Overview of Department of Defense Use of the Electromagnetic Spectrum

Changes from October 8, 2020 to February 10, 2021

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Overview of Department of Defense Use of the ~~October 8, 2020~~February 10, 2021
Electromagnetic Spectrum
John R. Hoehn
Communication using the electromagnetic spectrum (“the spectrum”) enables a number Communication using the electromagnetic spectrum (“the spectrum”) enables a number of
Analyst in Military Analyst in Military
of modern military capabilities. The Department of Defense (DOD) uses modern military capabilities. The Department of Defense (DOD) uses ~~electromagnetic radiation~~
Capabilities and Programs Capabilities and Programs
electromagnetic radiation to enable military communications, navigation, radar, to enable military communications, navigation, radar, nonintrusive inspection of aircraft, and nonintrusive inspection of aircraft, and

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

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

spectrum. These technologies designed to deny access to the spectrum are part of a series of spectrum. These technologies designed to deny access to the spectrum are part of a series of

systems and technologies that are commonly referred to as anti-access/area denial capabilities. 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 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 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 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. 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 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 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 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 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: 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 (i.e., the ability of one radio or computer system to talk to another). Each of the ~~military~~
military services has developed robust networks of their own; however, many are often unable to communicate with services has developed robust networks of their own; however, many are often unable to communicate with
one another. one another.
  DOD’s ability to keep pace with technological advances by potential adversaries. Adversaries such as Adversaries such as
Russia, China, Iran, and North Korea have developed systems to challenge the U.S. military’s ability to 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. 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 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 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 Federal Communications Commission (FCC) authorized the Ligado 5G network, which could affect the
global positioning system’s radio signals. global positioning system’s radio signals.
  Spectrum sharing. Emerging technologies and policies are demonstrating that DOD and Emerging technologies and policies are demonstrating that DOD and ~~commercial~~
commercial systems are able to use the same frequencies without degrading DOD’s capabilities. The process for 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 identifying such potential spectrum-sharing frequencies and the ability to develop technologies quickly
may also be of interest to Congress. may also be of interest to Congress.
Congressional Research Service   The interagency process for spectrum allocation. Questions about the interagency process Questions about the interagency process emerged after emerged after
the FCC authorized Ligado’s 5G network to operate, despite the fact that DOD and several other federal the FCC authorized Ligado’s 5G network to operate, despite the fact that DOD and several other federal
agencies disagreed with that decision. agencies disagreed with that decision.
  Anticipating future spectrum needs for both commercial and military users. Much attention Much attention ~~has~~
has focused on 5G technologies. However, new technologies—like a future sixth generation (6G) of 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 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. technologies may change how DOD uses the spectrum and may require a different spectrum allocation.
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7 Overview of Department of Defense Use of the Electromagnetic Spectrum
he Department of Defense (DOD) is the largest federal user of the electromagnetic 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 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 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 for military operations. Thus, any changes to spectrum could affect DOD operations, both
domestically and with allies abroad. Further, DOD has invested significantly in spectrum-domestically and with allies abroad. Further, DOD has invested significantly in spectrum-
dependent technologies. A summary of some of these technologies, including wireless dependent technologies. A summary of some of these technologies, including wireless
communications, satellites, radar technologies that support situational awareness, signal communications, satellites, radar technologies that support situational awareness, signal
intelligence and electronic warfare technologies, is provided below. Changes in spectrum may intelligence and electronic warfare technologies, is provided below. Changes in spectrum may
affect how DOD can use, manipulate, or develop these technologies. affect how DOD can use, manipulate, or develop these technologies.
The Department of Defense (DOD), partly through congressional action, has begun to re- The Department of Defense (DOD), partly through congressional action, has begun to re-
prioritize its management and use of the spectrum. Since 2018prioritize its management and use of the spectrum. Since 2018, the DOD has created new the DOD has created new
organizational structures and is in the process of developing new strategies and policies, organizational structures and is in the process of developing new strategies and policies,
recognizing the importance the spectrum plays in military operations. A recent Joint recognizing the importance the spectrum plays in military operations. A recent Joint
Electromagnetic Spectrum Operations publication states: Electromagnetic Spectrum Operations publication states:
[t]he electromagnetic spectrum (EMS) is a maneuver space essential for facilitating control [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 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 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 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 advantage. Freedom of maneuver and action within the EMS are essential to US and
multinational operations.1 multinational operations.1
What Is the Electromagnetic Spectrum?2
The electromagnetic spectrum is the range of wavelengths or frequencies of electromagnetic 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 (seradiation. It includes radio waves, microwaves, visible light, X-rays, and gamma rays (see Figure
1). Electromagnetic radiation is all around us. It can be produced by natural sources, such as . Electromagnetic radiation is all 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, 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 lasers, and X-ray machines. Electromagnetic radiation travels through space, air, and sometimes
solid materials in the form of waves. These waves are called electromagnetic waves because they solid materials in the form of waves. These waves are called electromagnetic waves because they
have both electric and magnetic properties. Such waves vary in frequency,3 wavelength,4 and 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 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 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. longer wavelengths (e.g., radio waves) have lower frequencies and lower energy.

1 Department of Defense, 1 Department of Defense, Joint Electromagnetic Spectrum Operations, JP 3-85, Washington, DC, March 22, 2020, p. v, , 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. https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp3_85.pdf?ver=2020-04-09-140128-347.
2 This section was written by John R. Hoehn. For more information, see CRS In Focus IF11155, 2 This section was written by John R. Hoehn. For more information, see CRS In Focus IF11155, Defense Primer:
Military Use of the Electromagnetic Spectrum, by John R. Hoehn. , 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. 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 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. each second.
4 Wavelength is the distance between adjacent peaks in a series of periodic waves. 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, National Aeronautics and Space Administration, “The Electromagnetic Spectrum,” 2020,
https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html. https://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html.
Scientists and engineers have discovered many practical uses for electromagnetic radiation. For 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 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. 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 kill Medical professionals use machines to focus high frequency, high energy gamma rays to kill
cancerous cells. Thus, common technologies use electromagnetic radiation to enable a wide cancerous cells. Thus, common technologies use electromagnetic radiation to enable a wide
variety of uses. In applications across civil, commercial, and government sectors, the 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 characteristics of the waves used often drive the use. Below are examples of electromagnetic
radiation uses and applications. radiation uses and applications.
 Radio frequency waves can be used to transmit messages between electronic  Radio frequency waves can be used to transmit messages between electronic
devices. Radio waves have varying wavelengths and characteristics that affect devices. Radio waves have varying wavelengths and characteristics that affect
how much, how far, and in what conditions data can be transmitted between a 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 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 distances, and can penetrate seawater, but cannot support high data rates. These
waves are useful for communications with submarines. Other radio waves can waves are useful for communications with submarines. Other radio waves can
travel a long distance and pass through solid objects, like buildings and trees, travel a long distance and pass through solid objects, like buildings and trees,
making them useful for mobile communications. Still other radio waves can making them useful for mobile communications. Still other radio waves can
travel short distances and cannot penetrate dense objects, but offer greater travel short distances and cannot penetrate dense objects, but offer greater
bandwidth and speed. These radio waves may be useful for high-data bandwidth and speed. These radio waves may be useful for high-data
applications, such as downloading or streaming videos within a home or office. applications, such as downloading or streaming videos within a home or office.
 Microwaves have higher throughput—data upload and download rates—than  Microwaves have higher throughput—data upload and download rates—than
radio waves and therefore are able to transmit more data. However, microwaves 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, 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 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 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 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 the waves cannot penetrate solid objects, and uses this characteristic to gauge
time and distance to an object. Microwaves are also used in satellite time and distance to an object. Microwaves are also used in satellite
communications, which experience few obstacles in their transmission path. communications, which experience few obstacles in their transmission path.
 Infrared radiation (IR) is used in household items such as remote controls.  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 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 receiver converts the light signals to electrical signals, instructing
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Overview of Department of Defense Use of the Electromagnetic Spectrum
microprocessors to carry out commands.5 Similarly, infrared lasers can be used microprocessors to carry out commands.5 Similarly, infrared lasers can be used
for point-to-point communications over short distances to provide high-speed, for point-to-point communications over short distances to provide high-speed,
reliable connections. Infrared signals can travel only short distances and can be reliable connections. Infrared signals can travel only short distances and can be
blocked by obstacles. blocked by obstacles.
 X-rays can penetrate optically opaque materials and are routinely used in aircraft  X-rays can penetrate optically opaque materials and are routinely used in aircraft
maintenance to identify cracks in airframes. X-rays are high-energy, high- maintenance to identify cracks in airframes. X-rays are high-energy, high-
frequency ionizing radiation; they have enough energy to remove an electron 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 from (ionize) an atom or molecule, which could lead to mutations in a human
cell’s DNA, and could lead to cancer.6 cell’s DNA, and could lead to cancer.6
 Certain technologies can detect gamma rays—high-energy radiation—to help  Certain technologies can detect gamma rays—high-energy radiation—to help
identify potential nuclear events. Similar to X-rays, gamma rays present identify potential nuclear events. Similar to X-rays, gamma rays present
biological risks. biological risks.
Federal Spectrum Allocation
In the United States, the National Telecommunications and Information Administration (NTIA) 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 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 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 NTIA manages radio spectrum use by federal agencies,8 while the FCC manages ~~non-federal~~nonfederal
use—that is, radio spectrum use of the private sector, including broadcasting, mobile 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 communication use, commercial, industrial, personal uses, and state and local government uses.9
Both agencies coordinate on frequency allocation and assignment, and in setting technical Both agencies coordinate on frequency allocation and assignment, and in setting technical
requirements to avoid interference.10 requirements to avoid interference.10
The The allocation of radio spectrum involves designating certain frequency segments for specific of radio spectrum involves designating certain frequency segments for specific
uses, such as mobile communications, satellite, and TV broadcasting. The uses, such as mobile communications, satellite, and TV broadcasting. The assignment of radio of radio
frequencies occurs after the spectrum has been allocated for a specific use. The FCC assigns frequencies occurs after the spectrum has been allocated for a specific use. The FCC assigns
frequencies and grants licenses to nonfederal users to use certain segments or certain 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 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 specific segment of the radio spectrum.12 The two agencies coordinate on radio spectrum

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

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

Source: U.S. Government Accountability Office, 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. , 13-472, May 2013, p. 6, https://www.gao.gov/assets/660/654794.pdf.
Notes: The figure shows allocated radio spectrum for DOD applications, with multiple uses operating in one The figure shows allocated 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). 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, 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 intelligence the military also uses the infrared and ultraviolet spectrums for laser technologies and intelligence
collection (seecollection (see Figure 3). Infrared and ultraviolet lasers have greater bandwidth than radio . Infrared and ultraviolet lasers have greater bandwidth than radio
frequencies, enabling the dissemination of large volumes of data (e.g., video) across long 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 satellite distances due to signal strength. The military can also use lasers offensively, to dazzle satellite
sensors, destroy drones, and for other purposes.19 sensors, destroy drones, and for other purposes.19

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

Source: Marczak, Jan & Andrzej, Koss & Targowski, Piotr & Michalina, GÃƒÂ³ra & Strzelec, Marek & Antoni, Marczak, Jan & Andrzej, Koss & Targowski, Piotr & Michalina, GÃƒÂ³ra & Strzelec, Marek & Antoni,
SarzyÃ…Â„ski & Wojciech, Skrzeczanowski & Ostrowski, Roman & Rycyk, Antoni. (2008). Characterization of SarzyÃ…Â„ski & Wojciech, Skrzeczanowski & Ostrowski, Roman & Rycyk, Antoni. (2008). Characterization of
Laser Cleaning of Artworks. Sensors. 8. 10.3390/s8106507. Laser Cleaning of Artworks. Sensors. 8. 10.3390/s8106507.
These applications can be combined to provide an overall military capability, such as command These applications can be combined to provide an overall military capability, such as command
and control (C2) or electronic warfare. The following discussion provides examples of DOD and control (C2) or electronic warfare. The following discussion provides examples of DOD
spectrum applications. spectrum applications.
Communications
Military commanders have become accustomed to communicating with their forces nearly Military commanders have become accustomed to communicating with their forces nearly
instantaneously. Commanders may use wired communications (e.g., landline phones, computers) instantaneously. Commanders may use wired communications (e.g., landline phones, computers)
or wireless technologies (e.g., radio systems)—technologies that use radio frequencies (spectrum) 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 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 there is no physical connection between the sender and receiver. The radio frequencies use range
from low-bandwidth options, such as transferring small strings of text, to highly data-intensive from low-bandwidth options, such as transferring small strings of text, to highly data-intensive
applications, such as full motion video and video teleconferencing. The systems can be located applications, such as full motion video and video teleconferencing. The systems can be located
terrestrially (either with ground forces or on ships), in the air, or in space (i.e., on satellites). In terrestrially (either with ground forces or on ships), in the air, or in space (i.e., on satellites). In
general, communications systems use radio and microwave frequencies; however, some emerging general, communications systems use radio and microwave frequencies; however, some emerging
communications technologies use lasers—transmitting light, instead of radio waves, between 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 receivers.20 Radios use different frequencies depending on the required range and amount of data
they are required to transmit. Ground-based radios are typically used at short ranges, limited by they are required to transmit. Ground-based radios are typically used at short ranges, limited by
line of sight, that span no more than 50 miles. In general, militaries use satellites to communicate line of sight, that span no more than 50 miles. In general, militaries use satellites to communicate
over longer distances. over longer distances.
Terrestrial Radios
For more than a century, the U.S. military has used ground-based (terrestrial) radios to 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 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 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 new frequency bands to transmit larger amounts of data. Systems like the Joint Tactical Radio

20 Stephen Carlson, “Marines conduct field test of laser-based communications system,” 20 Stephen Carlson, “Marines conduct field test of laser-based communications system,” UPI, August 27, 2018, , August 27, 2018,
https://www.upi.com/Defense-News/2018/08/27/Marines-conduct-field-test-of-laser-based-communications-system/https://www.upi.com/Defense-News/2018/08/27/Marines-conduct-field-test-of-laser-based-communications-system/
3511535389333/. 3511535389333/.
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System (JTRS) provide new electronics to modulate the radio frequencies, enabling greater data System (JTRS) provide new electronics to modulate the radio frequencies, enabling greater data
transmission and encryption for security. Many of these terrestrial radios are limited to line-of-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, 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 use multiple frequency bands to transmit data—this radio system uses frequencies from 30 MHz
– 2000 MHz.21 – 2000 MHz.21
For several decades, the military has mostly used satellites to provide beyond-line-of-sight For several decades, the military has mostly used satellites to provide beyond-line-of-sight
(BLOS) radio transmissions—signals traveling over the horizon, typically defined as extending (BLOS) radio transmissions—signals traveling over the horizon, typically defined as extending
no more than 50 milesno more than 50 miles . However, a few terrestrial-based systems can provide BLOS capabilities. . However, a few terrestrial-based systems can provide BLOS capabilities.
An example is the AN/TRC-170 Tropospheric Scatter Microwave Radio Terminal (seeAn 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 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 capability for communications with ground forces at ranges of up to 100 nautical miles
(approximately 115 standard miles), depending on weather conditions. (approximately 115 standard miles), depending on weather conditions.
Figure 4. AN/TRC-170 Tropospheric Scatter Microwave Radio Terminal

Source: https://www.marines.mil/News/News-Display/Article/1169154/the-antrc-170-continues-to-stayreliable-https://www.marines.mil/News/News-Display/Article/1169154/the-antrc-170-continues-to-stayreliable-
for-the-corps/. for-the-corps/.
Notes: Photo by Lance Cpl. Cody Lemons. Photo by Lance Cpl. Cody Lemons.
Satellite Communications
Long-distance satellite communications range from data feeds for unmanned aircraft systems Long-distance satellite communications range from data feeds for unmanned aircraft systems
(also known as drones) to hardened signals for nuclear command, control, and communications.23 (also known as drones) to hardened signals for nuclear command, control, and communications.23
Satellite communications generally use multiple frequency bands to transmit data more quickly. Satellite communications generally use multiple frequency bands to transmit data more quickly.
While satellite communications enables long–distance transmissions, it introduces latency (or While satellite 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 time delay) because the transmissions must travel (at the speed of light) up and down to the
satellite in orbit.24 Most communications satellites operate in geosynchronous orbit (GEO), which satellite in orbit.24 Most communications satellites operate in geosynchronous orbit (GEO), which

