
filters to transmitters or receivers. For example, a National Science 
Foundation official said the agency is currently working to resolve 
interference to receivers that collect and process satellite signals 
from a nearby TV transmitter that was operating in compliance with FCC 
rules.[Footnote 26] IRAC members said that negotiation among federal 
spectrum users is aided by access to NTIA's database on federal 
spectrum use and by each agency having a designated spectrum manager. 
NTIA officials told us that most cases of harmful interference 
involving federal spectrum users are resolved between the cognizant 
parties rather than through NTIA. 

Spectrum Management Agency Actions: 

NTIA has mandated the use of standards for receiver performance for 
many federal users. NTIA sets mandatory standards for federal spectrum 
users in its Manual of Regulations and Procedures for Federal Radio 
Frequency Management. According to NTIA officials, these mandatory 
standards for receivers apply to about 60 percent of federal spectrum 
assignments, including land mobile radio, fixed, radar, and 
aeronautical mobile telemetry systems, and additional mandatory 
standards set by federal spectrum users like FAA cover another 10 
percent of federal spectrum assignments. NTIA and federal spectrum 
users adopt industry-developed standards when they are available for a 
given service.[Footnote 27] For federal spectrum uses that have very 
specific applications or lack a commercial equivalent, NTIA can 
establish its own standards, as it did for radar systems, or choose to 
not establish standards.[Footnote 28] NTIA's mandatory standards, 
whether set from industry standards or established by NTIA, are used 
to certify federal equipment, and when procuring equipment, federal 
spectrum users must set specifications that comply with the NTIA 
mandatory standards. NTIA has reported that these mandated standards 
have done much to prevent interference to federal spectrum users and 
that mandated standards establish a baseline of performance but do not 
prevent users from moving to more efficient or better receivers. 
[Footnote 29] 

FCC has not set mandatory receiver standards for nonfederal spectrum 
users. FCC has specific statutory authority to establish minimum 
performance standards for home electronic equipment, like 
televisions,[Footnote 30] but FCC officials said that the Commission 
lacks direct authority to impose regulations governing receiver 
performance in other cases outside home electronics. Therefore, FCC 
has generally relied on the marketplace to incentivize nonfederal 
licensees and manufacturers to produce receivers that can reject 
unwanted signals and limit interference. As noted in the previous 
section, manufacturers and commercial licensees have taken actions 
such as adopting industry standards to improve receiver performance. 
While FCC has generally relied on the marketplace to improve receiver 
performance, it has provided incentives to spectrum users to do so in 
specific cases. For example, FCC defined the minimum levels of 
performance that a receiver must meet to make a claim of harmful 
interference in the 800 MHz band. Specifically, FCC set minimum levels 
for receiver performance for non-cellular systems, primarily public 
safety radios, as part of the reconfiguration of the 800 MHz band to 
mitigate interference between non-cellular and cellular systems. 
[Footnote 31] Therefore, spectrum users that choose to use receivers 
that do not meet the minimum levels are not entitled to full 
protection from interference. The public safety community and 
manufacturers recommended that FCC set objective criteria to qualify 
for interference protection. In this case, FCC reported that taking 
further action to improve receiver performance, like requiring public 
safety radios to fully comply with industry standards to claim harmful 
interference, would impose costs that outweighed the resulting 
interference protection. 

FCC and NTIA have also taken specific actions in response to cases of 
interference involving receiver performance. FCC and NTIA officials 
said that interference cases, both potential and realized, are 
generally handled on a case-by-case basis, so actions are taken that 
address the particulars of each case. In rulemakings for new services, 
FCC often invites comment about any receiver characteristics that 
should be taken into account, particularly for receivers currently in 
use in adjacent bands. In some cases, FCC has required that a new 
spectrum user protect the incumbent services in the adjacent band from 
harmful interference regardless of the performance of the receivers in 
use, a policy known as "first-in-time rights." The Advanced Wireless 
Services (AWS)-1 spectrum, for example, was reallocated for flexible 
fixed or mobile service, such as voice and data content, which raised 
concerns about potential interference with incumbent licensees in the 
adjacent band used for broadcast auxiliary services.[Footnote 32] The 
new AWS-1 licensee purchased and arranged for the installation of new 
filters for the incumbent's receivers to avoid causing harmful 
interference as required by FCC rules for AWS-1 spectrum. NTIA's 
Institute for Telecommunication Sciences (ITS) investigates cases of 
potential or realized interference and identifies strategies to 
mitigate interference. ITS officials told us that ITS tends to work on 
interference cases that are particularly complicated or difficult to 
remedy rather than on more general interference or receiver concerns. 
For example, ITS investigated interference to fixed-satellite service 
(space-to-earth) stations in the 4 GHz band from radar systems 
operating in the adjacent band. The ITS report identified the source 
of the interference, in this case primarily because of poor filtering, 
and listed various solutions to remedy the interference. Moreover, 
NTIA is currently leading an interagency working group to examine 
receiver performance standards for GPS devices for federal users and 
the feasibility of accommodating terrestrial broadband systems in the 
bands adjacent to GPS. However, based on a 2011 Silicon Flatirons 
Center workshop of experts from government, industry, and academia, 
one theme drawn from reviewing case studies of adjacent band 
interference was that information can be lost when interference 
problems are resolved on a case-by-case basis, as other operators with 
similar problems might not have access to the resolution of other 
cases.[Footnote 33] 

In addition to mandatory standards and case-by-case actions, NTIA and 
FCC have completed reports, requested research, held workshops, and 
taken other actions on receiver performance. 

* Reports. NTIA's reports on the topic include a 2003 report 
summarizing existing receiver standards, both voluntary and mandatory, 
established by federal agencies, industry associations, and 
international groups, and a 2005 report compiling existing 
interference protection criteria for various radio services used by 
the federal government.[Footnote 34] 

* Requested research by federal advisory committees. In 2010, NTIA's 
CSMAC studied interference and dynamic spectrum access that resulted 
in recommendations on guard bands, equipment standards, and 
enforcement aimed primarily at NTIA and federal spectrum users. 
[Footnote 35] In 2012, FCC's TAC studied receivers and spectrum and 
presented recommendations to FCC.[Footnote 36] 

* Public notices and workshops. FCC has taken steps to seek 
stakeholder input and encourage dialogue on receiver performance 
though public notices and workshops on receivers and spectrum 
efficiency. In 2003, FCC issued a Notice of Inquiry seeking public 
input on whether and how it should incorporate receiver performance 
specifications into its spectrum policy.[Footnote 37] Stakeholders 
submitted comments that varied in their support for greater action, 
whether taken by FCC or the market, though a majority of comments 
favored a market driven approach, like voluntary industry standards 
for receivers. In 2007, FCC closed the proceeding stating that action 
did not appear to be needed at that time; FCC officials said that the 
comments from the rulemaking presented no clear solution, particularly 
as no single solution fit all interference problems.[Footnote 38] More 
recently, FCC held a 2-day workshop in March 2012 dedicated to 
spectrum efficiency and receivers. Participants, including licensees, 
federal agencies, equipment manufacturers, and component providers, 
examined the characteristics of receivers and how their performance 
can affect the efficient use of spectrum and opportunities for the 
creation of new services. Most participants in the workshop's 
concluding panel, which was comprised of a mix of stakeholders, noted 
that the status quo, as it relates to receiver performance, was not 
sustainable and that further action is needed. 

Several Challenges Impede Further Improvements to Receiver Performance: 

Although manufacturers, commercial licensees, and the federal 
government have taken steps to improve receiver performance, many of 
those with whom we spoke commented on what they perceive to be the 
challenges to further improvements. These challenges include the lack 
of coordination across industries when developing receiver standards, 
the lack of incentives to improve receivers, and the difficulty 
accommodating a changing spectrum environment. 

Lack of Coordination among Those Developing Standards: 

Standards are often developed for a single industry operating within a 
defined area of spectrum, such as the cellular industry. While members 
of a particular industry coordinate with each other, they may have 
little or no communication with services operating in adjacent 
spectrum bands. Although standards-setting bodies have published 
receiver standards for many services, FCC officials and several other 
stakeholders we interviewed told us that standards are often not 
developed in coordination with stakeholders representing adjacent 
services. For example, some aviation equipment operates in the 
frequencies above the FM radio band. The aviation community sets its 
own standards, while the FM radio community develops its own 
standards. Each group has its own representatives who communicate 
within their own industry but not with those in the other industry. 
This lack of coordination and lack of information sharing means that 
the impact of standards set by one group upon other groups is not 
always assessed, and immunity to adjacent-band interference is not 
necessarily addressed. 

