SPECTRUM 

MANAGEMENT

Further Consideration 

of Options to Improve 

Receiver Performance 

Needed

Report to Congressional Committees

February 2013

GAO-13-265

United States Government Accountability Office

GAO
United States Government Accountability Office

Highlights of GAO-13-265, a report to 

congressional committees 

February 2013 

SPECTRUM MANAGEMENT

Further Consideration of Options to Improve 

Receiver Performance Needed

Why GAO Did This Study

The growth of commercial wirelessbroadband 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 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. 

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. 

View GAO-13-265. For more information, 

contact Mark Goldstein at (202) 512-2834 or 

goldsteinm@gao.gov. 
Page i GAO-13-265 Spectrum Management

Letter 1 

Background 4

Selected Manufacturers and Commercial Licensees Have Taken a 

Variety of Actions to Improve Receiver Performance 12

The Federal Government Has Used Standards, Procurement, and 

Other Actions to Improve Receiver Performance 16

Several Challenges Impede Further Improvements to Receiver 

Performance 23

Stakeholders and Reports Identified Standards, Interference 

Limits, and Other Options to Improve Receiver Performance 28

Conclusions 36

Recommendation for Executive Action 37

Agency Comments and Our Evaluation 38

Appendix I Objectives, Scope, and Methodology 39

Appendix II Comments from the Department of Commerce 45

Appendix III Comments from the Federal Communications Commission 46

Appendix IV GAO Contact and Staff Acknowledgments 48

Tables

Table 1: Options Identified by Stakeholders and Reports to 

Improve Receiver Performance 30

Table 2: Organizations and Individuals Interviewed 40

Figures

Figure 1: Examples of Services by Frequency Band 5

Figure 2: Components of a Communications System 6

Figure 3: Classification of Interference 8

Figure 4: Types of Adjacent Band Interference 9

Figure 5: Perfect and Imperfect Filtering 10

Contents 
Page ii GAO-13-265 Spectrum Management

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

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Page 1 GAO-13-265 Spectrum Management 

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.1

 As new spectrumdependent 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 

 

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). 

 
 

Page 2 GAO-13-265 Spectrum Management

National Telecommunications and Information Administration (NTIA).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.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 

 

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).
 

Page 3 GAO-13-265 Spectrum Management

characteristics increasingly constrain effective and efficient spectrum 

use.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.5

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)

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?

6

 

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). 

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 

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.
 

Page 4 GAO-13-265 Spectrum Management

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.

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.7

 

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.

FCC and NTIA manage the radio 

frequency spectrum in the United States through allocation and 

assignment: 

Background
 

Page 5 GAO-13-265 Spectrum Management

• 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. (Fig. 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

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.8

 

8

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

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.
 

Page 6 GAO-13-265 Spectrum Management

• 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 fig. 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
 

Page 7 GAO-13-265 Spectrum Management

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.”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,10

• 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.

has two main 

causes (see fig. 4):

 

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.

10Public Law 112-96 required GAO to study interference between adjacent spectrum 

uses, rather than co-channel interference between users of the same spectrum. 
 

Page 8 GAO-13-265 Spectrum Management

• 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
 

Page 9 GAO-13-265 Spectrum Management

Figure 4: Types of Adjacent Band Interference

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 
 

Page 10 GAO-13-265 Spectrum Management

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
 

Page 11 GAO-13-265 Spectrum Management

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.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.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.13

 

11For 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). 

12Statement 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.

13In 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). 
 

Page 12 GAO-13-265 Spectrum Management

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.

Some industry-led organizations have adopted voluntary standards for 

receivers.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.

 

14According 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.

Selected 

Manufacturers and 

Commercial 

Licensees Have Taken 

a Variety of Actions to 

Improve Receiver 

Performance 

Voluntary Industry 

Standards
 

Page 13 GAO-13-265 Spectrum Management

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 communicationstechnology industry, including equipment manufacturers and 

commercial licensees, and is an American National Standards 

Institute (ANSI) accredited standards developing organization.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.16

• In the aviation industry, RTCA, Inc. develops minimum performance 

standards for aviation-related receivers.17

 

15ANSI 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. 

 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 

16When 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. 

17RTCA 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. 
 

Page 14 GAO-13-265 Spectrum Management

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.18

 

18The 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. 

In 

other cases, compliance testing might be carried out by those purchasing 

the equipment. For example, TIA representatives told us that many of 
 

Page 15 GAO-13-265 Spectrum Management

TIA’s member companies are involved in testing equipment against 

standards, although TIA is not itself involved in the certification process.

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.19

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.

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.

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 

 

19Fixed 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.

Negotiation, 

Improvements to 

Technology, and 

Information Sharing
 

Page 16 GAO-13-265 Spectrum Management

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.20

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.

 

20A 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). 