21 L3Harris, “L3Harris Falcon III® AN/PRC-117G(V)1(C) Multiband Networking Manpack Radio,” press release, 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. 2020, https://www.harris.com/solution/harris-falcon-iii-an-prc-117gv1c-multiband-networking-manpack-radio.
22 U.S. Marine Corps, “The AN/TRC-170 Continues to Stay Reliable for the Corps,” press release, May 2, 2017, 22 U.S. Marine Corps, “The AN/TRC-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/. https://www.marines.mil/News/News-Display/Article/1169154/the-antrc-170-continues-to-stayreliable-for-the-corps/.
23 These radio signals are designed to operate during a nuclear event, when most other electronic transmissions are 23 These radio signals are designed to operate during a nuclear event, when most other electronic transmissions are
disrupted. disrupted.
24 While there is a time delay when “drone” operators in the United States fly large unmanned aircraft in other parts of 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 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 control uses multiple methods of landing, and taxiing) to reduce the effect of lag. Nuclear command and control uses multiple methods of
communications—not just satellites—to issue orders to nuclear forces. This includes the E-4B National Airborne communications—not just satellites—to issue orders to nuclear forces. This includes the E-4B National Airborne
Operations Center and the E-6 Take Charge and Move Out systems. Operations Center and the E-6 Take Charge and Move Out systems.
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is approximately 22,000 miles from the Earth’s surface. This allows for satellite terminals to is approximately 22,000 miles from the Earth’s surface. This allows for satellite terminals to
remain in position, rather than having to track a satellite in either low or middle earth orbits. remain in position, rather than having to track a satellite in either low or middle earth orbits.
The U.S. military operates several global satellite communication constellations including The U.S. military operates several global satellite communication constellations including
 Advanced Extremely High Frequency (AEHF),25  Advanced Extremely High Frequency (AEHF),25
 Wideband Global Satellite Communications (WGS),26 and  Wideband Global Satellite Communications (WGS),26 and
 Mobile User Objective System (MUOS).27  Mobile User Objective System (MUOS).27
In addition to its own satellites, the DOD uses commercial satellites for communications. This is In addition to its own satellites, the DOD uses commercial satellites for communications. This is
due, in part, to the limited bandwidth available on DOD-operated satellites (i.e., the number of due, in part, to the limited bandwidth available on DOD-operated satellites (i.e., the number of
satellites on orbit, the amount of data each satellite is able to transmit, as well as some limitations satellites on orbit, the amount of data each satellite is able to transmit, as well as some limitations
of coverage). Examples of satellite communications companies that contract with the DOD of coverage). Examples of satellite communications companies that contract with the DOD
include Inmarsat, Viasat, Iridium, and Intelsat.28 include Inmarsat, Viasat, Iridium, and Intelsat.28
Situational Awareness
Another defense application of the electromagnetic spectrum is the use of radio waves, 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 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 location of friendly and enemy forces. This is done through various technologies, as described
below. below.
Radar and LIDAR
The most common situational awareness application is radar; however, recently light detection 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 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 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 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 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-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 surveillance, particularly for identifying quality pictures. These systems are used for long-range surveillance, particularly for identifying
ships and aircraft. Higher-band frequencies provide target-quality pictures, but lack the same 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 effective range. Radar and LIDAR systems are commonly associated with air defense, military
aviation, artillery, and space systems. While radar has become ubiquitous in military formations, aviation, artillery, and space systems. While radar has become ubiquitous in military formations,
LIDAR technologies are still being developed. LIDAR technologies are still being developed.
Passive Radar
Another technology that the U.S. and its competitors are developing is passive radar. Passive 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 radars do not emit radio signals; instead, they listen to radio signals emitted from the target. Some

25 For more information, see Air Force Space Command, “Advanced Extremely High Frequency System,” fact sheet, 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-March 22, 2017, https://www.afspc.af.mil/About-Us/Fact-Sheets/Display/Article/249024/advanced-extremely-high-
frequency-system/. frequency-system/.
26 For more information, see U.S. Air Force, “Wideband Global SATCOM Satellite,” fact sheet, November 15, 2015, 26 For more information, see U.S. Air Force, “Wideband Global SATCOM Satellite,” fact sheet, November 15, 2015,
https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104512/wideband-global-satcom-satellite/. 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),” 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. 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,” 28 Sandra Erwin, “Satcom Conumdrum: Air Force Contemplating Right Mix of Commercial, Military Satellites,”
~~SapceNews~~SpaceNews, May 6, 2019, https://spacenews.com/satcom-conumdrum-air-force-contemplating-right-mix-of-, May 6, 2019, https://spacenews.com/satcom-conumdrum-air-force-contemplating-right-mix-of-
commercial-military-satellites/. commercial-military-satellites/.
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analysts argue that passive radars have the potential to detect low-observable aircraft such as the 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 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 measurable radar signal reflected back to its source—at certain frequencies and flight profiles
(e.g., head on or the side).29 Furthermore, because passive radars do not emit a signal, it is (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 intelligence). Other analysts note difficult to detect them using traditional methods (i.e., signals intelligence). Other analysts note
that, while passive radars may aid in the detection of stealth systems, they do not necessarily 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 provide the information needed to target and engage the systems and are therefore most useful as
cues for other sensors.30 Advances in microelectronics allow passive radar technology to detect cues for other sensors.30 Advances in microelectronics allow passive radar technology to detect
different frequencies, such as cellular signals, that are traditionally not captured, enabling the different frequencies, such as cellular signals, that are traditionally not captured, enabling the
potential detection of a wider range of aircraft. At the 2018 Berlin Airshow, a German radar 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 cellular company tested a newly developed passive radar to identify and track an F-35 using cellular
frequencies among other techniques.31 China and Russia have funded research and development 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 efforts to further develop these technologies.32 The DOD has funded research for this technology
through the Defense Advanced Research Projects Agency (DARPA).33 through the Defense Advanced Research Projects Agency (DARPA).33
Signals Intelligence
Signals intelligence (SIGINT) systems primarily detect and collect spectrum emissions. These Signals intelligence (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 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, artillery, and vehicles. frequencies and observe heat signatures of personnel, missiles, aircraft, artillery, and vehicles.
One subset of SIGINT is collecting communications signals to analyze how militaries 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 communicate—such as what time radios transmit, from what location, and specific radio
frequencies—as well as the data transmitted. A second subset of SIGINT is electronic frequencies—as well as the data transmitted. A second subset of SIGINT is electronic
intelligence. This intelligence discipline analyzes frequencies, patterns, operating procedures—intelligence. This intelligence discipline analyzes frequencies, patterns, operating procedures—
among other information—of any other system that utilizes the spectrum. This includes radars, among other information—of any other system that utilizes the spectrum. This includes radars,
satellite systems, and signal jammers, among other systems. satellite systems, and signal jammers, among other systems.
Infrared Sensors
Hot objects emit radiation in the infrared segment of the spectrum. The higher their temperature 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 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 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 Hellfire air-to-ground missiles, guide missiles onto targets. The AIM-9X air-to-air and AGM-114 Hellfire air-to-ground missiles,

29 Dimitrios Oikonomou, Panagiotis Nomikos, and George Limnaios, et al., “Passive Radars and their use on the 29 Dimitrios Oikonomou, Panagiotis Nomikos, and George Limnaios, et al., “Passive Radars and their use on the
Modern Battlefield,” Modern Battlefield,” Journal of Computations & Modelling, vol. 9, no. 2 (2019), pp. 37-61. , vol. 9, no. 2 (2019), pp. 37-61.
30 These analysts argue that passive radars typically use lower frequencies which do not provide a sufficient position to 30 These analysts argue that passive radars typically use lower frequencies which do not provide a sufficient position to
target a munition. Typical air defense radars use higher band frequencies to provide quality targeting data. Furthermore, target a munition. Typical 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 the geometry to detect aircraft with passive radar systems can be extremely difficult, particularly if the source of the
radio energy is not known. Tyler Rogoway, “No, Passive Radar Isn't Going to Make Stealth Technology Obsolete radio energy is not known. Tyler Rogoway, “No, Passive Radar Isn't Going to Make Stealth Technology Obsolete
Anytime Soon,” Anytime Soon,” The Drive, September 30, 2019, https://www.thedrive.com/the-war-zone/30100/no-passive-radar-isnt-, September 30, 2019, https://www.thedrive.com/the-war-zone/30100/no-passive-radar-isnt-
stealth-ending-magic-people. stealth-ending-magic-people.
31 Ibid. See also Sebastian Sprenger, “Stealthy No More? A German Radar Vendor Says It Tracked the F-35 Jet in 31 Ibid. See also Sebastian Sprenger, “Stealthy No More? A German Radar Vendor Says It Tracked the F-35 Jet in
2018—from a Pony Farm,” 2018—from a Pony Farm,” C4ISRNet, September 29, 2019, https://www.c4isrnet.com/intel-geoint/sensors/2019/09/30/, 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/. 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, “UMTS passive radar implementation with two stage tracking algorithm,” 32 Gökhan Soysal and E.F.E. Murat, “UMTS 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/Communications Faculty of Sciences University of Ankara Series, 2016, pp. 29-53, https://dergipark.org.tr/en/
download/article-file/778904. download/article-file/778904.
33 J.R. Wilson, “New frontiers in passive radar and sonar,” 33 J.R. Wilson, “New frontiers in passive radar and sonar,” Military & Aerospace Electronics, February 8, 2016, , February 8, 2016,
https://www.militaryaerospace.com/communications/article/16709052/new-frontiers-in-passive-radar-and-sonar. For https://www.militaryaerospace.com/communications/article/16709052/new-frontiers-in-passive-radar-and-sonar. For
more information on DARPA, see CRS Report R45088, more information on DARPA, see CRS Report R45088, Defense Advanced Research Projects Agency: Overview and
Issues for Congress, by Marcy E. Gallo. , by Marcy E. Gallo.
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for example, use infrared guidance.34 Aircraft use Infrared Search and Track (IRST) pods to for example, use infrared guidance.34 Aircraft use Infrared Search and Track (IRST) pods to
identify enemy aircraft, particularly as advances in aircraft design embrace low radar cross-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 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 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. for the F-15C Eagle.35 Several space systems use infrared technologies to detect missile launches.
The Space-Based Infrared Surveillance (SBIRS) constellation uses six satellites in The Space-Based Infrared Surveillance (SBIRS) constellation uses six satellites in
geosynchronous orbit, as well as additional satellites in highly elliptical orbits (seegeosynchronous orbit, as well as additional satellites in highly elliptical orbits (see Figure 5) to to
provide an early warning capability for missile launches.36 The Space Force is developing a provide an early warning capability for missile launches.36 The Space Force is developing a
follow-on constellation for SBIRS. The Space Development Agency is developing a hypersonic follow-on constellation for SBIRS. The Space Development Agency is developing a hypersonic
missile detection constellation in low-earth orbit that would use infrared technologies similar to missile detection constellation in low-earth orbit that would use infrared technologies similar to
SBIRS.37 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/. 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 Electronic warfare (EW) is the use of the electromagnetic spectrum to gain and maintain military
control of it.38 SIGINT capabilities allow military forces to understand where adversary forces are control of it.38 SIGINT capabilities allow military forces to understand where adversary forces are
located as well as what frequencies they use for communications and radars. This intelligence, located as well as what frequencies they use for communications and radars. This intelligence,

34 U.S. Air Force, “AIM-9 Sidewinder,” press release, December 18, 2004, https://www.af.mil/About-Us/Fact-Sheets/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/. Display/Article/104557/aim-9-sidewinder/.
35 U.S. Navy FY2021 Aircraft Procurement Line Item 0515 Infrared Search and Track (IRST), at https://apps.dtic.mil/ 35 U.S. Navy FY2021 Aircraft Procurement Line Item 0515 Infrared Search and Track (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 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/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. U_P40_F01500_BSA-2_BA-5_APP-3010F_PB_2021.pdf.
36 Lockheed Martin, “Space Based Infrared Surveillance SBIRS,” press release, 2020, at 36 Lockheed Martin, “Space Based Infrared Surveillance SBIRS,” press release, 2020, at
https://www.lockheedmartin.com/en-us/products/sbirs.html. https://www.lockheedmartin.com/en-us/products/sbirs.html.
37 Sandra Erwin, “Space Development Agency to Deploy Hypersonic Missile Defense Satellites by 2022,” 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-June 7, 2020, at https://spacenews.com/space-development-agency-to-deploy-hypersonic-missile-defense-satellites-by-
2022/. 2022/.
38 See CRS In Focus IF11118, 38 See CRS In Focus IF11118, Defense Primer: Electronic Warfare, by John R. Hoehn. , by John R. Hoehn.
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which the military calls electronic support, is then used to develop an operational plan to jam (i.e., which the military calls 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 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. own forces, militaries can develop techniques to protect themselves from attacks.
Electronic warfare affects all military domains—land, air, sea, space, and cyberspace—and each Electronic warfare affects all military domains—land, air, sea, space, and cyberspace—and each
of the military services has its own EW capabilities and programs. EW capabilities are of the military services has its own EW capabilities and programs. EW capabilities are
traditionally divided into two distinct categories: terrestrial and airborne. Because each kind of traditionally 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 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 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 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 due to variance in the terrain in which they operate. Ground EW capabilities are used to intercept
and to jam radios and artillery radars. Recent uses include jamming improvised explosive devices and to jam radios and artillery radars. Recent uses include jamming improvised explosive devices
in Iraq and Afghanistan.39 Airborne EW is used to intercept, decrypt, and disrupt communications, 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 E-2 radars, and other C2 systems over a large area. Examples of airborne EW aircraft include the E-2
Hawkeye, the EA-18G Growler, and the EC-130H Compass Call.40 Hawkeye, the EA-18G Growler, and the EC-130H Compass Call.40
Spectrum Operations41
Numerous military operations use the spectrum, including command and control (C2), signature Numerous military operations use the spectrum, including command and control (C2), signature
management, and navigation warfare. Overviews of these operations are discussed below. 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 all of the above applications to One type of spectrum operation is Command and Control. C2 uses all of the above applications to
develop a common operating picture (location of friendly and enemy forces) and communicate 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 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 mission focus, from a few radios and computers for platoon- and company-level operations to
specialized satellites and aircraft for joint operations such as nuclear C2. Command and control specialized satellites and aircraft for joint operations such as nuclear C2. Command and control
aircraft, such as the E-8C Joint STARS, use communications systems and synthetic aperture 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 radars to develop a comprehensive picture of the battlespace to direct ground forces to their most
effective positions for countering enemy forces.42 effective positions for countering enemy forces.42
Signature Management
Low observable weapons systems manipulate the spectrum to reduce their electromagnetic 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 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, 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 creating narrow radio beams to reduce the probability of detection or intercept, and reducing
spectrum emissions. These design approaches can be used in ships (e.g., Zumwalt-class spectrum emissions. These design approaches can be used in ships (e.g., Zumwalt-class

39 For more information on ground electronic warfare systems see CRS Report R45919, 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. , by John R. Hoehn.
40 For more information about these aircraft systems see CRS Report R44572, 40 For more information about these aircraft systems see CRS Report R44572, U.S. Airborne Electronic Attack
Programs: Background and Issues for Congress, by John R. Hoehn. , by John R. Hoehn.
41 This section was written by John R. Hoehn. 41 This section was written by John R. Hoehn.
42 U.S. Air Force, 42 U.S. Air Force, E-8C Joint STARS, Washington, DC, September 23, 2015, https://www.af.mil/About-Us/Fact-Sheets/, Washington, DC, September 23, 2015, https://www.af.mil/About-Us/Fact-Sheets/
Display/Article/104507/e-8c-joint-stars/. 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 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 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. right angles) to reduce or prevent the radio signals from returning to their original source.
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destroyer), aircraft (e.g., the B-2 Spirit and the F-35 Lightning II), and radar systems (e.g., the destroyer), aircraft (e.g., the B-2 Spirit and the F-35 Lightning II), and radar systems (e.g., the
AN/APG-81 actively electronically scanned array radar).44 These systems look to reduce their AN/APG-81 actively electronically scanned array radar).44 These systems look to reduce their
signature in the microwave and infrared parts of the spectrum. signature in the microwave and infrared parts of the spectrum.
Communications systems are also focused on reducing their signature. Using beam-forming, 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 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 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 potentially target potential adversaries to use their SIGINT capabilities to find U.S. forces, and potentially target
them with long-range munitions. them with long-range munitions.
Navigation Warfare
According to DOD, navigation warfare (NAVWAR) is “deliberate offensive and defensive actions According to DOD, navigation warfare (NAVWAR) is “deliberate offensive and defensive actions
to assure friendly use and prevent adversary use of [precision, navigation, and timing] PNT to assure friendly use and prevent adversary use of [precision, navigation, and timing] PNT
information through coordinated employment of space, cyberspace, and electronic warfare (EW) information through coordinated employment of space, cyberspace, and electronic warfare (EW)
capabilities. NAVWAR is further enabled by supporting activities such as ISR and EMS 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. management.”45 The Global Positioning System (GPS) performs navigation warfare for the U.S.
military by providing precision, navigation, and timing (semilitary by providing precision, navigation, and timing (see Figure 6). Competing PNT systems . Competing PNT systems
have been developed by other nations, including Russia (GLONASS), China (Beidou), and the have been developed by other nations, including Russia (GLONASS), China (Beidou), and the
European Union (Galileo).46 European Union (Galileo).46
Figure 6. The Global Positioning System (GPS) Constellation

