Overview of Department of Defense Use of the Electromagnetic Spectrum

Overview of Department of Defense Use of the Electromagnetic Spectrum

Overview of Department of Defense Use of the August 10, 2021
Electromagnetic Spectrum
John R. Hoehn,
Communication using the electromagnetic spectrum (“the spectrum”) enables a number of
Coordinator
modern military capabilities. The Department of Defense (DOD) uses electromagnetic radiation
Analyst in Military
to enable military communications, navigation, radar, nonintrusive inspection of aircraft, and
Capabilities and Programs
other equipment. DOD also heavily relies on electromagnetic radiation for intelligence,

surveillance, and reconnaissance (ISR) applications such as missile early warning and signals
Jill C. Gallagher
intelligence. Individual branches of the military (e.g., the Air Force, Army, Marine Corps, Navy
Analyst in
and Space Force) currently are allotted significant ranges of frequency bands to enable various
Telecommunications
equipment and applications that support military operations.
Policy

Potential adversaries like China and Russia have observed how the United States wages war
through conflicts ranging from Desert Storm to Allied Force, Iraqi Freedom, and Enduring
Kelley M. Sayler
Freedom over the past 30 years. These potential adversaries have identified the DOD’s use of the
Analyst in Advanced
Technology and Global
spectrum as a critical enabler, and, as a result, have developed weapon systems, particularly
electronic warfare (EW) platforms, designed to challenge the DOD’s ability to effectively use the
Security

spectrum. These technologies designed to deny access to the spectrum are part of a series o f
systems and technologies that are commonly referred to as anti-access/area denial capabilities.

Several new and emerging technologies and methods to employ existing technologies (called
concepts) are being developed to counter these challenges. These new technologies include directed energy, artificial
intelligence, and counter-unmanned aircraft systems. Concepts like Joint All Domain Command and Control (JADC2) and
Mosaic Warfare look to change the nature of how the DOD communicates and uses the spectrum.
The U.S. government manages access to and use of spectrum. As the nation continues to experience significant growth in
commercial wireless services (e.g., mobile phones, mobile applications, video streaming, Wi-Fi), demand for spectrum has
increased. Congress has enacted policies to make additional spectrum available for commercial use, in some cases
reallocating spectrum from federal agency use to commercial use. As Congress considers policies that reallocate spectrum
from DOD to commercial use, it may consider the following issues:
 Interoperability (i.e., the ability of one radio or computer system to talk to another). Each of the military
services has developed robust networks of their own; however, many are often unable to communicate with
one another.
 DOD’s ability to keep pace with technological advances by potential adversaries. Adversaries such as
Russia, China, Iran, and North Korea have developed systems to challenge the U.S. military’s ability to
access the spectrum and to reduce the effectiveness of future technologies.
 The private sector’s increasing interest in using frequencies traditionally reserved for the military.
The advent of fifth generation communications technologies (5G) has increased the demand for multiple
different frequency bands, which has the potential to disrupt military operations. For example, in 2020 the
Federal Communications Commission (FCC) authorized the Ligado 5G network, which could affect the
global positioning system’s radio signals.
 Spectrum sharing. Emerging technologies and policies are demonstrating that DOD and commercial
systems are able to use the same frequencies without degrading DOD’s capabilities. The process for
identifying such potential spectrum-sharing frequencies and the ability to develop technologies quickly
may also be of interest to Congress.
 The interagency process for spectrum allocation. Questions about the interagency process emerged after
the FCC authorized Ligado’s 5G network to operate, despite the fact that DOD and several other federal
agencies disagreed with that decision.
 Anticipating future spectrum needs for both commercial and military users. Much attention has
focused on 5G technologies. However, new technologies—like a future sixth generation (6G) of
communications technologies—will increase demand for additional spectrum. Moreover, new military
technologies may change how DOD uses the spectrum and may require a different spectrum allocation.
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Contents
What Is the Electromagnetic Spectrum?.............................................................................. 1
Federal Spectrum Allocation ............................................................................................. 3
Current Military Applications of the Spectrum..................................................................... 4
Communications ....................................................................................................... 6
Terrestrial Radios ................................................................................................. 6
Satel ite Communications ...................................................................................... 7
Situational Awareness................................................................................................. 8
Radar and LIDAR ................................................................................................ 8
Passive Radar ...................................................................................................... 8
Signals Intel igence .............................................................................................. 9
Infrared Sensors ................................................................................................... 9
Electronic Warfare ................................................................................................... 10
Spectrum Operations ..................................................................................................... 11
Command and Control ............................................................................................. 11
Signature Management ............................................................................................. 11
Navigation Warfare .................................................................................................. 12
Command and Control (C2) ...................................................................................... 13
Emerging Military Applications of the Spectrum................................................................ 13
Fifth Generation (5G) Communications ...................................................................... 13
Use and Applications of Artificial Intel igence (AI)....................................................... 15
Directed-Energy (DE) Technologies ........................................................................... 15
Laser Communications........................................................................................ 16
Directed-Energy Weapons ................................................................................... 17
Counter-Unmanned Aircraft Systems (C-UAS) ............................................................ 19
Emerging Concepts ....................................................................................................... 20
DOD Spectrum Strategies and Policies ............................................................................. 21
Potential Spectrum Issues for Congress ............................................................................ 23
Technical Chal enges ............................................................................................... 23
Communications System Interoperability ............................................................... 23
Adversary Spectrum Interference Developments ..................................................... 24
Spectrum Sharing ............................................................................................... 25
DOD Spectrum Organizational Issues ......................................................................... 27
Commercial Demand for Federal Spectrum ................................................................. 28
Increasing Demand for Spectrum .......................................................................... 29
Unintended Commercial Frequency Interference ..................................................... 31
Interagency Disputes........................................................................................... 33
Anticipating Future Spectrum Needs ..................................................................... 34
Potential Questions for Congress ..................................................................................... 34
Legislative Activity ............................................................................................ 39

Figures
Figure 1. The Electromagnetic Spectrum ............................................................................ 2
Figure 2. U.S. Department of Defense (DOD) Use of Radio Spectrum .................................... 5
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Figure 3. Spectrum Used for DOD Laser Technologies ......................................................... 6
Figure 4. AN/TRC-170 Tropospheric Scatter Microwave Radio Terminal ................................ 7
Figure 5. The Space-Based Infrared Surveil ance (SBIRS) Constel ation ............................... 10
Figure 6. The Global Positioning System (GPS) Constel ation ............................................. 12
Figure 7. U.S. Marine Corps Free Space Optics Communications System .............................. 16
Figure 8. Visualization of JADC2 Vision .......................................................................... 20

Appendixes
Appendix. Ligado Networks ........................................................................................... 36

Contacts
Author Information ....................................................................................................... 40

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Overview of Department of Defense Use of the Electromagnetic Spectrum

he Department of Defense (DOD) is the largest federal user of the electromagnetic
spectrum (“the spectrum”). It holds frequencies across multiple bands to support a number
T of technologies and uses. DOD utilizes spectrum on a day-to-day basis, for training, and
for military operations. Thus, any changes to spectrum could affect DOD operations, both
domestical y and with al ies abroad. Further, DOD has invested significantly in spectrum-
dependent technologies. A summary of some of these technologies, including wireless
communications, satel ites, radar technologies that support situational awareness, signal
intel igence and electronic warfare technologies, is provided below. Changes in spectrum may
affect how DOD can use, manipulate, or develop these technologies.
The Department of Defense (DOD), partly through congressional action, has begun to re-
prioritize its management and use of the spectrum. Since 2018, the DOD has created new
organizational structures and is in the process of developing new strategies and policies,
recognizing the importance the spectrum plays in military operations. A rec ent Joint
Electromagnetic Spectrum Operations publication states
[t]he electromagnetic spectrum (EMS) is a maneuver space essential for facilitating control
within the operational environment (OE) and impacts all portions of the OE and military
operations ... Just as in the physical domains and in cyberspace, military forces maneuver
and conduct operations within the EMS to achieve tactical, operational, and strategic
advantage. Freedom of maneuver and action within the EMS are essential to US and
multinational operations.1
What Is the Electromagnetic Spectrum?2
The electromagnetic spectrum is the range of wavelengths or frequencies of electromagnetic
radiation. It includes radio waves, microwaves, visible light, X-rays, and gamma rays (see Figure
1). Electromagnetic radiation is al around us. It can be produced by natural sources, such as
lightning or the sun, or by man-made sources, such as radio transmitters, microwave ovens,
lasers, and X-ray machines. Electromagnetic radiation travels through space, air, and sometimes
solid materials in the form of waves. These waves are cal ed electromagnetic waves because they
have both electric and magnetic properties. Such waves vary in frequency,3 wavelength,4 and
energy. Scientists classify electromagnetic waves by their wavelength or frequency. Waves with
shorter wavelengths (e.g., gamma rays) have higher frequencies and higher energy; waves with
longer wavelengths (e.g., radio waves) have lower frequencies and lower energy.

1 Department of Defense, Joint Electromagnetic Spectrum Operations, JP 3-85, Washington, DC, March 22, 2020, p. v,
https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp3_85.pdf?ver=2020-04-09-140128-347.
2 T his section was written by John R. Hoehn. For more information, see CRS In Focus IF11155, Defense Primer:
Military Use of the Electrom agnetic Spectrum , by John R. Hoehn.
3 Frequency is the property of a wave that describes how many wave patterns or cycles pass by in a period of time.
Frequency is measured in Hertz (Hz). A wave with a frequency of 1 Hz means that one wave (peak -to-peak) passes by
each second.
4 Wavelength is the distance between adjacent peaks in a series of periodic waves.
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Overview of Department of Defense Use of the Electromagnetic Spectrum

Figure 1. The Electromagnetic Spectrum

Source: National Aeronautics and Space Administration, “The Electromagnetic Spectrum,” 2020,
https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html.
Scientists and engineers have discovered many practical uses for electromagnetic radiation. For
example, mobile phones convert human voice and digital information into signals that can be
transmitted by low frequency, low energy radio waves to enable wireless communications.
Medical professionals use machines to focus high frequency, high energy gamma rays to kil
cancerous cel s. Thus, common technologies use electromagnetic radiation to enable a wide
variety of uses. In applications across civil, commercial, and government sectors, the
characteristics of the waves used often drive the use. Below are examples of electromagnetic
radiation uses and applications.
 Radio frequency waves can be used to transmit messages between electronic
devices. Radio waves have varying wavelengths and characteristics that affect
how much, how far, and in what conditions data can be transmitted between a
sender and a receiver. Some very low frequency radio waves can travel long
distances, and can penetrate seawater, but cannot support high data rates. These
waves are useful for communications with submarines. Other radio waves can
travel a long distance and pass through solid objects, like buildings and trees,
making them useful for mobile communications. Stil other radio waves can
travel short distances and cannot penetrate dense objects, but offer greater
bandwidth and speed. These radio waves may be useful for high-data
applications, such as downloading or streaming videos within a home or office.
 Microwaves have higher throughput—data upload and download rates—than
radio waves and therefore are able to transmit more data. However, microwaves
are more limited in range and can be disrupted by solid objects. Hence,
microwaves are often used for point-to-point transmissions. Microwaves are also
used in radars—systems that send out pulses of high frequency waves that reflect
off an object and back to the source. This technology capitalizes on the fact that
the waves cannot penetrate solid objects, and uses this characteristic to gauge
time and distance to an object. Microwaves are also used in satel ite
communications, which experience few obstacles in their transmission path.
 Infrared radiation (IR) is used in household items such as remote controls.
Remote controls shoot pulses of IR energy to a receiver in a TV, for example. The
receiver converts the light signals to electrical signals, instructing
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microprocessors to carry out commands.5 Similarly, infrared lasers can be used
for point-to-point communications over short distances to provide high-speed,
reliable connections. Infrared signals can travel only short distances and can be
blocked by obstacles.
 X-rays can penetrate optical y opaque materials and are routinely used in aircraft
maintenance to identify cracks in airframes. X-rays are high-energy, high-
frequency ionizing radiation; they have enough energy to remove an electron
from (ionize) an atom or molecule, which could lead to mutations in a human
cel ’s DNA, and could lead to cancer.6
 Certain technologies can detect gamma rays—high-energy radiation—to help
identify potential nuclear events. Similar to X-rays, gamma rays present
biological risks.
Federal Spectrum Allocation
In the United States, the National Telecommunications and Information Administration (NTIA)
and the Federal Communications Commission (FCC) jointly manage use of the radio spectrum
(3 Hz to 300 GHz) to balance U.S. government interests, private interests, and the public good.7
NTIA manages radio spectrum use by federal agencies,8 while the FCC manages nonfederal
use—that is, radio spectrum use of the private sector, including broadcasting, mobile
communication use, commercial, industrial, personal uses, and state and local government uses.9
Both agencies coordinate on frequency al ocation and assignment, and in setting technical
requirements to avoid interference.10
The allocation of radio spectrum involves designating certain frequency segments for specific
uses, such as mobile communications, satel ite, and TV broadcasting. The assignment of radio
frequencies occurs after the spectrum has been al ocated for a specific use. The FCC assigns
frequencies and grants licenses to nonfederal users to use certain segments or certain
frequencies.11 The NTIA assigns frequencies to federal agencies, authorizing them to operate in a
specific segment of the radio spectrum.12 The two agencies coordinate on radio spectrum

5 Jim Lucas, “What is Infrared,” Live Science, February 27, 2019, https://www.livescience.com/50260-infrared-
radiation.html.
6 American Cancer Society, What are x-rays and gamma rays?, accessed February 26, 2019, https://www.cancer.org/
cancer/cancer-causes/radiation-exposure/x-rays-gamma-rays/what -are-xrays-and-gamma-rays.html.
7 T he NT IA and FCC also represent U.S. interests at international forums, such as the World Radiocommunication
Conference (WRC) that works to globalize and harmonize spectrum allocation to facilitate international
communications. T hus, allocation decisions are also dependent on agreements, treaties, and regulations that drive
international use of the spectrum. For more information, see NT IA, “Spectrum Sharing,” accessed February 26, 2020,
https://www.ntia.doc.gov/legacy/osmhome/EPS/openness/sp_rqmnts/sharing7.html.
8 P.L. 102-538.
9 47 U.S.C. §303.
10 Spectrum decisions are also driven by international decisions to coordinate spectrum use and facilitate global
communications.
11 T he FCC also designates some bands for unlicensed use. T hese bands are open for users (e.g., medical device
makers, Wi-Fi equipment makers) who agree to adhere to certain technical requirements so that their equipment does
not interfere with other unlicensed uses or nearby licensed uses.
12 NT IA, Federal Government Spectrum Compendium, Washington, DC, August 21, 2017, https://www.ntia.doc.gov/
other-publication/2017/federal-government-spectrum-compendium.
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al ocation and real ocation as specified in a Memorandum of Understanding (MOU).13 The MOU,
which dates back to 1940,14 establishes a framework for compliance with the statutory
requirements and stipulates that the Chairman of the FCC and Assistant Secretary for
Communications and Information (i.e., the lead administrator for the NTIA), shal meet
biannual y to conduct joint spectrum planning.
The NTIA uses the Interdepartment Radio Advisory Committee (IRAC) as an interagency radio
spectrum coordination body which consists of technical representatives from many agencies.15
The IRAC advises the NTIA on federal radio spectrum needs so that it can represent the interests
of federal agencies in discussions with the FCC. The FCC engages with the NTIA on spectrum
discussions when changes in al ocation or use may affect federal agency activities. After
al ocation occurs, federal users obtain authorization from NTIA—usual y referred to as a
frequency assignment. The DOD Chief Information Officer participates in the IRAC. The DOD’s
participation is guided by department policy.16
Current Military Applications of the Spectrum17
Nearly every modern weapons system—such as those used by airplanes, satel ites, tanks, ships,
and radios—depends on the spectrum to function. The military uses applications across the
electromagnetic spectrum to support communications, situational awareness, military operations,
and emerging technologies. These applications range from using very low -frequency radio waves
to communicate with submarines underwater, to microwaves for datalinks to connect weapons
systems (e.g., aircraft, satel ites, ground forces, ships). Figure 2 shows various applications in the
radio segment of the electromagnetic spectrum.18

