Overview of Department of Defense Use of the Electromagnetic Spectrum Updated October 8 2020 Congressional Research Service https crsreports congress gov R46564 SUMMARY Overview of Department of Defense Use of the Electromagnetic Spectrum Communication using the electromagnetic spectrum “the spectrum” enables a number of modern military capabilities The Department of Defense DOD uses electromagnetic radiation to enable military communications navigation radar nonintrusive inspection of aircraft and other equipment DOD also heavily relies on electromagnetic radiation for intelligence surveillance and reconnaissance ISR applications such as missile early warning and signals intelligence Individual branches of the military e g the Air Force Army Marine Corps Navy and Space Force currently are allotted significant ranges of frequency bands to enable various equipment and applications that support military operations R46564 October 8 2020 John R Hoehn Analyst in Military Capabilities and Programs Jill C Gallagher Analyst in Telecommunications Policy Kelley M Sayler Analyst in Advanced Technology and Global Security Potential adversaries like China and Russia have observed how the United States wages war through conflicts ranging from Desert Storm to Allied Force Iraqi Freedom and Enduring Freedom over the past 30 years These potential adversaries have identified the DOD’s use of the spectrum as a critical enabler and as a result have developed weapon systems particularly electronic warfare EW platforms designed to challenge the DOD’s ability to effectively use the 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 Several new and emerging technologies and methods to employ existing technologies called concepts are being developed to counter these challenges These new technologies include directed energy artificial intelligence and counter-unmanned aircraft systems Concepts like Joint All Domain Command and Control JADC2 and Mosaic Warfare look to change the nature of how the DOD communicates and uses the spectrum The U S government manages access to and use of spectrum As the nation continues to experience significant growth in commercial wireless services e g mobile phones mobile applications video streaming Wi-Fi demand for spectrum has increased Congress has enacted policies to make additional spectrum available for commercial use in some cases reallocating spectrum from federal agency use to commercial use As Congress considers policies that reallocate spectrum from DOD to commercial use it may consider the following issues  Interoperability i e the ability of one radio or computer system to talk to another Each of the military services has developed robust networks of their own however many are often unable to communicate with one another  DOD’s ability to keep pace with technological advances by potential adversaries Adversaries such as Russia China Iran and North Korea have developed systems to challenge the U S military’s ability to access the spectrum and to reduce the effectiveness of future technologies  The private sector’s increasing interest in using frequencies traditionally reserved for the military The advent of fifth generation communications technologies 5G has increased the demand for multiple different frequency bands which has the potential to disrupt military operations For example in 2020 the Federal Communications Commission FCC authorized the Ligado 5G network which could affect the global positioning system’s radio signals Spectrum sharing Emerging technologies and policies are demonstrating that DOD and commercial systems are able to use the same frequencies without degrading DOD’s capabilities The process for identifying such potential spectrum-sharing frequencies and the ability to develop technologies quickly may also be of interest to Congress  Congressional Research Service  The interagency process for spectrum allocation Questions about the interagency process emerged after the FCC authorized Ligado’s 5G network to operate despite the fact that DOD and several other federal agencies disagreed with that decision  Anticipating future spectrum needs for both commercial and military users Much attention has focused on 5G technologies However new technologies—like a future sixth generation 6G of communications technologies—will increase demand for additional spectrum Moreover new military technologies may change how DOD uses the spectrum and may require a different spectrum allocation Congressional Research Service Overview of Department of Defense Use of the Electromagnetic Spectrum Contents What Is the Electromagnetic Spectrum 1 Federal Spectrum Allocation 3 Current Military Applications of the Spectrum 4 Communications 6 Terrestrial Radios 6 Satellite Communications 7 Situational Awareness 8 Radar and LIDAR 8 Passive Radar 8 Signals Intelligence 9 Infrared Sensors 9 Electronic Warfare 10 Spectrum Operations 11 Command and Control 11 Signature Management 11 Navigation Warfare 12 Command and Control C2 13 Emerging Military Applications of the Spectrum 13 Fifth Generation 5G Communications 13 Use and Applications of Artificial Intelligence AI 15 Directed-Energy DE Technologies 15 Laser Communications 15 Directed-Energy Weapons 16 Counter-Unmanned Aircraft Systems C-UAS 18 Emerging Concepts 19 Potential Spectrum Issues for Congress 20 Technical Challenges 20 Communications System Interoperability 20 Adversary Spectrum Interference Developments 21 Spectrum Sharing 23 DOD Spectrum Organizational Issues 25 Commercial Demand for Federal Spectrum 26 Increasing Demand for Spectrum 26 Unintended Commercial Frequency Interference 28 Interagency Disputes 30 Anticipating Future Spectrum Needs 31 Potential Questions for Congress 31 Figures Figure 1 The Electromagnetic Spectrum 2 Figure 2 U S Department of Defense DOD Use of Radio Spectrum 5 Figure 3 Spectrum Used for DOD Laser Technologies 6 Figure 4 AN TRC-170 Tropospheric Scatter Microwave Radio Terminal 7 Congressional Research Service Overview of Department of Defense Use of the Electromagnetic Spectrum Figure 5 The Space-Based Infrared Surveillance SBIRS Constellation 10 Figure 6 The Global Positioning System GPS Constellation 12 Figure 7 U S Marine Corps Free Space Optics Communications System 16 Figure 8 Visualization of JADC2 Vision 19 Appendixes Appendix Ligado Networks 33 Contacts Author Information 36 Congressional Research Service Overview of Department of Defense Use of the Electromagnetic Spectrum he Department of Defense DOD is the largest federal user of the electromagnetic spectrum “the spectrum” It holds frequencies across multiple bands to support a number 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 domestically and with allies abroad Further DOD has invested significantly in spectrumdependent technologies A summary of some of these technologies including wireless communications satellites radar technologies that support situational awareness signal intelligence and electronic warfare technologies is provided below Changes in spectrum may affect how DOD can use manipulate or develop these technologies T The Department of Defense DOD partly through congressional action has begun to reprioritize its management and use of the spectrum Since 2018 the DOD has created new organizational structures and is in the process of developing new strategies and policies recognizing the importance the spectrum plays in military operations A recent Joint Electromagnetic Spectrum Operations publication states t he electromagnetic spectrum EMS is a maneuver space essential for facilitating control within the operational environment OE and impacts all portions of the OE and military operations Just as in the physical domains and in cyberspace military forces maneuver and conduct operations within the EMS to achieve tactical operational and strategic advantage Freedom of maneuver and action within the EMS are essential to US and multinational operations 1 What Is the Electromagnetic Spectrum 2 The electromagnetic spectrum is the range of wavelengths or frequencies of electromagnetic radiation It includes radio waves microwaves visible light X-rays and gamma rays see Figure 1 Electromagnetic radiation is 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 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 have both electric and magnetic properties Such waves vary in frequency 3 wavelength 4 and energy Scientists classify electromagnetic waves by their wavelength or frequency Waves with shorter wavelengths e g gamma rays have higher frequencies and higher energy waves with longer wavelengths e g radio waves have lower frequencies and lower energy 1 Department of Defense Joint Electromagnetic Spectrum Operations JP 3-85 Washington DC March 22 2020 p v https www jcs mil Portals 36 Documents Doctrine pubs jp3_85 pdf ver 2020-04-09-140128-347 2 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 3 Frequency is the property of a wave that describes how many wave patterns or cycles pass by in a period of time Frequency is measured in Hertz Hz A wave with a frequency of 1 Hz means that one wave peak-to-peak passes by each second 4 Wavelength is the distance between adjacent peaks in a series of periodic waves Congressional Research Service 1 Overview of Department of Defense Use of the Electromagnetic Spectrum Figure 1 The Electromagnetic Spectrum Source National Aeronautics and Space Administration “The Electromagnetic Spectrum ” 2020 https imagine gsfc nasa gov science toolbox emspectrum1 html Scientists and engineers have discovered many practical uses for electromagnetic radiation For example mobile phones convert human voice and digital information into signals that can be transmitted by low frequency low energy radio waves to enable wireless communications Medical professionals use machines to focus high frequency high energy gamma rays to kill cancerous cells Thus common technologies use electromagnetic radiation to enable a wide variety of uses In applications across civil commercial and government sectors the characteristics of the waves used often drive the use Below are examples of electromagnetic radiation uses and applications    Radio frequency waves can be used to transmit messages between electronic devices Radio waves have varying wavelengths and characteristics that affect how much how far and in what conditions data can be transmitted between a sender and a receiver Some very low frequency radio waves can travel long distances and can penetrate seawater but cannot support high data rates These waves are useful for communications with submarines Other radio waves can travel a long distance and pass through solid objects like buildings and trees making them useful for mobile communications Still other radio waves can travel short distances