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

44 For more information on select low observable aircraft, see CRS Report R44463, 44 For more information on select low observable aircraft, see CRS Report R44463, Air Force B-21 Raider Long-Range
Strike Bomber, by Jeremiah Gertler, and CRS Report RL30563, , by Jeremiah Gertler, and CRS Report RL30563, F-35 Joint Strike Fighter (JSF) Program, by Jeremiah , by Jeremiah
Gertler. For more information on the Zumwalt-class destroyer, see CRS Report RL32109, Gertler. For more information on the Zumwalt-class destroyer, see CRS Report RL32109, Navy DDG-51 and DDG-
1000 Destroyer Programs: Background and Issues for Congress, by Ronald O'Rourke. , by Ronald O'Rourke.
45 Department of Defense, 45 Department of Defense, Space Operations, JP 3-14, Washington, DC, April 10, 2018, pp. II-3, https://www.jcs.mil/, JP 3-14, Washington, DC, April 10, 2018, pp. II-3, https://www.jcs.mil/
Portals/36/Documents/Doctrine/pubs/jp3_14.pdf. Portals/36/Documents/Doctrine/pubs/jp3_14.pdf.
46 U.S. GPS Office, “Other Global Navigation Satellite Systems (GNSS),” press release, January 30, 2020, at 46 U.S. GPS Office, “Other Global Navigation Satellite Systems (GNSS),” press release, January 30, 2020, at
https://www.gps.gov/systems/gnss/. 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 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 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 enable decisionmaking.47 According to DOD, these communications need to be interoperable
(interoperability between communications systems revolves around the protocols such as (interoperability between communications systems revolves around the protocols such as
frequency hopping and encryption, as well as the frequencies uses) to facilitate information frequency hopping and encryption, as well as the frequencies uses) to facilitate information
sharing, agile to adjust to the operating environment, and trusted to ensure the information in the 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 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 information in a timely fashion to enable commanders and their staff to make decisions. Thus C2
systems collect information from intelligence systems and build a picture of the operating systems collect information from intelligence systems and build a picture of the operating
environment for the commander and their staff to make effective decisions (some analysts environment for the commander and their staff to make effective decisions (some analysts
combine C2 with computers, communications, intelligence, surveillance, and reconnaissance combine C2 with computers, communications, intelligence, surveillance, and reconnaissance
systems [C4ISR] to talk about the entire system enabling decisionmaking). To create these 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 networks, DOD utilizes computers to manage and process data and communications equipment
so that commanders can act upon the data transmitted to them. 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 The following section discusses emerging technologies and concepts that could affect the
military’s use of the spectrum. military’s use of the spectrum.
Fifth Generation (5G) Communications49
The fifth generation (5G) of mobile technologies will increase the speed of data transfer and The fifth generation (5G) of mobile technologies will increase the speed of data transfer and
improve bandwidth over existing fourth generation (4G) technologies, in turn potentially enabling improve bandwidth over existing fourth generation (4G) technologies, in turn potentially enabling
new military and commercial applications. 5G technologies plan to use three segments of the new military and commercial applications. 5G technologies plan to use three segments of the
electromagnetic spectrum: high band (also called millimeter wave, or MMW), which operates electromagnetic spectrum: high band (also called millimeter wave, or MMW), which operates
between around 24 and 300 gigahertz (GHz); mid band, which operates between 1 GHz and 6 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 collectively GHz; and low band, which operates below 1 GHz. Mid band and low band are often collectively
referred to as sub-6.50 Each band offers different capabilities. High-band spectrum offers ultra-fast 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 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 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 computing) compared with existing 4G technologies. Low-band spectrum offers the widespread
coverage needed for many internet-of-things applications. coverage needed for many internet-of-things applications.
5G technologies could have a number of potential military applications, particularly for 5G technologies could have a number of potential military applications, particularly for
autonomous vehicles, C2, logistics, maintenance, augmented and virtual reality, and intelligence, autonomous vehicles, C2, logistics, maintenance, augmented and virtual reality, and intelligence,
surveillance, and reconnaissance (ISR) systems—all of which would benefit from improved data surveillance, and reconnaissance (ISR) systems—all of which would benefit from improved data

47 Department of Defense, 47 Department of Defense, Joint Communications System, JP 6-0, Washington, DC, June 10, 2015, Incorporating , 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-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. 10-15-172254-827.
48 This section was written by John R. Hoehn and Kelley M. Sayler. 48 This section was written by John R. Hoehn and Kelley M. Sayler.
49 This section is derived from CRS In Focus IF11251, 49 This 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, , by John R. Hoehn and Kelley M. Sayler. For more information on 5G, see CRS Report R45485, Fifth-
Generation (5G) Telecommunications Technologies: Issues for Congress, by Jill C. Gallagher and Michael E. DeVine. , by Jill C. Gallagher and Michael E. DeVine.
50 For more information on 5G spectrum allocation, see CRS Report R45485, 50 For more information on 5G spectrum allocation, see CRS Report R45485, Fifth-Generation (5G)
Telecommunications Technologies: Issues for Congress, by Jill C. Gallagher and Michael E. DeVine. , 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 rates and lower latency (i.e., less time delay).51 Autonomous military vehicles, like their
commercial counterparts, could potentially circumvent on-board data processing limitations by commercial counterparts, could potentially circumvent on-board data processing limitations by
storing large databases (e.g., maps) in the cloud. 5G technologies could also be incorporated into 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 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 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 additionally enable other data-intensive activities, such as logistics and maintenance, and could additionally enable
augmented or virtual reality environments that could enhance training.52 Finally, C2 systems augmented or virtual reality environments that could enhance training.52 Finally, C2 systems
could benefit from the high speed, low latency capability of 5G.53 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 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 installations stages of testing and experimentation for 5G applications. It has selected 12 military installations
as test beds for various applications and aspects of the technology: as test beds for various applications and aspects of the technology:
 Marine Corps Logistics Base Albany, GA (smart warehouses);  Marine Corps Logistics Base Albany, GA (smart warehouses);
 Naval Base San Diego, CA (for smart warehouses);  Naval Base San Diego, CA (for smart warehouses);
 Hill Air Force Base, UT (spectrum sharing between 5G and airborne radar);  Hill Air Force Base, UT (spectrum sharing between 5G and airborne radar);
 Joint Base Lewis-McChord, WA (augmented and virtual reality);  Joint Base Lewis-McChord, WA (augmented and virtual reality);
 Nellis Air Force Base, NV (survivable command and control and network  Nellis Air Force Base, NV (survivable command and control and network
enhancement); enhancement);
 Naval Base Norfolk, VA (ship-wide and pier connectivity);  Naval Base Norfolk, VA (ship-wide and pier connectivity);
 Joint Base Pearl Harbor-Hickam, HI (enhancing aircraft mission readiness);  Joint Base Pearl Harbor-Hickam, HI (enhancing aircraft mission readiness);
 Joint Base San Antonio, TX (augmented reality support of maintenance and  Joint Base San Antonio, TX (augmented reality support of maintenance and
training and evaluating DOD’s 5G core security experimentation network); training and evaluating DOD’s 5G core security experimentation network);
 Tinker Air Force Base, OK (spectrum sharing between military communications  Tinker Air Force Base, OK (spectrum sharing between military communications
and 5G); and 5G);
 Camp Pendleton, CA (connectivity for forward operating bases and tactical  Camp Pendleton, CA (connectivity for forward operating bases and tactical
operations centers); operations centers);
 Ft. Hood, TX (connectivity for forward operating bases and tactical operations  Ft. Hood, TX (connectivity for forward operating bases and tactical operations
centers); and centers); and
 Ft. Irwin National Training Center, CA (for connectivity for forward operating  Ft. Irwin National Training Center, CA (for connectivity for forward operating
bases and tactical operations centers).54 bases and tactical operations centers).54
On September 18, 2020, DOD released a Request for Information seeking input on best methods 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 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 allocation and shared use of 5G networks for domestic operations, and other issues related to the allocation and shared use

51 The U.S. military currently uses satellites for the preponderance of its long-distance communications; however, 51 The 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, 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. causing delays in the execution of military operations.
52 Justin Doubleday, “DOD Releases Second Tranche of Draft 5G Proposal Requests,” 52 Justin Doubleday, “DOD Releases Second Tranche of Draft 5G Proposal Requests,” Inside Defense, December 9, , December 9,
2019, https://insidedefense.com/insider/dod-releases-second-tranche-draft-5g-proposal-requests. 2019, https://insidedefense.com/insider/dod-releases-second-tranche-draft-5g-proposal-requests.
53 Defense Innovation Board, 53 Defense Innovation Board, The 5G Ecosystem: Risks and Opportunities for DOD, April 2019, , April 2019,
https://media.defense.gov/2019/Apr/03/2002109302/-1/-1/0/DIB_5G_STUDY_04.03.19.PDF. https://media.defense.gov/2019/Apr/03/2002109302/-1/-1/0/DIB_5G_STUDY_04.03.19.PDF.
54 Justin Doubleday, “DOD Releases Second Tranche of Draft 5G Proposal Requests,” 54 Justin Doubleday, “DOD Releases Second Tranche of Draft 5G Proposal Requests,” Inside Defense, December 9, , December 9,
2019, https://insidedefense.com/insider/dod-releases-second-tranche-draft-5g-proposal-requests; and Department of 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 5G Technology Testing, Experimentation,” Defense, “DOD Names Seven Installations as Sites for Second Round of 5G Technology Testing, Experimentation,”
press release, June 3, 2020, https://www.defense.gov/Newsroom/Releases/Release/Article/2206761/dod-names-seven-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/. 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 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.”the Department of Defense’s spectrum for training, readiness, and lethality.” 56 DOD requested 56 DOD requested
$1.5 billion for microelectronics/5G in FY2021, but it did not provide a further breakdown in $1.5 billion for microelectronics/5G in FY2021, but it did not provide a further breakdown in
funding between microelectronics and 5G.57 funding between microelectronics and 5G.57
Use and Applications of Artificial Intelligence (AI)58
DOD is researching cognitive electronic warfare systems that use artificial intelligence to identify DOD is researching cognitive electronic warfare systems that use artificial intelligence to identify
novel electronic emissions, determine whether the emission originates from a hostile source, and 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 develop an effective jamming signal. According to former DOD electronic warfare official
William Conley, “a future battlespace will contain threat signals not previously observed, [so] it William Conley, “a future battlespace will contain threat signals not previously observed, [so] it
will be essential for many platforms to be executing real time decision algorithms.”59 DOD is also will 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 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 “spoofing,” capabilities. For example, Digital Radio Frequency Memory could be used to
generate false radar returns that complicate adversary targeting.60 generate false radar returns that complicate adversary targeting.60
Similarly, DOD is exploring AI-enabled dynamic spectrum sharing. Because spectrum is Similarly, DOD is exploring AI-enabled dynamic spectrum sharing. Because spectrum is
currently allocated in set segments, allocation cannot be responsive to changes in the volume of currently allocated in set segments, allocation cannot be responsive to changes in the volume of
traffic across segments (i.e.traffic across segments (i.e., some segments may be overwhelmed while others are underutilized), some segments may be overwhelmed while others are underutilized),
leading to inefficiencies. DARPA has sponsored the Spectrum Collaboration Challenge (SC2), leading to inefficiencies. DARPA has sponsored the Spectrum Collaboration Challenge (SC2),
which “aims to ensure that the exponentially growing number of military and civilian wireless which “aims to ensure that the exponentially growing number of military and civilian wireless
devices will have full access to the increasingly crowded electromagnetic spectrum.”61 Teams devices will 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 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 learning algorithms to develop options for dynamic spectrum sharing, in which radios
autonomously coordinate to optimize spectrum use. autonomously coordinate to optimize spectrum use.
Directed-Energy (DE) Technologies
A number of directed energy technologies, including laser communications and directed-energy A number of directed energy technologies, including laser communications and directed-energy
weapons, make use of the electromagnetic spectrum.62 weapons, make use of the electromagnetic spectrum.62
Laser Communications
DOD is testing systems that use focused infrared energy to transmit data—a concept known as DOD is testing systems that use focused infrared energy to transmit data—a concept known as
laser communications. For example, Free Space Optics (FSO) “is an optical communication laser communications. For example, Free Space Optics (FSO) “is an optical communication

55 DOD, Request for Information, 55 DOD, Request for Information, Defense Spectrum Sharing Request for Information, Published September 18, 2020, , Published September 18, 2020,
https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&
index=&is_active=true&page=1. index=&is_active=true&page=1.
56 Ibid. 56 Ibid.
57 DOD 57 DOD FY2021 Defense Budget Overview: Irreversible Implementation of the National Defense Strategy, Washington, , Washington,
DC, May 13, 2020, pp. 1-8, https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2021/DC, May 13, 2020, pp. 1-8, https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2021/
fy2021_Budget_Request_Overview_Book.pdf. fy2021_Budget_Request_Overview_Book.pdf.
58 For a general discussion of military applications of artificial intelligence, see CRS Report R45178, 58 For a general discussion of military applications of artificial intelligence, see CRS Report R45178, Artificial
Intelligence and National Security, by Kelley M. Sayler. , by Kelley M. Sayler.
59 “EW, Cyber Require Next-Gen Hardware: Conley,” 59 “EW, Cyber Require Next-Gen Hardware: Conley,” Breaking Defense, September 27, 2019, , September 27, 2019,
https://breakingdefense.com/2019/09/ew-cyber-require-next-gen-hardware-conley/. https://breakingdefense.com/2019/09/ew-cyber-require-next-gen-hardware-conley/.
60 Ibid. 60 Ibid.
61 DARPA, “Spectrum Collaboration Challenge (SC2),” https://www.darpa.mil/program/spectrum-collaboration-61 DARPA, “Spectrum Collaboration Challenge (SC2),” https://www.darpa.mil/program/spectrum-collaboration-
challenge. challenge.
62 Other directed energy technologies include laser range finders, target designators, and remote sensors. 62 Other directed energy technologies include laser range finders, target designators, and remote sensors.
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system that transfers data on a highly secured and nearly undetectable infrared laser, separate system that transfers data on a highly secured and nearly undetectable infrared laser, separate
from the radio frequency spectrum…. This allows more users on a single network and larger files, from the radio frequency spectrum…. This allows more users on a single network and larger files,
imagery and information to be transmitted.”63 The Marine Corps requested procurement funding imagery and information to be transmitted.”63 The Marine Corps requested procurement funding
in FY2019 and FY2020; however, it does not appear have requested funds in FY2021. It is 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 (seunclear 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-https://www.upi.com/Defense-News/2018/08/27/Marines-conduct-field-test-of-laser-based-
communications-system/3511535389333/. communications-system/3511535389333/.
Notes: The picture caption reads: “U.S. Marines test the Free Space Optics laser communications system earlier 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.” this month at Camp Hansen in Okinawa, Japan. Photo by Sgt. Timothy Valero/U.S. Marine Corps.”
Directed-Energy Weapons64
DOD defines directed-energy (DE) weapons as those using concentrated electromagnetic energy, DOD defines directed-energy (DE) weapons as those using concentrated electromagnetic energy,
rather than kinetic energy, to “incapacitate, damage, disable, or destroy enemy equipment, rather than kinetic energy, to “incapacitate, damage, disable, or destroy enemy equipment,
facilities, and/or personnel.”65 DE weapons could be used by ground forces in counter rocket,66 facilities, and/or personnel.”65 DE weapons could be used by ground forces in counter rocket,66
artillery, and mortar (C-RAM), counter-unmanned aircraft systems (C-UAS), or short-range air artillery, and mortar (C-RAM), counter-unmanned aircraft systems (C-UAS), or short-range air
defense (SHORAD) missions.67 They could offer low costs per shot and—assuming access to a defense (SHORAD) missions.67 They could offer low costs per shot and—assuming access to a
sufficient power supply—nearly limitless magazines that, in contrast to existing conventional 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 systems, could enable an efficient and effective means of defending against missile salvos or
swarms of unmanned systems.68 Theoretically, DE weapons could also provide options for boost-swarms of unmanned systems.68 Theoretically, DE weapons could also provide options for boost-

