The document covers a number of details regarding the Ligado Networks and the advancement of 5G.
According to the document, former NASA Administrator Daniel Goldin claims that FCC’s approval of the proposal by Ligado Networks to repurpose satellite spectrum in the L-Band for high-power terrestrial use should be upheld because it will help advance American leadership in 5G technologies.
“Winning the race to 5G — against China and other countries — is important, but Ligado’s proposed network is largely irrelevant to 5G,” the GPS Innovation Alliance said in response. “The availability of Ligado’s spectrum for terrestrial use will not contribute to the advancement of 5G but will instead undermine U.S. Global Positioning System receivers and devices that are foundational to wireless technology in general, including 5G.”
In addition, the GPS Innovation Alliance’s stated in its ex party that the use of L-Band spectrum is not critical for 5G services.
Other points mentioned in the document include that Ligado’s spectrum is not internationally harmonized, significantly diminishing its effectiveness as a 5G band, and that Ligado’s proposed network simply will not offer a 5G service. According to the GPS Innovation Alliance, Ligado merely proposes to offer limited internet of things services, primarily delivered over custom private networks to specific geographic areas for limited vehicular and utility operations. Not only is this not a 5G service offering, but similar services are already being provided by wireless service providers, the alliance added.
The letter highlights what appears to be different characterizations of the engineering information in the FCC’s record, and suggests that these contrasting statements “support a careful re-examination of the bases of the Ligado Order and a stay of the decision while that occurs.”
“GPSIA appreciates your continued interest and efforts in this proceeding, and your willingness to consider whether a stay of the Ligado order may be appropriate,” the letter states. “As the record in this proceeding makes clear, sound technical analyses were conducted on Ligado’s network by DOT — a neutral third-party U.S. government expert on GPS. Further evaluation of those analyses should prompt the Commission to set aside the Ligado order so that its understanding of the DoT ABC Report can be better aligned with the authors of the report.”
Hold on Third FCC Chairmanship. In a related report, the chairman of the Senate Armed Services Committee Sen. Jim Inhofe (R-Okla.) on July 28 placed a hold on the nomination of O’Rielly to another five-year term chairing the commission.
Inhofe said he would block O’Rielly until the nominee “publicly commits to vote to overturn the current Ligado order,” according to a report from Space News.
“Over the past few months, I have sent letters, held hearings and called countless officials to highlight what we all know to be true: the FCC’s Ligado order is flawed and will lead to significant harm to our military and the thousands of individuals and businesses that rely on GPS,” Inhofe said.
At first it was a flurry of letters and public statements from U.S. senators and members of the house. Then there was a senate hearing on the topic, and the issue was discussed in several other hearings.
The Federal Communications Commission’s (FCC) approval of a long-standing request by Ligado Networks continues to be controversial. The request was to make terrestrial broadcasts on a frequency near that used by GPS. Broadcasts which, according to analyses by the departments of Defense and Transportation, will interfere with GPS reception for many users.
Now it looks as though Congress is ready to move beyond talk and enact one or more pieces of legislation. These would require an independent technical review of the FCC’s decision and place limits on the ability of Ligado Networks to use the license it was granted.
Congressional interest has been fueled both by member concerns and a regular drumbeat of input from constituents. The recently formed Keep GPS Working Coalition is just one example. It was created from a larger group of more than 70 companies and organizations across a broad swath of industries that has gone on record against the decision and has been supporting congressional action.
National Defense Authorization Act
A primary vehicle for congressional action looks to be the National Defense Authorization Act (NDAA) for 2021. Unlike other “annual” legislation that often gets sidetracked or delayed during election years, Congress has passed an NDAA for each of the past 59 years. As such, it is a particularly powerful tool.
This is doubly so in this case, as the member of Congress that has been the most outspoken critic of the FCC’s decision is Senator Jim Inhofe (R-OK). He chairs the Senate Armed Services Committee that has direct responsibility for the NDAA.
Responding to conflicting claims about the findings of government and private tests, the bill requires the Defense department to contract with the National Academies of Science, Engineering and Medicine for an independent technical review.
Evaluating Potential Impact on GPS
Among other things, the review will compare the different methods of evaluating the potential impact on GPS services from Ligado’s transmissions, and determine which of those was the most effective in guarding against any harm.
The bill also prohibits the Defense Secretary from spending any money to comply with the FCC’s order until the Congress has been given an estimate of the total cost to the department of coping with Ligado’s transmissions.
While the FCC order requires Ligado to modify or replace any government receivers impacted by its operations, the Defense department and others have said this is only a small fraction of the overall costs they would incur.
The bill requires the Defense Department estimate to consider a much larger scope of costs including:
To upgrade, repair, or replace potentially affected receivers
To modify, repair, or replace equipment, pares, associated ancillary equipment, software, facilities, operating manuals, training, or compliance with regulations, including with regard to the underlying platform or system in which a capability of the Global Positioning System is embedded; and,
For personnel of the department to engineer, validate, and verify that any required remediation provides the Department with the same operational capability for the affected system prior to terrestrial operation in the 1525 to 1559 megahertz or 1626.5 to 1660.5 megahertz bands of electromagnetic spectrum.