and cannot penetrate dense objects but offer greater bandwidth and speed These radio waves may be useful for high-data applications such as downloading or streaming videos within a home or office Microwaves have higher throughput—data upload and download rates—than radio waves and therefore are able to transmit more data However microwaves are more limited in range and can be disrupted by solid objects Hence microwaves are often used for point-to-point transmissions Microwaves are also used in radars—systems that send out pulses of high frequency waves that reflect off an object and back to the source This technology capitalizes on the fact that the waves cannot penetrate solid objects and uses this characteristic to gauge time and distance to an object Microwaves are also used in satellite communications which experience few obstacles in their transmission path Infrared radiation IR is used in household items such as remote controls Remote controls shoot pulses of IR energy to a receiver in a TV for example The receiver converts the light signals to electrical signals instructing Congressional Research Service 2 Overview of Department of Defense Use of the Electromagnetic Spectrum   microprocessors to carry out commands 5 Similarly infrared lasers can be used for point-to-point communications over short distances to provide high-speed reliable connections Infrared signals can travel only short distances and can be blocked by obstacles X-rays can penetrate optically opaque materials and are routinely used in aircraft maintenance to identify cracks in airframes X-rays are high-energy highfrequency ionizing radiation they have enough energy to remove an electron from ionize an atom or molecule which could lead to mutations in a human cell’s DNA and could lead to cancer 6 Certain technologies can detect gamma rays—high-energy radiation—to help identify potential nuclear events Similar to X-rays gamma rays present biological risks Federal Spectrum Allocation In the United States the National Telecommunications and Information Administration NTIA and the Federal Communications Commission FCC jointly manage use of the radio spectrum 3 Hz to 300 GHz to balance U S government interests private interests and the public good 7 NTIA manages radio spectrum use by federal agencies 8 while the FCC manages nonfederal use—that is radio spectrum use of the private sector including broadcasting mobile communication use commercial industrial personal uses and state and local government uses 9 Both agencies coordinate on frequency allocation and assignment and in setting technical requirements to avoid interference 10 The allocation of radio spectrum involves designating certain frequency segments for specific uses such as mobile communications satellite and TV broadcasting The assignment of radio 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 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 Jim Lucas “What is Infrared ” Live Science February 27 2019 https www livescience com 50260-infraredradiation html 6 American Cancer Society What are x-rays and gamma rays accessed February 26 2019 https www cancer org cancer cancer-causes radiation-exposure x-rays-gamma-rays what-are-xrays-and-gamma-rays html 7 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 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 https www ntia doc gov legacy osmhome EPS openness sp_rqmnts sharing7 html 8 P L 102-538 9 47 U S C §303 10 Spectrum decisions are also driven by international decisions to coordinate spectrum use and facilitate global communications 11 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 not interfere with other unlicensed uses or nearby licensed uses 12 NTIA Federal Government Spectrum Compendium Washington DC August 21 2017 https www ntia doc gov other-publication 2017 federal-government-spectrum-compendium 5 Congressional Research Service 3 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 biannually to conduct joint spectrum planning The NTIA uses the Interdepartment Radio Advisory Committee IRAC as an interagency radio spectrum coordination body which consists of technical representatives from many agencies 15 The IRAC advises the NTIA on federal radio spectrum needs so that it can represent the interests of federal agencies in discussions with the FCC The FCC engages with the NTIA on spectrum discussions when changes in allocation or use may affect federal agency activities After 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 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 and radios—depends on the spectrum to function The military uses applications across the electromagnetic spectrum to support communications situational awareness military operations and emerging technologies These applications range from using very low-frequency radio waves to communicate with submarines underwater to microwaves for datalinks to connect weapons systems e g aircraft satellites ground forces ships Figure 2 shows various applications in the radio segment of the electromagnetic spectrum 18 “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 the FCC and Nancy J Victory Assistant Secretary for Communications and Information U S Department of Commerce available at https www ntia doc gov files ntia publications fccntiamou_01312003 pdf 14 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 conduct joint spectrum planning 15 NTIA “Interdepartment Radio Advisory Committee IRAC ” accessed February 26 2020 https www ntia doc gov page interdepartment-radio-advisory-committee-irac 16 Combined Communications-Electronics Board CCEB Guide to Spectrum Management in Military Operations APC 190 C September 2007 http www acqnotes com Attachments ACP%20190 C %20Guide%20to%20Spectrum%20Managing%20in%20Military%20Operations pdf and Thomas P Kidd III “Military Spectrum Management ” Presentation November 2019 http ustti org wp-content uploads 2019 11 Day-4-1_Military-Spectrum-Management_20180-0907 pdf 17 This section was written by John R Hoehn For more information on DOD spectrum operations see CRS In Focus IF11155 Defense Primer Military Use of the Electromagnetic Spectrum by John R Hoehn 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 13 Congressional Research Service 4 Overview of Department of Defense Use of the Electromagnetic Spectrum Figure 2 U S Department of Defense DOD Use of Radio Spectrum Examples of DOD Systems Operating in the Radio Spectrum 3 kHz – 300 GHz Source U S Government Accountability Office Spectrum Management Federal Relocation Costs and Auction Revenues 13-472 May 2013 p 6 https www gao gov assets 660 654794 pdf Notes 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 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 collection see Figure 3 Infrared and ultraviolet lasers have greater bandwidth than radio frequencies enabling the dissemination of large volumes of data e g video across long distances due to signal strength The military can also use lasers offensively to dazzle satellite sensors destroy drones and for other purposes 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 19 Congressional Research Service 5 Overview of Department of Defense Use of the Electromagnetic Spectrum Figure 3 Spectrum Used for DOD Laser Technologies Infrared and Ultraviolet Radiation Used for Laser Technologies Source Marczak Jan Andrzej Koss Targowski Piotr Michalina Góra Strzelec Marek Antoni Sarzyński Wojciech Skrzeczanowski Ostrowski Roman Rycyk Antoni 2008 Characterization of Laser Cleaning of Artworks Sensors 8 10 3390 s8106507 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 spectrum applications Communications Military commanders have become accustomed to communicating with their forces nearly instantaneously Commanders may use wired communications e g landline phones computers or wireless technologies e g radio systems —technologies that use radio frequencies spectrum to transmit messages over-the-air between devices Wireless communications are often used when there is no physical connection between the sender and receiver The radio frequencies use range from low-bandwidth options such as transferring small strings of text to highly data-intensive 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 general communications systems use radio and microwave frequencies however some emerging communications technologies use lasers—transmitting light instead of radio waves between receivers 20 Radios use different frequencies depending on the required range and amount of data they are required to transmit Ground-based radios are typically used at short ranges limited by line of sight that span no more than 50 miles In general militaries use satellites to communicate over longer distances Terrestrial Radios For more than a century the U S military has used ground-based terrestrial radios to communicate In their infancy during World War I and World War II these radios were used to transmit voice communications to coordinate forces Radio systems have since evolved to use new frequency bands to transmit larger amounts of data Systems like the Joint Tactical Radio Stephen Carlson “Marines conduct field test of laser-based communications system ” UPI August 27 2018 https www upi com Defense-News 2018 08 27 Marines-conduct-field-test-of-laser-based-communications-system 3511535389333 20 Congressional Research Service 6 Overview of Department of Defense Use of the Electromagnetic Spectrum 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-ofsight range due to the curvature of the earth Some like the PRC-117 Multiband Manpack Radio use multiple frequency bands to transmit data—this radio system uses frequencies from 30 MHz – 2000 MHz 21 For several decades the military has mostly used satellites to provide beyond-line-of-sight BLOS radio transmissions—signals traveling over the horizon typically defined as extending no more than 50 miles However a few terrestrial-based systems can provide BLOS capabilities An example is the AN TRC-170 Tropospheric Scatter Microwave Radio Terminal see Figure 4 22 This radio uses microwaves to bounce signals off the troposphere providing a BLOS capability for communications with ground forces at ranges of up to 100 nautical miles approximately 115 standard miles depending on weather conditions Figure 4 AN TRC-170 Tropospheric Scatter Microwave Radio Terminal Source https www marines mil News News-Display Article 1169154 the-antrc-170-continues-to-stayreliablefor-the-corps Notes Photo by Lance Cpl Cody Lemons Satellite Communications 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 Satellite communications generally use multiple frequency bands to transmit data more quickly 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 satellite in orbit 24 Most communications satellites