63 Department of Defense, “Okinawa Marines Test Future of Wireless Communications,” press release, August 24, 63 Department of Defense, “Okinawa Marines Test 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-2018, at https://www.defense.gov/Explore/News/Article/Article/1611671/okinawa-marines-test-future-of-wireless-
communications/. communications/.
64 This section is derived from CRS Report R46458, 64 This section is derived from CRS Report R46458, Emerging Military Technologies: Background and Issues for
Congress, by Kelley M. Sayler. , by Kelley M. Sayler.
65 Joint Chiefs of Staff, Electronic Warfare, Joint Publication 3-13.1, February 8, 2012, 65 Joint Chiefs of Staff, Electronic Warfare, Joint Publication 3-13.1, February 8, 2012, ppp. 1-16. . 1-16.
66 For example, see CRS Report R45098, 66 For example, see CRS Report R45098, U.S. Army Weapons-Related Directed Energy (DE) Programs: Background
and Potential Issues for Congress, by Andrew Feickert. , by Andrew Feickert.
67 For more information about the role of DE weapons in C-UAS missions, see CRS In Focus IF11426, 67 For more information about the role of DE weapons in C-UAS missions, see CRS In Focus IF11426, Department of
Defense Counter-Unmanned Aircraft Systems, by John R. Hoehn and Kelley M. Sayler. , by John R. Hoehn and Kelley M. Sayler.
68 Although research has been conducted on chemically fueled lasers, most countries are now pursuing solid state 68 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 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 the shot. Some analysts have noted that the cost per shot could thus be between $1 and $20. See power required to fire the shot. Some analysts have noted that the cost per shot could thus be between $1 and $20. See
Ariel Robinson, “Directed Energy Weapons: Will They Ever Be Ready?,” Ariel Robinson, “Directed Energy Weapons: Will They Ever Be Ready?,” National Defense, July 1, 2015, at , July 1, 2015, at
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phase missile intercept, given their speed-of-light travel time; however, as in the case of 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 hypersonic missile defense, experts disagree on the affordability, technological feasibility, and
utility of this application.69 utility of this application.69
High-powered microwave weapons, a subset of DE weapons, could be used as a nonkinetic 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 means of disabling electronics, communications systems, and improvised explosive devices, or as
a nonlethal “heat ray” system for crowd control. a nonlethal “heat ray” system for crowd control.
Although the United States has been researching directed energy since the 1960s, some experts Although the United States has been researching directed energy since the 1960s, some experts
have observed that “actual directed-energy programs … have frequently fallen short of have observed that “actual directed-energy programs … have frequently fallen short of
expectations,” with DOD investing billions of dollars in programs that were ultimately expectations,” with DOD investing billions of dollars in programs that were ultimately
cancelled.70 Others contend that developments in commercial lasers could be leveraged for cancelled.70 Others contend that developments in commercial lasers could be leveraged for
military applications.71 Directed-energy weapons programs, however, continue to raise questions military applications.71 Directed-energy weapons programs, however, continue to raise questions
about their technological maturity, including questions about their ability to improve beam quality 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 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.72 requirements so that the weapons could be integrated into current platforms.72
The U.S. Navy fielded the first operational U.S. DE weapon,73 the Laser Weapon System The U.S. Navy fielded the first operational U.S. DE weapon,73 the Laser Weapon System
(LaWS), in 2014 aboard the USS (LaWS), in 2014 aboard the USS Ponce. LaWS was a 30-kilowatt (-kW) laser prototype that . LaWS was a 30-kilowatt (-kW) laser prototype that
“was capable of blinding enemy forces as a warning, shooting down drones, disabling boats, or “was capable of blinding enemy forces as a warning, shooting down drones, disabling boats, or
damaging helicopters.”74 The Navy plans to deploy its 60-kW laser, HELIOS, aboard the USS damaging helicopters.”74 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 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 Directed Energy Mobile Short-Range Air Defense System—on Stryker fighting vehicles in
FY2022.75 Similarly, the Air Force is currently conducting field assessments of several counter-FY2022.75 Similarly, the Air Force is currently conducting field assessments of several counter-
UAS DE systems, including both laser and high-powered microwave systems.76 UAS DE systems, including both laser and high-powered microwave systems.76
The Army, Navy, Air Force, and DARPA each have additional DE development programs The Army, Navy, Air Force, and DARPA each have additional DE development programs
underway, with the Pentagon requesting $235 million for directed-energy weapons and directed-underway, with the Pentagon requesting $235 million for directed-energy weapons and directed-

https://www.nationaldefensemagazine.org/articles/2015/7/1/2015july-directed-energy-weapons-will-they-ever-be-https://www.nationaldefensemagazine.org/articles/2015/7/1/2015july-directed-energy-weapons-will-they-ever-be-
ready. ready.
69 See, for example, James N. Miller and Frank A. Rose, “Bad Idea: Space-Based Interceptors and Space-Based 69 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 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 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,’” 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-February 19, 2020, at https://insidedefense.com/daily-news/pentagon-punts-mdas-laser-ambitions-shifts-funding-
toward-osd-led-laser-scaling. toward-osd-led-laser-scaling.
70 Paul Scharre, Preface to “Directed-Energy Weapons: Promise and Prospects,” Center for a New American Security, 70 Paul Scharre, Preface to “Directed-Energy Weapons: Promise and Prospects,” Center for a New American Security,
April 2015, p. 4. April 2015, p. 4.
71 See Ariel Robinson, “Directed Energy Weapons.” 71 See Ariel Robinson, “Directed Energy Weapons.”
72 Ibid. 72 Ibid.
73 For more information see73 For more information see, CRS Report R44175, CRS Report R44175, Navy Lasers, Railgun, and Gun-Launched Guided Projectile:
Background and Issues for Congress, by Ronald O'Rourke. , by Ronald O'Rourke.
74 Kyle Mizokami, “The U.S. Army Plans To Field the Most Powerful Laser Weapon Yet,” 74 Kyle Mizokami, “The U.S. Army Plans To Field the Most Powerful Laser Weapon Yet,” Popular Mechanics, ,
August 7, 2019. August 7, 2019.
75 Lockheed Martin, “Lockheed Martin’s HELIOS Laser Weapon System Takes Step Toward Ship Integration,” March 75 Lockheed Martin, “Lockheed Martin’s HELIOS Laser Weapon System Takes Step Toward Ship Integration,” March
11, 2020, at https://news.lockheedmartin.com/2020-03-11-Lockheed-Martins-HELIOS-Laser-Weapon-System-Takes-11, 2020, at https://news.lockheedmartin.com/2020-03-11-Lockheed-Martins-HELIOS-Laser-Weapon-System-Takes-
Step-Toward-Ship-Integration; and Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, Step-Toward-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, “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/at https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2021/
fy2021_Budget_Request_Overview_Book.pdf. fy2021_Budget_Request_Overview_Book.pdf.
76 Kyle Mizokami, “The Air Force Mobilizes Its Laser and Microwave Weapons Abroad,” 76 Kyle Mizokami, “The Air Force Mobilizes Its Laser and Microwave Weapons Abroad,” Popular Mechanics, April 9, , April 9,
2020, at https://www.popularmechanics.com/military/weapons/a32083799/laser-microwave-weapons/. 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 energy defensive capabilities in FY2020; the FY2021 budget overview does not provide the
topline funding request for DE weapons.77 These programs are intended to scale up power levels topline funding request for DE weapons.77 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 from around 150 kW, as is currently feasible, to around 300 kW, a level at which cruise missiles
could potentially be intercepted, by FY2022 and to around 500 kW by FY2024.78 could potentially be intercepted, by FY2022 and to around 500 kW by FY2024.78
Counter-Unmanned Aircraft Systems (C-UAS)79
Unmanned aircraft systems (UAS), commonly called drones, have proliferated rapidly and are Unmanned aircraft systems (UAS), commonly called drones, have proliferated rapidly and are
available to nation states and to non-state actors and individuals. These systems could provide 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 intelligence, surveillance, and U.S. adversaries with a low-cost means of conducting intelligence, surveillance, and
reconnaissance missions against—or attacking—U.S. forces. Furthermore, many smaller UASs reconnaissance missions against—or attacking—U.S. forces. Furthermore, many smaller UASs
cannot be detected by traditional air defense systems due to their size, construction material, and cannot be detected by traditional air defense systems due to their size, construction material, and
flight altitude. flight altitude.
C-UAS can employ a number of methods to detect the presence of hostile or unauthorized UAS. 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, 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 or sound signatures, respectively. A second method is to use radar systems. However, these
methods are not always capable of detecting small UAS due to the limited signatures and size of methods are not always capable of detecting small 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 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 using radio frequency sensors. These methods can be—and often are—combined to provide a
more effective, layered detection capability. more effective, layered detection capability.
Once detected, the UAS may be engaged or disabled. Electronic warfare “jamming” can interfere 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 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 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, 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 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 developing and procuring a number of different C-UAS technologies to try to ensure a robust
defensive capability. defensive capability.
In December 2019, DOD streamlined its various counter-small UAS (C-sUAS) programs, naming In December 2019, DOD streamlined its various counter-small UAS (C-sUAS) programs, naming
the Army as the executive agent tasked with overseeing all DOD C-sUAS development efforts. the Army as the executive agent tasked with overseeing all DOD C-sUAS development efforts.
On January 6, 2020, the Secretary of Defense approved the implementation plan of the new 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 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, 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, 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 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 command and control system are to be further developed. According to media reports, during its

77 Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, Defense Budget Overview: United 77 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. States Department of Defense Fiscal Year 2020 Budget Request, March 2019, p. 9.
78 Despite a lack of consensus regarding the precise power level needed to neutralize different target sets, it is generally 78 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 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 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, 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 , by Ronald O'Rourke, and Sydney J. Freedberg Jr., “Lasers to Kill
Cruise Missiles Sought by Navy, Air Force, Army,” Cruise Missiles Sought by Navy, Air Force, Army,” Breaking Defense, October 29, 2019. For information about , October 29, 2019. For information about
DOD’s Laser Scaling Plan, see Jason Sherman, “New Laser Scaling Plan sets directed-energy efforts, FY-19 DOD’s Laser Scaling Plan, see Jason Sherman, “New Laser Scaling Plan sets directed-energy efforts, FY-19
contracts,” contracts,” Inside Defense, April 17, 2019, at https://insidedefense.com/daily-news/new-laser-scaling-plan-sets-, April 17, 2019, at https://insidedefense.com/daily-news/new-laser-scaling-plan-sets-
directed-energy-efforts-fy-19-contracts. directed-energy-efforts-fy-19-contracts.
79 This section is derived from CRS In Focus IF11426, 79 This section is derived from CRS In Focus IF11426, Department of Defense Counter-Unmanned Aircraft Systems, by , by
John R. Hoehn and Kelley M. Sayler. John R. Hoehn and Kelley M. Sayler.
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first year of operation, the office is to additionally produce a DOD Directive on C-sUAS, a threat first year of operation, the office is to additionally produce a DOD Directive on C-sUAS, a threat
assessment of C-sUAS capabilities, a DOD C-sUAS strategy, and a Joint Capability Development assessment of C-sUAS capabilities, a DOD C-sUAS strategy, and a Joint Capability Development
Document outlining operational requirements for future systems.80 Document outlining operational requirements for future systems.80
Emerging Concepts81
DOD is developing a series of concepts, many of which are enabled by AI, to improve multi-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, domain command and control (C2) and execute the National Defense Strategy. For example,
DOD is developing a concept, Joint All Domain Command and Control (JADC2), to direct forces DOD is developing a concept, Joint All Domain Command and Control (JADC2), to direct forces
across multiple domains (air, space, cyber, land, sea).82 According to defense officials, across multiple domains (air, space, cyber, land, sea).82 According to defense officials,
commanders currently execute C2 by exchanging data through manpower-intensive processes commanders currently execute C2 by exchanging data through manpower-intensive processes
that typically focus on a single domain. This reduces a commander’s situational awareness, speed that typically focus on a single domain. This reduces a commander’s situational awareness, speed
of of ~~decision making~~decisionmaking, and ability to rapidly and continuously integrate capabilities across domains. , and ability to rapidly and continuously integrate capabilities across domains.
These processes are not automated and typically provide single domain awareness.83 In contrast, These processes are not automated and typically provide single domain awareness.83 In contrast,
JADC2 is to enhance information-sharing across domains through “a combination of new JADC2 is to enhance information-sharing across domains through “a combination of new
technology, processes and new organizations.”84 technology, processes and new organizations.”84
~~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. 85 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~~
~~cellular and Wi-Fi networks to transmit data to match riders and provide driving instructions. The~~
~~military equivalent might be using all available intelligence sensors—particularly space, air and~~
~~maritime-based sensors—to detect adversary targets. Artificial intelligence algorithms would then~~
~~identify where different missiles, aircraft, and artillery units are to determine the best to assign to~~
~~an emerging target. Finally, using the optimal communications method the algorithms would then~~
~~direct the appropriate munition onto the target. The Air Force has been designated as the~~Figure 8. Visualization of JADC2 Vision Source: https://www.monch.com/mpg/news/ew-c4i-channel/7334-saic-and-usaf-partner-for-jadc2.html.

80 Theresa Hitchens, “DoD Winnowing Efforts To Counter Small Drones,” 80 Theresa Hitchens, “DoD Winnowing Efforts To Counter Small Drones,” Breaking Defense, March 5, 2020, at , March 5, 2020, at
https://breakingdefense.com/2020/03/dod-winnowing-efforts-to-counter-small-drones/. https://breakingdefense.com/2020/03/dod-winnowing-efforts-to-counter-small-drones/.
81 This section was written by John R. Hoehn, Kelley M. Sayler, and Nishawn S. Smagh. 81 This section was written by John R. Hoehn, Kelley M. Sayler, and Nishawn S. Smagh.
82 For more information about JADC2, see CRS In Focus IF11493, 82 For more information about JADC2, see CRS In Focus IF11493, Joint All-Domain Command and Control (JADC2), ,
by John R. Hoehnby John R. Hoehn.
83 For example, the Air Force fields the Air Operations Center which provides command and control of air and space 83 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 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 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 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 structures are geographically focused, and do not provide insights into potential adversary operations in other
geographic regions. geographic regions.
84 Jay Koester, “JADC2 ‘Experiment 2’ provides looking glass into future experimentation,” 84 Jay Koester, “JADC2 ‘Experiment 2’ provides looking glass into future experimentation,” U.S. Army, April 23, , April 23,
2020, at https://www.army.mil/article/234900/2020, at https://www.army.mil/article/234900/
jadc2_experiment_2_provides_looking_glass_into_future_experimentation. jadc2_experiment_2_provides_looking_glass_into_future_experimentation.
~~85 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/.~~
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19

Congressional Research Service 19 Overview of Department of Defense Use of the Electromagnetic Spectrum 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. 85 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 cellular and Wi-Fi networks to transmit data to match riders and provide driving instructions. The military equivalent might be using all available intelligence sensors—particularly space, air and maritime-based sensors—to detect adversary targets. Artificial intelligence algorithms would then identify where different missiles, aircraft, and artillery units are to determine the best to assign to an emerging target. Finally, 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.86 JADC2 is executive agent charged with overseeing the services’ first-year JADC2 activities.86 JADC2 is
intended to reach full operational capability by 2035.87 intended to reach full operational capability by 2035.87
Similarly, DARPA has researched a concept called “Mosaic Warfare,” intended to leverage AI to Similarly, DARPA has researched a concept called “Mosaic Warfare,” intended to leverage AI to
network systems and sensors, prioritize incoming sensor data, and autonomously determine the network systems and sensors, prioritize incoming sensor data, and autonomously determine the
optimal composition of forces. Such concepts could provide a comprehensive common operating optimal composition of forces. Such concepts could provide a comprehensive common operating
picture, coordinate operations across warfare domains, and challenge adversaries’ targeting picture, coordinate operations across warfare domains, and challenge adversaries’ targeting
calculations. These concepts additionally propose limiting the amount of and/or disguising calculations. These concepts additionally propose limiting the amount of and/or disguising
electronic emissions in the spectrum to further complicate adversaries’ ability to target U.S. electronic emissions in the spectrum to further complicate adversaries’ ability to target U.S.
forces. forces.
Potential Spectrum Issues for Congress88
As Congress considers several policy implications of the use of the spectrum, several potential 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, issues emerge. These issues can be categorized broadly as technical issues, organizational issues,
and issues related to commercial use of the spectrum. and issues related to commercial use of the spectrum.
Technical Challenges
This section discusses several potential technical issues associated with the spectrum. These This section discusses several potential technical issues associated with the spectrum. These
include communications system interoperability, adversary technological development, and include communications system interoperability, adversary technological development, and
spectrum sharing technologies to enable commercial applications. spectrum sharing technologies to enable commercial applications.
Communications System Interoperability
One challenge the DOD is confronted with is system interoperability both between individual One challenge the DOD is confronted with is system interoperability both between individual
weapons systems as well as between each of the military services. This issue has been weapons systems as well 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—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 the F-22 uses the intra-flight data link (IFDL) and the F-35 uses the multifunction advanced data
85 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/. 86 The 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. 87 Ibid. 88 This section was written by John R. Hoehn and Jill C. Gallagher. Congressional Research Service 20 Overview of Department of Defense Use of the Electromagnetic Spectrum link (MADL)—preventing these two Air Force fighter jets from sharing information with each link (MADL)—preventing these two Air Force fighter jets from sharing information with each
other.89 Each service develops its command, control, and communications systems to meet their other.89 Each service develops its command, control, and communications systems to meet their
individual needs. For instance, the Navy uses the AEGIS ballistic missile defense system—which individual needs. For instance, the Navy uses the AEGIS ballistic missile defense system—which
is installed on guided missile cruisers and destroyers—which is currently unable to transmit radar is installed 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. 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 all As mentioned, 5G encompasses low-band, mid-band, and high-band spectrum. DOD uses all
three bands for its operations. While the bulk of its holdings are in the low-band and mid-band 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 millimeter wave or MMW) frequencies for high-spectrum, DOD also uses high-band (including millimeter wave or MMW) frequencies for high-
profile military applications such as Advanced Extremely High Frequency satellites that provide profile military applications such as Advanced Extremely High Frequency satellites that provide
assured global communications for U.S. forces. Coordinating investments across four branches of assured global communications for U.S. forces. Coordinating investments across four branches of
government, three bands of spectrum, and across multiple geographies is a challenge. government, three bands of spectrum, and across multiple geographies is a challenge.