There is also no publicly available compendium of current receiver 
performance standards or specifications to facilitate coordination or 
understanding across spectrum uses. FCC officials explained that while 
receiver performance standards have been developed for some services, 
there is no catalog of these standards, making it difficult to locate 
this information. FCC officials also told us that information about 
actual receiver performance is not readily available. Typically, this 
information only surfaces in the context of a rulemaking. For example, 
FCC made requests to equipment manufacturers for information about 
their receivers and was told by several that the information was 
proprietary, as companies did not want competitors to acquire 
information about signal strength or the energy level of devices, 
among other information. 

In addition, since standards are largely voluntary for commercial 
users, the extent that industry standards are used remains unknown. In 
fact, just because voluntary standards exist does not mean that 
licensees and manufacturers will use them. For example, with regard to 
the recommended practices for the manufacture of television sets, it 
is not known whether all manufacturers adhere to the recommended 
practices since the practices are voluntary and television licensees 
that broadcast television signals do not manufacture television sets 
or specify their operating characteristics--a situation known as 
decoupled receivers.[Footnote 39] 

Lack of Incentives to Improve Receivers: 

A lack of incentives for spectrum users and equipment manufacturers to 
improve receiver performance was another challenge that many industry 
associations and other stakeholders we interviewed cited. As one 
industry researcher explained, there are no incentives for 
manufacturers to build more robust receivers, primarily because the 
manufacturers will not receive the benefits. Rather, those who want to 
make more spectrum available or share spectrum will benefit. One 
industry representative stated that the real question is one of 
motivation. Improved receiver performance to limit adjacent band 
interference often requires the addition of filters and can increase 
the size, weight, power consumption, and cost of the receiver. 
Additionally, there is no business case that can explain why a 
business would accept these downsides so that others can benefit when 
implementing a new system in an adjacent band. Another industry 
representative echoed that position and told us that, independently, 
the private sector has no motivation to spend its time and resources 
to protect spectrum for other users, allow enhancements to other 
services, or accommodate new entrants. Instead, as one stakeholder 
commented, companies have an incentive to make the cheapest receiver 
possible--that is, a receiver with poor filtering capabilities that is 
more sensitive to emissions from other bands--and no incentive to work 
with licensees in neighboring spectrum bands. 

Similar to commercial users, federal users also lack incentives to 
improve receiver performance. The PCAST report stated that federal 
users currently have no incentive to improve the efficiency with which 
they use their own spectrum allocation, nor does the federal system as 
a whole have incentives to improve its overall efficiency. Further, we 
have previously reported that federal users often use proven, older 
technologies that were designed to meet a specific mission and may be 
less efficient than more modern systems.[Footnote 40] NTIA's CSMAC 
also recently recommended that the federal government, including NTIA, 
consider incentives, rules, and policies to, among other things, 
improve the capability of receiving devices to reject adjacent channel 
interference.[Footnote 41] 

Lastly, the use of private negotiation, which has been used regularly 
to resolve interference within the cellular industry, can be difficult 
in cases where there are dissimilar services or many parties. When 
disputes involve similar services in the same band, operators have 
similar incentives that facilitate private dispute resolution. This 
may not be the case when licensees with different services or in 
adjacent bands are involved. Also, when the number of users is 
relatively small, negotiation between parties may be able to resolve 
the problem. However, when there are many users involved, the 
transaction costs may be prohibitively high. For example, for services 
where receivers are decoupled from licensees, as in the case of 
television, the large number of receivers and potential lack of 
coordination among individual parties makes private negotiation a less 
feasible option. 

Difficulty Accommodating a Changing Spectrum Environment: 

Stakeholders we interviewed cited accommodating changes to the 
spectrum environment as a challenge to improving receiver performance. 
As FCC attempts to accommodate new services and users, the Commission 
often alters how licensees can use spectrum bands. This repurposing of 
spectrum, either from a prior use or from no use, often gives rise to 
concerns over interference, concerns that involve receiver performance 
because incumbent services have manufactured receivers to operate 
without interference problems in the current environment. However, if 
that environment changes, receivers currently in use may experience 
increased interference. This was the case in the 2.3 GHz band, where 
interference concerns arose between two different services--Wireless 
Communications Service (WCS) and Satellite Digital Audio Radio Service 
(SDARS)--allocated to adjacent spectrum. Although the WCS allocation 
allowed for mobile service, the rules limiting out-of-band emissions 
for transmitters made mobile service impractical. After years of 
attempting unsuccessfully to deploy a mobile service, the WCS 
licensees petitioned for rule changes. In considering the WCS 
licensees petition, the performance of the SDARS receivers was one of 
the critical areas of contention. SDARS receivers were not capable of 
filtering out stronger signals in adjacent spectrum. These receiver 
concerns required technical rules that effectively created guard bands 
on each sides of the SDARS spectrum to prevent interference.[Footnote 
42] 

Innovation on the part of current spectrum users is another factor 
that can change the spectrum environment. Current spectrum users may 
decide to make changes to the configuration of their system based on 
business needs. Such changes can result in interference to adjacent 
spectrum holders. For example, both Nextel, a cellular provider, and 
public safety agencies had licenses to operate in the 800 MHz band. 
Nextel decided to convert its mobile radio architecture from one that 
used high antenna sites atop buildings or towers to one that used a 
short-range cellular architecture with low antenna sites to provide 
more capacity in crowded urban areas. Even though Nextel's transmitted 
power was below customary levels, the low antenna sites caused 
interference for other users, including public-safety land mobile-
radio users, when they were close to Nextel transmitter sites. 
[Footnote 43] In 2004, FCC, in response to input from stakeholders 
including Nextel and the public safety community, proposed 
reconfiguring the 800 MHz band to separate the two systems.[Footnote 
44] 

Current practices and policies related to receiver performance may 
constrain repurposing of spectrum going forward. Representatives from 
three industry associations told us that it is difficult to build 
receivers to accommodate an unknown future. As one industry 
association member told us, the problem is not a lack of information 
on the current environment but a lack of predictability about the 
future environment. To make meaningful decisions about current 
receiver performance, the future use of spectrum would need to be 
better defined. FCC's TAC stated that part of the problem of increased 
receiver interference was the result of receivers having been built 
without adequate knowledge of future environmental performance 
constraints. Moreover, several stakeholders we interviewed also said 
that it would be difficult and could take considerable time to upgrade 
or replace receivers and equipment currently in use once deployed. In 
November 2012, an FCC official also testified that receiver 
performance is increasingly becoming a limiting factor in the 
repurposing of spectrum for new uses and in packing services closer 
together, and the official said that a continuing challenge for FCC 
will be to maximize the amount of usable spectrum for cost effective 
deployment of new communication services while sufficiently protecting 
incumbent receivers.[Footnote 45] FCC officials also said that 
interference problems between adjacent bands are growing and are more 
common in rulemakings; as noted in a recent proceeding on wireless 
innovation and investment, FCC stated that these rulemakings can be 
protracted, create uncertainty, and discourage investment.[Footnote 46] 

Stakeholders and Reports Identified Standards, Interference Limits, 
and Other Options to Improve Receiver Performance: 

Given the challenges that exist to improving receiver performance, 
stakeholders we interviewed identified options that could be taken or 
led by FCC and NTIA, with the aim of increasing spectrum efficiency. 
Below we list several recurring options based on our interviews with 
industry associations, manufacturers and commercial licensees, federal 
agencies, and representatives from academia and research 
organizations, as well as our review of reports from federal advisory 
committees and workshops on this topic (see table 1). This list of 
options is not exhaustive, but provides information on options that 
could be implemented alone or in combination. Moreover, the options 
could be applied to varying degrees; that is, applied to specific 
spectrum uses or boundaries between two different uses or on a wider 
scale. In fact, many stakeholders we interviewed indicated that each 
case of adjacent-band interference is unique, so a one-size-fits-all 
solution is likely not desirable or possible. 