operate in geosynchronous orbit GEO which L3Harris “L3Harris Falcon III® AN PRC-117G V 1 C Multiband Networking Manpack Radio ” press release 2020 https www harris com solution harris-falcon-iii-an-prc-117gv1c-multiband-networking-manpack-radio 22 U S Marine Corps “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 23 These radio signals are designed to operate during a nuclear event when most other electronic transmissions are disrupted 24 While there is a time delay when “drone” operators in the United States fly large unmanned aircraft in other parts of the world this is augmented by automation and local ground control stations for critical phases of flight i e takeoff landing and taxiing to reduce the effect of lag Nuclear command and control uses multiple methods of 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 21 Congressional Research Service 7 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 The U S military operates several global satellite communication constellations including    Advanced Extremely High Frequency AEHF 25 Wideband Global Satellite Communications WGS 26 and Mobile User Objective System MUOS 27 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 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 include Inmarsat Viasat Iridium and Intelsat 28 Situational Awareness Another defense application of the electromagnetic spectrum is the use of radio waves microwaves and infrared radiation to develop a picture of the battle space by determining the location of friendly and enemy forces This is done through various technologies as described below Radar and LIDAR The most common situational awareness application is radar however recently light detection and ranging LIDAR systems are also used Both technologies send out an electromagnetic signal and sense the portion that is reflected back to determine an object’s distance speed and sometimes altitude Radars operate on different radio and microwave frequencies depending on their purpose Lower-band frequency radars provide a longer range picture of the battle space but because of clutter undesired signals returned to the radar they are not able to provide targetquality 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 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 LIDAR technologies are still being developed Passive Radar Another technology that the U S and its competitors are developing is passive radar Passive radars do not emit radio signals instead they listen to radio signals emitted from the target Some 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-highfrequency-system 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 27 For more information see Space and Naval Warfare Systems Command “Mobile User Objective System MUOS ” fact sheet December 2011 https www secnav navy mil rda Documents muos_overview_for_asn_rda_12-27-11-s pdf 28 Sandra Erwin “Satcom Conumdrum Air Force Contemplating Right Mix of Commercial Military Satellites ” SpaceNews May 6 2019 https spacenews com satcom-conumdrum-air-force-contemplating-right-mix-ofcommercial-military-satellites 25 Congressional Research Service 8 Overview of Department of Defense Use of the Electromagnetic Spectrum analysts argue that passive radars have the potential to detect low-observable aircraft such as the B-2 bomber and the F-35 fighter jet that are optimized for low radar cross section—the amount of measurable radar signal reflected back to its source—at certain frequencies and flight profiles 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 that while passive radars may aid in the detection of stealth systems they do not necessarily provide the information needed to target and engage the systems and are therefore most useful as cues for other sensors 30 Advances in microelectronics allow passive radar technology to detect 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 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 efforts to further develop these technologies 32 The DOD has funded research for this technology through the Defense Advanced Research Projects Agency DARPA 33 Signals Intelligence Signals 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 frequencies and observe heat signatures of personnel missiles aircraft artillery and vehicles One subset of SIGINT is collecting communications signals to analyze how militaries communicate—such as what time radios transmit from what location and specific radio frequencies—as well as the data transmitted A second subset of SIGINT is electronic intelligence This intelligence discipline analyzes frequencies patterns operating procedures— among other information—of any other system that utilizes the spectrum This includes radars 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 relative to their surrounding environment the easier they are to detect using infrared sensors The U S military has long used infrared signatures to track enemy aircraft and ground vehicles and to guide missiles onto targets The AIM-9X air-to-air and AGM-114 Hellfire air-to-ground missiles Dimitrios Oikonomou Panagiotis Nomikos and George Limnaios et al “Passive Radars and their use on the Modern Battlefield ” Journal of Computations Modelling vol 9 no 2 2019 pp 37-61 30 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 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 Anytime Soon ” The Drive September 30 2019 https www thedrive com the-war-zone 30100 no-passive-radar-isntstealth-ending-magic-people 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 ” C4ISRNet September 29 2019 https www c4isrnet com intel-geoint sensors 2019 09 30 stealthy-no-more-a-german-radar-vendor-says-it-tracked-the-f-35-jet-in-2018-from-a-pony-farm 32 Gökhan Soysal and E F E Murat “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 download article-file 778904 33 J R Wilson “New frontiers in passive radar and sonar ” Military Aerospace Electronics February 8 2016 https www militaryaerospace com communications article 16709052 new-frontiers-in-passive-radar-and-sonar For more information on DARPA see CRS Report R45088 Defense Advanced Research Projects Agency Overview and Issues for Congress by Marcy E Gallo 29 Congressional Research Service 9 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 crosssections to make radar detection more difficult The Navy is currently funding development of an IRST pod for the F-18E F Super Hornet and the Air Force has been procuring IRST capabilities for the F-15C Eagle 35 Several space systems use infrared technologies to detect missile launches The Space-Based Infrared Surveillance SBIRS constellation uses six satellites in geosynchronous orbit as well as additional satellites in highly elliptical orbits see Figure 5 to 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 missile detection constellation in low-earth orbit that would use infrared technologies similar to SBIRS 37 Figure 5 The Space-Based Infrared Surveillance SBIRS Constellation Source https spacenews com air-force-tests-ground-station-for-full-missile-warning-constellation Electronic Warfare 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 located as well as what frequencies they use for communications and radars This intelligence 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 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 FY2021 Aircraft Procurement Line Item F01500 F-15 at https apps dtic mil procurement Y2021 AirForce stamped U_P40_F01500_BSA-2_BA-5_APP-3010F_PB_2021 pdf 36 Lockheed Martin “Space Based Infrared Surveillance SBIRS ” press release 2020 at https www lockheedmartin com en-us products sbirs html 37 Sandra Erwin “Space Development Agency to Deploy Hypersonic Missile Defense Satellites by 2022 ” Space News June 7 2020 at https spacenews com space-development-agency-to-deploy-hypersonic-missile-defense-satellites-by2022 38 See CRS In Focus IF11118 Defense Primer Electronic Warfare by John R Hoehn 34 Congressional Research Service 10 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 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 EW has its respective advantages and disadvantages multiple capabilities may be required to provide a desired effect Terrestrial EW sensors and jammers—which can be located on land or on ships at sea—are limited by the amount of power available these capabilities are also limited due to variance in the terrain in which they operate Ground EW capabilities are used to intercept and to jam radios and artillery radars Recent uses include jamming improvised explosive devices in Iraq and Afghanistan 39 Airborne EW is used to intercept decrypt and disrupt communications radars and other C2 systems over a large area Examples of airborne EW aircraft include the E-2 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 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 develop a common operating picture location of friendly and enemy forces and communicate the commander’s orders Command and control is resourced according to a unit’s size and mission focus from a few radios and computers for platoon- and company-level operations to specialized 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 radars to develop a comprehensive picture of the battlespace to direct ground forces to their most effective positions for countering enemy forces 42 Signature Management Low observable weapons systems manipulate the spectrum to reduce their electromagnetic signature such as radar returns 43 radio emissions and even heat This signature management can take many forms for example reducing a radar signature through physical or other means creating narrow radio beams to reduce the probability of detection or intercept and reducing 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 Ground Electronic Warfare Background and Issues for Congress by John R Hoehn 40 For more information about these aircraft systems see CRS Report R44572 U S Airborne Electronic Attack Programs Background and Issues for Congress by John R Hoehn 41 This section was written by John R Hoehn 42 U S Air Force E-8C Joint STARS Washington DC September 23 2015 https www af mil About-Us Fact-Sheets Display Article 104507 e-8c-joint-stars 43 Radar works by emitting a radio signal and then listening for the signal to return Low observable technologies use different materials known as radar absorbing material and different shapes typically reducing the number of 90° or right angles to reduce or prevent the radio signals from returning to their original source Congressional Research Service 11 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 signature in the microwave and infrared parts of the spectrum Communications systems are also focused on reducing their signature Using beam-forming reduced power and other