NextNav has entered an agreement to acquire additional spectrum licenses in the lower 900 MHz band (902 MHz to 928 MHz) from Telesaurus Holdings and Skybridge Spectrum Foundation. This acquisition, valued at up to $50 million, significantly expands NextNav’s spectrum portfolio by an additional 4 MHz.
With the completion of this transaction, NextNav’s total spectrum assets will surge to 3.5 billion MHz-PoPs, which marks a significant leap in the company’s capacity to offer reliable and precise positioning and timing solutions.
The transaction involves an initial cash payment of $2.5 million due within 30 days following the court’s authorization to proceed. The balance will be settled in NextNav common stock, contingent upon reaching specific milestones, the final transfer of licenses and obtaining necessary regulatory approvals. The successful closure of this deal is subject to Court and regulatory clearances, including approval from the Federal Communications Commission (FCC).
NextNav aims to deliver PNT solutions that use 3D geolocation and PNT technology, facilitated by its ownership of low-band licensed spectrum. The company’s technologies are designed to ensure accurate, reliable and resilient 3D PNT solutions across a broad spectrum of applications, ranging from critical infrastructure and GPS resiliency to various commercial use cases.
The Federal Communications Commission (FCC) is investigating whether the use of Russian and Chinese foreign satellite systems by U.S. mobile phones and other devices poses security threats.
The FCC has concerns that U.S. handheld devices are receiving and processing GNSS signals from satellites controlled by foreign adversaries in violation of commission rules.
The FCC is seeking answers from handset manufacturers Apple, Google, Motorola, Nokia, Samsung and others that collectively cover more than 90% of the U.S. smartphone marketplace.
“There is no established record of what security threats, if any, these signals carry and whether the manufacturers of handheld devices are processing these signals in violation of the Commission’s rules,” an FCC spokesperson said in a statement.
Representative Mike Gallagher, chair of the U.S. House Select Committee on the Strategic Competition Between the United States and the Chinese Communist Party, wrote FCC Chair Jessica Rosenworcel earlier this week raising concern about reports that U.S. cell phones were receiving and processing signals from Chinese and Russian satellites.
The FCC has only approved U.S. phones to receive and process signals from the U.S. Global Positioning System (GPS) and the European Galileo GNSS.
uAvionix has received Federal Communications Commission (FCC) approval, coordinated with the Federal Aviation Administration (FAA), to operate its SkyLink C-band command and control (C2) radios for beyond visual line of sight (BVLOS) operations at the Choctaw Nation of Oklahoma Emerging Technology test site.
The radios — operating on aviation-protected C-band frequencies — will be controlled by uAvionix’s SkyLine cloud-based C2 network solution that supports fleet management, network health monitoring, detect and avoid, and roaming between multiple radio networks and ground stations.
According to uAvionix, with the BVLOS Waiver, businesses looking to use aviation-protected C-band and other radio networks for assured control and non-payload communications can now develop, test and implement solutions for business initiatives such as package delivery and medical resupply.
With over 200,000 tribal members and more than 11,000 employees, the Choctaw Nation is the third largest Indian nation in the United States. It is developing an aviation test facility in southeastern Oklahoma that utilizes more than 44,600 acres of remote land it tribally owns to support the innovative research, development, test and evaluation of emerging manned and unmanned aerial system technologies in a safe and low-risk environment.
Interested businesses should contact the Choctaw Nation and uAvionix to support implementation and scaling of uncrewed aerial system operations with multiple C2 links including aviation protected C-band.
The same 91 signers also sent an identical letter to President Biden.
April 24, 2023
Dear Senators and Members of Congress:
Last year, many of the undersigned wrote in reflection of the unprecedented opposition to the Federal Communications Commission’s (FCC’s) Ligado Order(1) across the vast federal and commercial user base of Global Positioning System (GPS), satellite communications and weather forecasting services. Three years after adoption of the Order, as eight petitions for reconsideration remain pending, (2) we again urge you to work together with the FCC to stay and ultimately set aside the Order. (3) Critically, this is now necessitated by the crucial, previously unavailable information that was produced at the direction of Congress: the independent technical review undertaken by the National Academies of Sciences, Engineering, and Medicine (NAS) (4) analyzing the potential interference issues related to the Ligado Order.