Each of the options listed below entail advantages and disadvantages, 
as identified by stakeholders and reports, and thus implementing any 
of these options would involve trade-offs. Through our interviews, a 
commonly mentioned disadvantage of improving receiver performance was 
that receivers would cost more, as more components are used in their 
manufacture. In addition, many stakeholders also said that actions to 
upgrade or replace existing, legacy receivers could be costly or take 
a long time, particularly in the case of equipment designed to last 
for many years. Stakeholders frequently stated that an advantage of 
improving receiver performance was increased spectrum efficiency. It 
is difficult to quantify or estimate the overall costs and benefits of 
improving receiver performance or the amount of spectrum to be gained 
through improving receiver performance, especially given the numerous 
and varied uses of spectrum. FCC, NTIA, and others have studied many 
of these options, and at a conceptual level, the advantages and 
disadvantages are well known. However, some of these options have not 
been implemented, while others have only been implemented in limited 
cases. Therefore, the practical effects of each option, that is, what 
would happen if the option is implemented, are not well known. Many of 
the stakeholders we interviewed indicated that receiver performance is 
an important aspect of spectrum efficiency, so that it warrants 
further consideration as spectrum management agencies and spectrum 
users look for ways to make more efficient use of spectrum. For 
example, a group of experts convened by the Silicon Flatirons Center 
agreed that the advance of wireless technologies and maturing 
infrastructures had reached an inflection point where past methods of 
governance were no longer adequate and generally supported that 
spectrum management agencies more explicitly consider receivers when 
drafting rules.[Footnote 47] 

Table 1: Options Identified by Stakeholders and Reports to Improve 
Receiver Performance: 

Greater use of industry-developed standards: 
* Voluntary, industry Standards; (status quo for commercial spectrum 
users); 
Description: Standards-setting bodies and industry groups 
develop voluntary standards, which can include parameters to help 
prevent interference from adjacent spectrum users; 
Advantages: 
* Viewed by some as successful in mitigating interference; 
* Less likely to fall behind industry change or slow innovation 
compared to mandatory standards; 
Disadvantages: 
* May not be used by manufacturers and licensees; 
* Viewed by some as insufficient to date to incent licensees and 
manufacturers to improve receiver performance. 

Greater use of industry-developed standards: 
* Safe harbor; 
Description: Compliance with industry standards would be 
a prerequisite to claim harmful interference, so spectrum users that do 
not meet standards would not be entitled to interference protection 
from spectrum management agencies; 
Advantages: 
* Less likely to fall behind industry change or slow innovation 
compared to mandated standards; 
* Allows manufacturers flexibility in choosing to comply or not; 
Disadvantages: 
* Some lower-performing receivers would not be 
entitled to protection, which could be difficult in the case of widely 
deployed consumer devices. 

Greater use of industry-developed standards: 
* Mandatory standards; (status quo for many federal spectrum users); 
Description: Receiver standards would be mandatory, likely through 
regulation; 
Advantages: 
* Easy to implement compared to other approaches, as it can be 
verified through testing; 
* Approach is already widely used by NTIA; 
* Viewed by some as successful in mitigating interference; 
Disadvantages: 
* Mandated standards, if set by FCC or NTIA, could potentially slow 
innovation; 
* Raises questions about FCC's authority to broadly regulate receivers. 

Greater use of industry-developed standards: 
Interference limits; 
Description: This approach would explicitly set the level of 
interfering signals that a receiver would have to tolerate before 
making a claim of harmful interference; 
Advantages: 
* Provides spectrum users with greater certainty by setting a 
criterion for claiming harmful interference; 
* Could help enable private negotiation to resolve interference; 
* Does not mandate a specific technology or design; 
Disadvantages: 
* Complex to develop and enforce, compared to standards; 
* Untested approach. 

Greater use of industry-developed standards: 
Additional information on spectrum use; 
Description: Make additional information available on spectrum use and 
the characteristics of systems, including receivers; 
Advantages: 
* Enables more informed decision-making by spectrum managers and users; 
* Helps new entrants better understand the potential for interference; 
* Quick to implement compared to other approaches; 
Disadvantages: 
* Raises concerns about proprietary and classified information; 
* Though quick to implement, requires resources to implement and 
maintain; 
* May be insufficient on its own to improve receiver performance. 

Greater use of industry-developed standards: 
Research and development; 
Description: Promote research and development on receiver technologies 
and modeling; 
Advantages: 
* Provide more accurate information on current and prospective 
receiver performance; 
* Could help enable improvements to receivers and help lower cost of 
high-performing receivers; 
Disadvantages: 
* Advances in receiver technologies, particularly filters, may not be 
widely applicable; 
* Federal government may lack infrastructure to directly support 
research. 

Source: GAO analysis of interviews and reports. 

[End of table] 

Greater Use of Industry-Developed Standards: 

Many stakeholders we interviewed and reports we reviewed stated that 
greater use of industry standards could take different forms. Use of 
standards, voluntary and mandatory, has been long discussed and is 
widely understood since standards are currently used by nonfederal and 
federal spectrum users to varying degrees. For instance, NTIA has 
mandated use of industry standards for receivers for many federal 
spectrum uses, as noted earlier. Stakeholders offered three main ways 
that industry-developed standards could be used: voluntary, a safe 
harbor allowing spectrum users that meet standards to receive 
protection from harmful interference, and mandatory, all described in 
greater detail in table 1. 

Stakeholders we interviewed varied in their support for these options, 
but many opposed mandatory standards. Many stakeholders told us they 
prefer the industry-led, voluntary standard-creating process, in 
contrast to government-created and mandated standards, as they believe 
industry-developed voluntary standards can be responsive and flexible 
to changing conditions. While mandatory standards were often opposed 
as an overall option to improve receiver performance, some 
stakeholders told us mandatory standards could be used in limited 
cases, such as when market forces do not sufficiently incentivize the 
production of robust receivers or when receivers are not tied to the 
licensee (i.e., decoupled receivers). For the safe harbor option, 
whereby compliance with extant industry standards would serve as a 
prerequisite for receiving protection from interference, several 
industry associations and individual stakeholders we spoke with 
supported this option. In 2003, NTIA recommended that FCC adopt 
industry standards on a voluntary or recommended basis, with FCC only 
granting protection for services with receivers that meet standards, 
and in doing so, NTIA suggested that FCC give priority to bands being 
reallocated to avoid problems encountered with legacy systems. 
[Footnote 48] In addition, federal programs have encouraged compliance 
with industry standards among nonfederal spectrum users through grants 
or other funding. For example, the Department of Homeland Security's 
Emergency Communications Grant program requires that funds used by 
public safety agencies to purchase land mobile radio systems comply 
with industry standards set by TIA. As part of the transition from 
analog to digital television, NTIA offered coupons to subsidize 
consumer purchases of converter boxes, but the coupons could only be 
used to purchase converter boxes that met minimum performance 
standards.[Footnote 49] 

Regardless of the form of standards used, there are some overarching 
advantages and disadvantages. Advantages of greater use of industry-
developed standards are that this option makes use of existing 
standards and that the open, consensus-based process used to develop 
most industry standards helps ensure they reflect the knowledge and 
input of a range of industry and government perspectives. 
Disadvantages are that standards may not keep pace with industry 
change and can be prescriptive, limiting flexibility of manufacturers 
and licensees. Also, industry standards do not exist for all services. 
Further, as discussed earlier, industry standards tend to focus within 
a band or service rather than looking across boundaries; however, a 
few stakeholders we interviewed said FCC or NTIA could encourage 
standards-settings bodies to address particular problems, such as 
interference, or encourage more cross-industry bodies to help enhance 
industry standards. Some additional advantages and disadvantages apply 
to different forms of greater use of industry-developed standards, as 
listed in table 1. 

Interference Limits: 

Another option identified by stakeholders we interviewed and cited by 
reports was interference limits. The interference limits approach 
would explicitly set the level of energy--that is, the strength of the 
unwanted signal from adjacent bands--that a receiver would have to 
tolerate before making a claim of harmful interference. This is in 
contrast to the current situation where expectations of receiver 
performance have almost always been implicit--that is, receivers have 
been expected to operate within the same parameters as their 
associated transmitters--which can lead to conflicts when parties have 
a different understanding of these expectations.[Footnote 50] 

Interference limits differ from the safe-harbor standards option 
discussed above, since under the interference limits approach, the 
prerequisite for claiming harmful interference is demonstrating that 
the level of energy the receiver is exposed to exceeds a predetermined 
level, rather than demonstrating a receiver complies with industry 
standards, typically stated as specific performance characteristics. 

Recently, reports from both a working group within FCC's TAC and PCAST 
recommended that FCC test interference limits. The TAC working group 
recommended that FCC identify one or more pieces of spectrum, 
specifically adjacent spectrum allocations, that are good candidates 
for interference limits and initiate multi-stakeholder groups of 
relevant industry and government representatives to work out issues 
and implementation choices for these pieces of spectrum. PCAST 
recommended that NTIA and FCC take steps to consider both transmitters 
and receivers in its spectrum management policies and specified that 
an initial step should be trying interference limits. Other approaches 
to interference rights have been proposed, including one that aims to 
replace FCC's current policy of first-in-time rights--whereby FCC 
protects incumbent users and thus receivers from interference as a 
result of rule changes--to a policy where users would have to self-
protect against interference in adjacent bands.[Footnote 51] 

The advantages of this option cited by stakeholders and reports that 
we reviewed are that it would provide spectrum users with greater 
certainty, as it sets a criterion for harmful interference. In 
addition, this option could help enable private negotiation rather 
than FCC involvement to resolve potential and realized interference. 
Another advantage is that this option does not mandate a specific 
technology or design, leaving such choices to manufacturers and 
others. Among the disadvantages cited by stakeholders and reports are 
that this option would be more complex to develop and enforce compared 
to standards. Also, this option has not been used or tested, so it 
could take considerable time and resources to test and considerable 
time to implement and the practical effects and outcomes are unknown. 
[Footnote 52] 

Additional Information on Spectrum Use: 

Many stakeholders we interviewed said that additional transparency and 
sharing of information on spectrum use and system characteristics by 
FCC and NTIA could help mitigate interference problems involving 
receivers by facilitating greater understanding of the systems already 
in place and thus the potential for interference to arise from the 
deployment of a new system in adjacent spectrum. In general, 
stakeholders identified two ways that additional information could be 
made available. 