The House version of the NDAA also provides that:
“The Secretary of Defense may not enter into a contract, or extend or renew a contract, with an entity that engages 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.”
RETAIN GPS and Satellite Communications Act
Senator Inhofe has also announced he will introduce stand-alone legislation when Congress returns from summer recess. His “Recognizing and Ensuring Taxpayer Access to Infrastructure Necessary for GPS and Satellite Communications Act,” or “RETAIN GPS and Satellite Communications Act,” would require Ligado to modify or replace any receiver, including those used by private citizens, that would be impacted by Ligado’s operations.
This modification would be required before the FCC’s order allowing them to transmit could come into force. Most observers opine that the number of impacted civil receivers in the U.S. is so great that this would effectively deny Ligado use of the frequency.
Introduction of the RETAIN GPS and Satellite Communications Act was planned for before the summer recess. Its delay until after was likely to provide more time to recruit co-sponsors.
GPS Interference a ‘Niche’ Issue
One observer commented that “GPS and the FCC Ligado order are really niche issues. As time goes on, more and more members of Congress will hear about it from constituents and be appalled.”
The delay will also allow time for the mammoth NDAA bill to clear Congress. RETAIN GPS would then have more chance for the spotlight.
Many industry observers have opined that regardless of congressional action, Ligado will struggle to find a successful 5G or other business model that will generate a significant revenue stream from the spectrum.
As public concern continues to grow and Congress responds with legislation, it may turn out that Ligado finally won the battle at the FCC but ended up losing the war.
Not surprisingly, the primary topic at the July 1 meeting of the National Space-based Positioning, Navigation and Timing Advisory Board was the Federal Communications Commission (FCC) decision on Ligado Networks.
In it Captain Sullenberger cited many of the issues the board’s vice chair, Brad Parkinson, discussed later in the meeting. Sullenberger’s statement is available here.
In his presentation, Parkinson called the FCC decision “a grave error.” He outlined his rationale in 21 information-packed slides.
Parkinson summarized his presentation up front with three points:
Repurposing the Mobile Satellite Services (MSS) radio spectrum is very high risk and brings virtually no near-term benefit to the United States.
The risks affect much more than the Department of Defense: high-value civil applications are also in jeopardy.
Any such repurposing should have been subject to a formal rulemaking process.
At the end of the presentation, the board voted unanimously to adopt the presentation, with slight modifications, as a reference document for posting on the board’s website.
The group had previously made strong recommendations to the Departments of Defense and Transportation to oppose any such action by the FCC. Both departments have done that and are continuing to do.
Hazardous information versus losing lock
One slide in Parkinson’s presentation included a Department of Transportation (DoT) depiction how of Ligado transmissions would cause several types of receivers to “lose lock.” This graphic was used in a recent DoT presentation to the FCC.
DOT briefing to FCC: “Concerns Over Ligado Order & Authorization,” June 2020. (Slide: DOT)
Heretofore DoT has usually discussed the points at which Ligado transmissions would cause a 25% increase in the noise floor for receivers. This is an important metric as tests have shown that beyond that point many receiver types begin to give hazardously misleading information. DoT officials have used the example that the 1dB limit is like putting a load limit on vehicles crossing a bridge so that the bridge never reaches its breaking point. An important consideration with a safety-of-life application like GPS.
The National Space-Based PNT Advisory Board. (Board photo)
A receiver often gives inaccurate positioning and timing data, possibly hazardously misleading information, before it “loses lock” and stops providing any information at all. It is more difficult for a receiver to “acquire lock” than to track satellites and provide information, so equipment is rarely able to function again until it moves out of the area of interference.
When asked why DoT would bother to show such information to the FCC, one official suggested that loss of lock was more in line with the criteria the Commission used in making the Ligado decision. The hope was that, by showing that even this flawed standard had significant impacts which the FCC perhaps did not fully recognize, further technical discussions and reconsiderations could be realized.
Other Topics
While discussion of the FCC’s decision took the most time in the on-line meeting, several other issues were discussed as well.
Colonel Curtis Hernandez from the National Security Council briefly described development of a new space-based PNT policy to replace NSDP-39 which was put in place by President Bush in 2004.
He was not able to provide any specifics as it is a draft and still under consideration. Answering a question, he did say that the draft policy outlined the responsibilities of various departments, including for interference detection and monitoring.
Adam Balkcum from the Office of Science and Technology Policy discussed his office’s nascent efforts to investigate non-GNSS PNT as directed by the recent Executive Order on Responsible Use of PNT. The question of whether this includes possible PNT services from low earth orbit and geostationary satellites remains an open one.
Other presenters included:
Seth Jonas of the National Security Council staff on the recent Executive Order on Responsible Use of PNT,
Andrew Hansen of the Volpe Transportation Systems Center who spoke about efforts to monitor for GPS interference, especially in the post-FCC Ligado decision environment, and
NASA’s Chris Bonniksen discussed issues with operating and funding the agency’s Global Differential GPS system.
The agenda for the meeting and presentations are available here, as will be the meeting minutes once they have been finalized.
Signing the letter were Senators Mike Lee, Brian Schatz, Ron Johnson, Edward Markey, Ted Cruz, Mark Warner, John Thune and Chris Coons. All except for Senator Coons serve on the Senate Committee on Commerce, Science and Transportation, which oversees the FCC. Senator Coons serves on the appropriations subcommittee that funds the FCC each year.