We greatly appreciate your administration’s opposition to the Ligado Order and commitment that the National Telecommunications and Information Administration (NTIA), on behalf of the executive branch, will continue to actively pursue its petition for reconsideration of the Order. (5) As you know, the pending petitions for reconsideration convincingly demonstrate that the Ligado Order is legally and factually deficient. In the pending petitions, parties showed that the Ligado Order is fundamentally flawed, incompatible with the FCC’s rules and inadequate in protecting incumbent services from the harmful interference from Ligado’s proposed operations. This substantial documentation, among many other concerns from federal and commercial users, resulted in Congress enacting bipartisan legislation in consecutive years after the FCC’s adoption of the Ligado Order, mandating NAS’s independent technical review and requiring the Department of Defense (DoD) to brief federal representatives across the government “at the highest level of classification” on the potential for widespread harm from Ligado’s proposed terrestrial operations. (6) On this basis alone, the FCC should stay the Order in an acknowledgement that it clearly did not account for the full, real-world risk of harm associated with a nationwide terrestrial deployment in the L-band.
While the pending petitions have a strong likelihood of success on their own merits, the FCC’s rules and the public interest now require the FCC to reconsider the Order in response to the extensive analysis in the NAS Report. (7) This new, previously unavailable information presented in the Congressionally-mandated independent technical review confirms that Ligado’s proposed terrestrial operations would cause harmful interference (8) at significant ranges to incumbent L-band services across a broad range of deployment scenarios. This is consistent with the well-supported and robustly documented analyses and determinations of the federal government, (9) including fourteen federal agencies and departments, (10) and commercial parties (11) alike. Importantly, as concisely stated by DoD and detailed in the NAS Report, “[t]he terrestrial network authorized by [the Ligado Order] will create unacceptable harmful interference for DoD missions. The mitigation techniques and other regulatory provision [sic] in [the Ligado Order] are insufficient to protect national security missions.”(12)
The unequivocal conclusions of the NAS Report constitute the exact type of previously unavailable information that the FCC’s rules (13) dictate must be addressed on reconsideration. Indeed, NTIA stated on behalf of the executive branch that the NAS Report “offers the [FCC] an important opportunity to reconsider Ligado’s Authorization.”(14) We therefore urge you to work with the FCC to address the harm from Ligado’s proposed terrestrial network to critical GPS, satellite communications, and weather forecasting services by staying the Order, addressing the previously unavailable information contained in the NAS Report, and resolving the pending petitions for reconsideration.
Sincerely,
AccuWeather, Inc.
Aerospace Industries Association
Agricultural Retailers Association
Airborne Public Safety Association
Aircraft Electronics Association
Aircraft Owners and Pilots Association
Airlines for America
Alabama Agricultural Aviation Association
ALERT Users Group
Allied Pilots Association
Air Line Pilots Association, International
American Geophysical Union
American Meteorological Society
American Rental Association
American Road & Transportation Builders Association
American Weather and Climate Industry Association
Arizona Agricultural Aviation Association
Arkansas Agricultural Aviation Association
Associated Equipment Distributors
Association for Uncrewed Vehicle Systems International
(1) Ligado Amendment to License Modification Applications, IBFS File Nos. SES-MOD-20151231-00981, SAT-MOD-20151231-00090, and SAT-MOD-20151231-00091, Order and Authorization, 35 FCC Rcd 3772 (2020) (“Ligado Order” or “Order”).
(2) More than twenty parties in total signed petitions for reconsideration of the Ligado Order and all of these petitions remain pending before the FCC. See Petitions for Reconsideration of the National Telecommunications and Information Administration; the Air Line Pilots Association, International; the American Road & Transportation Builders Association, the American Farm Bureau Federation, and the Association of Equipment Manufacturers; the Joint Aviation Petitioners; Iridium Communications Inc., Flyht Aerospace Solutions Ltd., Aireon LLC, and Skytrac Systems Ltd.; Lockheed Martin Corporation; Trimble Inc.; and the Resilient Navigation and Timing Foundation, IB Docket Nos. 11-109 & 12-340 (all filed on or about May 22, 2020). The ten “Joint Aviation Petitioners” consist of the Aerospace Industries Association, the Aircraft Owners and Pilots Association, Airlines for America, Aviation Spectrum Resources, Inc., the Cargo Airline Association, the General Aviation Manufacturers Association, the Helicopter Association International, the International Air Transport Association, the National Air Transportation Association and the National Business Aviation Association.