techniques these systems are designed to be low probability of intercept low probability of detection LPI LPD The intent is to make it more difficult for potential adversaries to use their SIGINT capabilities to find U S forces and potentially target them with long-range munitions Navigation Warfare 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 information through coordinated employment of space cyberspace and electronic warfare EW capabilities NAVWAR is further enabled by supporting activities such as ISR and EMS management ”45 The Global Positioning System GPS performs navigation warfare for the U S military by providing precision navigation and timing see Figure 6 Competing PNT systems have been developed by other nations including Russia GLONASS China Beidou and the European Union Galileo 46 Figure 6 The Global Positioning System GPS Constellation Source https www gps gov multimedia images constellation jpg 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 F-35 Joint Strike Fighter JSF Program by Jeremiah Gertler For more information on the Zumwalt-class destroyer see CRS Report RL32109 Navy DDG-51 and DDG1000 Destroyer Programs Background and Issues for Congress by Ronald O'Rourke 45 Department of Defense Space Operations JP 3-14 Washington DC April 10 2018 pp II-3 https www jcs mil 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 https www gps gov systems gnss Congressional Research Service 12 Overview of Department of Defense Use of the Electromagnetic Spectrum Command and Control C2 C2 systems are the communications people and procedures that enable commanders to direct forces DOD states that communications systems are critical in providing timely information to enable decisionmaking 47 According to DOD these communications need to be interoperable interoperability between communications systems revolves around the protocols such as frequency hopping and encryption as well as the frequencies uses to facilitate information sharing agile to adjust to the operating environment and trusted to ensure the information in the system is accurate An important aspect of C2 systems is the ability to network and share information in a timely fashion to enable commanders and their staff to make decisions Thus C2 systems collect information from intelligence systems and build a picture of the operating environment for the commander and their staff to make effective decisions some analysts combine C2 with computers communications intelligence surveillance and reconnaissance systems C4ISR to talk about the entire system enabling decisionmaking To create these networks DOD utilizes computers to manage and process data and communications equipment so that commanders can act upon the data transmitted to them Emerging Military Applications of the Spectrum48 The following section discusses emerging technologies and concepts that could affect the military’s use of the spectrum Fifth Generation 5G Communications49 The fifth generation 5G of mobile technologies will increase the speed of data transfer and 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 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 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 services to high-density areas but is limited in range and more vulnerable to disruption Mid-band spectrum offers improved capacity and coverage faster service and new features like edge computing compared with existing 4G technologies Low-band spectrum offers the widespread coverage needed for many internet-of-things applications 5G technologies could have a number of potential military applications particularly for autonomous vehicles C2 logistics maintenance augmented and virtual reality and intelligence surveillance and reconnaissance ISR systems—all of which would benefit from improved data 47 Department of Defense Joint Communications System JP 6-0 Washington DC June 10 2015 Incorporating Change 1 October 4 2019 p vii https www jcs mil Portals 36 Documents Doctrine pubs jp6_0ch1 pdf ver 201910-15-172254-827 48 This section was written by John R Hoehn and Kelley M Sayler 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 FifthGeneration 5G Telecommunications Technologies Issues for Congress by Jill C Gallagher and Michael E DeVine 50 For more information on 5G spectrum allocation see CRS Report R45485 Fifth-Generation 5G Telecommunications Technologies Issues for Congress by Jill C Gallagher and Michael E DeVine Congressional Research Service 13 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 storing large databases e g maps in the cloud 5G technologies could also be incorporated into ISR systems which increasingly demand high-bandwidths to process exploit and disseminate information from a growing number of battlespace sensors Similarly 5G could reduce latency in other data-intensive activities such as logistics and maintenance and could additionally enable 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 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 as test beds for various applications and aspects of the technology      Marine Corps Logistics Base Albany GA smart warehouses Naval Base San Diego CA for smart warehouses Hill Air Force Base UT spectrum sharing between 5G and airborne radar Joint Base Lewis-McChord WA augmented and virtual reality Nellis Air Force Base NV survivable command and control and network enhancement    Naval Base Norfolk VA ship-wide and pier connectivity Joint Base Pearl Harbor-Hickam HI enhancing aircraft mission readiness Joint Base San Antonio TX augmented reality support of maintenance and training and evaluating DOD’s 5G core security experimentation network Tinker Air Force Base OK spectrum sharing between military communications and 5G Camp Pendleton CA connectivity for forward operating bases and tactical operations centers Ft Hood TX connectivity for forward operating bases and tactical operations centers and Ft Irwin National Training Center CA for connectivity for forward operating bases and tactical operations centers 54     On September 18 2020 DOD released a Request for Information seeking input on best methods for sharing spectrum between military and civilian users input on DOD ownership and operation of 5G networks for domestic operations and other issues related to the allocation and shared use 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 causing delays in the execution of military operations 52 Justin Doubleday “DOD Releases Second Tranche of Draft 5G Proposal Requests ” Inside Defense December 9 2019 https insidedefense com insider dod-releases-second-tranche-draft-5g-proposal-requests 53 Defense Innovation Board The 5G Ecosystem Risks and Opportunities for DOD April 2019 https media defense gov 2019 Apr 03 2002109302 -1 -1 0 DIB_5G_STUDY_04 03 19 PDF 54 Justin Doubleday “DOD Releases Second Tranche of Draft 5G Proposal Requests ” Inside Defense December 9 2019 https insidedefense com insider dod-releases-second-tranche-draft-5g-proposal-requests and Department of Defense “DOD Names Seven Installations as Sites for Second Round of 5G Technology Testing Experimentation ” press release June 3 2020 https www defense gov Newsroom Releases Release Article 2206761 dod-names-seveninstallations-as-sites-for-second-round-of-5g-technology-testin Congressional Research Service 14 Overview of Department of Defense Use of the Electromagnetic Spectrum of DOD spectrum 55 The intent DOD says is to “ensure the greatest effective and efficient use of the Department of Defense’s spectrum for training readiness and lethality ”56 DOD requested $1 5 billion for microelectronics 5G in FY2021 but it did not provide a further breakdown in funding between microelectronics and 5G 57 Use and Applications of Artificial Intelligence AI 58 DOD is researching cognitive electronic warfare systems that use artificial intelligence to identify novel electronic emissions determine whether the emission originates from a hostile source and develop an effective jamming signal According to former DOD electronic warfare official 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 researching options for using advances in computing power to improve electronic deception or “spoofing ” capabilities For example Digital Radio Frequency Memory could be used to generate false radar returns that complicate adversary targeting 60 Similarly DOD is exploring AI-enabled dynamic spectrum sharing Because spectrum is currently allocated in set segments allocation cannot be responsive to changes in the volume of traffic across segments i e some segments may be overwhelmed while others are underutilized leading to inefficiencies DARPA has sponsored the Spectrum Collaboration Challenge SC2 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 competing in SC2—the final competition was held in October 2019—leveraged AI and machine learning algorithms to develop options for dynamic spectrum sharing in which radios autonomously coordinate to optimize spectrum use Directed-Energy DE Technologies A number of directed energy technologies including laser communications and directed-energy weapons make use of the electromagnetic spectrum 62 Laser Communications 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 55 DOD Request for Information Defense Spectrum Sharing Request for Information Published September 18 2020 https beta sam gov opp 4851a65e2b2d4d73865a0e9865b0c28a view keywords spectrum sort -modifiedDate index is_active true page 1 56 Ibid 57 DOD FY2021 Defense Budget Overview Irreversible Implementation of the National Defense Strategy Washington DC May 13 2020 pp 1-8 https comptroller defense gov Portals 45 Documents defbudget fy2021 fy2021_Budget_Request_Overview_Book pdf 58 For a general discussion of military applications of artificial intelligence see CRS Report R45178 Artificial Intelligence and National Security by Kelley M Sayler 59 “EW Cyber Require Next-Gen Hardware Conley ” Breaking Defense September 27 2019 https breakingdefense com 2019 09 ew-cyber-require-next-gen-hardware-conley 60 Ibid 61 DARPA “Spectrum Collaboration Challenge SC2 ” https www darpa mil program spectrum-collaborationchallenge 62 Other directed energy technologies include laser range finders target designators and remote sensors Congressional Research Service 15 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 unclear how many FSO systems the Marine Corps procured see Figure 7 Figure 7 U S Marine Corps Free Space Optics Communications System Source https www upi com Defense-News 2018 08 27 Marines-conduct-field-test-of-laser-basedcommunications-system 3511535389333 Notes The picture caption reads “U S Marines test the Free Space Optics laser communications system earlier this month at Camp Hansen in Okinawa Japan Photo by Sgt Timothy Valero U S