The letter referred to the hearing held by the Senate Armed Services Committee on the issue, and stated that only parties opposed to the FCC’s action were heard. The senators were concerned that the public also hear from the FCC.
Thirteen specific questions covered topics including:
How long the proceeding was on the docket
What notice given federal agencies of the proposed final order
Which agencies were consulted and how input was considered
The adequacy of the guard band and how the FCC has used the 1-db interference standard in the past
The 13th question asked the FCC why it believed granting the application was in the public interest.
A copy of the letter is available on the Resilient Navigation and Timing Foundation website.
U.S. Federal Communications Commission (FCC) Chairman Ajit V. Pai has responded to a congressional letter expressing objections to the April 20 FCC decision to allow Ligado to establish a broadband network.
In a May 27 email sent to GPS World, the FCC wrote, “Given your interest in the Ligado order that the Commission adopted unanimously last month, we wanted to share with you the text of the letter Chairman Pai recently sent to members of Congress on this topic.”
The five-member FCC voted unanimously in April to approve an order to allow Ligado Networks to deploy a low-power nationwide 5G network. Experts and policy makers have said the broadband network could — or likely would — interfere with reception of GPS signals.
On May 7, a bipartisan group of 23 members of the House Armed Services Committee (HASC) sent a letter to the FCC questioning the decision, and this is the letter the FCC is now responding to.
The letter from Committee Chairman Adam Smith (D-Wash.) and Ranking Member Mac Thornberry (R-Texas) says the FCC order did not comply with Section 1698 of the National Defense Authorization Act for Fiscal Year 2017. That act prevents the commission from approving commercial terrestrial operations in certain portions of the L-band spectrum until 90 days after the commission resolves concerns of harmful interference to GPS devices.
The Senate Armed Services Committee held a hearing on the topic on May 6 with Department of Defense officials, and on May 15, 32 senators asked the FCC to address their concerns and stay the Ligado approval order while doing so.
“GPS has no right to operate in the spectrum in question, so there is nothing for Ligado to share.” — FCC Chairman Pai
The letter insists that GPS will remain protected. “Although your letter references the shared use of spectrum, the Commission’s L-band decision does not authorize any spectrum sharing between Ligado and GPS. In fact, spectrum in this band has been licensed to Ligado and predecessor companies for over 30 years — with those companies authorized to deploy terrestrially since 2004. And as mentioned above, one of the FCC’s conditions require separation of Ligado’s operations from GPS spectrum by means of a 23-megahertz guard band. Thus, any implication that the Commission has authorized Ligado to “share” spectrum that is currently allocated to GPS is incorrect. GPS has no right to operate in the spectrum in question, so there is nothing for Ligado to share.”
Download the full letter to Rep. Smith here. Download HASC letter to the FCC here.
The email to GPS World included the following statement: “The FCC is required by law to make its decision based on the facts in the record, and federal agencies, including the Department of Defense, were provided with multiple opportunities to put whatever facts they believed to be relevant into the record, including classified information, which the Commission has a process in place to protect.
“The Commission based its decision on all of the information in the record. Moreover, we are not aware of the FCC refusing any request by the Department of Defense to provide a briefing related to this matter.
“To the extent any federal agency opposed to the Ligado application chose not to share information with the Commission, that was the agency’s decision and suggests that it did not believe that the information in question would bolster its case.”
Spectrum regulation is much like land-use zoning: certain services are kept separate to avoid disturbing the neighbors. The U.S. Federal Communications Commission (FCC) has in effect allowed Ligado to build an outdoor concert venue next to a monastery, and by way of compensation, they offer free earplugs.
GPS/GNSS signals are extremely weak and the receivers are extremely sensitive. To give some perspective, by the time they get to the GPS receiver, GPS signals are about a factor of 20 less powerful than cosmic background noise. Ligado’s spectrum was licensed for mobile satellite services (MSS) and so was not likely to interfere with GPS.
“The U.S. Federal Communications Commission (FCC) has in effect allowed Ligado to build an outdoor concert venue next to a monastery, and by way of compensation, they offer free earplugs.”
With its new, and much more valuable license, Ligado now has a legal right to build a terrestrial cellular service. Exhaustive testing over the past 10 years has repeatedly demonstrated that such a system will interfere with high-precision GPS/GNSS receivers used in surveying, timing and Earth observation. The Department of Defense (DOD) has also made strong claims that such a system will cause harm to its systems. In all cases, the effect is much like riding a bicycle at night. You can see fine until someone comes around the corner with the high beams on and blinds you.
In its earlier filings, Ligado had asked for permission to transmit at a power level of 1500 Watts. In an amazing piece of legerdemain, they convinced the FCC, but not the Department of Transportation (DOT) or DOD, that by reducing transmit powers to 10 Watts, there would be no harm. This is a stunningly erroneous claim. As you lower the transmit power, you need many more cellular base stations to cover a given area. To use an analogy from my backyard, I can install one high-flow sprinkler head to cover the entire yard or a bunch of low-flow heads, each covering a small portion. Either way, the grass doesn’t care about anything other than inches of water, and I’m going to get wet if I run across the yard. Ligado’s core argument is equally wet. Nonetheless, it has great appeal to people who don’t understand how cellular systems work.