13 “Memorandum of Understanding Between the Federal Communications Commission and the National
T elecommunications and Information Administration,” signed on January 31, 2003 by Michael K. Powell, Chairman of
the FCC and Nancy J. Victory, Assistant Secretary for Communications and Information, U.S. Department of
Commerce, available at https://www.ntia.doc.gov/files/ntia/publications/fccntiamou_01312003.pdf.
14 T he MOU includes T his MOU establishes a framework for compliance with the statutory requirements and stipulates
that the Chairman of the FCC and Assistant Secretary for Communications and Information shall meet biannually to
conduct joint spectrum planning.
15 NT IA, “Interdepartment Radio Advisory Committee (IRAC),” accessed Febr uary 26, 2020,
https://www.ntia.doc.gov/page/interdepartment -radio-advisory-committee-irac.
16 Combined Communications-Electronics Board (CCEB), Guide to Spectrum Management in Military Operations
APC 190(C), September 2007, http://www.acqnotes.com/Attachments/
ACP%20190(C)%20Guide%20to%20Spectrum%20Managing%20in%20Military%20Operations.pdf , and T homas P .
Kidd III, “Military Spectrum Management,” Presentation, November 2019, http://ustti.org/wp-content/uploads/2019/
11/Day-4-1_Military-Spect rum-Management_20180-0907.pdf.
17 T his section was written by John R. Hoehn. For more information on DOD spectrum operations, see CRS In Focus
IF11155, Defense Prim er: Military Use of the Electrom agnetic Sp ectrum , by John R. Hoehn.
18 T he radio segment is typically described as those frequencies between 3 kilohertz (kHz) and 300 gigahertz (GHz).
T he highest frequency radio waves, from 300 megahertz (MHz) to 300 GHz, are called microwaves.
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Figure 2. U.S. Department of Defense (DOD) Use of Radio Spectrum
Examples of DOD Systems Operating in the Radio Spectrum (3 kHz–300 GHz)

Source: U.S. Government Accountability Office, Spectrum Management: Federal Relocation Costs and Auction
Revenues, 13-472, May 2013, p. 6, https://www.gao.gov/assets/660/654794.pdf.
Note: The figure shows al ocated radio spectrum for DOD applications, with multiple uses operating in one
band (1755-1850 MHz) and microwave systems in the upper bands (300 MHz-300 GHz).
Although the majority of military communications capabilities use radio waves and microwaves,
the military also uses the infrared and ultraviolet spectrums for laser technologies and intel igence
collection (see Figure 3). Infrared and ultraviolet lasers have greater bandwidth than radio
frequencies, enabling the dissemination of large volumes of data (e.g., video) across long
distances due to signal strength. The military can also use lasers offensively, to dazzle satel ite
sensors, destroy drones, and for other purposes.19

19 Hemani Kaushal and Georges Kaddoum, “Applications of Lasers for T actical Military Operations,” IEEE Access,
vol. 5 (September 22, 2017), pp. 20736 -20753, doi: 10.1109/ACCESS.2017.2755678.
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Figure 3. Spectrum Used for DOD Laser Technologies
Infrared and Ultraviolet Radiation Used for Laser Technologies

Source: Marczak, Jan et al. (2008). Characterization of Laser Cleaning of Artworks. Sensors. 8.
10.3390/s8106507. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3707465/.
These applications can be combined to provide an overal military capability, such as command
and control (C2) or electronic warfare. The following discussion provides examples of DOD
spectrum applications.
Communications
Military commanders have become accustomed to communicating with their forces nearly
instantaneously. Commanders may use wired communications (e.g., landline phones, computers)
or wireless technologies (e.g., radio systems)—technologies that use radio frequencies (spectrum)
to transmit messages over-the-air between devices. Wireless communications are often used when
there is no physical connection between the sender and receiver. The radio frequencies use range
from low-bandwidth options, such as transferring smal strings of text, to highly data-intensive
applications, such as full motion video and video teleconferencing. The systems can be located
terrestrial y (either with ground forces or on ships), in the air, or in space (i.e., on satel ites). In
general, communications systems use radio and microwave frequencies; however, some emerging
communications technologies use lasers—transmitting light, instead of radio waves, between
receivers.20 Radios use different frequencies depending on the required range and amount of data
they are required to transmit. Ground-based radios are typical y used at short ranges, limited by
line of sight, that span no more than 50 miles. In general, militaries use satel ites to communicate
over longer distances.
Terrestrial Radios
For more than a century, the U.S. military has used ground-based (terrestrial) radios to
communicate. In their infancy during World War I and World War II, these radios were used to
transmit voice communications to coordinate forces. Radio systems have since evolved to use
new frequency bands to transmit larger amounts of data. Systems like the Joint Tactical Radio
System (JTRS) provide new electronics to modulate the radio frequencies, enabling greater data

20 Stephen Carlson, “Marines conduct field test of laser-based communications system,” UPI, August 27, 2018,
https://www.upi.com/Defense-News/2018/08/27/Marines-conduct -field-test-of-laser-based-communications-system/
3511535389333/.
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transmission and encryption for security. Many of these terrestrial radios are limited to line-of-
sight range due to the curvature of the earth. Some, like the PRC-117 Multiband Manpack Radio,
use multiple frequency bands to transmit data—this radio system uses frequencies from 30 MHz
– 2000 MHz.21
For several decades, the military has mostly used satel ites to provide beyond-line-of-sight
(BLOS) radio transmissions—signals traveling over the horizon, typical y defined as extending
no more than 50 miles. However, a few terrestrial-based systems can provide BLOS capabilities.
An example is the AN/TRC-170 Tropospheric Scatter Microwave Radio Terminal (see Figure
4).22 This radio uses microwaves to bounce signals off the troposphere, providing a BLOS
capability for communications with ground forces at ranges of up to 100 nautical miles
(approximately 115 standard miles), depending on weather conditions.
Figure 4. AN/TRC-170 Tropospheric Scatter Microwave Radio Terminal

Source: https://www.marines.mil/News/N ews-Display/Article/1169154/the-antrc-170-continues-to-stayreliable-
for-the-corps/.
Note: Photo by Lance Cpl. Cody Lemons.
Satellite Communications
Long-distance satel ite communications range from data feeds for unmanned aircraft systems
(also known as drones) to hardened signals for nuclear command, control, and communications.23
Satel ite communications general y use multiple frequency bands to transmit data more quickly.
While satel ite communications enables long–distance transmissions, it introduces latency (or
time delay) because the transmissions must travel (at the speed of light) up and down to the
satel ite in orbit.24 Most communications satel ites operate in geosynchronous orbit (GEO), which
is approximately 22,000 miles from the Earth’s surface. This al ows for satel ite terminals to
remain in position, rather than having to track a satel ite in either low or middle earth orbits.

21 L3Harris, “L3Harris Falcon III® AN/PRC-117G(V)1(C) Multiband Networking Manpack Radio,” press release,
2020, https://www.harris.com/solution/harris-falcon-iii-an-prc-117gv1c-multiband-networking-manpack-radio.
22 U.S. Marine Corps, “T he AN/T RC-170 Continues to Stay Reliable for the Corps,” press release, May 2, 2017,
https://www.marines.mil/News/News-Display/Article/1169154/the-antrc-170-continues-to-stayreliable-for-the-corps/.
23 T hese radio signals are designed to operate during a nuclear event, when most other electronic transmissions are
disrupted.
24 While there is a time delay when “drone” operators in the United States fly large unmanned aircraft in other parts of
the world, this is augmented by automation and local ground control stations for critical phases of flight (i.e., takeoff
landing, and taxiing) to reduce the effect of lag. Nuclear command and contro l uses multiple methods of
communications—not just satellites—to issue orders to nuclear forces. T his includes the E-4B National Airborne
Operations Center and the E-6 T ake Charge and Move Out systems.
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The U.S. military operates several global satel ite communication constel ations including
 Advanced Extremely High Frequency (AEHF),25
 Wideband Global Satel ite Communications (WGS),26 and
 Mobile User Objective System (MUOS).27
In addition to its own satel ites, the DOD uses commercial satel ites for communications. This is
due, in part, to the limited bandwidth available on DOD-operated satel ites (i.e., the number of
satel ites on orbit, the amount of data each satel ite is able to transmit, as wel as some limitations
of coverage). Examples of satel ite communications companies that contract with the DOD
include Inmarsat, Viasat, Iridium, and Intelsat.28
Situational Awareness
Another defense application of the electromagnetic spectrum is the use of radio waves,
microwaves, and infrared radiation to develop a picture of the battle space by determining the
location of friendly and enemy forces. This is done through various technologies, as described
below.
Radar and LIDAR
The most common situational awareness application is radar; however, recently light detection
and ranging (LIDAR) systems are also used. Both technologies send out an electromagnetic
signal and sense the portion that is reflected back to determine an object’s distance, speed, and
sometimes altitude. Radars operate on different radio and microwave frequencies, depending on
their purpose. Lower-band frequency radars provide a longer-range picture of the battle space, but
because of clutter (undesired signals returned to the radar) they are not able to provide target-
quality pictures. These systems are used for long-range surveil ance, particularly for identifying
ships and aircraft. Higher-band frequencies provide target-quality pictures, but lack the same
effective range. Radar and LIDAR systems are commonly associated with air defense, military
aviation, artil ery, and space systems. While radar has become ubiquitous in military formations,
LIDAR technologies are stil being developed.
Passive Radar
Another technology that the U.S. and its competitors are developing is passive radar. Passive
radars do not emit radio signals; instead, they listen to radio signals emitted from the target. Some
analysts argue that passive radars have the potential to detect low-observable aircraft such as the
B-2 bomber and the F-35 fighter jet that are optimized for low radar cross section—the amount of
measurable radar signal reflected back to its source—at certain frequencies and flight profiles

25 For more information, see Air Force Space Command, “ Advanced Extremely High Frequency System,” fact sheet,
March 22, 2017, https://www.afspc.af.mil/About-Us/Fact-Sheets/Display/Article/249024/advanced-extremely-high-
frequency-system/.
26 For more information, see U.S. Air Force, “Wideband Global SAT COM Satellite,” fact sheet, November 15, 2015,
https://www.af.mil/About -Us/Fact -Sheets/Display/Article/104512/wideband-global-satcom-satellite/.
27 For more information, see Space and Naval Warfare Systems Command, “Mobile User Objective System (MUOS),”
fact sheet, December 2011, https://www.secnav.navy.mil/rda/Documents/muos_overview_for_asn_rda_12-27-11-s.pdf.
28 Sandra Erwin, “Satcom Conumdrum: Air Force Contemplating Right Mix of Commercial, Military Satellites,”
SpaceNews, May 6, 2019, https://spacenews.com/satcom-conumdrum-air-force-contemplating-right -mix-of-
commercial-military-satellites/.
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(e.g., head on or the side).29 Furthermore, because passive radars do not emit a signal, it is
difficult to detect them using traditional methods (i.e., signals intel igence). Other analysts note
that, while passive radars may aid in the detection of stealth systems, they do not necessarily
provide the information needed to target and engage the systems and are therefore most useful as
cues for other sensors.30 Advances in microelectronics al ow passive radar technology to detect
different frequencies, such as cel ular signals, that are traditional y not captured, enabling the
potential detection of a wider range of aircraft. At the 2018 Berlin Airshow, a German radar
company tested a newly developed passive radar to identify and track an F-35 using cel ular
frequencies among other techniques.31 China and Russia have funded research and development
efforts to further develop these technologies.32 The DOD has funded research for this technology
through the Defense Advanced Research Projects Agency (DARPA).33
Signals Intelligence
Signals intel igence (SIGINT) systems primarily detect and collect spectrum emissions. These
passive systems—that is, they do not emit their own signal—can listen to radio and radar
frequencies and observe heat signatures of personnel, missiles, aircraft, artil ery, and vehicles.
One subset of SIGINT is collecting communications signals to analyze how militaries
communicate—such as what time radios transmit, from what location, and specific radio
frequencies—as wel as the data transmitted. A second subset of SIGINT is electronic
intel igence. This intel igence discipline analyzes frequencies, patterns, operating procedures—
among other information—of any other system that utilizes the spectrum. This includes radars,
satel ite systems, and signal jammers, among other systems.
Infrared Sensors
Hot objects emit radiation in the infrared segment of the spectrum. The higher their temperature
relative to their surrounding environment, the easier they are to detect using infrared sensors. The
U.S. military has long used infrared signatures to track enemy aircraft and ground vehicles and to
guide missiles onto targets. The AIM-9X air-to-air and AGM-114 Hel fire air-to-ground missiles,
for example, use infrared guidance.34 Aircraft use Infrared Search and Track (IRST) pods to

29 Dimitrios Oikonomou, Panagiotis Nomikos, and George Limnaios et al., “Passive Radars and their use on the
Modern Battlefield,” Journal of Computations & Modelling, vol. 9, no. 2 (2019), pp. 37-61.
30 T hese analysts argue that passive radars typically use lower frequencies which do not provide a sufficient position to
target a munition. T ypical air defense radars use higher band frequencies to provide quality targeting data. Furthermore,
the geometry to detect aircraft with passive radar systems can be extremely difficult, particularly if the source of the
radio energy is not known. T yler Rogoway, “No, Passive Radar Isn't Going to Make Stealth T echnology Obsolete
Anytime Soon,” The Drive, September 30, 2019, https://www.thedrive.com/the-war-zone/30100/no-passive-radar-isnt-
stealth-ending-magic-people.
31 Ibid. See also Sebastian Sprenger, “Stealthy No More? A German Radar Vendor Says It T racked the F-35 Jet in
2018—from a Pony Farm,” C4ISRNet, September 29, 2019, https://www.c4isrnet.com/intel-geoint/sensors/2019/09/30/
stealthy-no-more-a-german-radar-vendor-says-it-tracked-the-f-35-jet-in-2018-from-a-pony-farm/.
32 Gökhan Soysal and E.F.E. Murat, “UMT S passive radar implementation with two stage tracking algorithm,”
Communications Faculty of Sciences University of Ankara Series, 2016, pp. 29 -53, https://dergipark.org.tr/en/
download/article-file/778904.
33 J.R. Wilson, “New frontiers in passive radar and sonar,” Military & Aerospace Electronics, February 8, 2016,
https://www.militaryaerospace.com/communications/article/16709052/new-frontiers-in-passive-radar-and-sonar. For
more information on DARPA, see CRS Report R45088, Defense Advanced Research Projects Agency: Overview and
Issues for Congress, by Marcy E. Gallo.
34 U.S. Air Force, “AIM-9 Sidewinder,” press release, December 18, 2004, https://www.af.mil/About-Us/Fact-Sheets/
Display/Article/104557/aim-9-sidewinder/.
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identify enemy aircraft, particularly as advances in aircraft design embrace low radar cross-
sections to make radar detection more difficult. The Navy is currently funding development of an
IRST pod for the F-18E/F Super Hornet, and the Air Force has been procuring IRST capabilities
for the F-15C Eagle.35 Several space systems use infrared technologies to detect missile launches.
The Space-Based Infrared Surveil ance (SBIRS) constel ation uses six satel ites in
geosynchronous orbit, as wel as additional satel ites in highly el iptical orbits (see Figure 5) to
provide an early warning capability for missile launches.36 The Space Force is developing a
follow-on constel ation for SBIRS. The Space Development Agency is developing a hypersonic
missile detection constel ation in low-earth orbit that would use infrared technologies similar to
SBIRS.37
Figure 5. The Space-Based Infrared Surveillance (SBIRS) Constellation