~~86 The 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.~~
~~87 Ibid.~~
~~88 This section was written by John R. Hoehn and Jill C. Gallagher.~~
~~89 Brian W. Everstine, “The F-22 and the F-35 Are Struggling to Talk 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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The Defense Innovation Board and FCC Commissioner Rosenworcel have suggested that DOD 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 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 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 fall behind other countries in sub-6 GHz deployments, and (b) ensure U.S. same so as to (a) not fall 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. forces may be able to operate and interoperate with those countries when abroad.
Industry observers assert that the significant innovations will come in the MMW spectrum, Industry observers assert that the significant innovations will come in the MMW spectrum,
including high-speed, low latency applications, providing the U.S. a competitive edge in the including high-speed, low latency applications, providing the U.S. a competitive edge in the
global defense market and on the battlefield. Still others assert that investments across all three global defense market and on the battlefield. Still others assert that investments across all three
bands will benefit DOD as 5G offers greater capacity, speeds, functionality, customization, and bands will benefit DOD as 5G offers greater capacity, speeds, functionality, customization, and
security. In deciding DOD appropriations, Congress may consider where and how federal funds security. In deciding DOD appropriations, Congress may consider where and how federal funds
for 5G should be invested. for 5G should be invested.
Adversary Spectrum Interference Developments
Another potential issue for Congress is balancing spectrum needs of commercial users and 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 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 critically dependent on the adversaries. The DOD states “[s]ince modern military operations are critically dependent on the
EMS, a key goal of our adversaries and enemies is to deny our ability to use it successfully.”90 EMS, a key goal of our adversaries and enemies is to deny our ability to use it successfully.”90
After observing how the U.S. military operates, potential adversaries like Russia and China have 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 identified the U.S. military’ reliance on the spectrum as a potential vulnerability. As a result, these
potential adversaries have focused on challenging the U.S. military’s network and EW potential adversaries have focused on challenging the U.S. military’s network and EW
capabilities—these systems are part of an overall approach called anti-access/area denial capabilities—these systems are part of an overall approach called anti-access/area denial
(A2/AD) which are intended to challenge the ability of the military from entering a contested area (A2/AD) which are intended to challenge the ability of the military from entering a contested area
like the Baltic states or the South China Sea.91 The FY2019 National Defense Authorization Act like the Baltic states or the South China Sea.91 The FY2019 National Defense Authorization Act
(NDAA) required DOD to contract an independent assessment of EW capabilities, with a report (NDAA) required DOD to contract an independent assessment of EW capabilities, with a report
due October 1, 2019.92 The Center for Strategic and Budgetary Assessments ultimately performed due October 1, 2019.92 The Center for Strategic and Budgetary Assessments ultimately performed
this assessment, providing an overview of adversary capabilities and doctrines.93 this assessment, providing an overview of adversary capabilities and doctrines.93
~~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.”94 McDermott describes a~~
~~close relationship between Russian signals intelligence 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.~~

89 Brian W. Everstine, “The F-22 and the F-35 Are Struggling to Talk 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/. 90 Department of Defense, 90 Department of Defense, Joint Electromagnetic Spectrum Operations, JP 3-85, Washington, DC, March 22, 2020, p. , 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. I-3, https://www.jcs.mil/Portals/36/Documents/Doctrine/pubs/jp3_85.pdf?ver=2020-04-09-140128-347.
91 For more information on adversary electronic warfare capabilities see CRS Report R45919, 91 For more information on adversary electronic warfare capabilities see CRS Report R45919, Ground Electronic
Warfare: Background and Issues for Congress, by John R. Hoehn. , by John R. Hoehn.
92 P.L. 115-232 §255. 92 P.L. 115-232 §255.
93 Bryan Clark, Whitney M. McNamara, and Timothy A. Walton, 93 Bryan Clark, Whitney M. McNamara, and Timothy A. Walton, Winning the Invisible War: Gaining an Enduring
~~U.S. Advantage in the Electromagnetic 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.~~
~~94 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. 42.~~
~~Congressional Research Service~~

21

Congressional Research Service 21 Overview of Department of Defense Use of the Electromagnetic Spectrum 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.”94 McDermott describes a close relationship between Russian signals intelligence 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. Most of the focus on Chinese EW operations has been on the air, maritime, and space domains.
According to According to Jane’s Defence Weekly, China has invested substantial resources into science and , China has invested substantial resources into science and
technology initiatives focused on improving its network and electronic warfare technology initiatives focused on improving its network and electronic warfare
capabilities.95 These investments include ground-based sensors and jammers, space-based capabilities.95 These investments include ground-based sensors and jammers, space-based
intelligence assets, and a number of airborne jammers.96 China is also investing in unmanned intelligence assets, and a number of airborne jammers.96 China is also investing in unmanned
systems that could potentially swarm to provide desired effects, including SIGINT interceptions systems that could potentially swarm to provide desired effects, including SIGINT interceptions
and electronic attack.97 China has also focused on developing advanced jammers and anti-satellite and electronic attack.97 China has also focused on developing advanced jammers and anti-satellite
technologies to deny U.S. forces access to satellites.98 For example, in 2007, China demonstrated technologies to deny U.S. forces access to satellites.98 For example, in 2007, China demonstrated
its ability to launch an anti-satellite weapon to destroy an old weather satellite in low earth orbit. its ability to launch an anti-satellite weapon to destroy an old weather satellite in low earth orbit.
According to the 2020 Annual Report on China Military Power, the DOD reported that “the PRC According to the 2020 Annual Report on China Military Power, the DOD reported that “the PRC
is developing electronic warfare capabilities such as satellite jammers; offensive cyber is developing electronic warfare capabilities such as satellite jammers; offensive cyber
capabilities; and directed-energy weapons.”99 capabilities; and directed-energy weapons.”99
A challenge for DOD has been in keeping pace with rapidly evolving technologies and A challenge for DOD has been in keeping pace with rapidly evolving technologies and
coordinating information on adversaries’ technologies and capabilities across DOD coordinating information on adversaries’ technologies and capabilities across DOD
components.100 In December 2018, the Government Accountability Office (GAO) issued a report components.100 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 stating that adversaries are developing electronic attack weapons to target U.S. systems with
sensitive electronic components, such as military sensors, communication, navigation, and sensitive electronic components, such as military sensors, communication, navigation, and
information systems.101 The Senate Armed Services Committee, citing the report, stated, “These information systems.101 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.”102~~
~~Spectrum Sharing~~
~~In the past, repurposing efforts have focused on reallocating spectrum from federal to nonfederal~~
~~use. As spectrum-sharing technologies emerged, Congress encouraged not only the reallocation of~~

U.S. Advantage in the Electromagnetic 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. 94 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. 42. 95 Tate Nurkin, Kelly Bedard, James Clad, et al., China’s Advanced Weapons Systems, IHS Jane's, May 12, 2018, p. 95 Tate 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/11, https://www.uscc.gov/sites/default/files/Research/
Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf. Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf.
96 Elsa Kania, China’s Strategic Situational Awareness Capabilities, Center for Strategic and International Studies, 96 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/. Washington, DC, July 29, 2019, https://ontheradar.csis.org/issue-briefs/china-situational-awareness/.
97 Tate Nurkin, Kelly Bedard, James Clad, et al., China’s Advanced Weapons Systems, IHS Jane's, May 12, 2018, p. 97 Tate 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/41, https://www.uscc.gov/sites/default/files/Research/
Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf. Jane%27s%20by%20IHS%20Markit_China%27s%20Advanced%20Weapons%20Systems.pdf.
98 Department of Defense, Defense Intelligence Agency, China Military Power: Modernizing a Force to Fight and Win, 98 Department of Defense, Defense Intelligence Agency, China Military Power: Modernizing a Force to Fight and Win,
2019, p. 42. 2019, p. 42.
99 Department of Defense, 99 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-Washington, DC, September 2020, p. 65, https://media.defense.gov/2020/Sep/01/2002488689/-1/-1/1/2020-DOD-
CHINA-MILITARY-POWER-REPORT-FINAL.PDF. CHINA-MILITARY-POWER-REPORT-FINAL.PDF.
100 100 Sydney J. Freedberg, Jr., “Who’ll Fix EW? Task Force Gropes for Answers,” Sydney J. Freedberg, Jr., “Who’ll Fix EW? Task Force Gropes for Answers,” Breaking Defense, December 18, , December 18,
2019, https://breakingdefense.com/2019/12/wholl-fix-ew-task-force-gropes-for-answers/. 2019, https://breakingdefense.com/2019/12/wholl-fix-ew-task-force-gropes-for-answers/.
101 U.S. Government Accountability Office, 101 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.~~
~~102 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.~~
~~Congressional Research Service~~

22

~~spectrum from federal to non-federal~~ Congressional Research Service 22 Overview of Department of Defense Use of the Electromagnetic Spectrum 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.”102 Spectrum Sharing In the past, repurposing efforts have focused on reallocating spectrum from federal to nonfederal use. As spectrum-sharing technologies emerged, Congress encouraged not only the reallocation of spectrum from federal to nonfederal entities, but also sharing between federal and commercial entities, but also sharing between federal and commercial
users. For example, the Middle Class Tax Relief and Job Creation Act of 2012 allowed federal users. For example, the Middle Class Tax Relief and Job Creation Act of 2012 allowed federal
agencies to receive payments for costs incurred when they are asked to relocate due to a spectrum 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.103 The Spectrum Pipeline Act of 2015 auction or when they agree to share use of their spectrum.103 The Spectrum Pipeline Act of 2015
appropriated funds for federal agencies to engage in planning and to conduct studies and analyses appropriated funds for federal agencies to engage in planning and to conduct studies and analyses
to examine the potential for spectrum reallocation or sharing.104 to examine the potential for spectrum reallocation or sharing.104
DOD has participated in several spectrum-sharing initiatives, some of which have resulted in the DOD has participated in several spectrum-sharing initiatives, some of which have resulted in the
reallocation or shared use of spectrum.105 For example, DOD, the Department of Homeland reallocation or shared use of spectrum.105 For example, DOD, the Department of Homeland
Security (DHS), the Federal Aviation Administration (FAA), and the National Oceanic and Security (DHS), the Federal Aviation Administration (FAA), and the National Oceanic and
Atmospheric Administration (NOAA) have studied the potential to combine surveillance, air Atmospheric Administration (NOAA) have studied the potential to combine surveillance, air
safety, and weather radar applications into a single, spectrum-conserving “system of systems” by safety, and weather radar applications into a single, spectrum-conserving “system of systems” by
2024. This system would allow the agencies to vacate 30 MHz of spectrum in the 1300–1350 2024. This system would allow the agencies to vacate 30 MHz of spectrum in the 1300–1350
band, thus making it available for reallocation for shared federal and band, thus making it available for reallocation for shared federal and ~~non-federal~~nonfederal use. use.
Additionally, DOD plans to conduct a comprehensive engineering study to determine the Additionally, DOD plans to conduct a comprehensive engineering study to determine the
potential for introducing advanced wireless services in this band without harming critical potential for introducing advanced wireless services in this band without harming critical
government operations.106 Agencies began studying the reallocation and sharing potential of the government operations.106 Agencies began studying the reallocation and sharing potential of the
spectrum in 2017, and are still actively studying potential use of the band. The studies are spectrum in 2017, and are still actively studying potential use of the band. The studies are
expected to inform future repurposing decisions.107 expected to inform future repurposing decisions.107
On August 10, 2020, the White House and DOD announced that a 100 MHz block of contiguous 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 will be made available for commercial use (e.g., mid-band spectrum in the 3450-3550 MHz band will be made available for commercial use (e.g.,
5G), and is expected to be auctioned in 20215G), and is expected to be auctioned in 2021.. DOD leveraged technical work performed by the . DOD leveraged technical work performed by the
NTIA to “devise a spectrum sharing framework that supports industry’s need for additional mid-NTIA to “devise a spectrum sharing framework that supports industry’s need for additional mid-
band spectrum while protecting critical national security requirements.”108 At its September 30, band spectrum while protecting critical national security requirements.”108 At its September 30,
~~2020 meeting, the FCC adopted a Further Notice of Proposed Rulemaking (FNPRM) allocating~~
~~the 3.45-3.55 GHz spectrum band for flexible-use service. It seeks comment on an appropriate~~
~~regime to coordinate non-federal and federal use and proposes a band plan, as well as technical,~~
~~licensing, and competitive bidding rules for the band, signaling that the FCC is moving forward~~
~~on the 2021 auction date.109~~
~~In addition, new technologies that would enable dynamic spectrum sharing—automated sharing~~
~~between federal and nonfederal users—are under development.110 For example, in September~~
~~2019, the FCC approved a spectrum sharing arrangement between commercial and federal users~~

As Identified by Federal Agencies, GAO-19-204SP, December 2018, p. 4, https://www.gao.gov/assets/700/695981.pdf. 102 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. 103 P.L. 112-96, Title VI, Subtitle G—Federal Spectrum Relocation, Section 6701 (a)(1)(B). 103 P.L. 112-96, Title VI, Subtitle G—Federal Spectrum Relocation, Section 6701 (a)(1)(B).
104 P.L. 114-74, Title X—Spectrum Pipeline, Section 1005 (a). 104 P.L. 114-74, Title X—Spectrum Pipeline, Section 1005 (a).
105 Mark Rockwell, “DOD looks to share more spectrum,” 105 Mark Rockwell, “DOD looks to share more spectrum,” Defense Systems, March 1, 2018, , March 1, 2018,
https://defensesystems.com/articles/2018/03/01/ntia-dod-spectrum-5g.aspx. https://defensesystems.com/articles/2018/03/01/ntia-dod-spectrum-5g.aspx.
106 Office of Science and Technology Policy, 106 Office of Science and Technology Policy, Emerging Technologies and Their Expected Impact on Non-Federal
Spectrum Demand, May 2019, https://www.whitehouse.gov/wp-content/uploads/2019/05/Emerging-Technologies-and-, May 2019, https://www.whitehouse.gov/wp-content/uploads/2019/05/Emerging-Technologies-and-
Impact-on-Non-Federal-Spectrum-Demand-Report-May-2019.pdf. Impact-on-Non-Federal-Spectrum-Demand-Report-May-2019.pdf.
107 U.S. Department of Commerce, 107 U.S. Department of Commerce, Annual Report on the Status of Spectrum Repurposing, August 2019, , August 2019,
https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf. https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf.
108 U.S. Department of Defense, “White House and DOD Announce Additional Mid-Band Spectrum Available for 5G 108 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/.~~
~~109 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.~~
~~110 The CBRS spectrum sharing arrangement is being used to model for other spectrum sharing arrangements. National~~
~~Telecommunications 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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Congressional Research Service 23 Overview of Department of Defense Use of the Electromagnetic Spectrum 2020 meeting, the FCC adopted a Further Notice of Proposed Rulemaking (FNPRM) allocating 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 well as technical, licensing, and competitive bidding rules for the band, signaling that the FCC is moving forward on the 2021 auction date.109 In addition, new technologies that would enable dynamic spectrum sharing—automated sharing between federal and nonfederal users—are under development.110 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), in the 3550-3700 MHz band (also known as Citizens Broadband Radio Service or CBRS),
whereby commercial users (licensed and unlicensed) will share spectrum with incumbent DOD whereby commercial users (licensed and unlicensed) will share spectrum with incumbent DOD
users. DOD will have priority access when needed while still allowing for licensed and users. DOD will have priority access when needed while still allowing for licensed and
unlicensed use. unlicensed use.
In December 2019, DOD issued a special notice seeking input from industry on 5G technology In December 2019, DOD issued a special notice seeking input from industry on 5G technology
development, including dynamic spectrum sharing technologies.111 DOD and the Department of development, including dynamic spectrum sharing technologies.111 DOD and the Department of
the Air Force sought input on effective methodologies (hardware, software, and systems) for the Air Force sought input on effective methodologies (hardware, software, and systems) for
sharing or coexistence between airborne radar systems and 5G cellular systems in shared sharing or coexistence between airborne radar systems and 5G cellular systems in shared
(completely or partially overlapping) spectral bands. The intent is to evaluate the impact of the (completely or partially 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, 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 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 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 between military and civilian users, and to identify issues of concern related to sharing spectrum
for DOD.112 for DOD.112
While policymakers and users are both interested in spectrum sharing, and see it as a way of 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 extending spectrum access for new users, the policies, approaches, technologies, and applications
are still emerging and may face challenges. Introducing new users into spectrum bands creates a are still emerging and may face challenges. Introducing new users into spectrum bands creates a
potential for interference with military capabilities; detecting and mitigating interference is a potential for interference with military capabilities; detecting and mitigating interference is a
challenge. Prioritization of use is another challenge, as is policy control and coordination with challenge. Prioritization of use is another challenge, as is policy control and coordination with
secondary users.113 Further, to maximize use of shared spectrum, users may need to know when secondary users.113 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 challenges for DOD, as it may spectrum is being used and when it is available which may present challenges for DOD, as it may
not want to share that information publicly. not want to share that information publicly.
On the one hand, industry stakeholders say that military and other federal users have more 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 spectrum than they need and that holding large swathes of spectrum for future use inhibits
~~innovations and restricts economic advancement.114 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.”115 The challenge for Congress is in encouraging policies that enable the~~
~~most efficient use of spectrum, while still protecting and prioritizing DOD mission critical~~
~~functions.~~