(3) The Commission should also not proceed with any companion rulemakings causing harmful interference to weather forecasting and hydrology services that could result in Ligado deployments, particularly in light of the analysis and recommendations presented in the “Spectrum Pipeline Reallocation 1675–1680 MHz Engineering Study (SPRES) Program Report. See Allocation and Service Rules for the 1675-1680 MHz Band, Notice of Proposed Rulemaking, 34 FCC Rcd 3352 (2019); U.S. Department of Commerce. National Oceanic and Atmospheric Administration. National Environmental Satellite Data Information Service. Spectrum Pipeline Reallocation 1675–1680 MHz Engineering Study (SPRES) Program Report. Silver Spring, MD: NESDIS, October 2020 (public release August 2022).
(4) National Academies of Sciences, Engineering, and Medicine, Analysis of Potential Interference Issues Related to FCC Order 20-48 (2022), https://doi.org/10.17226/26611 (“NAS Report”).
(5) Letter from Gina Raimondo, Secretary of Commerce, U.S. Dept. of Commerce, to The Honorable James M. Inhofe, ranking member, U.S. Senate Committee on Armed Services (June 22, 2021) (reiterating the NTIA’s position opposing the Ligado Order).
(6) William M. (Mac) Thornberry National Defense Authorization Act (“NDAA”) for Fiscal Year 2021, Pub. L. 116-283, 134 Stat. 4074 § 1663; NDAA for Fiscal Year 2022, Pub. L. 117-81, 135 Stat. 1541 § 1613.
(7) These statements are based on the publicly available portions of the NAS committee’s work. In addition, NAS prepared a classified annex, which further details the risks of Ligado’s proposed terrestrial network and additionally warrants FCC action.
(8) The term “harmful interference” is herein used to describe the results of the NAS Report. In turn, the undersigned believe the results of the NAS Report dictate that the FCC must reach the legal conclusion that Ligado’s operations would cause harmful interference under the FCC’s rules.
(9) See, e.g., National Telecommunications and Information Administration Reply to Ligado Networks LLC’s Opposition to Petitions for Reconsideration or Clarification, IB Docket Nos. 11-109 & 12-340, at 10 n.26 (filed June 8, 2020); U.S. Department of Transportation, Global Positioning System (GPS) Adjacent Band Compatibility Assessment, Final Report (Apr. 2018) (“DOT ABC Report”),
(10) See Memorandum from Thu Luu, Executive Agent for GPS, Department of the Air Force, to IRAC Chairman (Feb. 14, 2020).
(11) See, e.g., Letter from J. David Grossman, Executive Director, GPSIA, to Marlene H. Dortch, Secretary, FCC, IB Docket Nos. 11-109 et al., at 6 (Sept. 17, 2020); Letter from Bryan N. Tramont, Counsel to Iridium Communications Inc., to Marlene H. Dortch, Secretary, Federal Communications Commission, IB Docket Nos. 11-109 et al. (Jan. 19, 2022); Update to 2016 Technical Assessment of Ligado User Terminal Interference to Iridium attached to Iridium Communications Inc. et al., Petition for Reconsideration, IB Docket Nos. 11-109 et al. ( May 22, 2020).
(12) NAS Report at 6, 73.
(13) 47 C.F.R. § 1.106(c)(2).
(14)Press Release, NTIA, NTIA Statement on National Academies of Sciences Report (Sept. 9, 2022).
The Cybersecurity and Infrastructure Security Agency (CISA) at the Department of Homeland Security (DHS) recently released a three page “CISA Insights” document titled “Global Positioning System (GPS) Interference.” The January 2022 GPS jamming incident in Denver is discussed on the first page as an example of bad things that can happen and why GPS users should take precautions against interference.
Issued eleven months after the event, the report provides little new information, and leaves several important questions unanswered.
One of the most important questions is why it took so long to locate and end interference from a strong signal impacting such a large area.
The Federal Aviation Administration (FAA) was the first agency to become aware of the issue and the report credits the Enforcement Bureau of the Federal Communications Commission (FCC) with finding and terminating the spurious transmission.