Source: https://spacenews.com/air-force-tests-ground-station-for-ful -missile-warning-constel ation/.
Electronic Warfare
Electronic warfare (EW) is the use of the electromagnetic spectrum to gain and maintain military
control of it.38 SIGINT capabilities al ow military forces to understand where adversary forces are

35 U.S. Navy FY2021 Aircraft Procurement Line Item 0515 Infrared Search and T rack (IRST ), at https://apps.dtic.mil/
procurement/Y2021/Navy/stamped/U_P40_0515_BSA-1_BA-5_APP-1506N_PB_2021.pdf, and U.S. Air Force
FY2021 Aircraft Procurement Line Item F01500 F-15, at https://apps.dtic.mil/procurement/Y2021/AirForce/stamped/
U_P40_F01500_BSA-2_BA-5_APP-3010F_PB_2021.pdf.
36 Lockheed Martin, “Space Based Infrared Surveillance SBIRS,” press release, 2020, at
https://www.lockheedmartin.com/en-us/products/sbirs.html.
37 Sandra Erwin, “Space Development Agency to Deploy Hypersonic Missile Defense Satellites by 2022,” Space News,
June 7, 2020, at https://spacenews.com/space-development-agency-to-deploy-hypersonic-missile-defense-satellites-by-
2022/.
38 Doctrinally, DOD changes the term from electronic warfare to electromagnetic warfare with the release of JP 3 -85 in
May 2020. However, Congress has traditionally used, and continues to use the term electronic warfare in legislation.
For example P.L. 116-283. T his report uses the term electronic warfare to conform with co ngressional and committee
jurisdiction language. See CRS In Focus IF11118, Defense Prim er: Electronic Warfare, by John R. Hoehn.
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located as wel as what frequencies they use for communications and radars. This intel igence,
which the military cal s electronic support, is then used to develop an operational plan to jam (i.e.,
attack an adversary’s use of the spectrum) radio frequencies. Testing SIGINT capabilities on their
own forces, militaries can develop techniques to protect themselves from attacks.
Electronic warfare affects al military domains—land, air, sea, space, and cyberspace—and each
of the military services has its own EW capabilities and programs. EW capabilities are
traditional y divided into two distinct categories: terrestrial and airborne. Because each kind of
EW has its respective advantages and disadvantages, multiple capabilities may be required to
provide a desired effect. Terrestrial EW sensors and jammers—which can be located on land or
on ships at sea—are limited by the amount of power available; these capabilities are also limited
due to variance in the terrain in which they operate. Ground EW capabilities are used to intercept
and to jam radios and artil ery radars. Recent uses include jamming improvised explosive devices
in Iraq and Afghanistan.39 Airborne EW is used to intercept, decrypt, and disrupt communications,
radars, and other C2 systems over a large area. Examples of airborne EW aircraft include the EA-
18G Growler, and the EC-130H Compass Cal .40
Spectrum Operations41
Numerous military operations use the spectrum, including command and control (C2), signature
management, and navigation warfare. Overviews of these operations are discussed below.
Command and Control
One type of spectrum operation is Command and Control. C2 uses al of the above applications to
develop a common operating picture (location of friendly and enemy forces) and communicate
the commander’s orders. Command and control is resourced according to a unit’s size and
mission focus, from a few radios and computers for platoon- and company-level operations to
specialized satel ites and aircraft for joint operations such as nuclear C2. Command and c ontrol
aircraft, such as the E-8C Joint STARS, use communications systems and synthetic aperture
radars to develop a comprehensive picture of the battlespace to direct ground forces to their most
effective positions for countering enemy forces.42
Signature Management
Low observable weapons systems manipulate the spectrum to reduce their electromagnetic
signature, such as radar returns,43 radio emissions, and even heat. This signature management can
take many forms; for example, reducing a radar signature through physical or other means,
creating narrow radio beams to reduce the probability of detection or intercept, and reducing

39 For more information on ground electronic warfare systems see CRS Report R45919, Ground Electronic Warfare:
Background and Issues for Congress, by John R. Hoehn.
40 For more information about these aircraft systems see CRS Report R44572, U.S. Airborne Electronic Attack
Program s: Background and Issues for Congress, by John R. Hoehn.
41 T his section was written by John R. Hoehn.
42 U.S. Air Force, E-8C Joint STARS, Washington, DC, September 23, 2015, https://www.af.mil/About-Us/Fact-Sheets/
Display/Article/104507/e-8c-joint-stars/.
43 Radar works by emitting a radio signal and then listening for the signal to return. Low observable technologies use
different materials (known as radar absorbing material) and different shapes (typically reducing the number of 90° or
right angles) to reduce or prevent the radio signals from returning to their original source.
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spectrum emissions. These design approaches can be used in ships (e.g., Zumwalt-class
destroyer), aircraft (e.g., the B-2 Spirit and the F-35 Lightning II), and radar systems (e.g., the
AN/APG-81 actively electronical y scanned array radar).44 These systems look to reduce their
signature in the microwave and infrared parts of the spectrum.
Communications systems are also focused on reducing their signature. Using beam-forming,
reduced power, and other techniques, these systems are designed to be low probability of
intercept/low probability of detection (LPI/LPD). The intent is to make it more difficult for
potential adversaries to use their SIGINT capabilities to find U.S. forces, and potential y target
them with long-range munitions.
Navigation Warfare
According to DOD, navigation warfare (NAVWAR) is “[d]eliberate offensive and defensive
actions to assure friendly use and prevent adversary use of positioning, navigation, and timing
information through coordinated employment of space, cyberspace, and EW capabilities.
NAVWAR is further enabled by supporting activities such as ISR and EMS management.”45 The
Global Positioning System (GPS) performs navigation warfare for the U.S. military by providing
positioning, navigation, and timing (see Figure 6). Competing PNT systems have been developed
by other nations, including Russia (GLONASS), China (Beidou), and the European Union
(Galileo).46
Figure 6. The Global Positioning System (GPS) Constellation

Source: https://www.gps.gov/multimedia/images/constel ation.jpg.

44 For more information on select low observable aircraft, see CRS Report R44463, Air Force B-21 Raider Long-Range
Strike Bom ber, by Jeremiah Gertler, and CRS Report RL30563, F-35 Joint Strike Fighter (JSF) Program , by Jeremiah
Gertler. For more information on the Zumwalt -class destroyer, see CRS Report RL32109, Navy DDG-51 and DDG-
1000 Destroyer Program s: Background and Issues for Congress, by Ronald O'Rourke.
45 Department of Defense, DOD Dictionary of Military and Associated Terms, January 2021, at: https://www.jcs.mil/
Portals/36/Documents/Doctrine/pubs/dictionary.pdf.
46 U.S. GPS Office, “Other Global Navigation Satellite Systems (GNSS),” press release, January 30, 2020, at
https://www.gps.gov/systems/gnss/.
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Command and Control (C2)
C2 systems are the communications, people, and procedures that enable commanders to direct
forces. DOD states that communications systems are critical in providing timely information to
enable decisionmaking.47 According to DOD, these communications need to be interoperable
(interoperability between communications systems revolves around the protocols such as
frequency hopping and encryption, as wel as the frequencies uses) to facilitate information
sharing, agile to adjust to the operating environment, and trusted to ensure the information in the
system is accurate. An important aspect of C2 systems is the ability to network and share
information in a timely fashion to enable commanders and their staff to make decisions. Thus C2
systems collect information from intel igence systems and build a picture of the operating
environment for the commander and their staff to make effective decisions (some analysts
combine C2 with computers, communications, intel igence, surveil ance, and reconnaissance
systems [C4ISR] to talk about the entire system enabling decisionmaking). To create these
networks, DOD utilizes computers to manage and process data and communications equipment
so that commanders can act upon the data transmitted to them.
Emerging Military Applications of the Spectrum48
The following section discusses emerging technologies and concepts that could affect the
military’s use of the spectrum.
Fifth Generation (5G) Communications49
The fifth generation (5G) of mobile technologies wil increase the speed of data transfer and
improve bandwidth over existing fourth generation (4G) technologies, in turn potential y enabling
new military and commercial applications. 5G technologies plan to use three segments of the
electromagnetic spectrum: high band (also cal ed mil imeter wave, or MMW), which operates
between around 24 and 300 gigahertz (GHz); mid band, which operates between 1 GHz and 6
GHz; and low band, which operates below 1 GHz. Mid band and low band are often col ectively
referred to as sub-6.50 Each band offers different capabilities. High-band spectrum offers ultra-fast
services to high-density areas but is limited in range and more vulnerable to disruption. Mid-band
spectrum offers improved capacity and coverage, faster service, and new features (like edge
computing) compared with existing 4G technologies. Low-band spectrum offers the widespread
coverage needed for many internet-of-things applications.
5G technologies could have a number of potential military applications, particularly for
autonomous vehicles, C2, logistics, maintenance, augmented and virtual reality, and intel igence,
surveil ance, and reconnaissance (ISR) systems—al of which would benefit from improved data

47 Department of Defense, Joint Communications System , JP 6-0, Washington, DC, June 10, 2015, Incorporating
Change 1, October 4, 2019, p. vii, https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp6_0ch1.pdf?ver=2019-
10-15-172254-827.
48 T his section was written by John R. Hoehn and Kelley M. Sayler.
49 T his section is derived from CRS In Focus IF11251, National Security Implications of Fifth Generation (5G) Mobile
Technologies, by John R. Hoehn and Kelley M. Sayler. For more information on 5G, see CRS Report R45485, Fifth-
Generation (5G) Telecom m unications Technologies: Issues for Congress, by Jill C. Gallagher and Michael E. DeVine.
50 For more information on 5G spectrum allocation, see CRS Report R45485, Fifth-Generation (5G)
Telecom m unications Technologies: Issues for Congress, by Jill C. Gallagher and Michael E. DeVine.
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rates and lower latency (i.e., less time delay).51 Autonomous military vehicles, like their
commercial counterparts, could potential y circumvent on-board data processing limitations by
storing large databases (e.g., maps) in the cloud. 5G technologies could also be incorporated into
ISR systems, which increasingly demand high-bandwidths to process, exploit, and disseminate
information from a growing number of battlespace sensors. Similarly, 5G could reduce latency in
other data-intensive activities, such as logistics and maintenance, and could additional y enable
augmented or virtual reality environments that could enhance training.52 Final y, C2 systems
could benefit from the high speed, low latency capability of 5G.53
DOD has expressed interest in developing 5G networks and technologies. DOD is in the initial
stages of testing and experimentation for 5G applications. It has selected 12 military instal ations
as test beds for various applications and aspects of the technology:
 Marine Corps Logistics Base Albany, GA (smart warehouses);
 Naval Base San Diego, CA (for smart warehouses);
 Hil Air Force Base, UT (spectrum sharing between 5G and airborne radar);
 Joint Base Lewis-McChord, WA (augmented and virtual reality);
 Nel is Air Force Base, NV (survivable command and control and network
enhancement);
 Naval Base Norfolk, VA (ship-wide and pier connectivity);
 Joint Base Pearl Harbor-Hickam, HI (enhancing aircraft mission readiness);
 Joint Base San Antonio, TX (augmented reality support of maintenance and
training and evaluating DOD’s 5G core security experimentation network);
 Tinker Air Force Base, OK (spectrum sharing between military communications
and 5G);
 Camp Pendleton, CA (connectivity for forward operating bases and tactical
operations centers);
 Fort Hood, TX (connectivity for forward operating bases and tactical operations
centers); and
 Fort Irwin National Training Center, CA (for connectivity for forward operating
bases and tactical operations centers).54
On September 18, 2020, DOD released a Request for Information seeking input on best methods
for sharing spectrum between military and civilian users, input on DOD ownership and operation
of 5G networks for domestic operations, and other issues related to the al ocation and shared use

51 T he U.S. military currently uses satellites for the preponderance of its long-distance communications; however,
satellite communications can significantly increase latency due to the amount of distance a signal needs to travel,
causing delays in the execution of military operations.
52 Justin Doubleday, “DOD Releases Second T ranche of Draft 5G Proposal Requests,” Inside Defense, December 9,
2019, https://insidedefense.com/insider/dod-releases-second-tranche-draft -5g-proposal-requests.
53 Defense Innovation Board, The 5G Ecosystem: Risks and Opportunities for DOD, April 2019,
https://media.defense.gov/2019/Apr/03/2002109302/-1/-1/0/DIB_5G_ST UDY_04.03.19.PDF.
54 Justin Doubleday, “DOD Releases Second T ranche of Draft 5G Proposal Requests,” Inside Defense, December 9,
2019, https://insidedefense.com/insider/dod-releases-second-tranche-draft -5g-proposal-requests; and Department of
Defense, “DOD Names Seven Installations as Sites for Second Round of 5 G T echnology T esting, Experimentation,”
press release, June 3, 2020, https://www.defense.gov/Newsroom/Releases/Release/Article/2206761/dod-names-seven-
installations-as-sites-for-second-round-of-5g-technology-testin/.
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of DOD spectrum.55 The intent, DOD says, is to “ensure the greatest effective and efficient use of
the Department of Defense’s spectrum for training, readiness, and lethality.”56 DOD requested
$1.5 bil ion for microelectronics/5G in FY2021, but it did not provide a further breakdown in
funding between microelectronics and 5G.57
Use and Applications of Artificial Intelligence (AI)58
DOD is researching cognitive electronic warfare systems that use artificial intel igence to identify
novel electronic emissions, determine whether the emission originates from a hostile source, and
develop an effective jamming signal. According to former DOD electronic warfare official
Wil iam Conley, “a future battlespace wil contain threat signals not previously observed, [so] it
wil be essential for many platforms to be executing real time decision algorithms.”59 DOD is also
researching options for using advances in computing power to improve electronic deception, or
“spoofing,” capabilities. For example, Digital Radio Frequency Memory could be used to
generate false radar returns that complicate adversary targeting.60
Similarly, DOD is exploring AI-enabled dynamic spectrum sharing. Because spectrum is
currently al ocated in set segments, al ocation cannot be responsive to changes in the volume of
traffic across segments (i.e., some segments may be overwhelmed while others are underutilized),
leading to inefficiencies. DARPA has sponsored the Spectrum Collaboration Chal enge (SC2),
which “aims to ensure that the exponential y growing number of military and civilian wireless
devices wil have full access to the increasingly crowded electromagnetic spectrum.”61 Teams
competing in SC2—the final competition was held in October 2019—leveraged AI and machine
learning algorithms to develop options for dynamic spectrum sharing, in which radios
autonomously coordinate to optimize spectrum use.
Directed-Energy (DE) Technologies
A number of directed energy technologies, including laser communications and directed-energy
weapons, make use of the electromagnetic spectrum.62