* First, FCC and NTIA could make more information available on the 
characteristics of transmitters and receivers in use, potentially in 
conjunction with a spectrum inventory.[Footnote 53] The CSMAC 
Interference and Dynamic Spectrum Access Subcommittee recommended that 
NTIA, FCC, or other government entities responsible for managing 
spectrum establish a clearinghouse to make information available to 
those seeking to obtain access to spectrum; this will give entities 
considering new services visibility about the potential for 
interference for such equipment before they acquire spectrum and 
deploy equipment.[Footnote 54] NTIA said that resources for 
implementing this and other CSMAC recommendations were not included in 
recent budgets, but some of its ongoing band-specific and other 
initiatives correspond with these recommendations. 

* Second, FCC could also compile and share information on existing 
industry standards for receivers. The TAC working group on receivers 
and spectrum found that industry and government receiver standards and 
recommended practices may exist but are often unknown to manufacturers 
and users operating in adjacent bands. Therefore, the TAC working 
group recommended that FCC enhance its Spectrum Dashboard--a tool on 
FCC's website that provides information on how different frequency 
bands are being used and allows the public to search, map, and 
download data on licenses--to include receiver standards. 

In terms of advantages, making additional information available would 
enable more informed decision-making by NTIA, FCC, and spectrum users 
through enhanced planning and testing. Moreover, additional 
information could help new entrants better understand the spectrum 
environment and potential interference concerns before committing 
resources; as part of its report, the CSMAC Interference and Dynamic 
Spectrum Access Subcommittee stated that some of the interference 
problems in recent years were not anticipated by new entrants and 
might have been avoided by providing new entrants with the 
interference characteristics of receiving and transmitting equipment 
used in adjacent bands. FCC and NTIA could also take action on this 
option quickly, compared to other options. However, several 
stakeholders said that concerns about proprietary and classified 
information could make it difficult to implement this option. In 
addition, it would require resources, both from federal spectrum 
management agencies and spectrum users, to implement this option and 
keep it up to date. Finally, making additional information on spectrum 
use available may be insufficient on its own to address the challenges 
to improving receiver performance. 

Research and Development: 

To improve receiver performance and increase spectrum efficiency, the 
federal government could promote research and development for receiver 
technologies and modeling. FCC officials told us that not much is 
known about the actual performance of receivers. A 2010 report 
prepared by the CSMAC Interference and Dynamic Spectrum Access 
Subcommittee found that more research is needed to evaluate advances 
in technologies and what standards will yield more spectrally 
efficient equipment, since such advances may significantly alter cost-
performance trade-offs. More specifically, it recommended that the 
federal government could fund research to accelerate the development 
of filters to improve the performance of receivers, such as the 
ability to reject an undesired signal at frequencies close to the 
desired signal frequency, without affecting size or power consumption. 
The report also noted that a better dialogue between the filter 
community and spectrum managers is essential as filter performance has 
a large impact on spectrum efficiency. One licensee we interviewed 
said that more investment is needed to improve technology for 
receivers and that new technology could help lower the cost and 
increase the flexibility of devices. A group like the Wireless 
Spectrum Research and Development's Senior Steering Group could be 
used to help coordinate research in this area across the federal 
government.[Footnote 55] Additional information gleaned through 
research could enable spectrum managers and users to better understand 
the current state of receiver performance and help inform future 
choices. 

Stakeholders said that an advantage of research and development would 
be to provide FCC and NTIA with more accurate information on 
interference mitigation technologies that are feasible. Stakeholders 
said that research could also help enable improvements to receivers to 
help prevent interference problems across bands. Conversely, this 
option would require resources, not only to fund but also to 
coordinate research efforts across the federal government and the 
private sector. Also, certain advancements through research, like 
those in filtering, may not be applicable across spectrum uses. A few 
members from one industry association we interviewed also said that 
filters can help solve some but not all problems of adjacent band 
interference. Finally, the federal government may lack infrastructure 
(e.g., test bed, labs) to directly support research. 

Conclusions: 

As demand for and use of spectrum continues to increase, improving the 
performance of receivers is one of several ways to more efficiently 
use spectrum and accommodate new services. To date, there have been a 
limited number of instances where interference concerns driven by 
receiver performance have impeded a licensee's planned use of adjacent 
spectrum. Even so, PCAST and FCC, among others, have recognized the 
growing impact of receivers on efficient spectrum use, and adjacent-
band interference concerns may increase in years to come as spectrum 
management agencies look to allocate additional spectrum for wireless 
broadband and other new services in an already crowded environment. 
Therefore, many stakeholders feel that more can and should be done to 
improve receiver performance in concert with other efforts to increase 
spectrum efficiency--the status quo is increasingly becoming 
untenable. Stakeholders have identified and studied several options to 
improve receiver performance and the efficient use of spectrum. In 
some instances, these options entail direct federal intervention, such 
as imposing mandatory standards for receivers, whereas in others, 
federal policy creates an environment where industry participants' 
individual and collective actions can improve receiver performance. 
Each of these options entail advantages, including reduced actual and 
potential interference and improved spectrum efficiency, and 
disadvantages, including possibly higher equipment costs. FCC and NTIA 
have each explored receiver performance in the past, and recent 
recommendations from advisory committees specific to this topic 
provide Congress, NTIA and FCC, and industry stakeholders with options 
for further consideration and testing. Since the topic has been the 
subject of considerable study, the potential advantages and 
disadvantages of various options are generally understood. However, 
less is known about the practical effects of implementing these 
options to address interference. Several options have not been 
implemented, such as safe harbor standards and interference limits, 
and others, such as mandatory standards, have only been implemented 
for certain federal users, and it is unclear how these experiences 
would translate to nonfederal users. Greater understanding of the 
practical effects of these options will allow FCC to make more 
informed spectrum-management decisions moving forward to ensure the 
efficient and effective use of spectrum. 

Recommendation for Executive Action: 

To improve receiver performance and spectrum efficiency, we recommend 
that the Chairman of the Federal Communications Commission consider 
collecting information on the practical effects of various options to 
improve receiver performance, including consideration of small-scale 
pilot tests of these options. 

Agency Comments and Our Evaluation: 

We provided a draft of this report to the Department of Commerce 
(Commerce) and FCC for review and comment. In response to the draft 
report, Commerce and FCC provided written comments, which are 
reprinted in appendixes II and III, respectively. In its letter, 
Commerce said that it will continue to work with FCC on issues of 
potential interference. Commerce also emphasized the federal 
government's use of standards to improve receiver performance and the 
benefits of receiver performance characteristics as a factor in 
improving spectrum efficiency. In its letter, FCC said that the 
Commission has already initiated a process to gather information on 
the effects of options to improve receiver performance; FCC discussed 
various actions under way, which we describe in this report, including 
that FCC's TAC recently submitted to the Commission for consideration 
recommendations to improve receiver performance. These actions will 
help FCC to understand the potential advantages and disadvantages of 
various options to improve receiver performance. However, we do not 
believe that these actions will provide information on the practical 
effects of options that FCC might get from a pilot test or other 
information-collection efforts, which, as we note in the report, will 
allow FCC to make more informed spectrum-management decisions. 
Commerce and FCC also provided technical corrections to the draft 
report that we incorporated as appropriate. 

We are sending copies of this report to the Secretary of Commerce, the 
Chairman of the Federal Communications Commission, and the appropriate 
congressional committees. In addition, the report will be available at 
no charge on GAO's website at [hyperlink, http://www.gao.gov]. 

If you or members of your staff have any questions about this report, 
please contact me at (202) 512-2834 or goldsteinm@gao.gov. Contact 
points for our Offices of Congressional Relations and Public Affairs 
may be found on the last page of this report. Major contributors to 
this report are listed in appendix IV. 