So, moving forward and assuming the license stands, interference events will become more prevalent and GPS will be deemed “less reliable.” Because interference sources are largely untraceable, blame will rarely attach to Ligado. I expect that GNSS receiver vendors will incorporate improved filters into receivers and pass the cost along to buyers. Ligado, or more likely whoever it sells the spectrum to, will quickly move to petition for increased transmit powers to lower capital costs; after all, more base stations cost more. And so, the Visigoths have arrived, 4G in hand with a 5G label.
Logan Scott is founder and owner of Logan Scott Consulting, www.gpsexpert.net.
Leaders in the GNSS/PNT community are reacting to the Federal Communications Commission (FCC) decision to approve an order to allow Ligado Networks to deploy a low-power nationwide 5G network. The departments of Defense and Transportation have criticized the decision, concerned about interference with GPS signals.
Below are statements we have received from our readers.
Logan Scott, LS Consulting
Logan Scott
Spectrum regulation is much like land use zoning in that certain services are kept separate so as to avoid disturbing the neighbors. The FCC has in effect allowed Ligado to build an outdoor concert venue next to a monastery and by way of compensation, they offer free earplugs. GPS / GNSS signals are extremely weak and the receivers are extremely sensitive. To give some perspective, by the time they get to the GPS receiver, GPS signals are about a factor of 20 less powerful than cosmic background noise. Ligado’s spectrum is/was licensed for mobile satellite services (MSS) and so was not likely to interfere with GPS.
With their new, and much more valuable license, Ligado now has a legal right to build a terrestrial cellular service. Exhaustive testing over the last 10 years has repeatedly demonstrated that such a system will interfere with high precision GPS/GNSS receivers used in surveying, timing, and earth observation. The DoD has also made strong claims that such a system will cause harm to their systems. In all cases, the effect is much like riding a bicycle at night. You can see fine until someone comes around the corner with the high beams on and blinds you.
The FCC has in effect allowed Ligado to build an outdoor concert venue next to a monastery and by way of compensation, they offer free earplugs.
In their earlier filings, Ligado had asked for permission to transmit at a power level of 1500 Watts. In an amazing piece of legerdemain, they convinced the FCC, but not the DoT or DoD, that by reducing transmit powers to 10 Watts, there would be no harm. This is a stunningly erroneous claim. As you lower the transmit power, you need many more cellular basestations to cover a given area. To use an analogy from my backyard, I can install one high flow sprinkler head to cover the entire yard or a bunch of low flow heads, each covering a small portion. Either way, the grass doesn’t care about anything other than inches of water and I’m gonna get wet if I run across the yard. Ligado’s core argument is equally wet. Nonetheless, it has great appeal to people who don’t understand how cellular systems work.
So, moving forward and assuming the license stands, interference events will become more prevalent and GPS will be deemed “less reliable”. Because interference sources are largely untraceable, blame will rarely attach to Ligado. I expect that GNSS receiver vendors will incorporate improved filters into receivers and pass the cost along to buyers. Ligado, or more likely whoever they sell the spectrum to, will quickly move to petition for increase transmit powers so as to lower capital costs; after all more basestations cost more. And so, the Visogoths have arrived, 4G in hand with a 5G label.
John Fischer, Orolia
John Fisher. (Photo: Orolia)
At Orolia, we support the position of the DOT, DHS and DOD and the measures they are taking to protect the GNSS band. However, interference is a fact of life in this band as the GNSS signals are very weak, so additional measures must be taken for resiliency, especially for critical infrastructure. Adversarial interference is much worse than this, so a range of solutions are possible: from the simple – for example, a horizon blocking antenna that shields energy from a nearby tower – to full multi-layer defenses that include RF filtering, advanced DSP filtering/detection, alternative PNT from STL signals, atomic clock and IMU backup, and CRPA antennas. No one solution covers every case, but the problem can be managed.
Mitch Narins, Strategic Synergies
Mitch Narins
It is quite concerning when a panel of lawyers makes a decision, despite the results of years and years of studies, and over the objections of our nation’s technical and operational Position, Navigation and Timing (PNT) experts. While I have championed the need for a complementary and resilient PNT system for many, many years, one cannot dispute the worldwide benefits that GPS and other GNSS have brought — from safety, security, and economic perspectives.
As noted in the FCC’s press release, “The order also requires Ligado to protect adjacent band incumbents by reporting its base station locations and technical operating parameters to potentially affected government and industry stakeholders prior to commencing operations, continuously monitoring the transmit power of its base station sites, and complying with procedures and actions for responding to credible reports of interference, including rapid shutdown of operations where warranted.” I believe that it is imperative that GPS users, both within the Government and in the private sector, understand:
How base station location information will be disseminated, what power levels and radiation patterns will be utilized, and what recourse GPS users will have to object to the proposed location and service;
How the service will be monitored for each base station location, what systems will be used to do the monitoring, and how the monitoring information will be publicly disseminated;
How reports of interference will be filed, how and by whom they will be determined to be “credible”, how and in what timeframe will a “rapid shutdown of operations” be accomplished, and how appropriate mitigations will be identified and implemented; and
Given the importance and concern associated with this action, what special oversight mechanisms, involving civilian and military participants, should be put in place to avert potential safety, security, and economic impacts to our nation’s critical infrastructure.