55 DOD, Request for Information, Defense Spectrum Sharing Request for Information, Published September 18, 2020,
https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&
index=&is_active=true&page=1.
56 Ibid.
57 DOD FY2021 Defense Budget Overview: Irreversible Implementation of the National Defense Strategy , Washington,
DC, May 13, 2020, pp. 1-8, https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2021/
fy2021_Budget_Request_Overview_Book.pdf.
58 For a general discussion of military applications of artificial intelligence, see CRS Report R45178, Artificial
Intelligence and National Security, by Kelley M. Sayler.
59 “EW, Cyber Require Next -Gen Hardware: Conley,” Breaking Defense, September 27, 2019,
https://breakingdefense.com/2019/09/ew-cyber-require-next -gen-hardware-conley/.
60 Ibid.
61 DARPA, “ Spectrum Collaboration Challenge (SC2),” https://www.darpa.mil/program/spectrum-collaboration-
challenge.
62 Other directed energy technologies include laser range finders, target designators, and remote sensors.
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Laser Communications63
DOD is currently experimenting with several laser communications systems to improve
communication data rates and to reduce the potential for adversaries to interfere (or jam) with
DOD communications. One application for laser communications DOD is testing systems is for
ground-based communications. This application uses focused infrared energy to transmit data.
For example, Free Space Optics (FSO) “is an optical communication system that transfers data on
a highly secured and nearly undetectable infrared laser, separate from the radio frequency
spectrum…. This al ows more users on a single network and larger files, imagery, and
information to be transmitted.”64 The Marine Corps requested procurement funding for FSO in
FY2019 and FY2020; however, it does not appear have requested funds in FY2021. It is unclear
how many FSO systems the Marine Corps procured (see Figure 7).
Figure 7. U.S. Marine Corps Free Space Optics Communications System

Source: https://www.upi.com/Defense-News/2018/08/27/Marines-conduct-field-test-of-laser-based-
communications-system/3511535389333/.
Notes: The picture caption reads, “U.S. Marines test the Free Space Optics laser communications system earlier
this month at Camp Hansen in Okinawa, Japan. Photo by Sgt. Timothy Valero/U.S. Marine Corps.”
Another application of laser communications is to relay data from one satel ite to another (i.e.,
inter-satel ite communications or space-to-space communications). Space laser communications
rely on a large network of satel ites operating in low earth orbit (LEO). Unlike radio frequencies,
lasers have a narrow linewidth—the beam that facilitates communication—which significantly
decreases the risk of signal jamming or disruption during point-to-point satel ite
communications.65 Additional y, point-to-point laser communications provide a “straight line”
path for data transfer. Laser communications in space do not rely on physical connections, such as
fiberoptic cables,66 thereby decreasing latency and potential y providing faster data rates. Indeed,
communications lasers can potential y transmit 10 to 100 times more data than radio

63 T his section was written by John R. Hoehn and Katherine Leahy.
64 Department of Defense, “Okinawa Marines T est Future of Wireless Communications,” press release, August 24,
2018, at https://www.defense.gov/Explore/News/Article/Article/1611671/okinawa-marines-test-future-of-wireless-
communications/.
65 Lisbeth Perez, “DoD Pioneering NextGen Satellites, Sensors in Space,” MeriTalk, June 23, 2021,
https://www.meritalk.com/articles/dod-pioneering-nextgen-satellites-sensors-in-space/.
66 Doug Mohney, “Space Lasers, Smart Antennas Are Key Enablers for Satellite Broadband,” Data Center Frontier,
March 3, 2021, https://datacenterfrontier.com/space-lasers-smart-antennas-are-key-enablers-for-satellite-broadband/.
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frequencies,67 increasing both capacity and speed.68 To achieve a web of information sharing, a
large group of satel ites must be launched into LEO in order to ensure that ground-based
terminals are in constant contact with a satel ite.
The Space Development Agency (SDA), Defense Advanced Research Projects Agency (DARPA),
Space Force, and Air Force Research Labs are interested in developing space-based laser
communications technologies. Commercial companies, including Google, Facebook, and
SpaceX, have also discussed the advantages of the high data rates and security offered by space
laser communication.69 On June 30, 2021 SpaceX launched the Transporter-2 Falcon 9 following
the launch of the Transporter-1 on January 24, 2021.70 These launches were considered rideshare
missions, meaning that each rocket contained both commercial and government satel ites.
Additional y, the Space Development Agency plans to launch 150 satel ites for laser
communications into LEO by September 2024.71
Directed-Energy Weapons72
DOD defines directed-energy (DE) weapons as those using concentrated electromagnetic energy,
rather than kinetic energy, to “incapacitate, damage, disable, or destroy enemy equipment,
facilities, and/or personnel.”73 DE weapons could be used by ground forces in counter rocket,74
artil ery, and mortar (C-RAM), counter-unmanned aircraft systems (C-UAS), or short-range air
defense (SHORAD) missions.75 They could offer low costs per shot and—assuming access to a
sufficient power supply—nearly limitless magazines that, in contrast to existing conventional
systems, could enable an efficient and effective means of defending against missile salvos or
swarms of unmanned systems.76 Theoretical y, DE weapons could also provide options for boost-

67 T hese proposed data rates are because laser communications systems use higher frequencies in the infrared and
potentially ultraviolet bands of the spectrum, as well as the elimination of weather and other atmospheric conditions.
68 National Aeronautics and Space Agency, “Laser Communications: Empowering More Data T han Ever Before,”
press release, May 12, 2021, https://www.nasa.gov/feature/goddard/2021/laser-communications-empowering-more-
data-than-ever-before.
69 Patrick T ucker, “Space Lasers Will Revolutionize Military Communications, If T hey Work,” Defense One, February
18, 2021, https://www.defenseone.com/technology/2021/02/space-lasers-will-revolutionize-military-communications-
if-they-work/172134/, and Sandra Erwin, “ DoD space agency to launch laser communications experiments on SpaceX
rideshare,” Space News, June 2, 2021, https://spacenews.com/dod-space-agency-to-launch-laser-communications-
experiments-on-spacex-rideshare/.
70 Sandra Erwin, “DoD space agency to launch laser communications experiments on SpaceX rideshare,” Space News,
June 2, 2021, https://spacenews.com/dod-space-agency-to-launch-laser-communications-experiments-on-spacex-
rideshare/.
71 Patrick T ucker, “Space Lasers Will Revolutionize Military Communications, If T hey Work,” Defense One, February
18, 2021, https://www.defenseone.com/technology/2021/02/space-lasers-will-revolutionize-military-communications-
if-they-work/172134/.
72 T his section is derived from CRS Report R46458, Emerging Military Technologies: Background and Issues for
Congress, by Kelley M. Sayler.
73 Joint Chiefs of Staff, Electronic Warfare, Joint Publication 3-13.1, February 8, 2012, pp. 1-16.
74 For example, see CRS Report R45098, U.S. Army Weapons-Related Directed Energy (DE) Programs: Background
and Potential Issues for Congress, by Andrew Feickert .
75 For more information about the role of DE weapons in C-UAS missions, see CRS In Focus IF11426, Department of
Defense Counter-Unm anned Aircraft System s, by John R. Hoehn and Kelley M. Sayler.
76 Although research has been conducted on chemically fueled lasers, most countries are now pursuing solid state
lasers, which are fueled by electrical power. As a result, the cost per shot is equivalent to the cost of the electrical
power required to fire t he shot. Some analysts have noted that the cost per shot could thus be between $1 and $20. See
Ariel Robinson, “ Directed Energy Weapons: Will T hey Ever Be Ready?,” National Defense, July 1, 2015, at
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phase missile intercept, given their speed-of-light travel time; however, as in the case of
hypersonic missile defense, experts disagree on the affordability, technological feasibility, and
utility of this application.77
High-powered microwave weapons, a subset of DE weapons, could be used as a nonkinetic
means of disabling electronics, communications systems, and improvised explosive devices, or as
a nonlethal “heat ray” system for crowd control.
Although the United States has been researching directed energy since the 1960s, some experts
have observed that “actual directed-energy programs … have frequently fal en short of
expectations,” with DOD investing bil ions of dollars in programs that were ultimately
cancel ed.78 Others contend that developments in commercial lasers could be leveraged for
military applications.79 Directed-energy weapons programs, however, continue to raise questions
about their technological maturity, including questions about their ability to improve beam quality
and control to militarily useful levels and their ability to meet power, cooling, and size
requirements so that the weapons could be integrated into current platforms.80
The U.S. Navy fielded the first operational U.S. DE weapon,81 the Laser Weapon System
(LaWS), in 2014 aboard the USS Ponce. LaWS was a 30-kilowatt (-kW) laser prototype that
“was capable of blinding enemy forces as a warning, shooting down drones, disabling boats, or
damaging helicopters.”82 The Navy plans to deploy its 60-kW laser, HELIOS, aboard the USS
Preble in 2021, while the Army plans to field its first “combat relevant” laser—the 50-kW
Directed Energy Mobile Short-Range Air Defense System—on Stryker fighting vehicles in
FY2022.83 Similarly, the Air Force is currently conducting field assessments of several counter-
UAS DE systems, including both laser and high-powered microwave systems.84
The Army, Navy, Air Force, and DARPA each have additional DE development programs
underway, with the Pentagon requesting $235 mil ion for directed-energy weapons and directed-

https://www.nationaldefensemagazine.org/articles/2015/7/1/2015july-directed-energy-weapons-will-they-ever-be-
ready.
77 See, for example, James N. Miller and Frank A. Rose, “ Bad Idea: Space-Based Interceptors and Space-Based
Directed Energy Systems,” Center for Strategic and International Studies, December 13, 2018, at
https://defense360.csis.org/bad-idea-space-based-interceptors-and-space-based-directed-energy-systems/; and Justin
Doubleday, “ Pentagon punts MDA‘s laser ambitions, shifts funding toward OSD-led ‘laser scaling,’” Inside Defense,
February 19, 2020, at https://insidedefense.com/daily-news/pentagon-punts-mdas-laser-ambitions-shifts-funding-
toward-osd-led-laser-scaling.
78 Paul Scharre, Preface to “Directed-Energy Weapons: Promise and Prospects,” Center for a New American Security,
April 2015, p. 4.
79 See Ariel Robinson, “Directed Energy Weapons.”
80 Ibid.
81 For more information see, CRS Report R44175, Navy Lasers, Railgun, and Gun-Launched Guided Projectile:
Background and Issues for Congress, by Ronald O'Rourke.
82 Kyle Mizokami, “ T he U.S. Army Plans T o Field the Most Powerful Laser Weapon Yet ,” Popular Mechanics,
August 7, 2019.
83 Lockheed Martin, “ Lockheed Martin’s HELIOS Laser Weapon System T akes Step T oward Ship Integration ,” March
11, 2020, at https://news.lockheedmartin.com/2020-03-11-Lockheed-Martins-HELIOS-Laser-Weapon-System-Takes-
Step-T oward-Ship-Integration; and Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer,
“Defense Budget Overview: United States Department of Defense Fiscal Year 2021 Budget Request,” February 2020,
at https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2021/
fy2021_Budget_Request_Overview_Book.pdf.
84 Kyle Mizokami, “ T he Air Force Mobilizes Its Laser and Microwave Weapons Abroad,” Popular Mechanics, April 9,
2020, at https://www.popularmechanics.com/military/weapons/a32083799/laser-microwave-weapons/.
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energy defensive capabilities in FY2020; the FY2021 budget overview does not provide the
topline funding request for DE weapons.85 These programs are intended to scale up power levels
from around 150 kW, as is currently feasible, to around 300 kW, a level at which cruise missiles
could potential y be intercepted, by FY2022 and to around 500 kW by FY2024.86
Counter-Unmanned Aircraft Systems (C-UAS)87
Unmanned aircraft systems (UAS), commonly cal ed drones, have proliferated rapidly and are
available to nation states and to non-state actors and individuals. These systems could provide
U.S. adversaries with a low-cost means of conducting intel igence, surveil ance, and
reconnaissance missions against—or attacking—U.S. forces. Furthermore, many smal er UASs
cannot be detected by traditional air defense systems due to their size, construction material, and
flight altitude.
C-UAS can employ a number of methods to detect the presence of hostile or unauthorized UAS.
The first is using electro-optical, infrared, or acoustic sensors to detect a target by its visual, heat,
or sound signatures, respectively. A second method is to use radar systems. However, these
methods are not always capable of detecting smal UAS due to the limited signatures and size of
such UAS. A third method is identifying the wireless signals used to control the UAS, commonly
using radio frequency sensors. These methods can be—and often are—combined to provide a
more effective, layered detection capability.
Once detected, the UAS may be engaged or disabled. Electronic warfare “jamming” can interfere
with a UAS’s communications link to its operator. Jamming devices can be as light as 5 to 10
pounds and therefore man-portable, or as heavy as several hundred pounds and in fixed locations
or mounted on vehicles. In addition, UAS can be neutralized or destroyed using guns, nets,
directed energy, traditional air defense systems, or even trained animals such as eagles. DOD is
developing and procuring a number of different C-UAS technologies to try to ensure a robust
defensive capability.
In December 2019, DOD streamlined its various counter-smal UAS (C-sUAS) programs, naming
the Army as the executive agent tasked with overseeing al DOD C-sUAS development efforts.
On January 6, 2020, the Secretary of Defense approved the implementation plan of the new
office, known as the Joint C-sUAS Office (JCO). Working in consultation with the combatant
commands and the Office of the Under Secretary of Defense for Acquisition and Sustainment,
JCO assessed over 40 fielded C-sUAS systems. On June 25, 2020, Maj. Gen. Sean Gainey,
director of the JCO, announced that seven C-sUAS defensive systems and one standardized
command and control system are to be further developed. According to media reports, during its

85 Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, Defense Budget Overview: United
States Department of Defense Fiscal Year 2020 Budget Request, March 2019, p. 9.
86 Despite a lack of consensus regarding the precise power level needed to neutralize different target sets, it is generally
believed that a laser of around 100 kW could engage UAVs, small boats, rockets, artillery, and mortar, whereas a laser
of around 300 kW laser could additionally engage cruise missiles flying in certain profiles (i.e., flying across—rather
than at —the laser). See, for example, CRS Report R41526, Navy Shipboard Lasers for Surface, Air, and Missile
Defense: Background and Issues for Congress, by Ronald O'Rourke, and Sydney J. Freedberg Jr., “ Lasers to Kill
Cruise Missiles Sought by Navy, Air Force, Army,” Breaking Defense, October 29, 2019. For information about
DOD’s Laser Scaling Plan, see Jason Sherman, “ New Laser Scaling Plan sets directed-energy efforts, FY-19
contracts,” Inside Defense, April 17, 2019, at https://insidedefense.com/daily-news/new-laser-scaling-plan-sets-
directed-energy-efforts-fy-19-contracts.
87 T his section is derived from CRS In Focus IF11426, Department of Defense Counter-Unmanned Aircraft Systems, by
John R. Hoehn and Kelley M. Sayler.
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first year of operation, the office is to additional y produce a DOD Directive on C-sUAS, a threat
assessment of C-sUAS capabilities, a DOD C-sUAS strategy, and a Joint Capability Development
Document outlining operational requirements for future systems.88
Emerging Concepts89
DOD is developing a series of concepts, many of which are enabled by AI, to improve multi-
domain command and control (C2) and execute the National Defense Strategy. For example,
DOD is developing a concept, Joint Al Domain Command and Control (JADC2), to direct forces
across multiple domains (air, space, cyber, land, sea).90 According to defense officials,
commanders currently execute C2 by exchanging data through manpower-intensive processes
that typical y focus on a single domain. This reduces a commander’s situational awareness, speed
of decisionmaking, and ability to rapidly and continuously integrate capabilities across domains.
These processes are not automated and typical y provide single domain awareness.91 In contrast,
JADC2 is to enhance information-sharing across domains through “a combination of new
technology, processes and new organizations.”92
Figure 8. Visualization of JADC2 Vision

Source: https://www.monch.com/mpg/news/ew-c4i-channel/7334-saic-and-usaf-partner-for-jadc2.html.