Signed by: 

Mark L. Goldstein: 
Director: 
Physical Infrastructure Issues: 

Appendix I: Objectives, Scope, and Methodology: 

This report examines efforts by commercial licensees, manufacturers, 
and the federal government to ensure that transmission systems are 
designed and operated so as to not compromise reasonable use of 
adjacent spectrum, with a focus on receiver performance as it relates 
to increasing the efficient use of spectrum. In particular, the report 
provides information on (1) actions taken by selected manufacturers 
and commercial licensees to improve receiver performance; (2) actions 
taken by the federal government to improve receiver performance; (3) 
challenges, if any, to improving receiver performance; and (4) options 
identified by stakeholders and reports to improve receiver performance. 

Scope and Methodology: 

To address the engagement's objectives, we reviewed relevant statutes 
and regulations, and Federal Communications Commission (FCC) and 
National Telecommunications and Information Administration (NTIA) 
documents related to spectrum management, interference, and 
transmission systems, with a focus on receivers. FCC and NTIA 
documents included presentations from FCC's March 2012 workshop on 
Spectrum Efficiency and Receiver Performance and NTIA's Receiver 
Spectrum Standards Phase 1-Summary of Research into Existing 
Standards, as well as various notices, orders, advisory committee 
reports, and other publications. We interviewed FCC and NTIA officials 
to learn about actions the spectrum management agencies have taken to 
improve receiver performance, with a focus on interference between 
adjacent spectrum users, and reviewed reports and workshops held by 
the agencies on the topic of receiver performance. We also interviewed 
members of NTIA's Interdepartment Radio Advisory Committee (IRAC), 
which consists of representatives from federal departments and 
agencies, and officials from the National Oceanic and Atmospheric 
Administration (NOAA) to learn about federal spectrum users' 
experiences with adjacent-band interference and actions to improve 
receiver performance to increase spectrum efficiency. 

We also interviewed a variety of other stakeholders outside the 
federal government--specifically industry associations, commercial 
licensees and manufacturers, and academics and representatives from 
research organizations--to learn about receiver performance and 
spectrum efficiency. We selected industry associations to cover a 
variety of spectrum uses and provide the perspectives of both 
licensees and manufacturers. We selected commercial licensees and 
manufacturers to ensure variety in frequency and application and to 
correspond to interference cases involving receiver concerns. We 
selected academics and representatives from research organizations 
based on participation in workshops on receiver performance, service 
on FCC or NTIA advisory committees, and recommendations from other 
interviewees, among other criteria. In addition, we interviewed 
officials from spectrum management agencies in Canada and the United 
Kingdom to learn about steps taken in those countries to improve 
receiver performance to increase spectrum efficiency. Across these 
interviews, we discussed the advantages and disadvantages of improving 
receiver performance to increase spectrum efficiency; actions taken by 
the commercial licensees, manufacturers, and the federal government to 
improve receiver performance; and options for additional action to 
improve receiver performance. 

Table 2 provides a complete list of those we interviewed for this 
report. The information and perspectives that we obtained from the 
interviews may not be generalized to all industry stakeholders that 
have an interest in spectrum efficiency and receiver performance. 
Rather, comments and views are reviewed in context with current 
literature on this topic. 

Table 2: Organizations and Individuals Interviewed: 

Industry associations: 

Association of Public-Safety Communications Officials; 
Consumer Electronics Association; 
CTIA - The Wireless Association; 
International Wireless Industry Consortium; 
National Association of Broadcasters; 
National Cable and Telecommunications Association; 
National Public Safety Telecommunications Council; 
National Spectrum Management Association; 
RTCA, Inc. 
Rural Carriers Association; 
Satellite Industry Association; 
Telecommunications Industry Association; 
Wireless Internet Service Providers Association. 

Commercial Licensees and Manufacturers: 

AT&T; 
Garmin International; 
John Deere; 
LightSquared; 
Motorola; 
Sprint; 
Trimble. 

Academics, representatives from research organizations, and 
consultants: 

Dale Hatfield, Silicon Flatirons Center; 
Dennis Roberson, Illinois Institute of Technology; 
Harold Feld, Public Knowledge; 
Evan Kwerel, FCC, and John Williams, Ambit; 
Michael Calabrese, New America Foundation; 
Michael Marcus, Marcus Spectrum Solutions LLC; 
Paul Kolodzy, Kolodzy Consulting LLC; 
Paul Sinderbrand, WCS Coalition Legal Counsel; 
Pierre de Vries, Silicon Flatirons Center; 
William Webb, Neul. 

Spectrum management agencies: 

Industry Canada; 
Ofcom - United Kingdom regulator. 

Source: GAO. 

[A] We included Evan Kwerel of FCC in this table since he was 
identified based on our criteria for selecting academics and 
representatives from research organizations to interview. 

[End of table] 

We also analyzed literature on receiver performance, standards, and 
interference from academic journals as well as workshop proceedings 
and reports on receiver performance and interference conducted by FCC, 
NTIA, and organizations like the Silicon Flatirons Center, Brookings 
Institution, and Aspen Institute. To identify relevant literature, we 
performed a search of papers and studies (from 2002 through 2012) from 
major electronic databases, such as ProQuest and SciSearch. We 
included studies that focused on interference between adjacent 
spectrum users and spectrum efficiency. We only included papers from 
scholarly peer-reviewed journals, government reports, conference 
papers, and other working papers. We also conducted a targeted search 
for proceedings from conferences that occurred between 2008 and 2012 
that covered receiver performance, spectrum, and interference. We 
reviewed the relevant papers, studies, and conference proceedings to 
identify options to improve receiver performance as well as the 
advantages and disadvantages of taking action to improve receiver 
performance. 

We also studied a judgmental sample of cases where receiver 
performance played a role in cases of potential or realized 
interference between adjacent spectrum users, to better understand the 
actions of commercial licensees, manufacturers, and the federal 
government as well as the trade-offs of solutions sought in each case. 
We selected cases to ensure variation in application or use (e.g., 
cellular telephone, navigation), federal and nonfederal users, and 
existence of receiver standards, among other characteristics. To 
compile a list of possible cases, we reviewed FCC and NTIA reports, 
including the FCC's Technological Advisory Council white paper on 
spectrum efficiency metrics that included an appendix on receiver 
performance and NTIA published reports on interference involving 
federal users, and discussed potential cases with officials from FCC 
and NTIA. We selected two cases that primarily involved nonfederal 
spectrum users: (1) interference between cellular and public safety 
services in the 800 MHz band, and (2) potential interference between 
satellite radio and wireless communication in the 2.3 GHz band. We 
sought to select a third case of interference involving federal 
spectrum users of radar systems. However, since our aim was to select 
cases that involved receiver performance problems, and since NTIA 
officials told us that many cases of interference involving federal 
spectrum users are resolved without substantial NTIA involvement, we 
did not select a particular interference case. Rather, we chose to 
study radar systems more generally. For each case, we analyzed 
relevant rulemaking proceedings, reports, and other documents to 
describe the types and extent of actions taken by stakeholders to 
limit interference and increase spectrum efficiency. In addition, we 
interviewed select licensees, industry associations, and manufacturers 
to better understand the circumstances of each case, actions taken to 
address interference, and the trade-offs of these actions. 

Case Study Descriptions: 

WCS/SDARS: In the 2.3 GHz band, interference concerns arose between 
two different services--terrestrial-based Wireless Communications 
Service (WCS) and chiefly satellite-based Satellite Digital Audio 
Radio Service (SDARS, or satellite radio)--allocated to adjacent parts 
of the bands with no guard bands separating the services. WCS allows a 
range of terrestrial-based services, including fixed, mobile, 
portable, and radiolocation services, though initial rules for the 
band made mobile service impractical. SDARS is primarily a satellite-
based service in which programming is sent directly from satellites to 
receivers that are either at a fixed location or in motion; however, 
SDARS licensees deployed terrestrial repeaters to address situations 
where skyscrapers and other impediments prevented a line-of-sight 
connection between satellites and receivers. In general, SDARS 
receivers must be highly sensitive to receive weak, satellite signals. 
Moreover, SDARS deployed before WCS, so SDARS receivers did not have 
to tolerate high-powered mobile operations in the adjacent WCS bands. 
SDARS licensees raised concerns over interference from a request to 
change rules to enable mobile services in the WCS spectrum, while WCS 
licensees and others raised concern over potential interference from 
the SDARS terrestrial repeaters. 