Marine Corps ” Directed-Energy Weapons64 DOD defines directed-energy DE weapons as those using concentrated electromagnetic energy rather than kinetic energy to “incapacitate damage disable or destroy enemy equipment facilities and or personnel ”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 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 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 boostDepartment 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-wirelesscommunications 64 This section is derived from CRS Report R46458 Emerging Military Technologies Background and Issues for Congress by Kelley M Sayler 65 Joint Chiefs of Staff Electronic Warfare Joint Publication 3-13 1 February 8 2012 pp 1-16 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 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 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 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 ” National Defense July 1 2015 at 63 Congressional Research Service 16 Overview of Department of Defense Use of the Electromagnetic Spectrum phase missile intercept given their speed-of-light travel time however as in the case of hypersonic missile defense experts disagree on the affordability technological feasibility and utility of this application 69 High-powered microwave weapons a subset of DE weapons could be used as a nonkinetic means of disabling electronics communications systems and improvised explosive devices or as a nonlethal “heat ray” system for crowd control Although the United States has been researching directed energy since the 1960s some experts have observed that “actual directed-energy programs … have frequently fallen short of 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 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 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 The U S Navy fielded the first operational U S DE weapon 73 the Laser Weapon System LaWS in 2014 aboard the USS Ponce LaWS was a 30-kilowatt -kW laser prototype that “was capable of blinding enemy forces as a warning shooting down drones disabling boats or damaging helicopters ”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 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 counterUAS DE systems including both laser and high-powered microwave systems 76 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 directedhttps www nationaldefensemagazine org articles 2015 7 1 2015july-directed-energy-weapons-will-they-ever-beready 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 https defense360 csis org bad-idea-space-based-interceptors-and-space-based-directed-energy-systems and Justin Doubleday “Pentagon punts MDA‘s laser ambitions shifts funding toward OSD-led ‘laser scaling ’” Inside Defense February 19 2020 at https insidedefense com daily-news pentagon-punts-mdas-laser-ambitions-shifts-fundingtoward-osd-led-laser-scaling 70 Paul Scharre Preface to “Directed-Energy Weapons Promise and Prospects ” Center for a New American Security April 2015 p 4 71 See Ariel Robinson “Directed Energy Weapons ” 72 Ibid 73 For more information see CRS Report R44175 Navy Lasers Railgun and Gun-Launched Guided Projectile Background and Issues for Congress by Ronald O'Rourke 74 Kyle Mizokami “The U S Army Plans To Field the Most Powerful Laser Weapon Yet ” Popular Mechanics August 7 2019 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-TakesStep-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 at https comptroller defense gov Portals 45 Documents defbudget fy2021 fy2021_Budget_Request_Overview_Book pdf 76 Kyle Mizokami “The Air Force Mobilizes Its Laser and Microwave Weapons Abroad ” Popular Mechanics April 9 2020 at https www popularmechanics com military weapons a32083799 laser-microwave-weapons Congressional Research Service 17 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 Counter-Unmanned Aircraft Systems C-UAS 79 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 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 cannot be detected by traditional air defense systems due to their size construction material and flight altitude C-UAS can employ a number of methods to detect the presence of hostile or unauthorized UAS The first is using electro-optical infrared or acoustic sensors to detect a target by its visual heat or sound signatures respectively A second method is to use radar systems However these methods are not always capable of detecting 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 using radio frequency sensors These methods can be—and often are—combined to provide a more effective layered detection capability Once detected the UAS may be engaged or disabled Electronic warfare “jamming” can interfere with a UAS’s communications link to its operator Jamming devices can be as light as 5 to 10 pounds and therefore man-portable or as heavy as several hundred pounds and in fixed locations or mounted on vehicles In addition UAS can be neutralized or destroyed using guns nets directed energy traditional air defense systems or even trained animals such as eagles DOD is developing and procuring a number of different C-UAS technologies to try to ensure a robust defensive capability In December 2019 DOD streamlined its various counter-small UAS C-sUAS programs naming 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 office known as the Joint C-sUAS Office JCO Working in consultation with the combatant commands and the Office of the Under Secretary of Defense for Acquisition and Sustainment JCO assessed over 40 fielded C-sUAS systems On June 25 2020 Maj Gen Sean Gainey director of the JCO announced that seven C-sUAS defensive systems and one standardized command and control system are to be further developed According to media reports during its 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 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 of around 300 kW laser could additionally engage cruise missiles flying in certain profiles i e flying across—rather than at—the laser See for example CRS Report R41526 Navy Shipboard Lasers for Surface Air and Missile Defense Background and Issues for Congress by Ronald O'Rourke and Sydney J Freedberg Jr “Lasers to Kill Cruise Missiles Sought by Navy Air Force Army ” Breaking Defense October 29 2019 For information about DOD’s Laser Scaling Plan see Jason Sherman “New Laser Scaling Plan sets directed-energy efforts FY-19 contracts ” Inside Defense April 17 2019 at https insidedefense com daily-news new-laser-scaling-plan-setsdirected-energy-efforts-fy-19-contracts 79 This section is derived from CRS In Focus IF11426 Department of Defense Counter-Unmanned Aircraft Systems by John R Hoehn and Kelley M Sayler Congressional Research Service 18 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 multidomain 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 across multiple domains air space cyber land sea 82 According to defense officials 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 of decisionmaking and ability to rapidly and continuously integrate capabilities across domains 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 technology processes and new organizations ”84 Figure 8 Visualization of JADC2 Vision Source https www monch com mpg news ew-c4i-channel 7334-saic-and-usaf-partner-for-jadc2 html Theresa Hitchens “DoD Winnowing Efforts To Counter Small Drones ” Breaking Defense March 5 2020 at 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 82 For more information about JADC2 see CRS In Focus IF11493 Joint All-Domain Command and Control JADC2 by John R Hoehn 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 naval forces in a specific area of operation For the Air Operations Center to share information and potentially tasking instructions with the Maritime Operations Center requires manual processes Similarly these command and control structures are geographically focused and do not provide insights into potential adversary operations in other geographic regions 84 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 80 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 intended to reach full operational capability by 2035 87 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 optimal composition of forces Such concepts could provide a comprehensive common operating picture coordinate operations across warfare domains and challenge adversaries’ targeting 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 forces Potential Spectrum Issues for Congress88 As Congress considers several policy implications of the use of the spectrum several potential issues emerge These issues can be categorized broadly as technical issues organizational issues and issues related to commercial use of the spectrum Technical Challenges This section discusses several potential technical issues associated with the spectrum These include communications system interoperability adversary technological development and spectrum sharing technologies to enable commercial applications Communications System Interoperability One 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 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 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-futurebattle-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 85 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 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 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 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 spectrum DOD also uses high-band including millimeter wave or MMW frequencies for highprofile military applications such as Advanced Extremely High Frequency satellites that provide assured global communications for U S forces Coordinating investments across four branches of government three bands of spectrum and across multiple geographies is a challenge The Defense Innovation Board and FCC Commissioner Rosenworcel have suggested that DOD should focus on sub-6 GHz deployments they argue that the rest of the world including China is deploying 5G for military use in the low-band and mid-band first and that the U S should do the same so as to a not 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 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 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 security In deciding DOD appropriations Congress may consider where and how federal funds for 5G should be invested Adversary Spectrum Interference Developments Another potential issue for Congress is balancing spectrum needs of commercial users and consumers and at the same time ensuring DOD has the spectrum it needs to keep pace with adversaries The DOD states “ s ince modern military operations are critically dependent on the 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 