88 T heresa Hitchens, “DoD Winnowing Efforts T o Counter Small Drones,” Breaking Defense, March 5, 2020, at
https://breakingdefense.com/2020/03/dod-winnowing-efforts-to-counter-small-drones/.
89 T his section was written by John R. Hoehn, Kelley M. Sayler, and Nishawn S. Smagh.
90 For more information about JADC2, see CRS In Focus IF11493, Joint All-Domain Command and Control (JADC2),
by John R. Hoehn.
91 For example, the Air Force fields the Air Operations Center which provides command and control of air and space
operations for a single combatant command. Similarly the Navy uses the Maritime Operations Center to command
naval forces in a specific area of operation. For the Air Operations Center to share information (and potentially tasking
instructions) with the Maritime Operations Center requires manual processes. Similarly these command and control
structures are geographically focused, and do not provide insights into potential adversary operations in other
geographic regions.
92 Jay Koester, “ JADC2 ‘Experiment 2’ provides looking glass into future experimentation,” U.S. Army, April 23,
2020, at https://www.army.mil/article/234900/
jadc2_experiment_2_provides_looking_glass_into_future_experimentation .
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DOD uses ride-sharing service Uber as an analogy to describe its desired end state for JADC2.
Uber combines two different apps—one for riders and a second for drivers. 93 Using the
respective users’ position, the Uber algorithm determines the optimal match based on distance,
travel time, and passengers (among other variables). The application then seamlessly provides
directions for the driver to follow, delivering the passenger to their destination. Uber relies on
cel ular and Wi-Fi networks to transmit data to match riders and provide driving instructions. The
military equivalent might be using al available intel igence sensors—particularly space, air and
maritime-based sensors—to detect adversary targets. Artificial intel igence algorithms would then
identify where different missiles, aircraft, and artil ery units are to determine the best to assign to
an emerging target. Final y, using the optimal communications method the algorithms would then
direct the appropriate munition onto the target. The Air Force has been designated as the
executive agent charged with overseeing the services’ first-year JADC2 activities.94 JADC2 is
intended to reach full operational capability by 2035.95
Similarly, DARPA has researched a concept cal ed “Mosaic Warfare,” intended to leverage AI to
network systems and sensors, prioritize incoming sensor data, and autonomously determine the
optimal composition of forces. Such concepts could provide a comprehensive common operating
picture, coordinate operations across warfare domains, and chal enge adversaries’ targeting
calculations. These concepts additional y propose limiting the amount of and/or disguising
electronic emissions in the spectrum to further complicate adversaries’ ability to target U.S.
forces.
DOD Spectrum Strategies and Policies96
DOD has recently changed its strategy and organizational structure for and focus on spectrum
operations. First, in May 2020, the Joint Staff released Joint Publication (JP) 3-85, which
documents DOD’s doctrine for Joint Electromagnetic Spectrum Operations.97 This document
states that the electromagnetic spectrum “is a maneuver space essential for facilitating control
within the operational environment (OE) and impacts al portions of the OE and military
operations.”98 JP 3-85 also changed how DOD trains and organizes for EMSO by combining
electronic warfare and spectrum management operations into a single function. Previously,
spectrum management and electronic warfare were two separate disciplines run by different
organizations within each military command.99 JP 3-85 notes that, while signals intel igence
supports EMSO, it remains an intel igence discipline tasked by the intel igence directorate.

93 Gen David Goldfein and Gen John Raymond, “America’s future battle network is key to multidomain defense,”
Defense News, February 27, 2020, at https://www.defensenews.com/opinion/commentary/2020/02/27/americas-future-
battle-network-is-key-to-multidomain-defense/.
94 T he services have a number of related programs that are designed to demonstrate the capabilities needed to execute
JADC2, including the Army’s Project Convergence and the Air Force’s Advanced Battle Management System. Jay
Koester, “ JADC2 ‘Experiment 2’ provides looking glass into future experimentation ,” U.S. Army, April 23, 2020, at
https://www.army.mil/article/234900/jadc2_experiment_2_provides_looking_glass_into_future_experimentation.
95 Ibid.
96 T his section was written by John R. Hoehn.
97 Department of Defense, Joint Electromagnetic Spectrum Operations, JP 3-85, Washington, DC, May 22,
2020, https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp3_85.pdf?ver=2020-04-09-140128-347.
98 Ibid., p. I-1.
99 T raditionally electronic warfare was managed by the operations directorate, while spectrum management was
delegated to the communications directorate—this is akin to the Chief Operations Officer and Chief Information
Officer in the commercial sector controlling different aspects and viewpoints of the spectrum environment. JP 3 -85
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Then, in September 2020, DOD released a new electromagnetic spectrum enterprise directive to
set policy and assign bureaucratic responsibilities for EMSO.100 This directive identifies the DOD
Chief Information Officer (CIO) as the primary staff assistant for spectrum management policy,
and the Undersecretary of Defense for Acquisition and Sustainment as the lead organization for
electronic warfare programs.101 The Undersecretary of Defense for Research and Engineering is
designated as the primary organization responsible for developing spectrum management and
electronic warfare technologies.
In October 2020, DOD released the Electromagnetic Spectrum Superiority Strategy.102 The
strategy outlines DOD’s intent to “develop superior EMS capabilities; evolve to an agile, fully
integrated EMS infrastructure; pursue total force EMS readiness; secure enduring partnerships for
EMS advantage; and establish effective EMS governance to support strategic and operational
objectives.”103 This strategy combines the DOD’s electromagnetic spectrum strategy from 2013
and the electronic warfare strategy from 2017. The 2013 strategy identified the commercial
sector’s increasing demand for spectrum, which DOD cal s “congestion.”104 The 2017 strategy
identified how potential adversaries are developing systems to chal enge U.S. dominance of the
spectrum, which DOD terms “contested.”105 The new 2020 strategy combines these two
approaches into a single document and outlines how DOD plans to meet commercial demand for
spectrum, while being able to support operations in a contested environment.
DOD announced in August 2021 that Secretary Austin had signed the Electromagnetic
Superiority Strategy Implementation Plan on July 15, 2021.106 While the Implementation Plan is
classified, senior DOD officials shared some details with the media.107 According to press reports,
EMS oversight wil shift to the DOD Chief Information Officer in the fal of 2021.108 In addition,
the plan creates a new organization cal ed the Joint EMS Operations Center (JEC) which wil be
led by a 2-star general or admiral.109 The JEC wil “be providing operational risk assessment and
identifying requirements and gaps to the office of the DOD chief information officer.”110

delegates the whole EMSO enterprise to the operations directorate.
100 Department of Defense, DOD Directive 3610.01: Electromagnetic Spectrum Enterprise Policy, September 4, 2020,
https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/361001p.pdf?ver =2020-09-04-112353-317.
101 Ibid., pp. 5-6.
102 Department of Defense, Electromagnetic Spectrum Superiority Strategy, October 29, 2020,
https://media.defense.gov/2020/Oct/29/2002525927/-1/-1/0/
ELECT ROMAGNET IC_SPECT RUM_SUPERIORIT Y_ST RAT EGY.PDF.
103 Ibid., p. i.
104 Department of Defense, Electromagnetic Spectrum Strategy, September 11, 2013, https://archive.defense.gov/news/
dodspectrumstrategy.pdf.
105 Department of Defense, Electronic Warfare Strategy, 2017.
106 Department of Defense, “ Department Prioritizes Electromagnetic Spectrum Superiority, Implementing 2020
Strategy,” press release, August 5, 2021,
https://www.defense.gov/Newsroom/Releases/Release/Article/2721086/department -prioritizes-electromagnetic-
spectrum-superiority-implementing-2020-s/.
107 Mark Pomerleau, “ DoD pledges militarywide alignment on electromagnetic spectrum ops,” C4ISRNet, August 5,
2021, https://www.c4isrnet.com/electronic-warfare/2021/08/05/new-plan-dod-pledges-militarywide-alignment -on-
electromagnetic-spectrum-ops/.
108 Ibid.
109 Jaspreet Gill, “ Pentagon moves to implement new EMS strategy,” Inside Defense, August 5, 2021,
https://insidedefense.com/daily-news/pentagon-moves-implement-new-ems-strategy.
110 Ibid.
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From an operational perspective, U.S. Strategic Command traditional y has been delegated
responsibility for the spectrum. The FY2021 National Defense Authorization Act (NDAA)
directed that “the Secretary of Defense shal transfer to an appropriate entity within the
Department of Defense al the responsibilities and functions of the Commander of the United
States Strategic Command that are germane to electromagnetic spectrum operations” within two
years.111
Potential Spectrum Issues for Congress112
As Congress considers several policy implications of the use of the spectrum, several potential
issues emerge. These issues can be categorized broadly as technical issues, organizational issues,
and issues related to commercial use of the spectrum.
Technical Challenges
This section discusses several potential technical issues associated with the spectrum. These
include communications system interoperability, adversary technological development, and
spectrum sharing technologies to enable commercial applications.
Communications System Interoperability
One chal enge the DOD is confronted with is system interoperability both between individual
weapons systems as wel as between each of the military services. This issue has been
documented with the F-22 and F-35 fighter aircraft developing incompatible data link protocols—
the F-22 uses the intra-flight data link (IFDL) and the F-35 uses the multifunction advanced data
link (MADL)—preventing these two Air Force fighter jets from sharing information with each
other.113 Each service develops its command, control, and communications systems to meet their
individual needs. For instance, the Navy uses the AEGIS bal istic missile defense system—which
is instal ed on guided missile cruisers and destroyers—which is currently unable to transmit radar
data to the Army’s Integrated Battle Command System (IBCS) which performs a similar function.
As mentioned, 5G encompasses low-band, mid-band, and high-band spectrum. DOD uses al
three bands for its operations. While the bulk of its holdings are in the low-band and mid-band
spectrum, DOD also uses high-band (including mil imeter wave or MMW) frequencies for high-
profile military applications such as Advanced Extremely High Frequency satel ites that provide
assured global communications for U.S. forces. Coordinating investments across four branches of
government, three bands of spectrum, and across multiple geographies is a chal enge.
The Defense Innovation Board and FCC Commissioner Rosenworcel have suggested that DOD
should focus on sub-6 GHz deployments; they argue that the rest of the world, including China, is
deploying 5G for military use in the low-band and mid-band first, and that the U.S. should do the
same so as to (a) not fal behind other countries in sub-6 GHz deployments, and (b) ensure U.S.
forces may be able to operate and interoperate with those countries when abroad.
Industry observers assert that the significant innovations wil come in the MMW spectrum,
including high-speed, low latency applications, providing the U.S. a competitive edge in the

111 P.L. 116-283 §152.
112 T his section was written by John R. Hoehn and Jill C. Gallagher.
113 Brian W. Everstine, “T he F-22 and the F-35 Are Struggling to T alk to Each Other … And to the Rest of USAF,” Air
Force Magazine, January 29, 2018, at https://www.airforcemag.com/article/the-f-22-and-the-f-35-are-struggling-to-
talk-to-each-other-and-to-the-rest-of-usaf/.
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global defense market and on the battlefield. Stil others assert that investments across al three
bands wil benefit DOD as 5G offers greater capacity, speeds, functionality, customization, and
security. In deciding DOD appropriations, Congress may consider where and how federal funds
for 5G should be invested.
Adversary Spectrum Interference Developments
Another potential issue for Congress is balancing spectrum needs of commercial users and
consumers, and at the same time ensuring DOD has the spectrum it needs to keep pace with
adversaries. The DOD states “[s]ince modern military operations are critical y dependent on the
EMS, a key goal of our adversaries and enemies is to deny our ability to use it successfully.”114
After observing how the U.S. military operates, potential adversaries like Russia and China have
identified the U.S. military’ reliance on the spectrum as a potential vulnerability. As a result, these
potential adversaries have focused on chal enging the U.S. military’s network and EW
capabilities—these systems are part of an overal approach cal ed anti-access/area denial
(A2/AD) which are intended to chal enge the ability of the military from entering a contested area
like the Baltic states or the South China Sea.115 The FY2019 National Defense Authorization Act
(NDAA) required DOD to contract an independent assessment of EW capabilities, with a report
due October 1, 2019.116 The Center for Strategic and Budgetary Assessments ultimately
performed this assessment, providing an overview of adversary capabilities and doctrines.117
For more than a decade, the Russian military has focused on modernizing its forces, with a
particular emphasis on command, control, communications, and computers (C4) and ISR
systems, of which EW plays an important part. According to military analyst Robert McDermott,
the Russian military views electronic warfare as a “type of armed struggle using electronic means
against enemy C4ISR to ‘change the quality of information,’ or using electronic means against
various assets to change the condition of the operational environment.”118 McDermott describes a
close relationship between Russian signals intel igence forces and EW forces, where several EW
units perform SIGINT functions. The Russian military’s emphasis on EW may create problems
for U.S. military forces if the Russians are able to deny significant portions of the EMS.
Most of the focus on Chinese EW operations has been on the air, maritime, and space domains.
According to Jane’s Defence Weekly, China has invested substantial resources into science and
technology initiatives focused on improving its network and electronic warfare
capabilities.119 These investments include ground-based sensors and jammers, space-based

114 Department of Defense, Joint Electromagnetic Spectrum Operations, JP 3-85, Washington, DC, March 22, 2020, p.
I-3, https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp3_85.pdf?ver=2020-04-09-140128-347.
115 For more information on adversary electronic warfare capabilities see CRS Report R45919, Ground Electronic
Warfare: Background and Issues for Congress, by John R. Hoehn.
116 P.L. 115-232 §255.
117 Bryan Clark, Whitney M. McNamara, and T imothy A. Walton, Winning the Invisible War: Gaining an Enduring
U.S. Advantage in the Electrom agnetic Spectrum , Center for Strategic and Budgetary Assessments, Washington, DC,
November 20, 2019, https://csbaonline.org/research/publications/winning-the-invisible-war-gaining-an-enduring-u.s-
advantage-in-the-electromagnetic-spectrum.
118 Robert N. McDermott, Russia’s Electronic Warfare Capabilities to 2025, p. 3, International Centre for Defence and
Security, September 2017. See Department of Defense, Defense Intelligence Agency, Russia Military Power, Building
a Military to Support Great Power Aspirations, 2017, p. 4 2.
119 T ate Nurkin, Kelly Bedard, James Clad, et al., China’s Advanced Weapons Systems, IHS Jane's, May 12, 2018, p.
11, https://www.uscc.gov/sites/default/files/Research/
Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf .
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intel igence assets, and a number of airborne jammers.120 China is also investing in unmanned
systems that could potential y swarm to provide desired effects, including SIGINT interceptions
and electronic attack.121 China has also focused on developing advanced jammers and anti-
satel ite technologies to deny U.S. forces access to satel ites.122 For example, in 2007, China
demonstrated its ability to launch an anti-satel ite weapon to destroy an old weather satel ite in
low earth orbit. According to the 2020 Annual Report on China Military Power, the DOD
reported that “the PRC is developing electronic warfare capabilities such as satel ite jammers;
offensive cyber capabilities; and directed-energy weapons.”123
A chal enge for DOD has been in keeping pace with rapidly evolving technologies and
coordinating information on adversaries’ technologies and capabilities across DOD
components.124 In December 2018, the Government Accountability Office (GAO) issued a report
stating that adversaries are developing electronic attack weapons to target U.S. systems with
sensitive electronic components, such as military sensors, communication, navigation, and
information systems.125 The Senate Armed Services Committee, citing the report, stated, “These
weapons are intended to degrade U.S. capabilities and could restrict situational awareness or may
affect military operations. The committee is concerned about the extent to which [DOD] is
planning and preparing to defend itself and operate in an environment where peer and near-peer
adversaries could use existing and emerging capabilities that degrade use of the electromagnetic
spectrum.”126
Spectrum Sharing
In the past, repurposing efforts have focused on real ocating spectrum from federal to nonfederal
use. As spectrum-sharing technologies emerged, Congress encouraged not only the real ocation of
spectrum from federal to nonfederal entities, but also sharing between federal and commercial
users. For example, the Middle Class Tax Relief and Job Creation Act of 2012 al owed federal
agencies to receive payments for costs incurred when they are asked to relocate due to a spectrum
auction or when they agree to share use of their spectrum.127 The Spectrum Pipeline Act of 2015