While one can model, and even test problems based on the location of facilities where aircraft would be expected to be operating close to the ground (e.g., airports and heliports), one can never be sure where a medevac or other first responder helicopter may have to set down in response to an accident or incident site. In keeping with the FCC’s own press release, it is unclear how a pilot experiencing problems with GPS (if, in fact the pilot could recognize such a problem) would be able to report the issue and have it mitigated in real time to support a safety or security mission — unless all areas around all ground transmitters were mapped and first responders could request specific ones to be turned off when operations were expected in a known area. Unfortunately, the limits of these operating areas are, many times, unknown or rapidly changing (e.g., forest fires) and any delay in reaction to unforeseen events could prove detrimental to safety, security, and economic wellbeing.
Mitre conducted a test wherein small Unmanned Aerial Systems (sUAS) could detect and avoid an aircraft based on receipt of its ADS-B squits. Perhaps these ground transmitters should include ADS-B receivers and automatically go off-air if a helicopter comes within a certain distance. I have no doubt that Ligado would not appreciate this solution …
I would hope that those who disagree with this decision will seek out a means to correct this through either the legislative or judicial branches or both. Personally, I cannot see how this either “promotes the general welfare” or “provides for the common defense” (I didn’t have to go to law school to come to those conclusions). I also believe that (1) the ever growing importance and criticality of PNT services should provoke the Congress to modify the makeup of the FCC to include PNT expertise at the very top; and (2) the FCC Office of Chief Engineer needs to become an independent point of expertise akin to the Office of Inspector General to preclude undue pressure and potential political “bending” of technical analyses.
Finally, regardless of whether one agrees or disagrees with the FCC’s order, no one can possibly believe that this decade-long tale of woe is an example of governmental “best practice.” As it took the energy and significant resources from so many more important PNT initiatives, I hope that a quality/leadership body (perhaps GAO and/or a group of IGs) take up the task to do an independent “lessons learned” assessment of this decade-long tale of woe needs to be carefully examined, as it took the energy and significant resources from so many more important PNT initiatives — we should never have to go through this ever again.
Mitch Narins is the principal consultant and owner of Strategic Synergies, LLC, a technical and management consulting firm that he formed after retiring following over four decades of U.S. government service with the FCC, US Navy/Marine Corps, and the Federal Aviation Administration.
Alison Brown
Allison Brown
GPS user equipment needs to be designed to be more resilient to interference. The threat to GPS has been well understood for many years but agencies and vendors have been slow to respond to improve national resiliency against jamming threats. The President signed into law the National GPS Timing Resilience and Security Act in 2018 and on 2/12/2020 signed an Executive Order on Strengthening National Resilience through Responsible Use of Positioning, Navigation, and Timing Services recognizing “the disruption or manipulation of these services has the potential to adversely affect the national and economic security of the United States.” The onus is now on vendors and agencies to develop resilient solutions that can operate in the presence of intentional and unintentional interference. These solutions would also mitigate any potential impact from the use of adjacent bands by operators such as Ligado to deploy 5G and Internet of Things services.
Ellen Hall
Ellen Hall
Overall, the GPS industry should be encouraged to do more to protect themselves from harmful interference. While it is too late for today’s receivers, the next generation needs to introduce more resilience. I agree with the House Armed Services Committee Chairman in saying, “While I strongly support development of the world’s most robust, safe and secure network, using L-band spectrum in such close proximity to critical GPS, as Ligado’s proposal requires, carries an unacceptable risk….”
The FCC said the approval order included stringent conditions aimed at ensuring that GPS would be vulnerable to harmful interference. It seems the only way to prevent harmful interference, would be to permanently fund an oversight commission to monitor Ligado’s system. I believe only Congress can appropriate funding for this effort, therefore the FCC’s decision should be a recommendation to Congress to implement. It is not enough to leave it to a five-person committee to “encourage” that “stringent conditions” are implemented. Enforcement is crucial. Critical infrastructure should be regulated to ensure that we can cope better with “noisy neighbors.”
The five-member Federal Communications Commission (FCC) voted unanimously to approve an order to allow Ligado Networks to deploy a low-power nationwide 5G network.
The approval comes despite objections from the U.S. Defense Department (DOD), other federal agencies and major U.S. airlines, all of whom are concerned about near-band interference with GPS.
The FCC said the approval order included stringent conditions aimed at ensuring GPS would not experience harmful interference.
“After many years of consideration, it is time for the FCC to make a decision and bring this proceeding to a close,” said FCC Chairman Ajit Pai in an April 16 news release. “We have compiled an extensive record, which confirms that it is in the public interest to grant Ligado’s application while imposing stringent conditions to prevent harmful interference.”
Ligado is seeking to repurpose a swath of L-band spectrum for a 5G network focused mainly on connecting smart devices and other internet-of-things services. According to the FCC, the order will “promote more efficient and effective use of our nation’s spectrum resources and ensure that adjacent band operations, including the Global Positioning System (GPS), are protected from harmful interference.”