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/. 109 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. 110 The CBRS spectrum sharing arrangement is being used to model for other spectrum sharing arrangements. National Telecommunications 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. 111 U.S. Department of Defense, “DOD Issues Special Notice Seeking Input From Industry on 5G Technology 111 U.S. Department of Defense, “DOD Issues Special Notice Seeking Input From Industry on 5G Technology
Development,” press release, December 2, 2019, https://www.defense.gov/Newsroom/Releases/Release/Article/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/. 2029707/dod-issues-special-notice-seeking-input-from-industry-on-5g-technology-developm/.
112 DOD, Request for Information, 112 DOD, Request for Information, Defense Spectrum Sharing Request for Information, Published September 18, 2020, , Published September 18, 2020,
https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&https://beta.sam.gov/opp/4851a65e2b2d4d73865a0e9865b0c28a/view?keywords=spectrum&sort=-modifiedDate&
index=&is_active=true&page=1. index=&is_active=true&page=1.
113 Frank Rayal, “Challenges & Impediments to Implementing Spectrum Sharing,” 113 Frank Rayal, “Challenges & Impediments to Implementing Spectrum Sharing,” Frank Rayal (blog), September 24, , September 24,
2012, “https://frankrayal.com/2012/09/24/challenges-impediments-to-implementing-spectrum-sharing/. 2012, “https://frankrayal.com/2012/09/24/challenges-impediments-to-implementing-spectrum-sharing/.
~~114 CTIA, “Benefits from Clearing Federal Spectrum Helps Government Agencies Modernize Operations, New CTIA~~
~~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.~~
~~115 Roslyn Layton, “GPS Interference Fears Are Today’s Y2K, Says Former UK Spectrum Director,” Forbes, May 8,~~
~~2020, https://www.forbes.com/sites/roslynlayton/2020/05/08/gps-interference-fears-are-todays-y2k-says-former-uk-~~
~~spectrum-director/#79d799e17329.~~
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Congressional Research Service 24 Overview of Department of Defense Use of the Electromagnetic Spectrum innovations and restricts economic advancement.114 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.”115 The challenge for Congress is in encouraging policies that enable the most efficient use of spectrum, while still protecting and prioritizing DOD mission critical functions.
DOD Spectrum Organizational Issues
Over the past several years, Congress has expressed interest in the DOD’s organization of 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 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 Defense—is tasked with synchronizing and integrating EW across DOD components by sharing
tactics, techniques, procedures, intelligence, and technologies. The EW EXCOM is responsible tactics, techniques, procedures, intelligence, and technologies. The EW EXCOM is responsible
for establishing DOD EW policy.116 The FY2019 NDAA mandated the creation of an EW Cross for establishing DOD EW policy.116 The FY2019 NDAA mandated the creation of an EW Cross
Functional Team to develop an electronic warfare strategy, including assessments of Functional Team to develop an electronic warfare strategy, including assessments of
vulnerabilities and capability gaps,117 leading to an acquisition plan. The most recent DOD EW vulnerabilities and capability gaps,117 leading to an acquisition plan. The most recent DOD EW
strategy was released in 2017. strategy was released in 2017.
The NDAA for FY2019 (P.L. 115-232, Section 1053) directed DOD to establish a cross- 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 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 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 chief information office (CIO) and the department’s electronic warfare strategy, into a single
policy: 118 the Electromagnetic Spectrum Superiority Strategy.119 In April 2019, DOD stood up the policy: 118 the Electromagnetic Spectrum Superiority Strategy.119 In April 2019, DOD stood up the
Electromagnetic Spectrum Operations (EMSO) Cross Functional Team, comprised of senior Electromagnetic Spectrum Operations (EMSO) Cross Functional Team, comprised of senior
members from each branch, the Joint Staff, U.S. Command, Cyber Command, and other offices. members from each branch, the Joint Staff, U.S. Command, Cyber Command, and other offices.
This organization has been active in updating DOD spectrum policy and strategy. In May 2020, This organization has been active in updating DOD spectrum policy and strategy. In May 2020,
the Joint Staff released new doctrine on Joint Electromagnetic Military Operations, elevating the the Joint Staff released new doctrine on Joint Electromagnetic Military Operations, elevating the
spectrum to a maneuver space.120 On September 4, 2020, DOD issued DOD Directive 3610.01, spectrum to a maneuver space.120 On September 4, 2020, DOD issued DOD Directive 3610.01,
Electromagnetic Spectrum Enterprise Policy, which sets DOD policy and roles and Electromagnetic Spectrum Enterprise Policy, which sets DOD policy and roles and
responsibilities for integrated DOD electromagnetic spectrum operations.121 responsibilities for integrated DOD electromagnetic spectrum operations.121 ~~In its version of the~~
~~FY2021 NDAA, the Senate proposed transferring responsibility for electronic warfare from~~
~~Strategic Command to the Vice Chairman of the Joint Chiefs of Staff.122~~
~~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,~~
~~satellite 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~~
~~reallocate spectrum for commercial wireless use.~~

On October 29, 2020, the EMS Operations Cross Functional Team released the DOD Spectrum Superiority Strategy.122 114 CTIA, “Benefits from Clearing Federal Spectrum Helps Government Agencies Modernize Operations, New CTIA 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. 115 Roslyn Layton, “GPS Interference Fears Are Today’s Y2K, Says Former UK Spectrum Director,” Forbes, May 8, 2020, https://www.forbes.com/sites/roslynlayton/2020/05/08/gps-interference-fears-are-todays-y2k-says-former-uk-spectrum-director/#79d799e17329. 116 10 U.S.C. §113. 116 10 U.S.C. §113.
117 P.L. 115-232 §918. 117 P.L. 115-232 §918.
118 The EMSO CFT is in the process of developing a new EMS strategy and anticipates releasing the strategy by the 118 The 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, end of 2020. Department of Defense, Electromagnetic Spectrum Strategy, September 11, 2013, , September 11, 2013,
https://dodcio.defense.gov/Portals/0/Documents/Spectrum/ESS.pdf. https://dodcio.defense.gov/Portals/0/Documents/Spectrum/ESS.pdf.
119 Lauren C. Williams, “DOD Preps New Electromagnetic Spectrum Strategy,” 119 Lauren C. Williams, “DOD Preps New Electromagnetic Spectrum Strategy,” Defense Systems, December 23, 2019, , December 23, 2019,
https://defensesystems.com/articles/2019/12/23/dod-spectrum-warfare-williams.aspx. https://defensesystems.com/articles/2019/12/23/dod-spectrum-warfare-williams.aspx.
120 While a maneuver space is not considered a domain, this implies 120 While a maneuver space is not considered a domain, this implies
121 Department of Defense, 121 Department of Defense, DOD Directive 3610.01: Electromagnetic Spectrum Enterprise Policy, September 4, 2020, , September 4, 2020,
https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/361001p.pdf?ver=2020-09-04-112353-317. https://www.esd.whs.mil/Portals/54/Documents/DD/issuances/dodd/361001p.pdf?ver=2020-09-04-112353-317.
122 122 ~~S. 4049 §173TRANSFER FROM COMMANDER OF UNITED STATES STRATEGIC COMMAND TO~~
~~CHAIRMAN OF THE JOINT CHIEFS OF STAFF OF RESPONSIBILITIES AND FUNCTIONS RELATING TO~~
~~ELECTROMAGNETIC SPECTRUM OPERATIONS.~~
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~~The growth in commercial wireless services has produced new revenues and new jobs for the~~
~~United States.123~~Department of Defense, Electromagnetic Spectrum Superiority Strategy, October 29, 2020, https://media.defense.gov/2020/Oct/29/2002525927/-1/- Congressional Research Service 25 Overview of Department of Defense Use of the Electromagnetic Spectrum 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. Finally, the FY2021 NDAA transfers responsibility for electronic warfare from Strategic Command to the Vice Chairman of the Joint Chiefs of Staff.123 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, satellite 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 reallocate spectrum for commercial wireless use. The growth in commercial wireless services has produced new revenues and new jobs for the United States.124 Hence the challenge for Congress is in balancing the allocation of spectrum for Hence the challenge for Congress is in balancing the allocation of spectrum for
commercial and consumer wireless services while protecting federal agency use of spectrum that commercial and consumer wireless services while protecting federal agency use of spectrum that
support mission-critical functions.support mission-critical functions.
This balance was recently demonstrated with the FCC’s Auction 107 for C-Band spectrum, which garnered approximately $81 billion from bidders.125 Federal agencies hold various segments of spectrum that commercial entities may be able to use 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 reallocate for wireless services. Since DOD is the largest holder of federal frequencies, policies to reallocate
spectrum for commercial use often affect DOD. As Congress considers policies to allocate spectrum for commercial use often affect DOD. As Congress considers policies to allocate
additional spectrum for commercial use, it may consider increasing demands for spectrum, the 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 impact on DOD systems and uses, unintended frequency interference, the interagency process for
allocating spectrum, and DOD’s ability to anticipate future spectrum needs. allocating 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), 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 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 maker, reported that in 2018, “global mobile data traffic amounted to 19.01 exabytes per
month;month;~~124~~126 by 2022, mobile data traffic is expected to reach 77.5 exabytes per month by 2022, mobile data traffic is expected to reach 77.5 exabytes per month
worldwide,”worldwide,”~~125~~127 which will increase demand for additional spectrum. which will increase demand for additional spectrum.
To accommodate new technologies, more users, and more data-intensive applications (e.g., video To accommodate new technologies, more users, and more data-intensive applications (e.g., video
streaming, gaming), global telecommunications providers and equipment makers around the streaming, gaming), global telecommunications providers and equipment makers around the
1/0/ELECTROMAGNETIC_SPECTRUM_SUPERIORITY_STRATEGY.PDF. 123 P.L. 116-283 §152 Transfer of Responsibilities and Functions Relating to Electromagnetic Spectrum Operations. 124 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. 125 Federal Communications Commission, “Auction 107 - 3.7 GHz,” press release, January 15, 2021, https://auctiondata.fcc.gov/public/projects/auction107. 126 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. 127 https://www.statista.com/statistics/271405/global-mobile-data-traffic-forecast/ Congressional Research Service 26 Overview of Department of Defense Use of the Electromagnetic Spectrum world developed 5G wireless networks and technologies. 5G technologies promise increased 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 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 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. 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—will help Providers expect that the 5G solution—additional spectrum and new 5G technologies—will help
to meet increasing demands for mobile data, support advanced 5G services to businesses, and to meet increasing demands for mobile data, support advanced 5G services to businesses, and
yield new 5G applications, including new military applications.yield new 5G applications, including new military applications.~~126~~128
However, the spectrum is already crowded with users, including federal agency users. DOD is However, the spectrum is already crowded with users, including federal agency users. DOD is
allocated about allocated about 3540% of federally-assigned spectrum,% of federally-assigned spectrum,~~127~~129 including significant frequency bands in including significant frequency bands in
the 1-6GHz range—prime spectrum for mobile telecommunication technologies. Some the 1-6GHz range—prime spectrum for mobile telecommunication technologies. Some
stakeholders and policymakers have called for the reallocation of federal agency spectrum for stakeholders and policymakers have called for the reallocation of federal agency spectrum for
commercial use, or incentives for some federal agencies to relinquish or share spectrum for 5G commercial use, or incentives for some federal agencies to relinquish or share spectrum for 5G
use.use.~~128~~130 DOD asserts that its spectrum supports military operations, and the research and DOD asserts that its spectrum supports military operations, and the research and
development of advanced technologies, thus should remain with DOD. development of advanced technologies, thus should remain with DOD.

~~123 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.~~
~~124 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.~~
~~125 https://www.statista.com/statistics/271405/global-mobile-data-traffic-forecast/~~
~~126 CRS In Focus IF11251, National Security Implications of Fifth Generation (5G) Mobile Technologies, by John R.~~
~~Hoehn and Kelley M. Sayler.~~
~~127 President’s Council of Advisors on Science & Technology,~~ ~~Report to the President: Realizing the Full Potential of~~
~~Government-Held Spectrum to Spur Economic Growth, July 2012, p. 5, https://www.broadinstitute.org/files/sections/~~
~~about/PCAST/2012%20pcast-spectrum.pdf.~~
~~128 https://www.politico.com/news/agenda/2020/02/22/pentagon-airwaves-midband-106240~~
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~~Starting in 1993, the Omnibus Budget Reconciliation Act (OBRA),129~~ Starting in 1993, the Omnibus Budget Reconciliation Act (OBRA),131 required the Secretary of required the Secretary of
Commerce to identify at least 200 MHz of spectrum used by the federal government for Commerce to identify at least 200 MHz of spectrum used by the federal government for
reallocation to new spectrum-based technologies (i.e., commercial use). Year after year, the U.S. reallocation to new spectrum-based technologies (i.e., commercial use). Year after year, the U.S.
government has continued to reallocate spectrum from federal to commercial wireless use. In its government has continued to reallocate 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 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-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 federal uses and have not directed the repurposing of spectrum to new federal uses; they also
prioritize exclusive non-federal use over sharing.”prioritize exclusive non-federal use over sharing.”~~130~~132 Congress may require the reallocation of Congress may require the reallocation of
specific spectrum bands, call for the identification of certain amounts of spectrum (e.g., 255 MHz specific spectrum bands, call for the identification of certain amounts of spectrum (e.g., 255 MHz
below 6 GHz), or call for testing and studies to identify appropriate spectrum for commercial below 6 GHz), or call for testing and studies to identify appropriate spectrum for commercial
use.use.~~131~~133 Since DOD holds about 40% of the federally-held spectrum, Since DOD holds about 40% of the federally-held spectrum,~~132~~134 it can be affected by these it can be affected by these
policies.policies.~~133~~135
Congress has tried to assess and address the impact of federal spectrum policies on agencies. For 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 example, in 2004 Congress established a program to help cover the costs that federal agencies
incur when spectrum is reallocated. Congress enacted the Commercial Spectrum Enhancement incur when spectrum is reallocated. Congress enacted the Commercial Spectrum Enhancement
Act (CSEA),Act (CSEA),~~134~~136 which created the Spectrum Relocation Fund (SRF). The SRF used revenues from 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. 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 However, as wireless technology use increased, and demand for mobile data continued to rise, the
U.S. government continued to examine and reallocate spectrum to meet emerging demands. Some U.S. government continued to examine and reallocate spectrum to meet emerging demands. Some
~~have argued that a piecemeal approach to spectrum planning is ineffective.135 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 will allow 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.136 In 2018,~~
~~two spectrum planning initiatives were launched.~~
~~The FCC developed the 5G FAST Plan, which identified spectrum for 5G use, and streamlined~~
~~regulations to speed 5G deployment.137 This plan provides insight into FCC actions (e.g., future~~
~~reallocations, auctions); however, the GAO found that the plan was not developed with outside~~