120 Elsa Kania, China’s Strategic Situational Awareness Capabilities, Center for Strategic and International Studies,
Washington, DC, July 29, 2019, https://ontheradar.csis.org/issue-briefs/china-situational-awareness/.
121 T ate Nurkin, Kelly Bedard, James Clad et al., China’s Advanced Weapons Systems, IHS Jane's, May 12, 2018, p.
41, https://www.uscc.gov/sites/default/files/Research/
Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf .
122 Department of Defense, Defense Intelligence Agency, China Military Power: Modernizing a Force to Fight and
Win, 2019, p. 42.
123 Department of Defense, Military and Security Developments Involving the People’s Republic of China 2020 ,
Washington, DC, September 2020, p. 65, https://media.defense.gov/2020/Sep/01/2002488689/-1/-1/1/2020-DOD-
CHINA-MILIT ARY-POWER-REPORT -FINAL.PDF.
124 Sydney J. Freedberg, Jr., “Who’ll Fix EW? T ask Force Gropes for Answers,” Breaking Defense, December 18,
2019, https://breakingdefense.com/2019/12/wholl-fix-ew-task-force-gropes-for-answers/.
125 U.S. Government Accountability Office, National Security: Long-Range Emerging Threats Facing the United States
As Identified by Federal Agencies, GAO-19-204SP, December 2018, p. 4, https://www.gao.gov/assets/700/695981.pdf.
126 U.S. Congress, House Committee on Armed Services, Report of the Committee on Armed Services on H.R. 2500
together with Additional and Dissenting Views, H.Rept. 116-120, 116th Cong., 1st sess., June 19, 2019, 36-763
(Washington: GPO, 2019), p. 69, https://www.govinfo.gov/content/pkg/CRPT -116hrpt120/html/CRPT-
116hrpt120.htm.
127 P.L. 112-96, T itle VI, Subtitle G—Federal Spectrum Relocation, Section 6701 (a)(1)(B).
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appropriated funds for federal agencies to engage in planning and to conduct studies and analyses
to examine the potential for spectrum real ocation or sharing.128
DOD has participated in several spectrum-sharing initiatives, some of which have resulted in the
real ocation or shared use of spectrum.129 For example, DOD, the Department of Homeland
Security (DHS), the Federal Aviation Administration (FAA), and the National Oceanic and
Atmospheric Administration (NOAA) have studied the potential to combine surveil ance, air
safety, and weather radar applications into a single, spectrum-conserving “system of systems” by
2024. This system would al ow the agencies to vacate 30 MHz of spectrum in the 1300–1350
band, thus making it available for real ocation for shared federal and nonfederal use. Additional y,
DOD plans to conduct a comprehensive engineering study to determine the potential for
introducing advanced wireless services in this band without harming critical government
operations.130 Agencies began studying the real ocation and sharing potential of the spectrum in
2017, and are stil actively studying potential use of the band. The studies are expected to inform
future repurposing decisions.131
On August 10, 2020, the White House and DOD announced that a 100 MHz block of contiguous
mid-band spectrum in the 3450-3550 MHz band wil be made available for commercial use (e.g.,
5G), and is expected to be auctioned in 2021. DOD leveraged technical work performed by the
NTIA to “devise a spectrum sharing framework that supports industry’s need for additional mid-
band spectrum while protecting critical national security requirements.”132 At its September 30,
2020 meeting, the FCC adopted a Further Notice of Proposed Rulemaking (FNPRM) al ocating
the 3.45-3.55 GHz spectrum band for flexible-use service. It seeks comment on an appropriate
regime to coordinate nonfederal and federal use and proposes a band plan, as wel as technical,
licensing, and competitive bidding rules for the band, signaling that the FCC is moving forward
on the 2021 auction date.133
In addition, new technologies that would enable dynamic spectrum sharing—automated sharing
between federal and nonfederal users—are under development.134 For example, in September
2019, the FCC approved a spectrum sharing arrangement between commercial and federal users
in the 3550-3700 MHz band (also known as Citizens Broadband Radio Service or CBRS),
whereby commercial users (licensed and unlicensed) wil share spectrum with incumbent DOD
users. DOD wil have priority access when needed while stil al owing for licensed and
unlicensed use.

128 P.L. 114-74, T itle X—Spectrum Pipeline, Section 1005 (a).
129 Mark Rockwell, “DOD looks to share more spectrum,” Defense Systems, March 1, 2018,
https://defensesystems.com/articles/2018/03/01/ntia-dod-spectrum-5g.aspx.
130 Office of Science and T echnology Policy, Emerging Technologies and Their Expected Impact on Non -Federal
Spectrum Dem and, May 2019, https://www.whitehouse.gov/wp-content/uploads/2019/05/Emerging-T echnologies-and-
Impact -on-Non-Federal-Spectrum-Demand-Report-May-2019.pdf.
131 U.S. Department of Commerce, Annual Report on the Status of Spectrum Repurposing, August 2019,
https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf.
132 U.S. Department of Defense, “White House and DOD Announce Additional Mid-Band Spectrum Available for 5G
by the end of the Summer,” press release, August 10, 2020, https://www.defense.gov/Newsroom/Releases/Release/
Article/2307275/white-house-and-dod-announce-additional-mid-band-spectrum-available-for-5g-by-t/.
133 FCC, “FCC Moves to Free Up 100 Megahertz of Critical Mid-Band Spectrum in the 3.45-3.55 GHz Band for 5G,”
press release, September 30, 2020, https://docs.fcc.gov/public/attachments/DOC-367236A1.pdf.
134 T he CBRS spectrum sharing arrangement is being used to model for other spectrum sharing arrangements. National
T elecommunications and Information Agency, “Spectrum Sharing Model Gaining Ground,” press release, May 1,
2019, https://www.ntia.doc.gov/blog/2019/spectrum-sharing-model-gaining-ground.
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In December 2019, DOD issued a special notice seeking input from industry on 5G technology
development, including dynamic spectrum sharing technologies.135 DOD and the Department of
the Air Force sought input on effective methodologies (hardware, software, and systems) for
sharing or coexistence between airborne radar systems and 5G cel ular systems in shared
(completely or partial y overlapping) spectral bands. The intent is to evaluate the impact of the
5G network on airborne radar systems and the radar systems’ impact on the 5G network,
employing both active and passive techniques to enable sharing or coexistence. In September
2020, DOD issued a request for information seeking new methods to facilitate spectrum sharing
between military and civilian users, and to identify issues of concern related to sharing spectrum
for DOD.136
While policymakers and users are both interested in spectrum sharing, and see it as a way of
extending spectrum access for new users, the policies, approaches, technologies, and applications
are stil emerging and may face chal enges. Introducing new users into spectrum bands creates a
potential for interference with military capabilities; detecting and mitigating interference is a
chal enge. Prioritization of use is another chal enge, as is policy control and coordination with
secondary users.137 Further, to maximize use of shared spectrum, users may need to know when
spectrum is being used and when it is available which may present chal enges for DOD, as it may
not want to share that information publicly.
On the one hand, industry stakeholders say that military and other federal users have more
spectrum than they need and that holding large swathes of spectrum for future use inhibits
innovations and restricts economic advancement.138 On the other hand, some defense advocates
say that as commercial use of spectrum is increasing, so is military use. These observers note that
agencies holding large swathes of spectrum see only risks in relinquishing spectrum; they note,
“no military planner would want to be known as the person who gave back spectrum
subsequently needed.”139 The chal enge for Congress is in encouraging policies that enable the
most efficient use of spectrum, while stil protecting and prioritizing DOD mission critical
functions.
DOD Spectrum Organizational Issues140
Over the past several years, Congress has expressed interest in the DOD’s organization of
spectrum-related issues. The EW Executive Committee—led by the Deputy Secretary of
Defense—is tasked with synchronizing and integrating EW across DOD components by sharing

135 U.S. Department of Defense, “DOD Issues Special Notice Seeking Input From Industry on 5G T echnology
Development,” press release, December 2, 2019, https://www.defense.gov/Newsroom/Releases/Release/Article/
2029707/dod-issues-special-notice-seeking-input -from-industry-on-5g-technology-developm/.
136 DOD, Request for Information, Defense Spectrum Sharing Request for Information, Published September 18, 2020,
https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&
index=&is_active=true&page=1.
137 Frank Rayal, “Challenges & Impediments to Implementing Spectrum Sharing,” Frank Rayal (blog), September 24,
2012, “https://frankrayal.com/2012/09/24/challenges-impediments-to-implementing-spectrum-sharing/.
138 CT IA, “Benefits from Clearing Federal Spectrum Helps Government Agencies Modernize Operations, New CT IA
Paper Finds,” press release, August 11, 2020, https://www.ctia.org/news/release-benefits-from-clearing-federal-
spectrum-helps-government-agencies-modernize-operations-new-ctia-paper-finds.
139 Roslyn Layton, “GPS Interference Fears Are T oday’s Y2K, Says Former UK Spectrum Director,” Forbes, May 8,
2020, https://www.forbes.com/sites/roslynlayt on/2020/05/08/gps-interference-fears-are-todays-y2k-says-former-uk-
spectrum-director/#79d799e17329.
140 T his section was written by John R. Hoehn.
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tactics, techniques, procedures, intel igence, and technologies. The EW EXCOM is responsible
for establishing DOD EW policy by recommending resource al ocation changes and proposing
electronic warfare governance, management, organizational, and operational reforms.141 The
FY2019 NDAA mandated the creation of an EW Cross Functional Team to develop an electronic
warfare strategy, including assessments of vulnerabilities and capability gaps,142 leading to an
acquisition plan.
The NDAA for FY2019 (P.L. 115-232, Section 1053) directed DOD to establish a cross-
functional team to oversee the implementation of an integrated spectrum strategy. The intent is to
meld two existing strategies, DOD’s 2013 electromagnetic spectrum strategy developed by the
chief information office (CIO) and the department’s electronic warfare strategy, into a single
policy: 143 the Electromagnetic Spectrum Superiority Strategy.144 In April 2019, DOD stood up the
Electromagnetic Spectrum Operations (EMSO) Cross Functional Team, comprised of senior
members from each branch, the Joint Staff, U.S. Strategic Command, Cyber Command, and other
offices. This organization has been active in updating DOD spectrum policy and strategy. In May
2020, the Joint Staff released new doctrine on Joint Electromagnetic Spectrum Operations,
elevating the spectrum to a maneuver space.145 On September 4, 2020, DOD issued DOD
Directive 3610.01, Electromagnetic Spectrum Enterprise Policy, which sets DOD policy and roles
and responsibilities for integrated DOD electromagnetic spectrum operations.146 On October 29,
2020, the EMS Operations Cross Functional Team authored the DOD Spectrum Superiority
Strategy, which was signed by the Secretary of Defense.147 This strategy recognizes the
importance of spectrum in support of military operations, and combines two traditional separate
disciplines—electronic warfare and spectrum management—to take a holistic view of the DOD
spectrum enterprise. Final y, the FY2021 NDAA transfers responsibility for electromagnetic
spectrum operations from Strategic Command to an appropriate entity within DOD.148
Commercial Demand for Federal Spectrum
As the nation continues to experience significant growth in commercial wireless services (e.g.,
mobile phones, mobile applications, video streaming, Wi-Fi), demand for spectrum has increased.
To meet current commercial and consumer demands, the U.S. government has identified
spectrum that is optimal for wireless communication use. Sometimes the spectrum targeted for
wireless services is in use by other commercial users (e.g., radio and television broadcasters,

141 10 U.S.C. §113 Notes.
142 P.L. 115-232 §918.
143 T he EMSO CFT is in the process of developing a new EMS strategy and anticipates releasing the strategy by the
end of 2020. Department of Defense, Electrom agnetic Spectrum Strategy, September 11, 2013,
https://dodcio.defense.gov/Portals/0/Documents/Spectrum/ESS.pdf.
144 Lauren C. Williams, “DOD Preps New Electromagnetic Spectrum Strategy,” Defense Systems, December 23, 2019,
https://defensesystems.com/articles/2019/12/23/dod-spectrum-warfare-williams.aspx.
145 While a maneuver space is not considered a domain, this implies
146 Department of Defense, DOD Directive 3610.01: Electromagnetic Spectrum Enterprise Policy, September 4, 2020,
https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/361001p.pdf?ver=2020-09-04-112353-317.
147 Department of Defense, Electromagnetic Spectrum Superiority Strategy, October 29, 2020,
https://media.defense.gov/2020/Oct/29/2002525927/-1/-1/0/
ELECT ROMAGNET IC_SPECT RUM_SUPERIORIT Y_ST RAT EGY.PDF.
148 P.L. 116-283 §152 T ransfer of Responsibilities and Functions Relating to Electromagnetic Spectrum Operations.
T his provision originated from S. 4049 §173, which would have transferred electromagn etic spectrum operations from
Strategic Command to the Chairman of the Joint Chiefs of Staff as a Chairman’s Controlled activity.ro
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satel ite communication providers). Sometimes the spectrum targeted is in use by federal
agencies. Since DOD holds spectrum across multiple bands, it has been affected by effort to
real ocate spectrum for commercial wireless use.
The growth in commercial wireless services has produced new revenues and new jobs for the
United States.149 Hence the chal enge for Congress is in balancing the al ocation of spectrum for
commercial and consumer wireless services while protecting federal agency use of spectrum that
support mission-critical functions. This balance was recently demonstrated with the FCC’s
Auction 107 for C-Band spectrum, which garnered approximately $81 bil ion from bidders.150
Federal agencies hold various segments of spectrum that commercial entities may be able to use
for wireless services. Since DOD is the largest holder of federal frequencies, policies to real ocate
spectrum for commercial use often affect DOD. As Congress considers policies to al ocate
additional spectrum for commercial use, it may consider increasing demands for spectrum, the
impact on DOD systems and uses, unintended frequency interference, the interagency process for
al ocating spectrum, and DOD’s ability to anticipate future spectrum needs.
Increasing Demand for Spectrum
As more people are using more data on more devices and as new technologies emerge (5G),
demand for mobile data (e.g., video) is increasing. Cisco, the U.S.-based network equipment
maker, reported that in 2018, “global mobile data traffic amounted to 19.01 exabytes per
month;151 by 2022, mobile data traffic is expected to reach 77.5 exabytes per month
worldwide,”152 which wil increase demand for additional spectrum.
To accommodate new technologies, more users, and more data-intensive applications (e.g., video
streaming, gaming), global telecommunications providers and equipment makers around the
world developed 5G wireless networks and technologies. 5G technologies promise increased
speeds, improved connectivity, and reduced latency (i.e., lag time when sending commands from
your device). However, for 5G, providers need large swathes of spectrum (100 MHz blocks) in
the low-band (below 1 GHz), mid-band (1-6 GHz), and high-band (above 6 GHz) radio spectrum.
Providers expect that the 5G solution—additional spectrum and new 5G technologies—wil help
to meet increasing demands for mobile data, support advanced 5G services to businesses, and
yield new 5G applications, including new military applications.153
However, the spectrum is already crowded with users, including federal agency users. DOD is
al ocated about 40% of federal y assigned spectrum,154 including significant frequency bands in
the 1-6GHz range—prime spectrum for mobile telecommunication technologies. Some
stakeholders and policymakers have cal ed for the real ocation of federal agency spectrum for