In response, members of both the Senate and House Armed Services Committees and other defense advocates are considering legislative action to overturn the order.
Two areas that rely heavily on the integrity of GPS signals include defense and transportation. The DOD issued a joint statement with the Department of Transportation (DOT) criticizing the FCC ruling.
“Americans rely on our Global Positioning System (GPS) each day for many things: to locate citizens in need of emergency assistance through our E-911 system, to secure our financial system, to order and receive shipments, to travel by car for work and leisure, to facilitate commercial trucking and construction work, and even to make a simple cellphone call. Our departments rely on GPS each day for all those reasons as well to coordinate tactical national security operations, launch spacecraft, track threats, and facilitate travel by air and sea. The proposed Ligado decision by the Federal Communications Commission will put all these uses of GPS at risk.”
House Armed Services Committee Chairman Adam Smith (D-Wash.) released a letter he sent to Defense Secretary Mark Esper and FCC Chairman Ajit Pai raising concerns about Ligado’s 5G network.
“While the United States must be a leader in the implementation of 5G networks, our creation of these networks must not hamper our military’s operational capacity in any way. China’s aggressive, global promotion of its 5G companies presents a considerable security challenge that must be addressed. However, Ligado’s proposal, which seeks a portion of spectrum adjacent to that used for Global Positioning Systems, poses an even larger security risk.
“The Department of Defense has been clear and direct: providing this license to Ligado would cause unacceptable operational impacts and adversely affect the military’s use of GPS. The military’s seamless use of GPS is vital to our national security. Our service members rely on GPS satellites for critical precision timing and navigation, and thousands of weapons systems are embedded with GPS signals.
“While I strongly support development of the world’s most robust, safe and secure network, using L-band spectrum in such close proximity to critical GPS, as Ligado’s proposal requires, carries an unacceptable risk that far outweighs the possibility of a 5G network.”
‘Risk of crippling’ GPS
Defense Secretary Mark Esper said via Twitter on Friday that the “Ligado proposal would needlessly imperil GPS-dependent national security capabilities. The Department continues to support domestic 5G options, but not at the risk of crippling our GPS networks. Nearly a dozen other federal agencies have joined us in opposing this proposal.”
“Although I appreciate the concerns that have been raised by certain Executive Branch agencies, it is the Commission’s duty to make an independent determination based on sound engineering. And based on the painstaking technical analysis done by our expert staff, I am convinced that the conditions outlined in this draft order would permit Ligado to move forward without causing harmful interference. For example, the draft order would authorize downlink operations at a power level that represents a greater than 99% reduction from what Ligado proposed in its 2015 application.”
Image: A-Digit/DigitalVision Vectors/Getty Images
The release also provided this background about the Ligado proposal, and the “conditions” under which the FCC decided to approve it.
In recent years, Ligado has amended its application to significantly reduce the power levels of its base stations from 32 dBW to 9.8 dBW (a reduction of 99.3%). Ligado has also committed to providing a significant (23 megahertz) guard-band using its own licensed spectrum to further separate its terrestrial base station transmissions from neighboring operations in the Radionavigation-Satellite Service allocation. As such, Ligado is now only seeking terrestrial use of the 1526-1536 MHz, 1627.5-1637.5 MHz, and 1646.5-1656.5 MHz bands. The Order is conditioned to reflect these technical requirements. It also requires Ligado to protect adjacent band incumbents by reporting its base station locations and technical operating parameters to potentially affected government and industry stakeholders prior to commencing operations, continuously monitoring the transmit power of its base station sites, and complying with procedures and actions for responding to credible reports of interference, including rapid shutdown of operations where warranted.
However, The decision “appears to ignore the well-documented views of the expert agencies charged with preserving the integrity of GPS, specifically on the critical issue of what constitutes harmful interference to users of Global Navigation Satellite Systems (GNSS),” said J. David Grossman, executive director of the GPS Innovation Alliance (GPSIA). He continued,
J. David Grossman
“GPSIA has consistently advocated for adoption of the 1-dB Standard as the only reliable mechanism that provides the predictability and certainty to ensure the continuation of the GPS success story, with the support of the Department of Defense, the Department of Transportation and numerous other federal agencies. The 1-dB Standard for radiofrequency-based services is critical for GNSS. The FCC’s press release refers to conditions placed on Ligado’s application to prevent harmful interference, and GPSIA and its members intend to carefully review the details of today’s order while continuing to vigorously advocate for promoting, protecting and enhancing GPS.”
Ligado Networks President and CEO Doug Smith issued this statement in reaction to the approval.
“Ligado thanks the Commissioners for moving promptly to approve the order regarding our applications. We greatly appreciate their unanimous support as well as the expert engineering analysis determining that a terrestrial network can be deployed in the L-band to advance our country’s economic and security interests while fully protecting GPS. Our spectrum can be very instrumental in the transition to 5G, and we look forward to utilizing satellite and terrestrial services to deploy customized private networks and deliver innovative, next-generation IoT solutions for the industrial sector.”
Positive reactions to the decision
On April 20, the FCC released a compilation of responses to the decision, all of them in support.