~~129 P.L. 103-66.~~
~~130 Ibid.~~
~~131~~ 128 CRS In Focus IF11251, National Security Implications of Fifth Generation (5G) Mobile Technologies, by John R. Hoehn and Kelley M. Sayler. 129 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. 130 https://www.politico.com/news/agenda/2020/02/22/pentagon-airwaves-midband-106240. 131 P.L. 103-66. 132 Ibid. 133 U.S. Department of Commerce, U.S. Department of Commerce, Annual Report on the Status of Spectrum Repurposing, August 2019, , August 2019,
https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf. https://www.ntia.doc.gov/files/ntia/publications/spectrum_repurposing_report_august_2019.pdf.
~~132~~134 U.S. Government Accountability Office, 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. , GAO-11-352, April 2011, p. 21, https://www.gao.gov/assets/320/318264.pdf.
~~133~~135 George Leopold, “DOD returns fire on spectrum relocation,” George Leopold, “DOD returns fire on spectrum relocation,” EE|Times, August 30, 2001, https://www.eetimes.com/, August 30, 2001, https://www.eetimes.com/
dod-returns-fire-on-spectrum-relocation/#. dod-returns-fire-on-spectrum-relocation/#.
~~134~~136 Title II of P.L. 108-494. Congressional Research Service 27 link to page 38 Overview of Department of Defense Use of the Electromagnetic Spectrum have argued that a piecemeal approach to spectrum planning is ineffective.137 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 will allow 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.138 In 2018, two spectrum planning initiatives were launched. The FCC developed the 5G FAST Plan, which identified spectrum for 5G use, and streamlined regulations to speed 5G deployment.139 This plan provides insight into FCC actions (e.g., future reallocations, auctions); however, the GAO found that the plan was not developed with outside entities, including the NTIA or other relevant stakeholders, including carriers.140 ~~Title II of P.L. 108-494.~~
~~135 U.S. House of Representatives, Committee on Energy and Commerce, Subcommittee on Communications and~~
~~Technology, 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, NTIA, at~~
~~https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/~~
~~1_Testimony_Khlopin.pdf. See also testimony of Scott Bergmann Senior Vice President, Regulatory Affairs CTIA, at~~
~~https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/~~
~~2_Testimony_Bergmann.pdf.~~
~~136 White House 5G Summit (recorded event), September 28, 2018, https://www.youtube.com/watch?v=lBbY8fvTidU.~~
~~137 FCC, “5G FAST Plan,” https://www.fcc.gov/5G.~~
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~~link to page 36~~

~~entities, including the NTIA or other relevant stakeholders, including carriers.138~~ In 2018, the In 2018, the
President directed the NTIA to develop a National Spectrum Strategy to set forth a “balanced, President directed the NTIA to develop a National Spectrum Strategy to set forth a “balanced,
forward-looking, flexible, and sustainable approach to spectrum management.”forward-looking, flexible, and sustainable approach to spectrum management.”~~139~~141 Federal Federal
agencies were directed to review current frequency assignments and spectrum usage to identify agencies were directed to review current frequency assignments and spectrum usage to identify
spectrum that could be reallocated or shared with commercial uses. NTIA held a Spectrum Policy spectrum that could be reallocated 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 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 new technologies and cooperation with commercial users, DOD is exploring opportunities to
share spectrum.share spectrum.~~140~~142 NTIA has reported that the National Spectrum Strategy is under development. NTIA has reported that the National Spectrum Strategy is under development.
Congress may be interested in encouraging coordination between the agencies to balance the 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 needs of commercial 5G providers and users and the mission critical needs of DOD. On the one
hand, reallocating spectrum from DOD may help to speed deployment of 5G networks, spur the hand, reallocating 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 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 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 affect military operations and result in the permanent loss of spectrum for DOD uses, including
critical defense operations and future capabilities. critical defense operations and future capabilities.
Unintended Commercial Frequency ~~Interference141~~Interference143
As new users, technologies, and services are introduced to the spectrum, the potential for As new users, technologies, and services are introduced to the spectrum, the potential for
interference may increase.interference may increase.~~142~~144 Interference occurs when unwanted radio frequency signals disrupt 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 allowing flexible use of~~
~~spectrum) may increase the potential for harmful interference.143~~
~~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]. Additionally, in~~
~~Section 1698 of the National Defense Authorization Act for Fiscal Year 2017 (P.L. 114-328)—~~
~~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~~

~~138~~ 137 U.S. House of Representatives, Committee on Energy and Commerce, Subcommittee on Communications and Technology, 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, NTIA, at https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/1_Testimony_Khlopin.pdf. See also testimony of Scott Bergmann Senior Vice President, Regulatory Affairs CTIA, at https://energycommerce.house.gov/sites/democrats.energycommerce.house.gov/files/documents/2_Testimony_Bergmann.pdf. 138 White House 5G Summit (recorded event), September 28, 2018, https://www.youtube.com/watch?v=lBbY8fvTidU. 139 FCC, “5G FAST Plan,” https://www.fcc.gov/5G. 140 U.S. Government Accountability Office, 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. , GAO-20-468, June 2020, pp. 12-13, https://www.gao.gov/assets/710/707530.pdf.
~~139~~141 White House, Office of the Press Secretary, “Presidential Memorandum on Developing a Sustainable Spectrum 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/Strategy for America’s Future,” presidential memorandum, October 25, 2018, https://www.whitehouse.gov/
presidential-actions/presidential-memorandum-developing-sustainable-spectrum-strategy-americas-future/. presidential-actions/presidential-memorandum-developing-sustainable-spectrum-strategy-americas-future/.
~~140~~142 NTIA, NTIA, NTIA Spectrum Policy Symposium Transcript, September 10, 2019, p. 12, https://www.ntia.doc.gov/files/, September 10, 2019, p. 12, https://www.ntia.doc.gov/files/
ntia/publications/09.10.19_npc_ntia_spectrum_policy_symposium.pdf. ntia/publications/09.10.19_npc_ntia_spectrum_policy_symposium.pdf.
~~141~~143 Fore a detailed discussion of potential 5G interference with the Global Positioning System, see the Fore a detailed discussion of potential 5G interference with the Global Positioning System, see the Appendix.
~~142~~144 Commerce Spectrum Management Advisory Committee (CSMAC), 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. Interim Report, May 19, 2010, p. 13, https://www.ntia.doc.gov/files/ntia/meetings/csmac_may19_idsa_final.pdf.
~~143 John Pahl, “Market Mechanisms for Spectrum Management: Spectrum Liberalisation and Interference~~
~~Management,” Background Paper submitted to ITU Workshop, “Shaping Tomorrow’s Network” Program, September~~
~~2006, https://www.scribd.com/document/60765650/Spectrum-Liberalisation-and-Interference-Management.~~
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~~GPS devices.”144~~Congressional Research Service 28 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 allowing flexible use of spectrum) may increase the potential for harmful interference.145 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]. Additionally, in Section 1698 of the National Defense Authorization Act for Fiscal Year 2017 (P.L. 114-328)—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.”146 While DOD did express its concerns to the FCC on the Ligado project, the FCC 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.asserted that the conditions it placed on Ligado (e.g., reducing power levels, creating a guard reducing power levels, creating a guard
band, reporting base station locations) would mitigate interference concerns. band, reporting base station locations) would mitigate interference concerns.
A recent dispute with Ligado Networks, LLC has highlighted key interference issues. On April 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 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 “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]MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5 MHz bands [of the electromagnetic spectrum]~~145~~147
that will primarily support Internet of Things (IoT) services.”that will primarily support Internet of Things (IoT) services.”~~146~~148
These frequency bands are traditionally used for satellite communications and position, These frequency bands are traditionally used for satellite communications and position,
navigation, and timing services, such as GPS.navigation, and timing services, such as GPS.~~147~~149 DOD opposed this decision—along with the DOD opposed this decision—along with the
Department of Homeland Security, Department of Transportation (DOT), Department of the Department of Homeland Security, Department of Transportation (DOT), Department of the
Interior, Department of Justice, the Federal Aviation Administration (FAA), and others.Interior, Department of Justice, the Federal Aviation Administration (FAA), and others.~~148~~150 That That
opposition was related to concerns that Ligado’s proposed terrestrial network could interfere with opposition was related to concerns that Ligado’s proposed terrestrial network could interfere with
signals from satellites to terrestrial GPS receivers and enabled devices.signals from satellites to terrestrial GPS receivers and enabled devices.~~149~~151 Despite federal agency 145 John Pahl, “Market Mechanisms for Spectrum Management: Spectrum Liberalisation and Interference Management,” Background Paper submitted to ITU Workshop, “Shaping Tomorrow’s Network” Program, September 2006, https://www.scribd.com/document/60765650/Spectrum-Liberalisation-and-Interference-Management. 146 ~~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 will~~
~~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 allocation of spectrum~~
~~among competing users and the impact of spectrum decisions on national security.~~
~~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~~

~~144~~ This provision is related to an earlier proposal from Ligado submitted to the FCC, which federal agencies, including This 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. DOD, opposed. Details on the proposal, the federal agency opposition, and congressional intent is available in S.Rept.
116-236, pp. 75, 275. 116-236, pp. 75, 275.
~~145~~147 CRS In Focus IF11155, CRS In Focus IF11155, Defense Primer: Military Use of the Electromagnetic Spectrum, by John R. Hoehn. , by John R. Hoehn.
~~146~~148 The FCC authorized Ligado to operate an Internet of Things network in the referenced frequency bands with The FCC authorized Ligado to operate an Internet of Things network in the referenced frequency bands with
conditions. Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-conditions. Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf. 48A1.pdf.
~~147~~149 Testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief Testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief
Information Officer, Gen John Raymond, Chief of Space Operations, and Thad Allen, Chairman of Space-Based Information Officer, Gen John Raymond, Chief of Space Operations, and Thad Allen, Chairman of Space-Based
Precision Navigation and Timing National Advisory Board, before the U.S. Congress, Senate Armed Services Precision Navigation and Timing National Advisory Board, before the U.S. Congress, Senate Armed Services
Committee, Committee, Department of Defense Spectrum Policy and the Impact of the Federal Communications Commission, 116th 116th
Cong., 2nd sess., May 6, 2020.Cong., 2nd sess., May 6, 2020.
~~148~~150 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary 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, 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/2020, at https://www.ntia.doc.gov/files/ntia/publications/
ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf. ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf.
~~149~~151 CRS In Focus IF11558, CRS In Focus IF11558, Spectrum Interference Issues: Ligado, the L-Band, and GPS, by Jill C. Gallagher, Alyssa K. , by Jill C. Gallagher, Alyssa K.
King, and Clare Y. Cho. King, and Clare Y. Cho.
Congressional Research Service Congressional Research Service

29 29

~~interests,150~~Overview of Department of Defense Use of the Electromagnetic Spectrum 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 will 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 allocation of spectrum among competing users and the impact of spectrum decisions on national security. 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,152 while others have questioned whether federal agencies should have to work through while others have questioned whether federal agencies should have to work through
NTIA to express its concerns on FCC decisions.NTIA to express its concerns on FCC decisions.~~151~~153
As the federal government strives to make spectrum available for 5G services, several spectrum 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 bands used for federal agency missions (DOD and other agencies) have been targeted for
reallocation or repurposing, affecting federal agency investments and missions. This includes reallocation 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 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 reallocation aside for auto safety technologies, Department of Education concerns regarding the reallocation
of the 2.5 GHz band from educational users, and the National Oceanic and Atmospheric 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. Administration and the 24 GHz band used for weather forecasting.
Congress has proposed initiatives to improve spectrum management and reduce spectrum 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, 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) 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 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 management. Some in Congress have proposed updates to the MOU between the FCC and NTIA
to clarify the government’s spectrum management and reallocation process.to clarify the government’s spectrum management and reallocation process.~~152~~154 Others have Others have
suggested to Congress that a third-party, such as the White House Office of Science and 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 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.technical reviewer or as an arbiter of conflicting technical reports and interference disputes.~~153~~
~~As spectrum is reallocated or reconfigured, some federal agencies are protesting.154 FCC has~~
~~acknowledged that as demand for spectrum increases, and more users gain access to the spectrum,~~
~~disputes are likely to increase as well. 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.~~
~~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~~155

~~150~~152 U.S. Government Accountability Office, Interdepartment Radio Advisory Committee: IRAC Representatives 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, 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. September 2004, pp. 3-4, https://www.gao.gov/new.items/d041028.pdf.
~~151~~153 Testimony of Thad Allen, Chairman of Space-Based Precision Navigation and Timing National Advisory Board, Testimony of Thad Allen, Chairman of Space-Based Precision Navigation and Timing National Advisory Board,
before the U.S. Congress, Senate Armed Services Committee, before the U.S. Congress, Senate Armed Services Committee, Department of Defense Spectrum Policy and the Impact
of the Federal Communications Commission,, 116th Cong., 2nd sess., May 6, 2020, p. 42, https://www.armed-116th Cong., 2nd sess., May 6, 2020, p. 42, https://www.armed-
services.senate.gov/imo/media/doc/20-21_05-06-2020.pdf. services.senate.gov/imo/media/doc/20-21_05-06-2020.pdf.
~~152~~154 See discussion on MOU and arbiter for spectrum disputes during Senate hearing (video): U.S. Congress, Senate See discussion on MOU and arbiter for spectrum disputes during Senate hearing (video): U.S. Congress, Senate
Committee on Commerce, Science, and Transportation, Committee on Commerce, Science, and Transportation, The State of U.S. Spectrum Policy, 116th Cong., 2nd sess., July , 116th Cong., 2nd sess., July
23, 2020. 23, 2020.
~~153 Ibid.~~
~~154 Letter from Elaine L. Chao, Secretary, U.S. Department of Transportation, 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, NTIA, 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 NTIA was sent to~~
~~the FCC, and includes letters from DOD to the Secretary of Commerce regarding concerns with recent spectrum~~
~~decisions, DOD to NTIA on spectrum concerns, and a Memorandum from the Air Force to NTIA on spectrum~~
~~concerns, signed by 12 members of this interagency spectrum working group).~~
~~Congressional Research Service~~

30

155 Ibid. Congressional Research Service 30 Overview of Department of Defense Use of the Electromagnetic Spectrum As spectrum is reallocated or reconfigured, some federal agencies are protesting.156 FCC has acknowledged that as demand for spectrum increases, and more users gain access to the spectrum, disputes are likely to increase as well. 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. 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 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 vehicle-to-everything (V2X). The Director notes that the identified use cases are driving research
and development (R&D) activities, as well as the standardization activities taking place in the and development (R&D) activities, as well as the standardization activities taking place in the
international standards development groups such as the International Telecommunications Union international standards development groups such as the International Telecommunications Union
(ITU) and the Third Generation Partnership Project (3GPP). Some technology firms advocate for (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 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 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 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 deploying 5G in selected bases to measure and monitor performance, and experiment with the
technologies. technologies.
The allocation of spectrum takes time, as does the buildout of a network that will operate in the The allocation of spectrum takes time, as does the buildout of a network that will operate in the
band. Often, by the time the spectrum is allocated and networks built, new technologies are band. Often, by the time the spectrum is allocated and networks built, new technologies are
emerging. For example, future sixth generation (6G) communications technologies, along with emerging. For example, future sixth generation (6G) communications technologies, along with
emerging military communications technologies. These technologies will most likely use the emerging military communications technologies. These technologies will most likely use the
spectrum differently than current systems; exactly how these systems will use the spectrum spectrum differently than current systems; exactly how these systems will use the spectrum
remains unclear.remains unclear.~~155~~157
Potential Questions for ~~Congress156~~Congress158
As Congress considers its role in spectrum policy and how the DOD manages its use of the 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 spectrum, several potential issues and questions arise. Below are a few potential Congress may
seek additional information: seek additional information:
 What actions can Congress or DOD take to ensure that mission critical systems  What actions can Congress or DOD take to ensure that mission critical systems
that operate in various segments of the electromagnetic spectrum (both that operate in various segments of the electromagnetic spectrum (both
domestically and abroad) are interoperable? domestically and abroad) are interoperable?
156 Letter from Elaine L. Chao, Secretary, U.S. Department of Transportation, 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, NTIA, 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 NTIA was sent to the FCC, and includes letters from DOD to the Secretary of Commerce regarding concerns with recent spectrum decisions, DOD to NTIA on spectrum concerns, and a Memorandum from the Air Force to NTIA on spectrum concerns, signed by 12 members of this interagency spectrum working group). 157 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. 158 This section was written by John R. Hoehn, Jill C. Gallagher, and Kelley M. Sayler. Congressional Research Service 31 Overview of Department of Defense Use of the Electromagnetic Spectrum  What changes, if any, should the DOD make in programs or investments in order  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 to maintain a technological edge in the use of the electromagnetic spectrum over
U.S. competitors? U.S. competitors?
 Does the U.S. government’s plan for spectrum allocation sufficiently balance  Does the U.S. government’s plan for spectrum allocation sufficiently balance
DOD requirements with the requirements of commercial applications? If so, DOD requirements with the requirements of commercial applications? If so,
how? how?
 What measures, if any, could accelerate spectrum repurposing, relocation, and/or  What measures, if any, could accelerate spectrum repurposing, relocation, and/or
sharing? sharing?
 Is DOD using the spectrum it has efficiently? How can DOD improve its  Is DOD using the spectrum it has efficiently? How can DOD improve its
spectrum efficiency? Is DOD adequately leveraging the spectrum to enable future spectrum efficiency? Is DOD adequately leveraging the spectrum to enable future
concepts like Multi-Domain Operations, Distributed Maritime Operations, and concepts like Multi-Domain Operations, Distributed Maritime Operations, and
JADC2? If so, how? JADC2? If so, how?
 As DOD relinquishes certain spectrum segments to commercial or shared use,  As DOD relinquishes certain spectrum segments to commercial or shared use,
how is it planning to ensure continued command and challenges in implementing how is it planning to ensure continued command and challenges in implementing
5G communications? 5G communications?