149 Recon Analytics, LLC, “How America’s 4G Leadership Propelled the U.S. Economy,” April 16, 2018,
https://api.ctia.org/wp-content/uploads/2018/04/Recon-Analytics_How-Americas-4G-Leadership-Propelled-US-
Economy_2018.pdf.
150 Federal Communications Commission, “Auction 107 - 3.7 GHz,” press release, January 15, 2021,
https://auctiondata.fcc.gov/public/projects/auction107.
151 An average person uses about 2-3 gigabytes per month. Collectively in 2018, consumers used about 19 billion
gigabytes per month. In 2022, consumers are expected to use 77.5 billion gigabytes per month.
152 https://www.statista.com/statistics/271405/global-mobile-data-traffic-forecast/
153 CRS In Focus IF11251, National Security Implications of Fifth Generation (5G) Mobile Technologies, by John R.
Hoehn and Kelley M. Sayler.
154 U.S. Government Accountability Office, NT IA Planning and Processes Need Strengthening to Promote the Efficient
Use of Spectrum by Federal Agencies, GAO-11-352, April 2011, p. 21, https://www.gao.gov/assets/320/318264.pdf.
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commercial use, or incentives for some federal agencies to relinquish or share spectrum for 5G
use.155 DOD asserts that its spectrum supports military operations, and the research and
development of advanced technologies, thus should remain with DOD.
Starting in 1993, the Omnibus Budget Reconciliation Act (OBRA),156 required the Secretary of
Commerce to identify at least 200 MHz of spectrum used by the federal government for
real ocation to new spectrum-based technologies (i.e., commercial use). Year after year, the U.S.
government has continued to real ocate spectrum from federal to commercial wireless use. In its
first Annual Report on the Status of Spectrum Repurposing (2019), NTIA notes, “[t]o date, most
repurposing activities and the statutory mandates for repurposing focus on accommodating non-
federal uses and have not directed the repurposing of spectrum to new federal uses; they also
prioritize exclusive non-federal use over sharing.”157 Congress may require the real ocation of
specific spectrum bands, cal for the identification of certain amounts of spectrum (e.g., 255 MHz
below 6 GHz), or cal for testing and studies to identify appropriate spectrum for commercial
use.158 Since DOD holds about 40% of the federal y held spectrum,159 it can be affected by these
policies.160
Congress has tried to assess and address the impact of federal spectrum policies on agencies. For
example, in 2004 Congress established a program to help cover the costs that federal agencies
incur when spectrum is real ocated. Congress enacted the Commercial Spectrum Enhancement
Act (CSEA),161 which created the Spectrum Relocation Fund (SRF). The SRF used revenues from
spectrum auctions to provide funding to defray the costs of relocating federal users to new bands.
However, as wireless technology use increased, and demand for mobile data continued to rise, the
U.S. government continued to examine and real ocate spectrum to meet emerging demands. Some
have argued that a piecemeal approach to spectrum planning is ineffective.162 They say it does not
provide companies or affected federal agencies with enough time or information to plan future
investments. Advocates assert that a long-term spectrum plan or pipeline wil al ow industry to
plan future investments and agencies to plan future improvements, reduce the time it takes to
bring spectrum to market, and perhaps assist in resolving ongoing spectrum disputes.163 In 2018,
two spectrum planning initiatives were launched.

155 https://www.politico.com/news/agenda/2020/02/22/pentagon-airwaves-midband-106240.
156 P.L. 103-66.
157 Ibid.
158 U.S. Department of Commerce, Annual Report on the Status of Spectrum Repurposing, August 2019,
https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf.
159 U.S. Government Accountability Office, NTIA Planning and Processes Need Strengthening to Promote the Efficient
Use of Spectrum by Federal Agencies, GAO-11-352, April 2011, p. 21, https://www.gao.gov/assets/320/318264.pdf.
160 George Leopold, “ DOD returns fire on spectrum relocation,” EE|Times, August 30, 2001, https://www.eetimes.com/
dod-returns-fire-on-spectrum-relocation/#.
161 T itle II of P.L. 108-494.
162 U.S. House of Representatives, Committee on Energy and Commerce, Subcommittee on Communications and
T echnology, hearings, “ Our Wireless Future: Building A Comprehensive Approach to Spectrum Policy,” 116th Cong.,
1st sess., July 16, 2019, https://energycommerce.house.gov/committee-activity/hearings/hearing-on-our-wireless-future-
building-a-comprehensive-approach-to. See testimony of Derek Khlopin, Senior Policy Advisor, NT IA, at
https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/
1_T estimony_Khlopin.pdf. See also testimony of Scott Bergmann Senior Vice President, Regulatory Affairs CT IA, at
https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/
2_T estimony_Bergmann.pdf.
163 White House 5G Summit (recorded event), September 28, 2018, https://www.youtube.com/watch?v=lBbY8fvT idU.
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The FCC developed the 5G FAST Plan, which identified spectrum for 5G use, and streamlined
regulations to speed 5G deployment.164 This plan provides insight into FCC actions (e.g., future
real ocations, auctions); however, the GAO found that the plan was not developed with outside
entities, including the NTIA or other relevant stakeholders, including carriers.165 In 2018, the
President directed the NTIA to develop a National Spectrum Strategy to set forth a “balanced,
forward-looking, flexible, and sustainable approach to spectrum management.”166 Federal
agencies were directed to review current frequency assignments and spectrum usage to identify
spectrum that could be real ocated or shared with commercial uses. NTIA held a Spectrum Policy
Symposium in August 2019 to seek public comment on the plan. DOD speakers noted that, with
new technologies and cooperation with commercial users, DOD is exploring opportunities to
share spectrum.167 NTIA has reported that the National Spectrum Strategy is under development.
Congress may be interested in encouraging coordination between the agencies to balance the
needs of commercial 5G providers and users and the mission critical needs of DOD. On the one
hand, real ocating spectrum from DOD may help to speed deployment of 5G networks, spur the
development of 5G use cases, and strengthen the U.S. position in the global 5G market. On the
other hand, DOD provides critical national defense functions; taking spectrum from DOD could
affect military operations and result in the permanent loss of spectrum for DOD uses, including
critical defense operations and future capabilities.
Unintended Commercial Frequency Interference168
As new users, technologies, and services are introduced to the spectrum, the potential for
interference may increase.169 Interference occurs when unwanted radio frequency signals disrupt
the transmission of information in systems operating in the same band or in nearby bands.
Interference is a persistent issue in spectrum management, and introducing new technologies, new
users, and broadening spectrum access (e.g., through spectrum sharing or al owing flexible use of
spectrum) may increase the potential for harmful interference.170
As the U.S. government seeks to use spectrum more flexible to support new uses, or more
cooperatively, through a shared approach, interference claims are likely to increase. For DOD,
Congress has enacted legislation to protect DOD systems from interference. For example,
pursuant to 10 U.S.C. §2281, Congress had authorized DOD to object “to any restriction on the
GPS System proposed by the head of a department or agency of the United States outside DOD
that would adversely affect the military potential of GPS” [emphasis added]. Additional y, in
Section 1698 of the National Defense Authorization Act for Fiscal Year 2017 (P.L. 114-328)—

164 FCC, “5G FAST Plan,” https://www.fcc.gov/5G.
165 U.S. Government Accountability Office, 5G Deployment: FCC Needs Comprehensive Strategic Planning to Guide
its Efforts, GAO-20-468, June 2020, pp. 12-13, https://www.gao.gov/assets/710/707530.pdf.
166 White House, Office of the Press Secretary, “Presidential Memorandum on Developing a Sustainable Spectrum
Strategy for America’s Future,” presidential memorandum, October 25, 2018, https://www.whitehouse.gov/
presidential-actions/presidential-memorandum-developing-sustainable-spectrum-strategy-americas-future/.
167 NT IA, NTIA Spectrum Policy Symposium Transcript, September 10, 2019, p. 12, https://www.ntia.doc.gov/files/
ntia/publications/09.10.19_npc_ntia_spectrum_policy_symposium.pdf.
168 Fore a detailed discussion of potential 5G interference with the Global Positioning System, see the Appendix.
169 Commerce Spectrum Management Advisory Committee (CSMAC), Interference and Dynamic Spectrum Access,
Interim Report, May 19, 2010, p. 13, https://www.ntia.doc.gov/files/ntia/meetings/csmac_may19_idsa_final.pdf.
170 John Pahl, “Market Mechanisms for Spectrum Management: Spectrum Liberalisation and Interference
Management,” Background Paper submitted to IT U Workshop, “Shaping T omorrow’s Network” Program, September
2006, https://www.scribd.com/document/60765650/Spectrum-Liberalisation-and-Interference-Management.
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codified at Section 343 of the Communications Act—prohibits the FCC from approving
commercial terrestrial operations in the bands proposed by Ligado “until 90 days after the
Commission resolves concerns of widespread harmful interference by such operations to covered
GPS devices.”171 While DOD did express its concerns to the FCC on the Ligado project, the FCC
asserted that the conditions it placed on Ligado (e.g., reducing power levels, creating a guard
band, reporting base station locations) would mitigate interference concerns.
A recent dispute with Ligado Networks, LLC has highlighted key interference issues. On April
20, 2020, the FCC unanimously approved an application by Ligado Networks LLC (Ligado) to
“deploy a low-power [9.8 decibel watts (dBW)] terrestrial nationwide network in the 1526-1536
MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5 MHz bands [of the electromagnetic spectrum]172
that wil primarily support Internet of Things (IoT) services.”173
These frequency bands are traditional y used for satel ite communications and position,
navigation, and timing services, such as GPS.174 DOD opposed this decision—along with the
Department of Homeland Security, Department of Transportation (DOT), Department of the
Interior, Department of Justice, the Federal Aviation Administration (FAA), and others.175 That
opposition was related to concerns that Ligado’s proposed terrestrial network could interfere with
signals from satel ites to terrestrial GPS receivers and enabled devices.176 Despite federal agency
opposition, the FCC unanimously approved the project, with the conditions (e.g., reducing power,
creating a guard band, reporting base station locations) that, the FCC commissioners assert,
would avoid interference between the two systems.
An issue of consideration for Congress may be in setting acceptable interference thresholds,
levels of acceptable risks that are consistent with international interference standards that wil
enable new technologies and protect DOD critical operations. Another area for Congress may be
in the resolution process, how and when federal agency concerns about interference are heard,
and how decisions may affect federal systems and operations. Congress may also consider
broader issues related to wireless technologies (e.g., 5G, 6G), such as the al ocation of spectrum
among competing users and the impact of spectrum decisions on national security.

171 T his provision is related to an earlier proposal from Ligado submitted to the FCC, which federal agencies, including
DOD, opposed. Details on the proposal, the federal agency opposition, and congressional intent is available in S.Rept.
116-236, pp. 75, 275.
172 CRS In Focus IF11155, Defense Primer: Military Use of the Electromagnetic Spectrum , by John R. Hoehn.
173 T he FCC authorized Ligado to operate an Internet of T hings network in the referenced frequency ban ds with
conditions. Federal Communications Communication Order 20 -48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf.
174 T estimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief
Information Officer, Gen John Raymond, Chief of Space Operations, and T had Allen, Chairman of Space -Based
Positioning Navigation and T iming National Advisory Board, before the U.S. Congress, Senate Armed Services
Committee, Departm ent of Defense Spectrum Policy and the Im pact of the Federal Com m unications Com m ission, 116th
Cong., 2nd sess., May 6, 2020.
175 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary
of Communications and Information, to Hon Ajit Pai, Chairman of the Federal Communications Commission, April 10,
2020, at https://www.ntia.doc.gov/files/ntia/publications/
ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf .
176 CRS In Focus IF11558, Spectrum Interference Issues: Ligado, the L-Band, and GPS, by Jill C. Gallagher, Alyssa K.
King, and Clare Y. Cho.
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Interagency Disputes
Congress may review the process by which the FCC and the NTIA, or other federal agencies,
resolve spectrum disputes. As noted, the FCC and NTIA operate under an MOU that requires
spectrum planning and coordination. The NTIA represents federal agency concerns in meetings
with the FCC. Some observers have questioned NTIA’s ability to represent federal agency
interests,177 while others have questioned whether federal agencies should have to work through
NTIA to express its concerns on FCC decisions.178
As the federal government strives to make spectrum available for 5G services, several spectrum
bands used for federal agency missions (DOD and other agencies) have been targeted for
real ocation or repurposing, affecting federal agency investments and missions. This includes
DOD concerns over the L-Band, DOT concerns over the reconfiguring of the 5.9 GHz band set
aside for auto safety technologies, Department of Education concerns regarding the real ocation
of the 2.5 GHz band from educational users, and the National Oceanic and Atmospheric
Administration and the 24 GHz band used for weather forecasting.
Congress has proposed initiatives to improve spectrum management and reduce spectrum
disputes. For example, the Senate-passed version of the FY2021 NDAA (S. 4049, enrolled,
Section 1084) (c)), would direct the NTIA to evaluate a range of information technology (IT)
modernization initiatives that would improve analysis of federal government spectrum use and
management. Some in Congress have proposed updates to the MOU between the FCC and NTIA
to clarify the government’s spectrum management and real ocation process.179 Others have
suggested to Congress that a third-party, such as the White House Office of Science and
Technology Policy (OSTP) or the National Academies of Science and Engineering, serve as a
technical reviewer or as an arbiter of conflicting technical reports and interference disputes.180
As spectrum is real ocated or reconfigured, some federal agencies are protesting.181 FCC has
acknowledged that as demand for spectrum increases, and more users gain access to the spectrum,
disputes are likely to increase as wel . Congress may examine the interagency spectrum planning
and dispute resolution processes to ensure that federal agency needs are heard, and that federal
agency investments are protected and that federal agency missions continue to be supported.

177 U.S. Government Accountability Office, Interdepartment Radio Advisory Committee: IRAC Representatives
Effectively Coordinate Federal Spectrum but Lack Seniority to Advise on Contentious Policy Issues, GAO-04-1028,
September 2004, pp. 3-4, https://www.gao.gov/new.items/d041028.pdf.
178 T estimony of T had Allen, Chairman of Space-Based Positioning Navigation and T iming National Advisory Board,
before the U.S. Congress, Senate Armed Services Committee, Departm ent of Defense Spectrum Policy and the Im pact
of the Federal Com m unications Com m ission, 116th Cong., 2nd sess., May 6, 2020, p. 42, https://www.armed-
services.senate.gov/imo/media/doc/20-21_05-06-2020.pdf.
179 See discussion on MOU and arbiter for spectrum disputes during Senate hearing (video): U.S. Congress, Senate
Committee on Commerce, Science, and T ransportation, The State of U.S. Spectrum Policy, 116th Cong., 2nd sess., July
23, 2020.
180 Ibid.
181 Letter from Elaine L. Chao, Secretary, U.S. Department of T ransportation, to Federal Communications Chairman
Ajit Pai, November 20, 2019, https://www.highways.org/wp-content/uploads/2019/12/sec-chao-letter-5.9-11-20-19.pdf;
Letter from Jim Blew, Assistant Secretary for Planning, U.S. Department of Education, to FCC Chairman Ajit Pai, June
7, 2019, https://ecfsapi.fcc.gov/file/10607076793462/190607-Education-EBSExParte.pdf; Letter from Douglas W.
Kinkoph, Associate Administrator, NT IA, to FCC Chairman Pai, April 10, 2020, https://www.ntia.doc.gov/files/ntia/
publications/ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf (this cover letter from NT IA was sent to
the FCC, and includes letters from DOD to the Secretary of Commerce regarding concerns with recent spectrum
decisions, DOD to NT IA on spectrum concerns, and a Memorandum from the Air Force to NT IA on spectrum
concerns, signed by 12 members of this interagency spectr um working group).
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Anticipating Future Spectrum Needs
In a report to the President by the Director of the Office of Science and Technology Policy
(OSTP), the Director cites the primary use cases for 5G: (1) enhanced mobile broadband; (2)
ultra-reliable and low latency communications; (3) massive machine type communications, also
known as massive Internet of Things (IoT); (4) fixed wireless technologies; and (5) enhanced
vehicle-to-everything (V2X). The Director notes that the identified use cases are driving research
and development (R&D) activities, as wel as the standardization activities taking place in the
international standards development groups such as the International Telecommunications Union
(ITU) and the Third Generation Partnership Project (3GPP). Some technology firms advocate for
increased investments in R&D to give the United States a competitive edge in the commercial 5G
market. DOD is supporting this R&D through the development of new technologies, such as the
dynamic spectrum sharing technologies to support the more efficient use of spectrum by
deploying 5G in selected bases to measure and monitor performance, and experiment with the
technologies.
The al ocation of spectrum takes time, as does the buildout of a network that wil operate in the
band. Often, by the time the spectrum is al ocated and networks built, new technologies are
emerging. For example, future sixth generation (6G) communications technologies, along with
emerging military communications technologies. These technologies wil most likely use the
spectrum differently than current systems; exactly how these systems wil use the spectrum
remains unclear.182
Potential Questions for Congress183
As Congress considers its role in spectrum policy and how the DOD manages its use of the
spectrum, several potential issues and questions arise. Below are a few potential Congress may
seek additional information:
 What actions can Congress or DOD take to ensure that mission critical systems
that operate in various segments of the electromagnetic spectrum (both
domestical y and abroad) are interoperable?
 What changes, if any, should the DOD make in programs or investments in order
to maintain a technological edge in the use of the electromagnetic spectrum over
U.S. competitors?
 Does the U.S. government’s plan for spectrum al ocation sufficiently balance
DOD requirements with the requirements of commercial applications? If so,
how?
 What measures, if any, could accelerate spectrum repurposing, relocation, and/or
sharing?
 Is DOD using the spectrum it has efficiently? How can DOD improve its
spectrum efficiency? Is DOD adequately leveraging the spectrum to enable future
concepts like Multi-Domain Operations, Distributed Maritime Operations, and
JADC2? If so, how?