FCC issued several notices of proposed rulemaking for both services 
since their allocation in the mid 1990s. FCC also encouraged the 
parties to negotiate an agreement to facilitate the adoption of rules 
for both services that would resolve the potential for interference. 
However, negotiations did not lead to a private resolution, and in 
2007, FCC opened a new proceeding to update the record on the 
potential interference. This culminated in a 2010 Report and Order and 
Second Report and Order that adopted rules addressing the potential 
interference.[Footnote 56] FCC adopted rules that, among other things, 
effectively created 5 MHz guard bands on each side of the SDARS 
spectrum to protect legacy SDARS receivers; the rules did not include 
any requirements specific to receiver performance. In 2012, FCC 
responded to petitions for reconsideration of that decision with a new 
order that adopted an agreement reached by AT&T and Sirius XM, which 
are now the primary license holders in the band.[Footnote 57] 

800 MHz band: Interference occurred between adjacent spectrum users in 
the 800 MHz band primarily because of the use of two different types 
of communications systems on interleaved channels. The two types of 
communications systems were (1) cellular-architecture multi-cell 
systems used by cellular telephone and enhanced specialized mobile 
radios and (2) high site systems used by public safety and well as 
private wireless and non-cellular specialized mobile radio licensees. 
Beyond the difference in systems, two other factors exacerbated the 
potential for interference: the close proximity of frequencies used by 
the commercial and public safety users and insufficient selectivity of 
many land mobile radios used by public safety users. 

Interference from cellular systems to public safety systems began to 
occur in the late 1990s as cellular licensees began deploying multi-
cell systems. Interference occurred even though all the licensees were 
operating in compliance with FCC rules for transmitters. After 
interference problems emerged, FCC brought together the relevant 
parties and encouraged them to develop more definitive information on 
the scope and severity of the problem and to recommend steps to 
mitigate interference. As a result, a working group created a Best 
Practices Guide to help prevent and mitigate interference in the band. 
Seeking a more comprehensive solution to the interference problem, 
Nextel--the primary license holder in the 800 MHz band--proposed 
reconfiguring the band to separate the different systems and then 
worked with many public safety and other industry associations to 
create an updated reconfiguration plan. In addition, the public safety 
community and equipment manufacturers recommended receiver performance 
specifications going forward that would serve as criteria for 
qualifying for interference protection. FCC adopted these 
recommendations in the rules it adopted for the 800 MHz band in 2004, 
which reconfigured the band and defined a technical standard for 
determining if a public safety or other non-cellular licensee is 
entitled to interference protection.[Footnote 58] 

[End of section] 

Appendix II: Comments from the Department of Commerce: 

United States Department of Commerce: 
The Assistant Secretary for Communications and Information: 
Washington, D.C. 20200: 

February 6, 2013: 

The Honorable Gene L. Dodaro: 
Comptroller General: 
U.S. Government Accountability Office: 
441 G Street, NW: 
Washington, DC 20548: 

Dear Comptroller General Dodaro: 

Thank you for the opportunity to review and comment on the U.S. 
Government Accountability Office's (GAO) draft report entitled 
Spectrum Management: Further Consideration of Options to improve 
Receiver Performance Needed (GAO-I3-265). The National 
Telecommunications and Information Administration (NTIA) appreciates 
the work that GAO has done to highlight the actions NTIA has taken to 
improve receiver performance, NTIA recognizes the benefits of receiver 
performance characteristics as a factor in improving the
efficiency and effectiveness of spectrum management and concurs with 
the draft report's findings. 

As discussed in the Report, the federal government uses standards to 
improve receiver performance. For example, NTIA mandated receiver 
standards for land mobile radio, fixed, and radar systems. The Federal 
Aviation Administration publishes Technical Standard Orders that refer 
to Radio Technical Commission for Aeronautics standards for aviation 
receivers. The United States Coast Guard uses maritime receiver 
standards developed by the International Electrotechnical Commission. 
The Inter-Range Instrumentation Group developed receiver standards for 
aeronautical telemetry systems. NTIA also requires compliance with 
industry-developed transmitter and receiver standards where applicable. 

NTIA will continue to work closely with the Federal Communications 
Commission (FCC) on particular service or band-specific proceedings in 
which issues arise regarding potential out-of-band and adjacent band 
interference between federal and non-federal systems. Through the 
notice and comment rulemaking process, or in pre-rulemaking 
collaborative efforts such as those now taking place in the Commerce 
Spectrum Management Advisory Committee, interested parties can be made 
aware of the performance characteristics of proposed and existing 
receiving and transmitting equipment on a case-by-case basis, which 
will better inform the FCC's proceedings. 

Thank you again for the opportunity to review and comment on the draft 
report. 

Sincerely, 

Signed by: 

Lawrence E. Strickling: 

[End of section] 

Appendix III: Comments from the Federal Communications Commission: 

Federal Communications Commission: 
Washington, DC 20554: 

February 8, 2013: 

Mr. Gene Dodaro: 
Comptroller General: 
Government Accountability Office: 
441 G Street, NW: 
Washington, DC 20548: 

Dear Mr. Dodaro: 

Thank you for the opportunity to review and comment on the Government 
Accountability Office's (GAO) draft report, entitled Spectrum 
Management: Further Consideration of Options to Improve Receive 
Performance Needed. In your draft report, you recommend that, to 
improve receiver performance and efficiency, the FCC consider 
collecting data on the practical effect of various options to
improve receiver performance. The FCC has already initiated this type 
of fact-gathering process. 

Receiver performance is an area of increased attention as the 
Commission seeks to make more efficient use of the radio frequency 
spectrum. Last year, Chairman Genachowski initiated a review of
spectrum efficiency and receiver standards with a two-day workshop 
held at FCC headquarters featuring a broad range of experts and 
stakeholders, including licensees, equipment manufacturers, and 
consumers. Commission staff also regularly participates in various 
technical groups organized by private sector entities to discuss ideas 
about how to address receiver spectrum issues and meets with filter 
and electronic component suppliers to discuss technology developments 
that hold promise for improving the interference rejection 
capabilities of receivers. Moreover, Chairman Genachowski tasked the
Commission's Technological Advisory Council (TAC) to study the issue 
of receiver performance. 

The Receivers and Spectrum Work Group of the TAC addressed the role of 
receivers in ensuring efficient use of the spectrum while avoiding 
potential obstacles to making spectrum available for new services. The 
TAC Work Group concluded generally that the private sector has 
published receiver standards for many services, but they often are not 
developed in coordination with adjacent services, are not well known, 
and their basis not well understood. The Work Group also introduced a 
new and novel approach to incentivize improved receiver performance. 
The new approach would establish an interference protection limit 
between services to define the signal levels that the services would be
expected to tolerate from adjacent services. Service providers and 
equipment manufacturers would then have the information they need to 
design their equipment to tolerate these signal levels. A licensee 
would need to demonstrate that it is experiencing signal levels above 
the limit in order to make a claim of harmful interference (harm claim 
threshold). 

In December 2012, the TAC submitted to the Commission for consideration 
recommendations to improve receiver performance. The recommendations 
include: 1) Implementing a web-accessible receiver standards and 
voluntary receiver specification repository through the FCC Dashboard; 
2) Fostering Multi-Stakeholder (MSH) Group(s) to consider an 
interference limits policy at one or more service boundaries, 
including current/future receiver performance levels; 3) Issuing 
appropriate requests for information on an interference limits policy 
focusing on current bands of interest; and 4) Establishing a focused 
effort to develop the needed technical foundation to support the 
establishment of harm claim thresholds. The TAC is also on schedule to 
release by the end of this month its While Paper on Interference 
Limits Policy recommendations and the use of harm claim thresholds to 
improve the interference tolerance of wireless systems. 

Receiver performance is becoming increasingly important as a limiting 
factor as the Commission moves to repurpose spectrum and pack more 
services closer together. The continuing challenge will be to
maximize the amount of usable spectrum for cost-effective deployment 
of new communication services while sufficiently protecting incumbent 
receivers. If receiver technology remains static or is unable to
keep pace with the rapid evolution of the transmission technologies, 
the challenges before the Commission will increase dramatically. 

The Commission has and will continue to collaborate with NTIA to make 
available a total of 500 MHz of additional federal and non-federal 
spectrum suitable for both mobile and fixed wireless broadband use by 
2020. To do this, the Commission is focusing on complementary 
approaches including: auctioning additional spectrum, removing 
regulatory barriers to flexible spectrum use, clearing new bands
for flexible broadband use and promoting advanced spectrum sharing 
techniques. Since the large majority of spectrum is shared among 
commercial and federal users, implementing any approach to make
additional spectrum available for mobile broadband will result in 
frequency adjacencies to federal users. Therefore a comprehensive 
approach between the FCC and NTIA will be needed to incorporate receiver
performance into our collective spectrum management responsibilities 
that involves both non-federal and federal spectrum users. 

We are committed to maximizing efficient use of the spectrum, 
including taking steps to improve receiver performance. To achieve 
these goals, the Commission will need to consider whether the
approach recommended by the TAC, other approaches, or a combination of 
approaches may be the best way forward. There are many factors to 
consider such as their effectiveness, viability and costs compared
to benefits, among others and further work that may need to be 
completed. Moreover, we will continue to work closely with NTIA and 
other federal stakeholders as we consider next steps. 