Despite an “established national coordination process,” the interference was unabated for 33 hours.
While the report does not give details of the delay, likely reasons include the large number of agencies involved, diffuse authorities and responsibilities, the lack of a national interference detection system or a GPS/PNT “command center,” and several decades of funding and staffing reductions for FCC’s Enforcement Bureau.
How and why it happened
One of the primary reasons for doing an analysis of an accident like this is to prevent similar events in the future. Yet the CISA report provides no helpful information in this regard. It does not identify the source, nor the chain of events leading to the presumably accidental interference.
Those who might take steps to ensure that their operations don’t accidentally interfere with GPS signals learn nothing from the document.
A similar GPS jamming event occurred in October 2022 in the Dallas area. That one lasted 44 hours and the source was never identified. One wonders if this could have been prevented if the CISA report had been issued earlier and included more information.
Why the general public was not warned
The FAA issued a Notice to Airmen as soon as it became aware of the problem. The CISA report says surface (road and highway), rail, and telecommunications users were also impacted. Undoubtedly other types of users were also affected. Yet despite the outage lasting almost a day and a half, no public warning was issued to inform and protect non-aviation interests.
At a minimum, such a warning could have saved companies a lot of trouble and effort. A trouble report during the event from one public safety system operator provides an example of the unnecessary effort expended because a company did not know about the on-going disruption:
“Approximately 1530 on 21 DEC 22 two of our base transceiver systems began to lose sync. The GPS receivers, control cabling, and surge protectors were replaced with no change to loss of sync. There are no other BTS affected other than three sites in Aurora, Colorado … also problems with the local public safety P25 simulcast systems which have lost GPS lock in this area. Spok provides critical encrypted health care communications at these facilities.”
Warning the public could also help prevent more serious consequences, like the loss of life and property.
Troubling assertion
In this case, no losses of life or property have been connected to the disruption.
Yet the CISA report makes a more affirmative statement that “No accidents or injuries occurred because of the GPS interference incident.”
While we all certainly hope that was the case, and it may well be true, the CISA statement is troublingly certain.
A fairer and more accurate statement would be that “…none occurred, that we know of…” This would acknowledge that GPS is a safety of life system in many applications, and the seriousness of interference events.
Striving to do better
After its discussion of the Denver incident the report says improving GPS interference detection and mitigation is a CISA priority. And they are leading an interagency review to improve things.
This will be an uphill battle.
One challenge is DHS and other departments and agencies have limited authorities. The FCC is legally responsible for ensuring transmitters don’t trespass into unauthorized frequencies. However, its resources are limited and, as an independent agency not part of the administration, its participation in cross-governmental efforts is entirely voluntary.
Another is the lack of a clear, authoritative leader and champion for positioning, navigation, and timing (PNT) issues within the federal government.
Executive branch policy scatters PNT-related tasks thinly across the administration. These are to be coordinated by a senior level executive committee tasked to make recommendations “…to the President, through the Assistant to the President for National Security Affairs, or the Executive Secretary of the National Space Council…”
It is not hard to imagine that the details of PNT policy are rarely, if ever, brought to the attention of the President. This can lead to a stalemate between much more junior White House officials and greatly inhibit action.
Let’s hope the CISA report, limited as it is, highlights for leadership the many challenges faced by folks across government who care about GPS reception and national PNT issues. And that, as they collaborate on good solutions, they get the policy and budget support they deserve.
Speaking at the National Press Club on Nov. 3, Federal Communications Commission (FCC) Chair Jessica Rosenworcel announced a plan to reorganize the agency to include a Space Bureau and a standalone Office of International Affairs.
The rationale for these moves, as explained in a press release, is to “help ensure that the FCC’s resources are better aligned so that the agency can continue to fulfill its statutory obligations and keep pace with the rapidly changing realities of the satellite industry and global communications policy.”
While neither GPS nor Ligado were mentioned in the press release, some have taken establishment of a Space Bureau as a sign the FCC may be reconsidering its decision regarding Ligado Networks.
By creating a Space Bureau, the reasoning goes, the commission is acknowledging a need to better focus on space-based users. A report this summer from the National Academies of Science said that some GPS and Iridium users would be harmed if Ligado Networks is allowed to operate as planned.