Attorney General Bill Barr: “I applaud FCC Chairman Pai’s proposal to make available L-band spectrum, to be used together with C-band spectrum, for deployment of advanced wireless services, including 5G. As I said in my speech at the Center for Strategic and International Studies, swift FCC action on spectrum is imperative to allow for the deployment of 5G. This is essential if we are to keep our economic and technological leadership and avoid forfeiting it to Communist China.” (Statement, 4/16/2020)
Secretary of State Mike Pompeo: “I commend Federal Communications Commission (FCC) Chairman Pai’s draft order that would release the L-Band spectrum. Quick action on this order, in conjunction with the allocation of a portion of the C-Band for 5G, is vital to our national security and will help ensure that the United States is the global leader in advanced technologies such as AI, the Internet of Things, edge computing, and the next generation of telemedicine. Accelerating the deployment of 5G is essential to our country’s growth, and global economic security.” (Statement, 4/16/2020)
Sen. Ron Johnson (WI): “In a time when connectivity is and will continue to be more important than ever, it’s great to see @AjitPaiFCC move forward with freeing up critical spectrum resources for #5G.” (Tweet, 4/16/2020)
Sen. Mark Warner (VA): “As the U.S. works to lead the world in 5G innovation and promote wider high-speed internet coverage, it’s all the more important to put our valuable mid-band spectrum to use. I urge the @FCC to follow the Chairman’s lead and approve Virginia-based @LigadoInsights’s application.” (Tweet, 4/16/2020)
Rep. Billy Long (MO): “I applaud @AjitPaiFCC and the @FCC for taking action to unlock vital L-band spectrum that has been held hostage by bureaucratic slow-walking for far too long. Jobs and 5G is a win-win for the country.” (Tweet, 4/16/2020)
Rep. Doris Matsui (CA): “I called on the @FCC to move forward with new, innovative uses of L-band spectrum to advance 5G. Glad to see the Commission take action on this front today to encourage efficient use of our spectrum.” (Tweet, 4/16/2020)
Former Rep. Bob Barr (GA): “Federal Communications Commission Chairman Ajit Pai’s decision to circulate a draft FCC Order would at long last move forward the process of opening up a segment of mid-band satellite spectrum for commercial use in 5G technology deserves praise. … If adopted by the five-member Commission headed by Pai, the draft Order would tangibly signal to the country and the world that the United States is committed to seize the leadership in deployment of 5G technology, a role China openly covets.” (Statement, 4/16/2020)
American Action Forum: “More good news from the FCC! 5G is incredibly important and this is yet another example of actions that will enable innovation in 5G and support the growing number of connected devices.” (Tweet, 4/16/2020)
American Enterprise Institute Visiting Scholar Mark Jamison: “@FCC approval of Ligado petition should accelerate 5G, bring diversity to marketplace, and increase efficient spectrum use. … Good leadership and bipartisan effort!” (Tweet, 4/20/20)
American Enterprise Institute Visiting Scholar Roslyn Layton: “Kudos @AjitPaiFCC for unlocking more vital mid-band spectrum for #5G. Record of 10 years shows @LigadoNetworks took many steps with agencies and firms to address potential issues with GPS. We must move quickly on 5G!” (Tweet, 4/16/2020)
Citizens Against Government Waste: “The FCC has the engineering expertise to determine the best use of this spectrum and whether alternative uses would cause undue interference. The adoption of the Chairman’s draft order will promote 5G and IoT development, while providing the necessary safeguards for services using adjacent bands, including GPS positioning. … The L-band would not be used at all for the foreseeable future unless the FCC takes action. Freeing up the spectrum requested by Ligado will not only expand the use of 5G, it will also help to prevent other countries, particularly China, from getting ahead of the U.S. in 5G deployment.” (Blog, 4/17/2020)
Competitive Carriers Association: “[We] commend Chairman Pai for circulating a draft order to approve Ligado’s applications, which will make much-needed mid-band spectrum, specifically L-band spectrum, available for terrestrial use. This long-awaited, positive progress comes at a critical time for all Americans, particularly those in rural areas, who are relying on mobile connections and services more than ever before. Mid-band spectrum provides real opportunities for deploying next-generation technologies, and competitive carriers are eager to access this valuable resource to expand and enhance their networks.” (Statement, 4/16/20)
Competitive Enterprise Institute: “Access to spectrum is crucial for our modern economy, connecting everything from radios, to cellphones, to satellites. But for too long, turf-wars between federal regulatory agencies have left spectrum bands largely unavailable for valuable commercial applications. Today’s FCC decision wrests spectrum away from bureaucratic waste and delivers it into the hands of people who will aide our economic recovery and resiliency in the aftermath of the COVID-19 pandemic.” (Statement, 4/16/2020)
CTIA—The Wireless Association: “We’re pleased to see that the FCC has managed to cut through the red tape to make a decision on Ligado. This multi-year process reveals the challenges at play in our nation’s spectrum policy and the need for stronger support for new commercial wireless services. We need to all learn lessons from this process and ensure that decisions on key spectrum bands like lower 3 GHz occur in a more expedited and collaborative manner.” (Statement, 4/16/2020)