The Federal 

Government Has 

Used Standards, 

Procurement, and 

Other Actions to 

Improve Receiver 

Performance
 

Page 17 GAO-13-265 Spectrum Management

Some federal spectrum users have specified, and in some cases 

mandated, standards for receiver performance that are often based on 

industry-developed standards.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.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.23

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 

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.

 

21In general, these mandated standards are more stringent than requirements for federal 

spectrum users set by NTIA, discussed in the section below.

22ASTM International is a standards-setting body that develops voluntary, consensusbased standards covering a range of engineering disciplines including aerospace, 

industrial, mechanical, and solar engineering. 

23For 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. 

Federal Spectrum User 

Actions
 

Page 18 GAO-13-265 Spectrum Management

operating in compliance with federal rules for transmitters.24

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.

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.

25

Federal spectrum users also privately negotiate with other spectrum 

users, both federal and nonfederal, to resolve interference concerns 

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.

 

24In 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).

25The 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.
 

Page 19 GAO-13-265 Spectrum Management

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.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.

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 industrydeveloped standards when they are available for a given service.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.28

 

26While 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. 

NTIA’s mandatory 

standards, whether set from industry standards or established by NTIA, 

are used to certify federal equipment, and when procuring equipment, 

27OMB Circular A-119 directs agencies to use voluntary consensus standards in lieu of 

government-unique standards except where inconsistent with law or otherwise impractical.

28NTIA 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. 

Spectrum Management 

Agency Actions
 

Page 20 GAO-13-265 Spectrum Management

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.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,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.31

 

29NTIA Comments on Interference Immunity Performance Specifications for Radio 

Receivers (Washington, D.C.: Nov. 12, 2003). 

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.

3047 U.S.C. § 302a(a)(2). 

31Reconfiguration 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).
 

Page 21 GAO-13-265 Spectrum Management

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.32

 

32AWS 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.

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 
 

Page 22 GAO-13-265 Spectrum Management

basis, as other operators with similar problems might not have access to 

the resolution of other cases.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.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.35 In 2012, FCC’s TAC studied receivers and spectrum and 

presented recommendations to FCC.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 

 

33Madelaine Maior, Efficient Interference Management: Regulation, Receivers, and Rights 

Enforcement, A report on a Silicon Flatirons Summit, held 18 October 2011 

(January 10, 2012). 

34NTIA 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.

35Dynamic 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. 

36The 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.
 

Page 23 GAO-13-265 Spectrum Management

input on whether and how it should incorporate receiver performance 

specifications into its spectrum policy.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.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.

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.

 

37This 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). 

38In closing the proceeding, FCC noted that it could address receiver performance 

problems in individual future proceedings for specific services or frequencies.

Several Challenges 

Impede Further 

Improvements to 

Receiver Performance
 

Page 24 GAO-13-265 Spectrum Management

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 adjacentband 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 

Lack of Coordination 

among Those Developing 

Standards
 

Page 25 GAO-13-265 Spectrum Management

television signals do not manufacture television sets or specify their 

operating characteristics—a situation known as decoupled receivers.

39

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.40

 

39In 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. 

NTIA’s CSMAC also recently 

40See GAO, Spectrum Management: Incentives, Opportunities, and Testing Needed to 

Enhance Spectrum Sharing, GAO-13-7 (Washington, D.C.: November 2012). 

Lack of Incentives to 

Improve Receivers
 

Page 26 GAO-13-265 Spectrum Management

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.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.

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-ofband 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 

 

41See Commerce Spectrum Management Advisory Committee, Interference and Dynamic 

Spectrum Access Subcommittee Final Report (Washington, D.C.: Nov. 8, 2010). 

Difficulty Accommodating 

a Changing Spectrum 

Environment
 

Page 27 GAO-13-265 Spectrum Management

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.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.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.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 

 

42See 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).

43Summary 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). 

44In 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).
 

Page 28 GAO-13-265 Spectrum Management

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.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.46

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 

 

45Statement 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. 

46In the Matter of Fostering Innovation and Investment in the Wireless Communications 

Market, 24 FCC Rcd. 11,322, 11,332 (2009). 

Stakeholders and 

Reports Identified 

Standards, 

Interference Limits, 

and Other Options to 

Improve Receiver 

Performance 
 

Page 29 GAO-13-265 Spectrum Management

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.47

 

47Pierre 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). 
 

Page 30 GAO-13-265 Spectrum Management

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

Options Description Advantages Disadvantages

Greater use of industry-developed standards

• Voluntary, industry 

standards

(status quo for 

commercial spectrum 

users) 

Standards-setting bodies and 

industry groups develop voluntary 

standards, which can include 

parameters to help prevent 

interference from adjacent 

spectrum users. 

• Viewed by some as successful 

in mitigating interference.

• Less likely to fall behind 

industry change or slow 

innovation compared to 

mandatory standards.

• May not be used by 

manufacturers and licensees.

• Viewed by some as insufficient to 

date to incent licensees and 

manufacturers to improve 

receiver performance.

• Safe harbor 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. 