Since the commission seems to be trying to prevent future Ligado-like controversies, it may also be ready to reconsider its Ligado decision. In February 2020 seven different petitions were filed by organizations and groups of organizations formally asking the FCC to reconsider. The commission has not yet responded to any of the petitions.
Few can disagree that aligning resources to more effective address constituent concerns is a good idea. At the same time reorganizations rarely, in and of themselves, prevent problems from recurring.
As one example, the FCC had been criticized for years for not including analyses of total costs and benefits to the nation of decisions it was considering. In January 2018, FCC Chairman Ajit Pai established the FCC’s Office of Economic Analysis to address those concerns.
Yet, despite Pai still being chair, the Office of Economic Analysis was not called upon to provide input to the commission’s deliberations on Ligado Network’s application. One of the pending petitions for reconsideration asserts that if the office had done a cost-benefit analysis, the commission’s decision would have been different. This is because the cost of even a small service degradation for potentially millions of GPS users would have very likely easily outweighed any benefit to the nation of granting Ligado Networks permission to operate.
Photo: Bill Oxford/iStock/Getty Images Plus/Getty Images
From its humble beginnings in the 1970s to its expanded use in the present day, GPS technology has been vital for nearly every industry from defense and aviation to farming and construction. GPS devices are designed to receive faint GPS signals transmitted from satellites about 12,000 miles away. Acknowledging this reality, regulators have historically maintained for GPS, which relies on such faint radio signals and sensitive equipment, an appropriately quiet spectrum neighborhood—populated by similar users.
With the NASEM report’s confirmation of harmful interference, the deficiencies of the FCC’s April 2020 decision are even more striking
Although these GPS signals and equipment have benefitted from decades of optimization, it is impractical to place highly sensitive GPS receivers designed to capture faint signals from remote transmission facilities immediately next to high-power communications equipment. Unlike those from communications systems, GPS signals are below the thermal noise floor when they are received. As a result, increases in that noise floor often decrease the availability of GPS services, which in turn places at risk high-consequence and safety-of-life services that rely on GPS.
Alex Damato
Why does this matter? In April 2020, the FCC approved a plan to deploy a terrestrial network in spectrum adjacent to the frequency bands used by GPS — operating communications signals that would be around two billion times more powerful than GPS signals at the same location.
This past September, the National Academies of Sciences, Engineering, and Medicine (NASEM) released a report detailing the harmful effects of a terrestrial communications network that would operate in a frequency band close to that of GPS.
Expert concern within 14 federal agencies and departments, a broad coalition in Congress, and the GPS industry resulted in a congressional mandate that NASEM conduct an independent technical review of potential interference to GPS. After a thorough review of the materials, NASEM concluded that the proposed terrestrial network would result in harmful interference to a substantial number of GPS receivers.
In particular, the report noted that high precision GPS devices, which are used in the most economically significant GPS applications, are the most vulnerable receiver class and likely to be affected by interference. The potential for any interference with GPS, especially with devices used by the Department of Defense, poses a threat to national security, the economy, and our daily lives.
With the NASEM report’s confirmation of harmful interference, the deficiencies of the FCC’s April 2020 decision are even more striking: potentially millions of farmers, pilots, construction companies, and first responders may be required to repair or replace GPS equipment at their own cost. Although the FCC assumed that this equipment could be repaired through upgrades or filters, some devices cannot be filtered without significant financial and performance costs, and some devices simply cannot be filtered at all.
GPS is estimated to provide up to $300 billion annually in benefits to the economy. Any disruption in GPS accuracy and usage would have detrimental effects on productivity and economic growth. Moreover, the year before the FCC’s flawed decision, another key report revealed that the loss of GPS service would have an average impact of $1 billion per-day on the nation.
The GPS Innovation Alliance will continue to work with all federal and industry stakeholders to maintain open channels of communication to connect, listen, and learn from all those involved in the discussion. As technological innovation continues, these debates on harmful interference are not going away, and GPSIA is looking forward to engaging further.
The LightSquared/Ligado Networks saga, now in its second decade, continues. On Sept. 9, the Committee to Review FCC Order 20-48 Authorizing Operation of a Terrestrial Radio Network Near the GPS Frequency Bands of the National Academies of Sciences, Engineering and Medicine (NASEM) released its consensus study. Both sides claim the report supports their position.