182 Some analysts have suggested that 6G, for instance might use spectrum in the 200 -1000 GHz range, however there
are no official stands that have been identified. Future DOD use of the spectrum remains unclear other than the
highlighted emerging technologies discussed earlier.
183 T his section was written by John R. Hoehn, Jill C. Gallagher, and Kelley M. Sayler.
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Overview of Department of Defense Use of the Electromagnetic Spectrum

 As DOD relinquishes certain spectrum segments to commercial or shared use,
how is it planning to ensure continued command and chal enges in implementing
5G communications?

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Appendix. Ligado Networks184
Concerns Regarding the FCC-Approved Ligado Network for
Mid-Band 5G Network
On April 20, 2020, the Federal Communications Commission (FCC) unanimously approved an
application by Ligado Networks LLC (Ligado) to “deploy a low-power [9.8 decibel watts (dBW)]
terrestrial nationwide network in the 1526-1536 MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5
MHz bands [of the electromagnetic spectrum]185 that wil primarily support Internet of Things
(IoT) services.”186 These frequency bands are traditional y used for satel ite operations.187 The
Department of Defense (DOD) opposed this decision, along with the Department of Homeland
Security, Department of Transportation (DOT), Department of the Interior, Department of Justice,
the Federal Aviation Administration (FAA), and others.188 That opposition related to concerns that
Ligado’s proposed network could interfere with signals from satel ites to Global Positioning
System (GPS) receivers.189 Congress may consider federal agency concerns, including DOD
concerns related to mission-critical systems and the FCC’s response, as it conducts oversight of
the FCC’s ruling. Congress may also consider broader issues related to fifth generation (5G)
mobile technologies, such as the al ocation of spectrum among competing users and the impact of
spectrum decisions on national security.
DOD Concerns and Related Studies on GPS Interference
In both its formal response to the FCC’s ruling and in its May 6, 2020, testimony before the
Senate Armed Services Committee (SASC), DOD cited two primary studies that shaped its belief
that the Ligado network “would cause unacceptable operational impacts and adversely affect the
military potential of GPS”: a 2018 DOT study and a 2016 classified study conducted by the U.S.
Air Force (USAF).190 The 2018 DOT study assessed the extent to which cel ular base stations

184 T his section was written by John R. Hoehn and Kelley M. Sayler. For more information see, CRS Insight IN11400,
DOD Concerns About the FCC-Approved Ligado Network, by Kelley M. Sayler and John R. Hoehn and CRS Insight
IN11414, The FCC-Approved Ligado Network and Potential Technical Issues for DOD Use of GPS, by John R. Hoehn,
Stephen M. McCall, and Kelley M. Sayler.
185 CRS In Focus IF11155, Defense Primer: Military Use of the Electromagnetic Spectrum , by John R. Hoehn.
186 T he FCC authorized Ligado to operate an Internet of T hings network in the referenced frequency bands with
conditions. Federal Communications Communication Order 20 -48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf.
187 T estimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief
Information Officer, Gen. John Raymond, Chief of Space Operations, and T had Allen, Chairman of Space -Based
Positioning, Navigation and T iming National Advisory Board, before the U.S. Congress, Senate Armed Services
Committee, Departm ent of Defense Spectrum Policy and the Im pact of the Federal Com m unications Com m ission , 116th
Cong., 2nd sess., May 6, 2020.
188 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary
of Communications and Information, to Hon. Ajit Pai, Chairman of the Federal Communications Commission, April
10, 2020, at https://www.ntia.doc.gov/files/ntia/publications/
ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf .
189 CRS In Focus IF11558, Spectrum Interference Issues: Ligado, the L-Band, and GPS, by Jill C. Gallagher, Alyssa K.
King, and Clare Y. Cho.
190 See Department of T ransportation, Global Positioning System (GPS) Adjacent Band Compatibility Assessment,
April 2018, https://www.transportation.gov/sites/dot.gov/files/docs/subdoc/186/dot-gps-adjacent -band-final-
reportapril2018.pdf, and written testimony of Dana Deasy, DOD Chief Information Officer, before the U.S. Congress,
Senate Armed Services Committee, Departm ent of Defense Spectrum Policy and the Im pact of the Federal
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with power levels ranging from -6 dBW to 31 dBW and cel ular handsets of -7 dBW would
interfere with GPS. (At the time of the study, Ligado proposed a base station power level of 32
dBW.) The study concluded that base stations at the proposed Ligado frequency would have to be
limited to 9.8 dBW to ensure the protection of certified avionics in most scenarios. In
conversation with CRS, DOT officials asserted that the protection of other categories of GPS
equipment—including noncertified aviation, general location/navigation, high precision, timing,
and space-based—could not be assured at this power level. DOD additional y recommended “that
proposals for use of bands adjacent to GPS should not be approved unless they meet the
transmission power levels described in the [DOT test].”191 Based on these recommendations,
Ligado submitted an amended application to the FCC, reducing its proposed power levels to 9.8
dBW.192 Per the FCC ruling, Ligado also agreed to maintain a 23-MHz guard-band of unused
spectrum designed to separate its transmissions from GPS, thus attempting to mitigate potential
interference.
Details available in the public domain describing the technical parameters of the 2016 classified
USAF study are limited; however, the USAF’s formal response to the FCC ruling notes that its
study,193 which specifical y tested potential interference with military GPS receivers, “supported
the conclusions drawn from the DOT testing ... conducted during the same month.” This may
suggest that the study may not provide evidence that a Ligado network—using the FCC-approved
specifications from the company’s 2018 amended application—would necessarily interfere with
GPS. Furthermore, according to FCC Chairman Ajit Pai,194 DOD neither submitted nor attempted
to submit the classified USAF study to the FCC for consideration. Nonetheless, DOD has
continued to cite these studies in its public objections to the ruling.
Michael Griffin, former Under Secretary of Defense for Research and Engineering (USD R&E),
has additional y asserted that any ground transmissions—regardless of power level—“would
drown out the very weak signals that come from [GPS] satel ites,” likening the effect of the
proposed Ligado network on GPS to attempting to listen to the rustling of leaves while 100 jet
aircraft simultaneously took off.195
Statutory Obligations with Regard to Potential GPS Interference
DOD has noted its statutory obligation, pursuant to 10 U.S.C. §2281, to object “to any restriction
on the GPS System proposed by the head of a department or agency of the United States outside
DOD that would adversely affect the military potential of GPS” [emphasis added]. Although the

Com m unications Com mission, 116th Cong., 2nd sess., May 6, 2020, at https://www.armed-services.senate.gov/imo/
media/doc/Deasy_05-06-20.pdf.
191 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary
of Communications and Information, to Hon. Ajit Pai, Chairman of the Federal Communications Commission, April
10, 2020.
192 Letter from Gerard Waldron, Counsel to Ligado Networks LLC, to Marlene H. Dortch, Secretary to the Federal
Communications Commission, May 31, 2018, at https://ecfsapi.fcc.gov/file/1053120688074/
Ligado%20License%20Modification%20Cover%20Letter%20and%20Amendment%20(5-31-2018).pdf.
193 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary
of Communications and Information, to Hon. Ajit Pai, Chairman of th e Federal Communications Commission, April
10, 2020.
194 Letter from Hon. Ajit Pai, Chairman of the Federal Communications Commission, to Rep. Donald Bacon et al., May
26, 2020, at https://docs.fcc.gov/public/attachments/DOC-364591A2.pdf.
195 Spoken testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, before the U.S.
Congress, Senate Armed Services Committee, Departm ent of Defense Spectrum Policy and the Im pact of the Federal
Com m unications Com mission, 116th Cong., 2nd sess., May 6, 2020.
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DOT and the USAF studies do not appear to provide evidence that a Ligado network would
adversely affect military GPS, neither definitively ruled out the potential for adverse effects. As a
result, Secretary of Defense Mark Esper concluded, “Consistent with my statutory
responsibilities, I believe there are too many unknowns and the risks are far too great to federal
operations to al ow Ligado’s proposed system to proceed.”196
DOD has additional y noted that Section 1698 of the National Defense Authorization Act for
Fiscal Year 2017 (P.L. 114-328)—codified at Section 343 of the Communications Act—prevents
the FCC from approving commercial terrestrial operations in the bands proposed by Ligado “until
90 days after the Commission resolves concerns of widespread harmful interference by such
operations to covered GPS devices.” DOD asserts that the FCC did not resolve such concerns
prior to approving Ligado’s application; paragraph 130 of the FCC ruling provides the FCC’s
justification for its belief that the concerns were “effectively resolved.”197
FCC Response to Concerns About Potential GPS Interference
Several Commissioners have provided statements and written correspondence directly addressing
how the FCC came to its decision. Commissioner Brendan Carr noted in a statement
accompanying the FCC’s decision that “after a thorough and multi-year review, the FCC’s
professional staff of engineers and other experts determined that we can advance America’s 5G
leadership while protecting GPS and other adjacent band services.”198 Commissioners Jessica
Rosenworcel and Geoffrey Starks termed the decision “an extremely close cal ,” but similarly
noted in their joint statement of concurrence that, despite the concerns of DOD and others about
potential GPS interference, “in the end, we are compel ed to support the expert technical analysis
done by the [FCC’s] engineering staff.”199 In a series of letters, Chairman Ajai Pai has outlined
the FCC’s decisionmaking process, the data the commission used to make its determination, and
the FCC’s technical analysis of potential interference.200

196 Letter from Hon. Mark Esper, Secretary of Defense, to Hon. Ajit Pai, Chairman of the Federal Communications
Commission, November 18, 2019, at https://www.ntia.doc.gov/files/ntia/publications/
ntia_letter_to_fcc_chairman_re_ligado_mss_atc_applications_dec._6_2019.pdf#page=6.
197 Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf.
198 Statement of Commissioner Brendan Carr, Re: LightSquared T echnical Working Group Report, IB Docket No. 11 -
109; LightSquared License Modification Application, IBFS Files Nos. SAT -MOD-20120928-00160-00161, SES-
MOD-20121001-00872, IB Docket No. 12-340; New LightSquared License Modification Applications, IBFS File Nos.
SES-MOD-20151231-00981, SAT -MOD20151231-00090, SAT -MOD-20151231-00091, IB Docket Nos. 11-109, 12-
340; Ligado Amendment to License Modification Applications, IBFS File Nos. SES-MOD-20151231- 00981, SAT -
MOD-20151231-00090, SAT -MOD-20151231-00091, IB Docket No. 11- 109, at https://docs.fcc.gov/public/
attachments/FCC-20-48A2.pdf.
199 Joint Statement of Commissioners Jessica Rosenworcel and Geoffrey Starks Concurrin g Re: LightSquared
T echnical Working Group Report, IB Docket No. 11 -109; LightSquared License Modification Application, IBFS Files
Nos. SAT -MOD-20120928-00160-00161, SES-MOD-20121001-00872, IB Docket No. 12-340; New LightSquared
License Modification Applications, IBFS File Nos. SES-MOD-20151231-00981, SAT -MOD20151231-00090, SAT -
MOD-20151231-00091, IB Docket Nos. 11-109, 12-340; Ligado Amendment to License Modification Applications,
IBFS File Nos. SES-MOD-20151231- 00981, SAT -MOD-20151231-00090, SAT -MOD-20151231-00091, IB Docket
No. 11- 109, at https://docs.fcc.gov/public/attachments/FCC-20-48A3.pdf.
200 For list of congressional correspondence, see https://www.fcc.gov/chairman-pais-letters-congress.
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Legislative Activity
The FY2021 National Defense Authorization Act (P.L. 116-283) contains five Ligado- or GPS
interference-related provisions:
1. Section 1611 requires DOD to develop a plan for a resilient and survivable
positioning, navigation, and timing capability within two years.201 This provision
would al ow DOD to reprogram resources as needed to develop the plan.
2. Section 1661 prohibits funds for retrofitting GPS devices or networks that use
GPS for the purposes of “[mitigating] harmful interference from commercial
terrestrial operations using the 1526–1536 megahertz band, the 1627.5–1637.5
megahertz band, or the 1646.5–1656.5 megahertz band” (i.e., the bands approved
for the Ligado network).202
3. Section 1662 prohibits funding for contracts with entities “that [engage] in
commercial terrestrial operations using the 1525–1559 megahertz band or the
1626.5–1660.5 megahertz band unless the Secretary has certified to the
congressional defense committees that such operations do not cause harmful
interference to a Global Positioning System device of the Department of
Defense.”203
4. Section 1663 directs the Secretary of Defense to seek an independent technical
assessment of the FCC’s Ligado authorization order (FCC 20-48) from the
National Academy of Sciences.204 This assessment is to “evaluate the potential
harmful interference concerns relating to Global Positioning System devices,”
review potential mitigation measures, and provide associated recommendations
to the department.
5. Section 1664 prohibits the Secretary of Defense from obligating or expending
funds to comply with the FCC’s Ligado authorization order until the Secretary
submits to the congressional defense committees an estimate of the cost
associated with any potential interference-mitigation measures.205

201 P.L. 116-283 §1611 Resilient and Survivable Positioning, Navigation, and T iming Capabilities.
202 P.L. 116-283 §1661 Prohibition on Availability of Funds for Certain Purposes Relating to the Global Positioning
System.
203 P.L. 116-283 §1662 Limitation on Awarding Contracts to Entities Operating Commercial T errestrial
Communication Networks that Cause Harmful Interference with the Global Positionin g System.
204 P.L. 116-283 §1663 Independent T echnical Review of Federal Communications Commission Order 20 -48.
205 P.L. 116-283 §1664 Estimate of Damages from Federal Communications Commission Order 20 -48.
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Author Information

John R. Hoehn, Coordinator
Kelley M. Sayler
Analyst in Military Capabilities and Programs
Analyst in Advanced Technology and Global

Security

Jill C. Gallagher

Analyst in Telecommunications Policy

Acknowledgments
This report benefitted from research assistance by Katherine Leahy during her internship.

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