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 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 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 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 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-totalk-to-each-other-and-to-the-rest-of-usaf 90 Department of Defense Joint Electromagnetic Spectrum Operations JP 3-85 Washington DC March 22 2020 p I-3 https www jcs mil Portals 36 Documents Doctrine pubs jp3_85 pdf ver 2020-04-09-140128-347 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 92 P L 115-232 §255 93 Bryan Clark Whitney M McNamara and Timothy A Walton Winning the Invisible War Gaining an Enduring 89 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 According to Jane’s Defence Weekly China has invested substantial resources into science and technology initiatives focused on improving its network and electronic warfare capabilities 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 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 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 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 capabilities and directed-energy weapons ”99 A challenge for DOD has been in keeping pace with rapidly evolving technologies and coordinating information on adversaries’ technologies and capabilities across DOD 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 sensitive electronic components such as military sensors communication navigation and information systems 101 The Senate Armed Services Committee citing the report stated “These 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 sadvantage-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 11 https www uscc gov sites default files Research 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 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 41 https www uscc gov sites default files Research 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 2019 p 42 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-DODCHINA-MILITARY-POWER-REPORT-FINAL PDF 100 Sydney J Freedberg Jr “Who’ll Fix EW Task Force Gropes for Answers ” Breaking Defense December 18 2019 https breakingdefense com 2019 12 wholl-fix-ew-task-force-gropes-for-answers 101 U S Government Accountability Office National Security Long-Range Emerging Threats Facing the United States 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 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 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 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 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 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 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 nonfederal use Additionally DOD plans to conduct a comprehensive engineering study to determine the potential for introducing advanced wireless services in this band without harming critical government operations 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 expected to inform future repurposing decisions 107 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 5G and is expected to be auctioned in 2021 DOD leveraged technical work performed by the NTIA to “devise a spectrum sharing framework that supports industry’s need for additional midband spectrum while protecting critical national security requirements ”108 At its September 30 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 CRPT116hrpt120 htm 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 105 Mark Rockwell “DOD looks to share more spectrum ” Defense Systems March 1 2018 https defensesystems com articles 2018 03 01 ntia-dod-spectrum-5g aspx 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-andImpact-on-Non-Federal-Spectrum-Demand-Report-May-2019 pdf 107 U S Department of Commerce Annual Report on the Status of Spectrum Repurposing August 2019 https www ntia doc gov files ntia publications spectrum_repurposing_report_august_2019 pdf 108 U S Department of Defense “White House and DOD Announce Additional Mid-Band Spectrum Available for 5G 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 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 unlicensed use 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 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 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 employing both active and passive techniques to enable sharing or coexistence In September 2020 DOD issued a request for information seeking new methods to facilitate spectrum sharing between military and civilian users and to identify issues of concern related to sharing spectrum for DOD 112 While policymakers and users are both interested in spectrum sharing and see it as a way of extending spectrum access for new users the policies approaches technologies and applications are 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 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 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 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 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 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 112 DOD Request for Information Defense Spectrum Sharing Request for Information Published September 18 2020 https beta sam gov opp 4851a65e2b2d4d73865a0e9865b0c28a view keywords spectrum sort -modifiedDate index is_active true page 1 113 Frank Rayal “Challenges Impediments to Implementing Spectrum Sharing ” Frank Rayal blog September 24 2012 “https frankrayal com 2012 09 24 challenges-impediments-to-implementing-spectrum-sharing 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 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 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 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 strategy was released in 2017 The NDAA for FY2019 P L 115-232 Section 1053 directed DOD to establish a crossfunctional team to oversee the implementation of an integrated spectrum strategy The intent is to meld two existing strategies DOD’s 2013 electromagnetic spectrum strategy developed by the chief information office CIO and the department’s electronic warfare strategy into a single policy 118 the Electromagnetic Spectrum Superiority Strategy 119 In April 2019 DOD stood up the Electromagnetic Spectrum Operations EMSO Cross Functional Team comprised of senior members from each branch the Joint Staff U S Command Cyber Command and other offices This organization has been active in updating DOD spectrum policy and strategy In May 2020 the Joint Staff released new doctrine on Joint Electromagnetic Military Operations elevating the 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 responsibilities for integrated DOD electromagnetic spectrum operations 121 In its version of the 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-federalspectrum-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-ukspectrum-director #79d799e17329 116 10 U S C §113 117 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 end of 2020 Department of Defense Electromagnetic Spectrum Strategy September 11 2013 https dodcio defense gov Portals 0 Documents Spectrum ESS pdf 119 Lauren C Williams “DOD Preps New Electromagnetic Spectrum Strategy ” Defense Systems December 23 2019 https defensesystems com articles 2019 12 23 dod-spectrum-warfare-williams aspx 120 While a maneuver space is not considered a domain this implies 121 Department of Defense DOD Directive 3610 01 Electromagnetic Spectrum Enterprise Policy September 4 2020 https www esd whs mil Portals 54 Documents DD issuances dodd 361001p pdf ver 2020-09-04-112353-317 114 Congressional Research Service 25 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 The growth in commercial wireless services has produced new revenues and new jobs for the United States 123 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 support mission-critical functions 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 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 impact on DOD systems and uses unintended frequency interference the interagency process for 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 demand for mobile data e g video is increasing Cisco the U S -based network equipment maker reported that in 2018 “global mobile data traffic amounted to 19 01 exabytes per month 124 by 2022 mobile data traffic is expected to reach 77 5 exabytes per month worldwide ”125 which will increase demand for additional spectrum To accommodate new technologies more users and more data-intensive applications e g video streaming gaming global telecommunications providers and equipment makers around the world developed 5G wireless networks and technologies 5G technologies promise increased speeds improved connectivity and reduced latency i e lag time when sending commands from your device However for 5G providers need large swathes of spectrum 100 MHz blocks in the low-band below 1 GHz mid-band 1-6 GHz and high-band above 6 GHz radio spectrum Providers expect that the 5G solution—additional spectrum and new 5G technologies—will help 122 S 4049 §173 Transfer from Commander of United States Strategic Command to Chairman of the Joint Chiefs of Staff of Responsibilities and Functions Relating to Electromagnetic Spectrum Operations 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-USEconomy_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 Congressional Research Service 26 Overview of Department of Defense Use of the Electromagnetic Spectrum to meet increasing demands for mobile data support advanced 5G services to businesses and yield new 5G applications including new military applications 126 However the spectrum is already crowded with users including federal agency users DOD is allocated about 40% of federally-assigned spectrum 127 including significant frequency bands in the 1-6GHz range—prime spectrum for mobile telecommunication technologies Some 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 use 128 DOD asserts that its spectrum supports military operations and the research and development of advanced technologies thus should remain with DOD Starting in 1993 the Omnibus Budget Reconciliation Act OBRA 129 required the Secretary of 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 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 repurposing activities and the statutory mandates for repurposing focus on accommodating nonfederal uses and have not directed the repurposing of spectrum to new federal uses they also prioritize exclusive non-federal use over sharing ”130 Congress may require the reallocation of 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 use 131 Since DOD holds about 40% of the federally-held spectrum 132 it can be