According to Ligado, the report confirms the FCC’s finding that the company’s operations “can co-exist with GPS.” It cited the report’s conclusion that “the technology to enable compatibility has been in use for over a decade, and most consumer equipment, commercial general navigation, timing, cellular and aviation receivers will not experience harmful interference from Ligado’s operations.”
The NASEM report also confirmed, the company said, the FCC’s finding that “[a] small percentage of very old and poorly designed GPS devices may require upgrading.” Ligado reaffirmed its commitment to “upgrade or replace” federal equipment negatively impacted by its operations and expressed its hope that now the Department of Defense (DOD) and the National Telecommunications and Information Administration “will stop blocking Ligado’s license authority and focus instead on working with Ligado to resolve potential impacts relating to all DOD systems.”
By contrast, the GPS Innovation Alliance applauded the NASEM’s “reaffirmation that Ligado’s terrestrial operations would have a harmful, real-world impact on the millions of federal and commercial users that rely on GPS, satellite communications, and weather forecasting services every single day.” It further stated that the report “demonstrates that Ligado would pose an unacceptable risk to services critical to safety-of-life operations, our national security, and our economy” and urged “government action to address the imminent, but preventable, harm that would result from Ligado’s deployment.”
According to the DOD, the NASEM study “confirms that Ligado’s system will interfere with DOD GPS receivers, which include high-precision GPS receivers.” The study also concludes, DOD says, that the FCC’s proposed mitigation and replacement measures “are impractical, cost prohibitive, and possibly ineffective.”
The NASEM committee pointed out repeatedly in its report that matters are more nuanced than represented by either side and that test results and harmful interference depend on many factors — including the receiver’s signal processing architecture, the amount of SNR loss, the use case, and the relevant failure modes. “The determination of harmful interference is dependent on the particulars,” it said.
The committee also bemoaned “a lack of a quantifiable definition of harmful interference” and “the lack of common receiver assumptions” and called for “more definitive receiver standards.” It also pointed out that “many spectrum conflicts could be avoided if receivers were better designed and implemented.”
The GPS user base is in the billions. Therefore, even if “most” receivers will not be harmed by Ligado’s operations, as the committee reported, tens of millions of devices will be. I highly recommend reading the full report.
“Precautionary principle: The principle that the introduction of a new product or process whose ultimate effects are disputed or unknown should be resisted.” — Oxford Languages
Photo: U.S. Fish and Wildlife Service
The Arctic National Wildlife Refuge spans almost 20 million acres. It is home to a vast array of wildlife from tiny pollinating flies to giant grizzly and polar bears.
It also has oil. Lots of oil.
Getting that oil out of the ground and to market would create jobs and benefit commerce. It would also harm the environment. Some wildlife would suffer.
Many argue the long-term harms of drilling outweigh the short-term benefits. The Biden administration agrees and has banned drilling to protect the refuge’s environment and wildlife.
The administration has taken a similarly conservative approach to preserving the spectrum environment for satellites.
Like the previous administration, it has urged the Federal Communications Commission (FCC) to not allow Ligado Networks’ use of frequencies adjacent to spectrum assigned to GPS and Iridium Communications. The concern is that Ligado’s more powerful transmissions will harm some existing users.
A recent report by the National Academies of Sciences, Engineering and Medicine validated that concern. As is the case with many complex environmental issues, the total number of impacted individuals, and the total negative impact to the nation, are unknown. They may be unknowable.
As an independent agency, the FCC gets recommendations from, but does not report to, the administration. To date it has not been swayed by formal appeals from the executive branch, nor by those from numerous industry and non-profit groups, to rescind its decision allowing Ligado to operate.
Like other agencies making environmental decisions, the commission should use the “precautionary principle” when thinking about new uses and users. It is a well-recognized and systematic method of linking science and public policy.
increasing public participation in decision making
shifting the burden of proof to the proponents of an activity
taking preventive action in the face of uncertainty
exploring a wide range of alternatives to possibly harmful actions.
The first three of these were part of the FCC’s process in its Ligado decision, though critics of the outcome might question how rigorously each was applied:
Hundreds of public comments were received before the order was issued.