~~155 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.~~
~~156 This section was written by John R. Hoehn, Jill C. Gallagher, and Kelley M. Sayler.~~
~~Congressional Research Service~~

31

~~Appendix. Ligado Networks157~~ Congressional Research Service 32 Overview of Department of Defense Use of the Electromagnetic Spectrum Appendix. Ligado Networks159
Concerns Regarding the FCC-Approved Ligado Network for Mid-
Band 5G Network
On April 20, 2020, the Federal Communications Commission (FCC) unanimously approved an 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)] 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 terrestrial nationwide network in the 1526-1536 MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5
MHz bands [of the electromagnetic spectrum]MHz bands [of the electromagnetic spectrum]~~158~~160 that will primarily support Internet of Things that will primarily support Internet of Things
(IoT) services.”(IoT) services.”~~159~~161 These frequency bands are traditionally used for satellite operations. These frequency bands are traditionally used for satellite operations.~~160~~162 The The
Department of Defense (DOD) opposed this decision, along with the Department of Homeland 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, Security, Department of Transportation (DOT), Department of the Interior, Department of Justice,
the Federal Aviation Administration (FAA), and others.the Federal Aviation Administration (FAA), and others.~~161~~163 That opposition related to concerns that That opposition related to concerns that
Ligado’s proposed network could interfere with signals from satellites to Global Positioning Ligado’s proposed network could interfere with signals from satellites to Global Positioning
System (GPS) receivers.System (GPS) receivers.~~162~~164 Congress may consider federal agency concerns, including DOD Congress may consider federal agency concerns, including DOD
concerns related to mission-critical systems and the FCC’s response, as it conducts oversight of 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) the FCC’s ruling. Congress may also consider broader issues related to fifth generation (5G)
mobile technologies, such as the allocation of spectrum among competing users and the impact of mobile technologies, such as the allocation of spectrum among competing users and the impact of
spectrum decisions on national security. 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 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 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 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. military potential of GPS”: a 2018 DOT study and a 2016 classified study conducted by the U.S.
Air Force (USAF).Air Force (USAF).~~163~~165 The 2018 DOT study assessed the extent to which The 2018 DOT study assessed the extent to which ~~“a typical~~ cellular basecellular base stations

~~157~~159 This section was written by John R. Hoehn and Kelley M. Sayler. For more information see This section was written by John R. Hoehn and Kelley M. Sayler. For more information see, CRS Insight IN11400, CRS Insight IN11400,
DOD Concerns About the FCC-Approved Ligado Network, by Kelley M. Sayler and John R. Hoehn and CRS Insight , by Kelley M. Sayler and John R. Hoehn and CRS Insight
IN11414, IN11414, The FCC-Approved Ligado Network and Potential Technical Issues for DOD Use of GPS, by John R. Hoehn, , by John R. Hoehn,
Stephen M. McCall, and Kelley M. Sayler. Stephen M. McCall, and Kelley M. Sayler.
~~158~~160 CRS In Focus IF11155, CRS In Focus IF11155, Defense Primer: Military Use of the Electromagnetic Spectrum, by John R. Hoehn. , by John R. Hoehn.
~~159~~161 The FCC authorized Ligado to operate an Internet of Things network in the referenced frequency bands with The FCC authorized Ligado to operate an Internet of Things network in the referenced frequency bands with
conditions. Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-conditions. Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf. 48A1.pdf.
~~160~~162 Testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief Testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, Dana Deasy, DOD Chief
Information Officer, Gen. John Raymond, Chief of Space Operations, and Thad Allen, Chairman of Space-Based Information Officer, Gen. John Raymond, Chief of Space Operations, and Thad Allen, Chairman of Space-Based
Precision Navigation and Timing National Advisory Board, before the U.S. Congress, Senate Armed Services Precision Navigation and Timing National Advisory Board, before the U.S. Congress, Senate Armed Services
Committee, Committee, Department of Defense Spectrum Policy and the Impact of the Federal Communications Commission,, 116th 116th
Cong., 2nd sess., May 6, 2020.Cong., 2nd sess., May 6, 2020.
~~161~~163 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary 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 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/10, 2020, at https://www.ntia.doc.gov/files/ntia/publications/
ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf. ntia_letter_to_fcc_chairman_re_ligado_applications_4.10.20.pdf.
~~162~~164 CRS In Focus IF11558, CRS In Focus IF11558, Spectrum Interference Issues: Ligado, the L-Band, and GPS, by Jill C. Gallagher, Alyssa K. , by Jill C. Gallagher, Alyssa K.
King, and Clare Y. Cho. King, and Clare Y. Cho.
~~163~~165 See Department of Transportation, See Department of Transportation, 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-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, reportapril2018.pdf, and written testimony of Dana Deasy, DOD Chief Information Officer, before the U.S. Congress,
Senate Armed Services Committee, Senate Armed Services Committee, Department of Defense Spectrum Policy and the Impact of the Federal
Congressional Research Service Congressional Research Service

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~~station power level of 29 dBW”~~Overview of Department of Defense Use of the Electromagnetic Spectrum with power levels ranging from -6 dBW to 31 dBW and cellular handsets of -7 dBW would interfere with GPS. (At the time of the study, Ligado would interfere with GPS. (At the time of the study, Ligado
proposed a base station power level of 32 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 non-certified aviation, general location/navigation, high precision, timing, and space-based—could not be assured at this power level.~~dBW.) The study concluded that a 29 dBW base station~~
~~would exceed allowable levels of interference, instead recommending that ground station~~
~~transmissions not exceed 9.8 dBW to ensure the protection of certified avionics in “the most~~
~~restrictive of the certified aviation scenarios examined.”~~ DOD additionally recommended “that DOD additionally recommended “that
proposals for use of bands adjacent to GPS should not be approved unless they meet the proposals for use of bands adjacent to GPS should not be approved unless they meet the
transmission power levels described in the [DOT test].”transmission power levels described in the [DOT test].”~~164~~166 Based on these recommendations, Based on these recommendations,
Ligado submitted an amended application to the FCC, reducing its proposed power levels to 9.8 Ligado submitted an amended application to the FCC, reducing its proposed power levels to 9.8
dBW.dBW.~~165~~167 Per the FCC ruling, Ligado also agreed to maintain a 23-MHz guard-band of unused 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 spectrum designed to separate its transmissions from GPS, thus attempting to mitigate potential
interference. interference.
Details available in the public domain describing the technical parameters of the 2016 classified 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 USAF study are limited; however, the USAF’s formal response to the FCC ruling notes that its
study,study,~~166~~168 which specifically tested potential interference with military GPS receivers, “supported which specifically tested potential interference with military GPS receivers, “supported
the conclusions drawn from the DOT testing ... conducted during the same month.” This may 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 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 specifications from the company’s 2018 amended application—would necessarily interfere with
GPS. Furthermore, according to FCC Chairman Ajit Pai,GPS. Furthermore, according to FCC Chairman Ajit Pai,~~167~~169 DOD neither submitted nor attempted DOD neither submitted nor attempted
to submit the classified USAF study to the FCC for consideration. Nonetheless, DOD has 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. 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), Michael Griffin, former Under Secretary of Defense for Research and Engineering (USD R&E),
has additionally asserted that any ground transmissions—regardless of power level—“would has additionally asserted that any ground transmissions—regardless of power level—“would
drown out the very weak signals that come from [GPS] satellites,” likening the effect of the drown out the very weak signals that come from [GPS] satellites,” likening the effect of the
proposed Ligado network on GPS to attempting to listen to the rustling of leaves while 100 jet proposed Ligado network on GPS to attempting to listen to the rustling of leaves while 100 jet
aircraft simultaneously took off.aircraft simultaneously took off.~~168~~170
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 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 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 DOD that would adversely affect the military potential of GPS” [emphasis added]. Although the of GPS” [emphasis added]. Although the
~~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~~

Communications Commission,, 116th Cong., 2nd sess., May 6, 2020, at https://www.armed-services.senate.gov/imo/116th Cong., 2nd sess., May 6, 2020, at https://www.armed-services.senate.gov/imo/
media/doc/Deasy_05-06-20.pdf. media/doc/Deasy_05-06-20.pdf.
~~164~~166 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary 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 of Communications and Information, to Hon. Ajit Pai, Chairman of the Federal Communications Commission, April
10, 2020. 10, 2020.
~~165~~167 Letter from Gerard Waldron, Counsel to Ligado Networks LLC, to Marlene H. Dortch, Secretary to the Federal 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/Communications Commission, May 31, 2018, at https://ecfsapi.fcc.gov/file/1053120688074/
Ligado%20License%20Modification%20Cover%20Letter%20and%20Amendment%20(5-31-2018).pdf. Ligado%20License%20Modification%20Cover%20Letter%20and%20Amendment%20(5-31-2018).pdf.
~~166~~168 Letter from Douglas Kinkoph, Associate Administrator Performing the Delegated Duties of the Assistant Secretary 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 of Communications and Information, to Hon. Ajit Pai, Chairman of the Federal Communications Commission, April
10, 2020. 10, 2020.
~~167~~169 Letter from Hon. Ajit Pai, Chairman of the Federal Communications Commission, to Rep. Donald Bacon et al., May 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. 26, 2020, at https://docs.fcc.gov/public/attachments/DOC-364591A2.pdf.
~~168~~170 Spoken testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, before the U.S. Spoken testimony of Michael Griffin, Undersecretary of Defense for Research and Engineering, before the U.S.
Congress, Senate Armed Services Committee, Congress, Senate Armed Services Committee, Department of Defense Spectrum Policy and the Impact of the Federal
Communications Commission,, 116th Cong., 2nd sess., May 6, 2020. 116th Cong., 2nd sess., May 6, 2020.
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Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 responsibilities, I believe there are too many unknowns and the risks are far too great to federal
operations to allow Ligado’s proposed system to proceed.”operations to allow Ligado’s proposed system to proceed.”~~169~~171
DOD has additionally noted that Section 1698 of the National Defense Authorization Act for DOD has additionally 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 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 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 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 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 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.”justification for its belief that the concerns were “effectively resolved.”~~170~~172
FCC Response to Concerns About Potential GPS Interference
Several Commissioners have provided statements and written correspondence directly addressing Several Commissioners have provided statements and written correspondence directly addressing
how the FCC came to its decision. Commissioner Brendan Carr noted in a statement 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 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 professional staff of engineers and other experts determined that we can advance America’s 5G
leadership while protecting GPS and other adjacent band services.”leadership while protecting GPS and other adjacent band services.”~~171~~173 Commissioners Jessica Commissioners Jessica
Rosenworcel and Geoffrey Starks termed the decision “an extremely close call,” but similarly Rosenworcel and Geoffrey Starks termed the decision “an extremely close call,” but similarly
noted in their joint statement of concurrence that, despite the concerns of DOD and others about noted in their joint statement of concurrence that, despite the concerns of DOD and others about
potential GPS interference, “in the end, we are compelled to support the expert technical analysis potential GPS interference, “in the end, we are compelled to support the expert technical analysis
done by the [FCC’s] engineering staff.”done by the [FCC’s] engineering staff.”~~172~~174 In a series of letters, Chairman Ajai Pai has outlined In a series of letters, Chairman Ajai Pai has outlined
the FCC’s the FCC’s ~~decision making~~decisionmaking process, the data the commission used to make its determination, and process, the data the commission used to make its determination, and
the FCC’s technical analysis of potential interference.the FCC’s technical analysis of potential interference.~~173~~
~~Potential Independent Review of Test Results~~
~~Due to the ongoing disagreement about the impact of Ligado’s proposed network on GPS, some~~
~~analysts have suggested that relevant tests should be independently reviewed by a “neutral~~
~~arbiter,” such as the National Academy of Sciences. According to a Pentagon spokesman, DOD~~175

~~169~~171 Letter from Hon. Mark Esper, Secretary of Defense, to Hon. Ajit Pai, Chairman of the Federal Communications 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/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. ntia_letter_to_fcc_chairman_re_ligado_mss_atc_applications_dec._6_2019.pdf#page=6.
~~170~~172 Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20- Federal Communications Communication Order 20-48, at https://docs.fcc.gov/public/attachments/FCC-20-
48A1.pdf. 48A1.pdf.
~~171~~173 Statement of Commissioner Brendan Carr, Re: LightSquared Technical Working Group Report, IB Docket No. 11- Statement of Commissioner Brendan Carr, Re: LightSquared Technical Working Group Report, IB Docket No. 11-
109; LightSquared License Modification Application, IBFS Files Nos. SAT-MOD-20120928-00160-00161, SES-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. 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-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-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/MOD-20151231-00090, SAT-MOD-20151231-00091, IB Docket No. 11- 109, at https://docs.fcc.gov/public/
attachments/FCC-20-48A2.pdf. attachments/FCC-20-48A2.pdf.
~~172~~174 Joint Statement of Commissioners Jessica Rosenworcel and Geoffrey Starks Concurring Re: LightSquared Joint Statement of Commissioners Jessica Rosenworcel and Geoffrey Starks Concurring Re: LightSquared
Technical Working Group Report, IB Docket No. 11-109; LightSquared License Modification Application, IBFS Files Technical 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 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-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, 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 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. No. 11- 109, at https://docs.fcc.gov/public/attachments/FCC-20-48A3.pdf.
~~173~~175 For list of congressional correspondence For list of congressional correspondence, see https://www.fcc.gov/chairman-pais-letters-congress. see https://www.fcc.gov/chairman-pais-letters-congress.
Congressional Research Service Congressional Research Service

3435 Overview of Department of Defense Use of the Electromagnetic Spectrum Legislative Activity The FY2021 National Defense Authorization Act (P.L. 116-283) contains five

~~would “support an impartial third party, one with demonstrated expertise in GPS testing,~~
~~conducting a thorough examination of all data collected during the preceding decade of testing.”~~
~~Such a review, which would delay execution of the FCC decision, would likely need the approval~~
~~of the congressional commerce committees.~~
~~Legislative Activity~~
~~Both the House and the Senate have proposed~~ Ligado- or GPS Ligado- or GPS interference-related provisions: 1. Section 1611 requires~~interference-related legislation in~~
~~their respective versions of the FY2021 National Defense Authorization Act. First, Section 1601~~
~~of the Senate version would require~~ DOD to develop a plan for a resilient and survivable DOD to develop a plan for a resilient and survivable
positioning, navigation, and timing capabilitypositioning, navigation, and timing capability~~. 174~~ within two years.176 This provision would allow DOD to reprogram This provision would allow DOD to reprogram
resources as needed to develop resources as needed to develop ~~this plan. Section 234 would require an independent assessment~~
~~from the National Academy of Sciences to evaluate the potential impacts of the proposed Ligado~~
~~Network on GPS.175 In addition, section 1083 would prevent the DOD from entering into a~~
~~contract with a corporation that would potentially interfere with GPS signals, and would require a~~
~~cost estimate to “the extent of covered costs and the range of eligible reimbursable costs~~
~~associated with interference resulting from such order and authorization to the Global Positioning~~
~~System.”176~~
~~Section 1609 of the House version of the bill has similar language to the Senate’s, prohibiting~~
~~funds to comply with the FCC order on Ligado; however, the House would not direct an~~
~~independent assessment of the Ligado proposal. 177 Section 1608 of the House bill additionally~~
~~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.” 178~~

~~Author Information~~

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

~~Security~~

~~Jill C. Gallagher~~

~~Analyst in Telecommunications Policy~~

~~174 S. 4049 §1601.~~
~~175 S. 4049 §234.~~
~~176 S. 4049 §1038.~~
~~177 H.R. 6395 §1609.~~
~~178 H.R. 6395 §1608.~~
~~Congressional Research Service~~

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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).177 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.”178 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.179 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.180 176 P.L. 116-283 §1611 Resilient and Survivable Positioning, Navigation, and Timing Capabilities. 177 P.L. 116-283 §1661 Prohibition on Availability of Funds for Certain Purposes Relating to the Global Positioning System. 178 P.L. 116-283 §1662 Limitation on Awarding Contracts to Entities Operating Commercial Terrestrial Communication Networks that Cause Harmful Interference with the Global Positioning System. 179 P.L. 116-283 §1663 Independent Technical Review of Federal Communications Commission Order 20-48. 180 P.L. 116-283 §1664 Estimate of Damages from Federal Communications Commission Order 20-48. Congressional Research Service 36 Overview of Department of Defense Use of the Electromagnetic Spectrum Author Information John R. Hoehn Kelley M. Sayler Analyst in Military Capabilities and Programs Analyst in Advanced Technology and Global Security Jill C. Gallagher Analyst in Telecommunications Policy

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