affected by these policies 133 Congress has tried to assess and address the impact of federal spectrum policies on agencies For example in 2004 Congress established a program to help cover the costs that federal agencies incur when spectrum is reallocated Congress enacted the Commercial Spectrum Enhancement Act CSEA 134 which created the Spectrum Relocation Fund SRF The SRF used revenues from spectrum auctions to provide funding to defray the costs of relocating federal users to new bands However as wireless technology use increased and demand for mobile data continued to rise the U S government continued to examine and reallocate spectrum to meet emerging demands Some have argued that a piecemeal approach to spectrum planning is ineffective 135 They say it does not 126 CRS In Focus IF11251 National Security Implications of Fifth Generation 5G Mobile Technologies by John R Hoehn and Kelley M Sayler 127 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 128 https www politico com news agenda 2020 02 22 pentagon-airwaves-midband-106240 129 P L 103-66 130 Ibid 131 U S Department of Commerce Annual Report on the Status of Spectrum Repurposing August 2019 https www ntia doc gov files ntia publications spectrum_repurposing_report_august_2019 pdf 132 U S 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 133 George Leopold “DOD returns fire on spectrum relocation ” EE Times August 30 2001 https www eetimes com dod-returns-fire-on-spectrum-relocation # 134 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-futurebuilding-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 Congressional Research Service 27 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 entities including the NTIA or other relevant stakeholders including carriers 138 In 2018 the President directed the NTIA to develop a National Spectrum Strategy to set forth a “balanced forward-looking flexible and sustainable approach to spectrum management ”139 Federal 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 Symposium in August 2019 to seek public comment on the plan DOD speakers noted that with new technologies and cooperation with commercial users DOD is exploring opportunities to share spectrum 140 NTIA has reported that the National Spectrum Strategy is under development Congress may be interested in encouraging coordination between the agencies to balance the needs of commercial 5G providers and users and the mission critical needs of DOD On the one hand 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 other hand DOD provides critical national defense functions taking spectrum from DOD could affect military operations and result in the permanent loss of spectrum for DOD uses including critical defense operations and future capabilities Unintended Commercial Frequency Interference141 As new users technologies and services are introduced to the spectrum the potential for interference may increase 142 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 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 138 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 139 White House Office of the Press Secretary “Presidential Memorandum on Developing a Sustainable Spectrum Strategy for America’s Future ” presidential memorandum October 25 2018 https www whitehouse gov presidential-actions presidential-memorandum-developing-sustainable-spectrum-strategy-americas-future 140 NTIA NTIA Spectrum Policy Symposium Transcript September 10 2019 p 12 https www ntia doc gov files ntia publications 09 10 19_npc_ntia_spectrum_policy_symposium pdf 141 Fore a detailed discussion of potential 5G interference with the Global Positioning System see the Appendix 142 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 143 John Pahl “Market Mechanisms for Spectrum Management Spectrum Liberalisation and Interference Congressional Research Service 28 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 ”144 While DOD did express its concerns to the FCC on the Ligado project the FCC asserted that the conditions it placed on Ligado e g reducing power levels creating a guard band reporting base station locations would mitigate interference concerns A recent dispute with Ligado Networks LLC has highlighted key interference issues On April 20 2020 the FCC unanimously approved an application by Ligado Networks LLC Ligado to “deploy a low-power 9 8 decibel watts dBW terrestrial nationwide network in the 1526-1536 MHz 1627 5-1637 5 MHz and 1646 5-1656 5 MHz bands of the electromagnetic spectrum 145 that will primarily support Internet of Things IoT services ”146 These frequency bands are traditionally used for satellite communications and position navigation and timing services such as GPS 147 DOD opposed this decision—along with the Department of Homeland Security Department of Transportation DOT Department of the Interior Department of Justice the Federal Aviation Administration FAA and others 148 That opposition was related to concerns that Ligado’s proposed terrestrial network could interfere with signals from satellites to terrestrial GPS receivers and enabled devices 149 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 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 144 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 116-236 pp 75 275 145 CRS In Focus IF11155 Defense Primer Military Use of the Electromagnetic Spectrum by John R Hoehn 146 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-2048A1 pdf 147 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 Precision Navigation and Timing National Advisory Board 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 148 Letter from Douglas Kinkoph Associate Administrator Performing the Delegated Duties of the Assistant Secretary of Communications and Information to Hon Ajit Pai Chairman of the Federal Communications Commission April 10 2020 at https www ntia doc gov files ntia publications ntia_letter_to_fcc_chairman_re_ligado_applications_4 10 20 pdf 149 CRS In Focus IF11558 Spectrum Interference Issues Ligado the L-Band and GPS by Jill C Gallagher Alyssa K King and Clare Y Cho Congressional Research Service 29 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 150 while others have questioned whether federal agencies should have to work through NTIA to express its concerns on FCC decisions 151 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 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 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 Administration and the 24 GHz band used for weather forecasting Congress has proposed initiatives to improve spectrum management and reduce spectrum disputes For example the Senate-passed version of the FY2021 NDAA S 4049 enrolled Section 1084 c would direct the NTIA to evaluate a range of information technology IT modernization initiatives that would improve analysis of federal government spectrum use and management Some in Congress have proposed updates to the MOU between the FCC and NTIA to clarify the government’s spectrum management and reallocation process 152 Others have suggested to Congress that a third-party such as the White House Office of Science and Technology Policy OSTP or the National Academies of Science and Engineering serve as a technical reviewer or as an arbiter of conflicting technical reports and interference disputes 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 150 U S Government Accountability Office Interdepartment Radio Advisory Committee IRAC Representatives Effectively Coordinate Federal Spectrum but Lack Seniority to Advise on Contentious Policy Issues GAO-04-1028 September 2004 pp 3-4 https www gao gov new items d041028 pdf 151 Testimony of Thad Allen Chairman of Space-Based Precision Navigation and Timing National Advisory Board 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 armedservices senate gov imo media doc 20-21_05-06-2020 pdf 152 See discussion on MOU and arbiter for spectrum disputes during Senate hearing video U S Congress Senate Committee on Commerce Science and Transportation The State of U S Spectrum Policy 116th Cong 2nd sess July 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 Congressional Research Service 30 Overview of Department of Defense Use of the Electromagnetic 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 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 international standards development groups such as the International Telecommunications Union ITU and the Third Generation Partnership Project 3GPP Some technology firms advocate for increased investments in R D to give the United States a competitive edge in the commercial 5G market DOD is supporting this R D through the development of new technologies such as the dynamic spectrum sharing technologies to support the more efficient use of spectrum by deploying 5G in selected bases to measure and monitor performance and experiment with the technologies The 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 emerging For example future sixth generation 6G communications technologies along with emerging military communications technologies These technologies will most likely use the spectrum differently than current systems exactly how these systems will use the spectrum remains unclear 155 Potential Questions for Congress156 As Congress considers its role in spectrum policy and how the DOD manages its use of the spectrum several potential issues and questions arise Below are a few potential Congress may seek additional information   What actions can Congress or DOD take to ensure that mission critical systems that operate in various segments of the electromagnetic spectrum both domestically and abroad are interoperable What changes if any should the DOD make in programs or investments in order to maintain a technological edge in the use of the electromagnetic spectrum over U S competitors 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 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 Overview of Department of Defense Use of the Electromagnetic Spectrum  Does the U S government’s plan for spectrum allocation sufficiently balance DOD requirements with the requirements of commercial applications If so how  What measures if any could accelerate spectrum repurposing relocation and or sharing Is DOD using the spectrum it has efficiently How can DOD improve its spectrum efficiency Is DOD adequately leveraging the spectrum to enable future concepts like Multi-Domain Operations Distributed Maritime Operations and JADC2 If so how As DOD relinquishes certain spectrum segments to commercial or shared use how is it planning to ensure continued command and challenges in implementing 5G communications   Congressional Research Service 32 Overview of Department of Defense Use of the Electromagnetic Spectrum Appendix