Critics note that opposition to the FCC’s eventual course of action was expressed by stakeholders across a very a broad spectrum of society.
The applicant, Ligado, was required to bear the burden of proof.
However, as the National Academies report says, different assumptions in Ligado’s analysis led it to an entirely different conclusion from studies done by the Department of Transportation.
The FCC order allowing Ligado to operate includes “preventative actions.”
Yet many see these preventative measures as unworkable window dressing. In the staid and reserved phrasing of the National Academies report, they “may in some cases not be practicable within operationally relevant time and financial parameters.”
Regardless of the virtues or sins of its process to date, the FCC’s path forward must hinge on the final tenant of the precautionary principle: “Exploring a wide range of alternatives in the face of uncertainty.”
The most obvious, simplest, and straightforward of these alternatives is for the FCC to assign Ligado different frequencies, ones more distant from those used by space-based applications.
Admittedly, this path is only “simple and straightforward” in concept. It will require restarting the frequency allocation process nearly from the beginning, detailed analyses, complex negotiations, and difficult decisions.
Yet the current situation means certain harm to an unknown but significant number of GPS and Iridium users. Harm that could, in some instances, be severe. Even life-threatening.
It also means harm for Ligado. As things stand now, the company will always be under a cloud in the minds of federal officials and other GPS and Iridium users. Ligado will also undoubtedly be blamed for a variety of problems not of its doing from solar weather to criminal jamming. And a significant mishap related to company-caused interference could cause it extreme harm. Perhaps even bringing about Ligado’s demise.
The radio frequency spectrum is a limited and critical national resource. The FCC’s desire to use it to best advantage is necessary and appropriate. This, however, requires great care to safeguard the overall environment and existing users.
Resolving the “Ligado issue” will require creativity and a departure from the adversarial approach that has characterized the FCC process to date. Let’s hope that as the commission reconsiders the issue, it finds a way for everyone to come out ahead.
“The new LightSquared business plan and the new FCC rules significantly expand the terrestrial transmission increasing the potential for interference to GPS receivers,” the U.S. departments of Defense and Transportation (DOD and DOT) wrote to the Federal Communications Commission in 2011 after the FCC granted the company permission to offer broadband via its satellite and base station networks to a wide variety of mobile broadband partners. The move — heralded by supporters as hastening the advent of 4G services across the country, especially in underserved communities — sent shockwaves across the GNSS/PNT community, which opposed the plan forcefully for the threat it posed to GPS.
Reborn in December 2015 as Ligado Networks, the company obtained the FCC’s unanimous approval in April 2020 for the use of spectrum near the L-bands used by GPS for its 5G network. It is scheduled to launch its first deployment at the end of September.
Nearly all the federal government, including DOD and DOT, as well as most manufacturers of GNSS receivers, are very strongly opposed. On September 9, the National Academies of Science, Engineering and Medicine’s Committee to Review FCC Order 20-48 will release its independent evaluation of the issue, as mandated by the 2021 National Defense Authorization Act.
The study, begun in May 2021, considered three issues:
1. Which of two prevailing proposed approaches for evaluating harmful interference is most effective to mitigate the risk of harm.
2. The potential for harmful interference from Ligado to mobile satellite services — such as Iridium.
3. The feasibility and practicality of the remedies proposed by the FCC.
I am very pleased to announce that Prof. Penina “Penny” Axelrad has joined GPS World’s Editorial Advisory Board.
Penny is a University of Colorado (CU) Distinguished Professor in the Ann and HJ Smead Department of Aerospace Engineering Sciences. She received her B.S. and M.S. degrees in Aeronautical and Astronautical Engineering from MIT and her Ph.D. in Aeronautics and Astronautics from Stanford University. She has been a member of the faculty at CU since 1992, serving as primary advisor for 25 Ph.D. graduates and many M.S. and undergraduate research students.
Penny has been active in research on GPS and PNT technology and applications for aircraft, spacecraft and remote sensing, as well as estimation of satellite orbits and attitude, since 1985, co-authoring more than 60 journal papers and 130 conference papers. She has served as principal investigator or co-investigator on grants and contracts totaling $17 million. She is a Fellow of the Institute of Navigation and the American Institute of Aeronautics and Astronautics, and a member of the National Academy of Engineering. Since 2013 she has served as a member of the National Space-Based Positioning, Navigation and Timing (PNT) Advisory Board.