• Less likely to fall behind 

industry change or slow 

innovation compared to 

mandated standards.

• Allows manufacturers flexibility 

in choosing to comply or not.

• Some lower-performing receivers 

would not be entitled to 

protection, which could be difficult 

in the case of widely deployed 

consumer devices.

• Mandatory standards

(status quo for many 

federal spectrum 

users) 

Receiver standards would be 

mandatory, likely through 

regulation.

• 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.

• Mandated standards, if set by 

FCC or NTIA, could potentially 

slow innovation.

• Raises questions about FCC’s 

authority to broadly regulate 

receivers. 

Interference limits This approach would explicitly set 

the level of interfering signals that 

a receiver would have to tolerate 

before making a claim of harmful 

interference. 

• 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.

• Complex to develop and enforce, 

compared to standards.

• Untested approach.

Additional information 

on spectrum use

Make additional information 

available on spectrum use and the 

characteristics of systems, 

including receivers.

• 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. 

• Raises concerns about improper 

disclosure of proprietary and 

classified information.

• Though quick to implement, 

requires resources to implement 

and maintain.

• May be insufficient on its own to 

improve receiver performance. 

Research and 

development

Promote research and 

development on receiver 

technologies and modeling.

• Provide more accurate 

information on current and 

prospective receiver 

performance.

• Could help enable 

improvements to receivers and 

help lower cost of highperforming receivers.

• 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.
 

Page 31 GAO-13-265 Spectrum Management

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 industrydeveloped 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.48

 

48NTIA Comments on Interference Immunity Performance Specifications for Radio 

Receivers (Washington, D.C.: Nov. 12, 2003).

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 

Greater Use of IndustryDeveloped Standards
 

Page 32 GAO-13-265 Spectrum Management

subsidize consumer purchases of converter boxes, but the coupons could 

only be used to purchase converter boxes that met minimum performance 

standards.49

Regardless of the form of standards used, there are some overarching 

advantages and disadvantages. Advantages of greater use of industrydeveloped 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.

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.50

 

49Rules 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. 

Interference limits differ from the safe-harbor standards 

50For 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, 

http://transition.fcc.gov/bureaus/oet/tac/tacdocs/WhitePaperTACInterferenceLimitsv1.0.pdf

Interference Limits
 

Page 33 GAO-13-265 Spectrum Management

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.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 

 

51For more information on this approach, see Evan Kwerel and John Williams, “ForwardLooking 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.
 

Page 34 GAO-13-265 Spectrum Management

test and considerable time to implement and the practical effects and 

outcomes are unknown.52

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.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.54

• Second, FCC could also compile and share information on existing 

industry standards for receivers. The TAC working group on receivers 

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.

 

52In 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. 

53Legislation 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. 

54This 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. 

Additional Information on 

Spectrum Use
 

Page 35 GAO-13-265 Spectrum Management

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.

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 

Research and 

Development
 

Page 36 GAO-13-265 Spectrum Management

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.55

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.

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.

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.

 

55Formed 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. 

Conclusions
 

Page 37 GAO-13-265 Spectrum Management

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.

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.

Recommendation for 

Executive Action
 

Page 38 GAO-13-265 Spectrum Management

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 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.

Mark L. Goldstein

Director

Physical Infrastructure Issues

Agency Comments

and Our Evaluation
Appendix I: Objectives, Scope, and 

Methodology

Page 39 GAO-13-265 Spectrum Management

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.

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 adjacentband 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 

Appendix I: Objectives, Scope, and 

Methodology 

Scope and Methodology
Appendix I: Objectives, Scope, and 

Methodology

Page 40 GAO-13-265 Spectrum Management

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
Appendix I: Objectives, Scope, and 

Methodology

Page 41 GAO-13-265 Spectrum Management

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,a 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. 

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 
Appendix I: Objectives, Scope, and 

Methodology

Page 42 GAO-13-265 Spectrum Management

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.

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.

Case Study Descriptions
Appendix I: Objectives, Scope, and 

Methodology

Page 43 GAO-13-265 Spectrum Management

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.1 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.2

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 

 

1

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). 

2

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). 
Appendix I: Objectives, Scope, and 

Methodology

Page 44 GAO-13-265 Spectrum Management

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.3

 

3

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). 
Appendix II: Comments from the Department 

of Commerce

Page 45 GAO-13-265 Spectrum Management

Appendix II: Comments from the Department 

of Commerce
Appendix III: Comments from the Federal 

Communications Commission 

Page 46 GAO-13-265 Spectrum Management

Appendix III: Comments from the Federal 

Communications Commission
Appendix III: Comments from the Federal 

Communications Commission 

Page 47 GAO-13-265 Spectrum Management
Appendix IV: GAO Contact and Staff 

Acknowledgments

Page 48 GAO-13-265 Spectrum Management

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

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.

Appendix IV: GAO Contact and Staff 

Acknowledgments 

GAO Contact

Staff 

Acknowledgments

(543305)
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