Ligado Networks157 Concerns Regarding the FCC-Approved Ligado Network for MidBand 5G Network On April 20 2020 the Federal Communications Commission FCC unanimously approved an application by Ligado Networks LLC Ligado to “deploy a low-power 9 8 decibel watts dBW terrestrial nationwide network in the 1526-1536 MHz 1627 5-1637 5 MHz and 1646 5-1656 5 MHz bands of the electromagnetic spectrum 158 that will primarily support Internet of Things IoT services ”159 These frequency bands are traditionally used for satellite operations 160 The Department of Defense DOD opposed this decision along with the Department of Homeland Security Department of Transportation DOT Department of the Interior Department of Justice the Federal Aviation Administration FAA and others 161 That opposition related to concerns that Ligado’s proposed network could interfere with signals from satellites to Global Positioning System GPS receivers 162 Congress may consider federal agency concerns including DOD concerns related to mission-critical systems and the FCC’s response as it conducts oversight of the FCC’s ruling Congress may also consider broader issues related to fifth generation 5G mobile technologies such as the allocation of spectrum among competing users and the impact of spectrum decisions on national security DOD Concerns and Related Studies on GPS Interference In both its formal response to the FCC’s ruling and in its May 6 2020 testimony before the Senate Armed Services Committee SASC DOD cited two primary studies that shaped its belief that the Ligado network “would cause unacceptable operational impacts and adversely affect the military potential of GPS” a 2018 DOT study and a 2016 classified study conducted by the U S Air Force USAF 163 The 2018 DOT study assessed the extent to which cellular base stations 157 This section was written by John R Hoehn and Kelley M Sayler For more information see CRS Insight IN11400 DOD Concerns About the FCC-Approved Ligado Network by Kelley M Sayler and John R Hoehn and CRS Insight IN11414 The FCC-Approved Ligado Network and Potential Technical Issues for DOD Use of GPS by John R Hoehn Stephen M McCall and Kelley M Sayler 158 CRS In Focus IF11155 Defense Primer Military Use of the Electromagnetic Spectrum by John R Hoehn 159 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-2048A1 pdf 160 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 Precision Navigation and Timing National Advisory Board 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 161 Letter from Douglas Kinkoph Associate Administrator Performing the Delegated Duties of the Assistant Secretary of Communications and Information to Hon Ajit Pai Chairman of the Federal Communications Commission April 10 2020 at https www ntia doc gov files ntia publications ntia_letter_to_fcc_chairman_re_ligado_applications_4 10 20 pdf 162 CRS In Focus IF11558 Spectrum Interference Issues Ligado the L-Band and GPS by Jill C Gallagher Alyssa K King and Clare Y Cho 163 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-finalreportapril2018 pdf and written testimony of Dana Deasy DOD Chief Information Officer before the U S Congress Senate Armed Services Committee Department of Defense Spectrum Policy and the Impact of the Federal Congressional Research Service 33 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 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 DOD additionally recommended “that proposals for use of bands adjacent to GPS should not be approved unless they meet the transmission power levels described in the DOT test ”164 Based on these recommendations Ligado submitted an amended application to the FCC reducing its proposed power levels to 9 8 dBW 165 Per the FCC ruling Ligado also agreed to maintain a 23-MHz guard-band of unused spectrum designed to separate its transmissions from GPS thus attempting to mitigate potential interference Details available in the public domain describing the technical parameters of the 2016 classified USAF study are limited however the USAF’s formal response to the FCC ruling notes that its study 166 which specifically tested potential interference with military GPS receivers “supported the conclusions drawn from the DOT testing conducted during the same month ” This may suggest that the study may not provide evidence that a Ligado network—using the FCC-approved specifications from the company’s 2018 amended application—would necessarily interfere with GPS Furthermore according to FCC Chairman Ajit Pai 167 DOD neither submitted nor attempted to submit the classified USAF study to the FCC for consideration Nonetheless DOD has continued to cite these studies in its public objections to the ruling Michael Griffin former Under Secretary of Defense for Research and Engineering USD R E has 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 proposed Ligado network on GPS to attempting to listen to the rustling of leaves while 100 jet aircraft simultaneously took off 168 Statutory Obligations with Regard to Potential GPS Interference DOD has noted its statutory obligation pursuant to 10 U S C §2281 to object “to any restriction on the GPS System proposed by the head of a department or agency of the United States outside DOD that would adversely affect the military potential of GPS” emphasis added Although the Communications Commission 116th Cong 2nd sess May 6 2020 at https www armed-services senate gov imo media doc Deasy_05-06-20 pdf 164 Letter from Douglas Kinkoph Associate Administrator Performing the Delegated Duties of the Assistant Secretary of Communications and Information to Hon Ajit Pai Chairman of the Federal Communications Commission April 10 2020 165 Letter from Gerard Waldron Counsel to Ligado Networks LLC to Marlene H Dortch Secretary to the Federal Communications Commission May 31 2018 at https ecfsapi fcc gov file 1053120688074 Ligado%20License%20Modification%20Cover%20Letter%20and%20Amendment%20 5-31-2018 pdf 166 Letter from Douglas Kinkoph Associate Administrator Performing the Delegated Duties of the Assistant Secretary of Communications and Information to Hon Ajit Pai Chairman of the Federal Communications Commission April 10 2020 167 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 168 Spoken testimony of Michael Griffin Undersecretary of Defense for Research and Engineering 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 Congressional Research Service 34 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 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 ”169 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 the FCC from approving commercial terrestrial operations in the bands proposed by Ligado “until 90 days after the Commission resolves concerns of widespread harmful interference by such operations to covered GPS devices ” DOD asserts that the FCC did not resolve such concerns prior to approving Ligado’s application paragraph 130 of the FCC ruling provides the FCC’s justification for its belief that the concerns were “effectively resolved ”170 FCC Response to Concerns About Potential GPS Interference Several Commissioners have provided statements and written correspondence directly addressing how the FCC came to its decision Commissioner Brendan Carr noted in a statement accompanying the FCC’s decision that “after a thorough and multi-year review the FCC’s professional staff of engineers and other experts determined that we can advance America’s 5G leadership while protecting GPS and other adjacent band services ”171 Commissioners Jessica 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 potential GPS interference “in the end we are compelled to support the expert technical analysis done by the FCC’s engineering staff ”172 In a series of letters Chairman Ajai Pai has outlined the FCC’s decisionmaking process the data the commission used to make its determination and the FCC’s technical analysis of potential interference 173 169 Letter from Hon Mark Esper Secretary of Defense to Hon Ajit Pai Chairman of the Federal Communications Commission November 18 2019 at https www ntia doc gov files ntia publications ntia_letter_to_fcc_chairman_re_ligado_mss_atc_applications_dec _6_2019 pdf#page 6 170 Federal Communications Communication Order 20-48 at https docs fcc gov public attachments FCC-2048A1 pdf 171 Statement of Commissioner Brendan Carr Re LightSquared Technical Working Group Report IB Docket No 11109 LightSquared License Modification Application IBFS Files Nos SAT-MOD-20120928-00160-00161 SESMOD-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 12340 Ligado Amendment to License Modification Applications IBFS File Nos SES-MOD-20151231- 00981 SATMOD-20151231-00090 SAT-MOD-20151231-00091 IB Docket No 11- 109 at https docs fcc gov public attachments FCC-20-48A2 pdf 172 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 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 SATMOD-20151231-00091 IB Docket Nos 11-109 12-340 Ligado Amendment to License Modification Applications IBFS File Nos SES-MOD-20151231- 00981 SAT-MOD-20151231-00090 SAT-MOD-20151231-00091 IB Docket No 11- 109 at https docs fcc gov public attachments FCC-20-48A3 pdf 173 For list of congressional correspondence see https www fcc gov chairman-pais-letters-congress Congressional Research Service 35 Overview of Department of Defense Use of the Electromagnetic Spectrum 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 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 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 positioning navigation and timing capability 174 This provision would allow DOD to reprogram 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 Analyst in Military Capabilities and Programs Kelley M Sayler Analyst in Advanced Technology and Global Security Jill C Gallagher Analyst in Telecommunications Policy 174 S 4049 §1601 S 4049 §234 176 S 4049 §1038 177 H R 6395 §1609 178 H R 6395 §1608 175 Congressional Research Service 36 Overview of Department of Defense Use of the Electromagnetic Spectrum Disclaimer This document was prepared by the Congressional Research Service CRS CRS serves as nonpartisan shared staff to congressional committees and Members of Congress It operates solely at the behest of and under the direction of Congress Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role CRS Reports as a work of the United States Government are not subject to copyright protection in the United States Any CRS Report may be reproduced and distributed in its entirety without permission from CRS However as a CRS Report may include copyrighted images or material from a third party you may need to obtain the permission of the copyright holder if you wish to copy or otherwise use copyrighted material Congressional Research Service R46564 · VERSION 3 · UPDATED 37