I overlapped with Penny at MIT in the mid-1980s. Now, nearly 40 years later, I look forward to her contributions to this magazine.
The latest chapter of the decades-long Lightsquared/Ligado saga will be revealed this week
The National Academies of Science, Engineering and Medicine (NASEM) will hold a public online briefing at 11 a.m. ET on Sept. 9 to present the results of its Ligado interference study. The committee’s report will be available at National Academies Press at that same time.
The decision by the Federal Communications Commission (FCC) to grant Ligado Networks permission to operate a terrestrial service in a frequency band adjacent to that used by GPS has been controversial since it was announced in April 2020.
The Executive Branch has formally objected to the decision because of its potential to interfere with various kinds of GPS receivers and requested its reversal. So have numerous industry groups.
The satellite communications company Iridium and some weather organizations also formally objected.
Seven different “Petitions for Reconsideration” were filed with the FCC in May 2020 reflecting a variety of engineering- and process-based objections. None have been acted upon and all are still open issues for the commission.
As a result of the long dispute over the potential for interference, the National Defense Authorization Act for 2021 required the Department of Defense (DOD) to contract with NASEM to examine the issue. The study effort began almost exactly a year ago with the announcement of a proposed study team.
According to the NAESM website:
This study will review Federal Communications Commission order FCC 20-48, which authorized Ligado Networks LLC to operate a low-power terrestrial radio network adjacent to the Global Positioning System (GPS) frequency band. It will consider how best to evaluate harmful interference to civilian and defense users of GPS, the potential for harmful interference to GPS users and DOD activities, and the effectiveness and feasibility of the mitigation measures proposed in the FCC order.
Specific results were intended to include:
which of the two prevailing proposed approaches to evaluating harmful interference concerns — one based on a signal-to-noise interference protection criterion and the other based on a device-by-device measurement of the GPS position error — most effectively mitigates risks of harmful interference with GPS services and DOD operations and activities
the potential for harmful interference from the proposed Ligado network to mobile satellite services — including GPS and other commercial or DOD services, and including the potential to affect DOD operations and activities
the feasibility, practicality and effectiveness of the mitigation measures proposed in the FCC order with respect to DOD devices, operations and activities.
Other relevant issues the study committee found are also expected to be discussed.
The NASEM committee has been meeting regularly since the end of September 2021 and has heard from numerous industry and interest groups on both sides of the issue. Materials presented as well as videos of the public portions of all the meetings are available at the group’s website.
Both a classified and an unclassified version of the report are supposed to be produced. No information has been released about whether the classified report has been completed and provided to the Department of Defense.
Based on previous NASEM reports, some observers predict the results of the study will not strongly support either side of the dispute. “Most of these kind of reports say, ‘On the one hand this, but on the other hand that.’ Usually they are not really conclusive. I expect both sides will find something in it to support their assertions and the dispute will continue as it has to date,” said one stakeholder.
The Canadian Positioning, Navigation and Timing Office (PNTO) is warning stakeholders that Ligado has asked the Canadian government for access to spectrum that neighbors that of GNSS services. The request has long been a major issue in the United States because of the risk of radio frequency interference for GNSS users.
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Innovation, Science and Economic Development’s (ISED) Spectrum Management and Telecommunications team announced on Aug. 19 a Notice of Application from Ligado Networks. The application seeks authority for providing terrestrial mobile services in the L-band (1526-1536 MHz in the MSS downlink, and 1627.5-1637.5 MHz and 1646.5-1656.5 MHz in the MSS uplink).
In its application, Ligado Canada is requesting that ISED adopt similar operational requirements and technical rules as those of the U.S. Federal Communications Commission. The rules are spelled out in 2020 FCC order 20-48, “FCC Ligado Amendment to License Modification Applications.” The operational requirements would allow Ligado Canada to provide ancillary terrestrial mobile services over specific portions of its licensed MSS spectrum.
Interested stakeholders can submit comments until Oct. 18 on ISED’s website. Respondents are requested to email their comments in Microsoft Word or Adobe PDF to [email protected].
CANSPACE Listserv is a service of Canadian Space Geodesy Forum and is administered by Dr. Richard Langley.