Sincerely, 

Signed by: 

Julius P. Knapp: 
Chief: 
Office of Engineering and Technology: 
Federal Communications Commission: 

[End of section] 

Appendix IV: GAO Contact and Staff Acknowledgments: 

GAO Contact: 

Mark L. Goldstein, (202) 512-2834 or goldsteinm@gao.gov: 

Staff Acknowledgments: 

In addition to the contact person named above, Michael Clements, 
Assistant Director; Nabajyoti Barkakati; Stephen Brown; Leia 
Dickerson; Sharon Dyer; Ryan Eisner; David Goldstein; Richard Hung; 
Bert Japikse; Joanie Lofgren; Maren McAvoy; Joshua Ormond; Amy 
Rosewarne; Hai Tran; Elizabeth Wood; and Nancy Zearfoss made key 
contributions to this report. 

[End of section] 

Footnotes: 

[1] The radio frequency spectrum is the part of the natural spectrum 
of electromagnetic radiation lying between the frequency limits of 3 
kilohertz (kHz) and 300 gigahertz (GHz). Radio frequencies are grouped 
into bands and are measured in units of Hertz, or cycles per second. 
The term kHz refers to thousands of Hertz, megahertz (MHz) to millions 
of Hertz, and GHz to billions of Hertz. The Hertz unit of measurement 
is used to refer to both the quantity of spectrum (such as 500 MHz of 
spectrum) and the frequency bands (such as the 1710-1755 MHz band). 

[2] NTIA is responsible for managing the federal government's use of 
spectrum while FCC is responsible for managing nonfederal spectrum use. 

[3] Because of the unresolved interference problem, FCC prohibited 
LightSquared from deploying its service commercially. FCC has an open 
proceeding as LightSquared proposed operating its service in a 
different frequency band; see Federal Communications Commission 
Invites Comments on LightSquared Request to Modify Its ATC 
Authorization, 27 FCC Rcd. 14,290 (2012). 

[4] President's Council of Advisors on Science and Technology, Report 
to the President: Realizing the Full Potential of Government-held 
Spectrum to Spur Economic Growth (July 2012). 

[5] Pub. L. No. 112-96, § 6408, 126 Stat 156, 232 (2012). 

[6] IRAC's main function is to assist NTIA in assigning frequencies 
and in developing policies, procedures, and technical criteria on 
management and use of spectrum. IRAC is comprised of representatives 
from 19 federal agencies that use spectrum. 

[7] The Department of State also plays a role in spectrum management 
by coordinating and mediating the U.S. position and leading the 
nation's delegation to international conferences on spectrum 
management. 

[8] Pub. L. No. 92-463, 86 Stat. 770 (1972), codified as amended at 5 
U.S.C. App. 2. 

[9] To be considered harmful interference, the affected system must be 
operating in accordance with [the International Telecommunication 
Union (ITU)] Radio Regulations. The ITU is an international 
organization within the United Nations System where governments and 
the private sector coordinate global telecom networks and services. 47 
C.F.R. § 2.1 and ITU Radio Regulations, Provisions of No. 1.169. 

[10] Public Law 112-96 required GAO to study interference between 
adjacent spectrum uses, rather than co-channel interference between 
users of the same spectrum. 

[11] For a list of situations where receiver performance was a 
significant issue affecting access to spectrum for new services, 
including the LightSquared and GPS example, see FCC Technical Advisory 
Council, Sharing Work Group, "Case Studies: The Role of Receiver 
Performance in Promoting Efficient Use of the Spectrum," Appendix C in 
Spectrum Efficiency Metrics White Paper (December 2011). 

[12] Statement of Ronald T. Repasi, Deputy Chief, Office of 
Engineering and Technology, Federal Communications Commission, Before 
the House Communications and Technology Subcommittee, Energy and 
Commerce Committee, U.S. House of Representatives. "The Role of 
Receivers in a Spectrum Scarce World." November 29, 2012. 

[13] In March 2010, an FCC task force issued the National Broadband 
Plan which recommended that FCC make 500 MHz of spectrum available for 
broadband within the next 10 years, and in June 2010, the President 
issued a memorandum with a similar goal for NTIA working in 
collaboration with FCC. See Federal Communications Commission, 
Connecting America: The National Broadband Plan (Washington, D.C.: 
Mar. 16, 2010) and Memorandum for the Heads of Executive Departments 
and Agencies, Unleashing the Wireless Broadband Revolution, 75 Fed. 
Reg. 38,387 (June 28, 2010). 

[14] According to Office of Management and Budget (OMB) guidance, a 
standard is the common and repeated use of rules, conditions, 
guidelines, or characteristics for products or related processes and 
production methods, and related management systems practices. See 
Office of Management and Budget Circular A-119. Pursuant to OMB 
Circular A-119, the term "standard," or "technical standard," as cited 
in the National Technology Transfer and Advancement Act of 1995, Pub. 
L. No. 104-113, § 12, 110 Stat. 775 (1995), also encompasses the 
definition of terms; classification of components; delineation of 
procedures; specification of dimensions, materials, performance, 
designs, or operations; measurement of quality and quantity in 
describing materials, processes, products, systems, services, or 
practices; test methods and sampling procedures; or descriptions of 
fit and measurements of size or strength. 

[15] ANSI oversees the creation, promulgation, and use of thousands of 
norms and guidelines that affect businesses in many sectors. Its 
mission is to enhance the global competitiveness of U.S. business and 
the U.S. quality of life by promoting and facilitating voluntary 
consensus standards and conformity assessment systems. ANSI is also 
actively engaged in accrediting programs that assess conformance to 
standards. 

[16] When a TIA standard is also an ANSI standard, ANSI reviews the 
standards-setting process and puts the standard out for public notice, 
in addition to TIA's steps and processes. 

[17] RTCA is a private, not-for-profit corporation that develops 
consensus-based recommendations on communications, navigation, 
surveillance, and air traffic management system issues. RTCA standards 
serve as a partial basis for subsequent FAA regulatory and 
certification processes. 

[18] The Project 25 Compliance Assessment Program (CAP) is a voluntary 
program that allows public safety equipment suppliers to formally 
demonstrate their products' compliance with a select group of 
requirements by testing them in recognized labs. CAP is a partnership 
of the Public Safety Communications Research program, the National 
Institute of Standards and Technology, the Department of Homeland 
Security, industry, and the public safety community. 

[19] Fixed point-to-point microwave service refers to a radio 
communication between two fixed points, such as between two stationary 
cell phone towers. These connections, known as links, are used for a 
variety of purposes, including connecting cellular sites to the 
telephone network and relaying television signals. 

[20] A group including Motorola, the Association of Public-Safety 
Communications Officials (APCO), Nextel Communications, CTIA, and the 
Public Safety Wireless Network (PSWN) developed the guide. See 
Avoiding Interference Between Public Safety Wireless Communications 
Systems and Commercial Wireless Communications Systems at 800 MHz, A 
Best Practices Guide (December 2000). 

[21] In general, these mandated standards are more stringent than 
requirements for federal spectrum users set by NTIA, discussed in the 
section below. 

[22] ASTM International is a standards-setting body that develops 
voluntary, consensus-based standards covering a range of engineering 
disciplines including aerospace, industrial, mechanical, and solar 
engineering. 

[23] For example, RTCA/DO-229D, Minimum Operational Performance 
Standards for Global Positioning System/Wide Area Augmentation System 
Airborne Equipment, dated December 13, 2006, Section 2, is 
incorporated by reference in Stand-Alone Airborne Navigation Equipment 
Using the Global Positioning System Augmented by the Satellite Based 
Augmentation System, TSO-C146c, 2 (2008), except as modified in 
appendix 1 of the TSO. 

[24] In investigating this interference, NTIA reported that the 
neighboring nonfederal services were operating in compliance with FCC 
rules and regulations for their transmitters, making it difficult to 
impose operating restrictions on the operators. Therefore, NTIA 
reported that practical solutions to solve the interference were to 
continue to develop receiver standards through RTCM, encourage 
mariners to use radios that are more resistant to interference, and to 
develop guidelines for future deployment of neighboring services to 
reduce interference. See NTIA-99-362, Evaluation of Marine VHF Radios: 
Performance in the Savannah, Ga. and New Orleans, La. Port Areas 
(Washington, D.C.: March 1999) and NTIA-99-363, Evaluation of Marine 
VHF Radios: Compliance to IEC Receiver Standards (Washington, D.C.: 
October 1999). 

[25] The requirements are included in DOD MIL-HDBK-237D, 
Electromagnetic Environmental Effects and Spectrum Certification 
Guidance for the Acquisition Process and DOD MIL STD 461F, 
Requirements for the Control of Electromagnetic Interference 
Characteristics of Subsystems and Equipment, among other documents. 

[26] While the parties work to find a solution to the interference, 
which could include getting a new frequency assignment for the TV 
transmitter from FCC, the TV operator turned off the transmitter. 

[27] OMB Circular A-119 directs agencies to use voluntary consensus 
standards in lieu of government-unique standards except where 
inconsistent with law or otherwise impractical. 

[28] NTIA officials said that the federal systems not currently 
covered by receiver standards are specialized systems operated for 
scientific and military purposes; for these applications, developing a 
standard is not practicable because only a limited number of systems 
are typically manufactured. In cases where there are not standards, 
NTIA officials said the agency assumes that federal users of spectrum 
will work out solutions to interference problems among themselves. 

[29] NTIA Comments on Interference Immunity Performance Specifications 
for Radio Receivers (Washington, D.C.: Nov. 12, 2003). 

[30] 47 U.S.C. § 302a(a)(2). 

[31] Reconfiguration involved separating previously interwoven 
cellular and non-cellular licenses into separate parts of the band. 
See In the Matter of Improving Public Safety Communications in the 800 
MHz band, 19 FCC Rcd. 14,969, 15,024, 15,027, 15,029 (2004). 

[32] AWS is the collective term used for new and innovative fixed and 
mobile terrestrial wireless applications including those using voice 
and data content, such as Internet browsing, message services, and 
full-motion video. Broadcast auxiliary service is primarily used for 
electronic news gathering to distribute live television shots from the 
field to the studio. 

[33] Madelaine Maior, Efficient Interference Management: Regulation, 
Receivers, and Rights Enforcement, A report on a Silicon Flatirons 
Summit, held 18 October 2011 (January 10, 2012). 

[34] NTIA Report 03-404, Receiver Spectrum Standards: Phase 1-Summary 
of Research into Existing Standards (Washington, D.C.: November 2003) 
and NTIA Report 05-432, Interference Protection Criteria: Phase 1-
Compilation from Existing Sources (Washington, D.C.: October 2005). 
The 2003 report summarized NTIA's review of existing standards and has 
not been updated since that time. 

[35] Dynamic spectrum access technology enables systems to actively 
search for unused spectrum and organize a network of transmitters and 
receivers to operate in it, thereby ensuring that no interference is 
caused to other users. Dynamic spectrum access technologies are 
currently able to sense for available frequencies before transmission 
(listen before talk), but not sense during transmission (listen while 
talk) which could allow more seamless communication while moving 
between spectrum bands. 

[36] The findings and recommendations from these advisory committees 
are described in greater detail in the last section of this report on 
options to improve receiver performance. 

[37] This Notice built off the work of the Spectrum Policy Task Force, 
established by the FCC Chairman in June 2002 to assist FCC in 
identifying and evaluating changes in spectrum policy that could 
increase the public benefits derived from the use of radio spectrum. 
In 2002, the Spectrum Policy Task Force Report recommended that FCC 
consider applying receiver performance requirements, through 
incentives, regulatory mandates, or some combination both, to 
facilitate greater access to spectrum. Spectrum Policy Task Force 
Report, ET Docket No. 02-135, 35, p.31 (November 2002). See also In 
the Matter of Interference Immunity Performance Specifications for 
Radio Receivers, Notice of Inquiry, 22 FCC Rcd. 8,941 (2007), and 
Review of the Commission's Rules and Policies Affecting the 
Conversation to Digital Television, 18 FCC Rcd. 6,039 (2003). 

[38] In closing the proceeding, FCC noted that it could address 
receiver performance problems in individual future proceedings for 
specific services or frequencies. 

[39] In general, decoupled receivers are receivers that are not 
controlled by the license holder that transmits signals for a service. 
Common examples of decoupled receivers include radios, televisions, 
and GPS devices. 

[40] See GAO, Spectrum Management: Incentives, Opportunities, and 
Testing Needed to Enhance Spectrum Sharing, [hyperlink, 
http://www.gao.gov/products/GAO-13-7] (Washington, D.C.: November 
2012). 

[41] See Commerce Spectrum Management Advisory Committee, Interference 
and Dynamic Spectrum Access Subcommittee Final Report (Washington, 
D.C.: Nov. 8, 2010). 

[42] See In the Matter of Amendment of Part 27 of the Commission's 
Rules to Govern the Operation of Wireless Communications Services in 
the 2.3 GHz Band, 25 FCC Rcd. 11,710 (2010). 

[43] Summary based on Pierre de Vries, Radio Regulation Summit: 
Defining Inter-channel Operating Rules, A report on a Silicon 
Flatirons Summit on Information Policy (Dec. 2, 2009). 

[44] In the Matter of Improving Public Safety in the 800MHz Band, 
Report and Order, 19 FCC Rcd. 14,969, 19 FCC Rcd. 19,651, 19 FCC Rcd. 
21,818 (2004). 

[45] Statement of Ronald T. Repasi, Deputy Chief, Office of 
Engineering and Technology, Federal Communications Commission, Before 
the House Communications and Technology Subcommittee, Energy and 
Commerce Committee, U.S. House of Representatives, "The Role of 
Receivers in a Spectrum Scarce World." November 29, 2012. 

[46] In the Matter of Fostering Innovation and Investment in the 
Wireless Communications Market, 24 FCC Rcd. 11,322, 11,332 (2009). 

[47] Pierre de Vries, Radio Regulation Summit: Defining Inter-channel 
Operating Rules, A report on a Silicon Flatirons Summit on Information 
Policy, held September 8-9, 2009 (Dec. 2, 2009). 

[48] NTIA Comments on Interference Immunity Performance Specifications 
for Radio Receivers (Washington, D.C.: Nov. 12, 2003). 

[49] Rules to Implement and Administer a Coupon Program for Digital-to-
Analog Converter Boxes, 72 Fed. Reg. 12,097, 12,101 (Mar. 15, 2007). 
Converter boxes allowed consumers with analog televisions to continue 
to be able to receive over-the-air television signals after the 
broadcasters switched to all digital broadcasts. 

[50] For more information, see Federal Communications Commission, 
Technological Advisory Council, Receivers and Spectrum Working Group, 
Interference Limits Policy: The use of harm claim thresholds to 
improve the interference tolerance of wireless systems, White Paper 
(Feb. 6, 2013), accessed Feb. 13, 2013, [hyperlink, 
http://transition.fcc.gov/bureaus/oet/tac/tacdocs/WhitePaperTACInterfere
nceLimitsv1.0.pdf].  

[51] For more information on this approach, see Evan Kwerel and John 
Williams, "Forward-Looking Interference Regulation," The Unfinished 
Radio Revolution: Eight Perspectives on Wireless Interference, ed. 
Pierre de Vries and Kaleb A. Sieh, vol. 9 of Journal on 
Telecommunications and High Technology Law (Boulder, CO: Spring 2011), 
516. 

[52] In the United Kingdom, Ofcom officials said that spectrum usage 
rights--an approach akin with those described above--have been 
implemented for one band; but, spectrum usage rights have not been 
more widely adopted or tested to date. 

[53] Legislation was introduced in the 112th Congress to address the 
lack of publicly available data on spectrum usage. Reforming Airwaves 
by Developing Incentives and Opportunistic Sharing Act, S. 455, § 3, 
112th Cong. (2011). The bill would have required FCC to prepare an 
inventory of radio spectrum bands managed by FCC, including the number 
of transmitters and receiver terminals in use and information on 
receiver performance. 

[54] This report included several recommendations to NTIA, FCC, and 
any other government entities responsible for spectrum management 
related to making information available on spectrum use and 
characteristics. See CSMAC, Interference and Dynamic Spectrum Access 
Subcommittee Final Report. 

[55] Formed as result of a 2010 Presidential Memorandum, Unleashing 
the Wireless Broadband Revolution, the Wireless Spectrum Research and 
Development's Senior Steering Group coordinates spectrum-related 
research and development activities across the federal government, and 
helps identify gaps in the government's research and development 
portfolio with respect to spectrally efficient technologies. 

[56] In the Matter of Amendment of Part 27 of the Commission's Rules 
to Govern the Operation of Wireless Communications Services in the 2.3 
GHZ Band, 25 FCC Rcd. 11,710 (2010). 

[57] In the Matter of Amendment of Part 27 of the Commission's Rules 
to Govern the Operation of Wireless Communications Services in the 2.3 
GHZ Band, 27 FCC Rcd. 13,651 (2012). 

[58] See In the Matter of Improving Public Safety in the 800MHz Band, 
19 FCC Rcd. 14,969, 14,973, Second Erratum, 19 FCC Rcd. 19,651, Third 
Erratum, 19 FCC Rcd. 21,818 (2004). 

[End of section] 

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