FreedomWorks: “Freeing up broadband spectrum will make America a global technological leader and will lead to innovations and developments that will improve quality of life across the country. Chairman Pai and the FCC should be applauded for their work resolving these matters[.]” (Blog, 4/15/2020)
Free State Foundation: “Chairman @AjitPaiFCC has made a commendable decision to act on @LigadoNetworks’ proposal to put L-band spectrum into use for next-gen wireless services. This move takes seriously the @FCC’s responsibility and the urgent need for more commercial spectrum.” (Tweet, 4/16/2020)
Georgetown Law Institute for Technology Law & Policy Distinguished Fellow Gigi Sohn: “This decision was a long time coming, but it’s the right one. … Kudos to @AjitPaiFCC for having the fortitude to move this forward.” (Tweet, 4/16/2020)
Information Technology & Innovation Foundation: “Great to see @FCC taking steps to finally approve @LigadoNetworks waiver for terrestrial use of their spectrum. This will be a boon to industrial IoT connectivity, bringing more productivity, safety, and resiliency for users of the network.” (Tweet, 4/16/2020)
International Center for Law & Economics: “Promoting deployment of 5G & next-gen IoT devices means finding new ways for incumbents to responsibly operate in ever-closer proximity. The @FCC’s Ligado order does that. Credit to @AjitPaiFCC for finding a way fwd that promotes innovation while limiting the risk of interference.” (Tweet, 4/16/2020)
Lincoln Network: “Access to spectrum is an essential feature in any working 5G plan. Frankly, one key barrier in opening up this vital resource is government’s stronghold on ‘beachfront’ spectrum whether they own it or not. … This proceeding has been in regulatory limbo for several years due in large part to government stakeholders’ speculative interference claims regarding GPS-applications. … The FCC’s draft order in this proceeding provides enough protection for incumbents in adjacent bands, adds more competition into the 5G-IoT space, and allows consumers to have more access to broadband. Everybody wins.” (Blog, 4/16/2020)
Mercatus Center Senior Fellow Brent Skorup: “Too often new tech is stalled by FCC regulation and incumbents. Chairman Pai pledged to breathe new life into Sec. 7. It’s great to see Chairman Pai and the FCC act on that pledge, liberalize spectrum, and expedite the deployment of new wireless services.” (Tweet, 4/16/2020)
National Security Institute: “Big move by @FCC Chairman @AjitPaiFCC today to support US 5G availability. This is a key nat sec issue w/ threat posed by China + econ benefits of broad 5G deployment in US.” (Tweet, 4/16/2020)
New America Foundation’s Open Technology Institute: “Kudos to @AjitPaiFCC @FCC for again standing up to Fed agencies trying to hoard spectrum they are not using – or, in this case, which is licensed to @LigadoNetworks! A big plus for #5G wireless ecosystem if it’s built out.” (Tweet, 4/16/2020)
R Street Institute: “If you can change your business model to be more productive and profitable, without hurting anyone else, then regulations shouldn’t stand in your way. Well done, @FCC!” (Tweet, 4/16/2020)
Progressive Policy Institute: “We applaud the FCC’s ongoing efforts to accelerate the deployment of 5G. Repurposing this commercial spectrum for a mobile broadband network is another step in the right direction.” (Tweet, 4/16/2020)
Public Knowledge: “The Chairman’s proposed Order reveals how the FCC has worked to both protect incumbent GPS users while allowing for pro-competitive commercial licensing of spectrum. … Congress has entrusted the FCC to strike the proper balance between the needs of incumbents and the potential benefits to new entrants or new users, and here, the FCC gets it right. In approving Ligado’s license, the FCC has taken an important step forward in its role as the sole arbiter of spectrum disputes and, in this instance, has correctly sided on behalf of the public interest to help deliver the potential of 5G to more Americans.” (Statement, 4/16/2020)
Technology Policy Institute: “Allowing the Ligado spectrum to lie fallow would represent a waste of valuable resources that could provide substantial benefits for consumers in the form of new Internet of Things and other uses. … Failure to approve the Ligado license modifications would have the opposite effect, transferring a large block of spectrum from the commercial sector back to the government. The Commission’s action today will avoid that outcome.” (Statement, 4/16/2020)
Wireless Infrastructure Association: “WIA applauds Chairman Pai for circulating a draft order to approve Ligado’s plans to deploy a nationwide network that would primarily support 5G and IoT services. After years of diligence, study, and discussion, today’s action is further evidence that the FCC bases its decisions on science and engineering. Freeing up more spectrum, especially mid-band spectrum, is vital to 5G deployment. Ligado’s proposal offers an enormous opportunity for infrastructure investment, deployment, and connectivity for Americans across the country right when we need it most.” (Statement, 4/16/2020)
Tells Space Advisory group spectrum issues a concern for all
Speaking to a gathering of space industry leaders, Dr. Brad Parkinson, the original chief architect for establishment of the Global Positioning System, outlined the threats to GPS signals posed by a proposal from Ligado Networks that is before the Federal Communications Commission (FCC).
The proposal, which was initially approved, has been pending since 2011 over concerns about its impact on reception of GPS signals.
When asked why the proposal has been pending for so long, Parkinson speculated a combination of the enormous sums of money potentially involved and difficulties for the FCC in arriving at an equitable solution were to blame.
“I hope they find some spectrum for Ligado,” he said. “Just not the spectrum they are asking for.” Referring to the powerful proposed transmissions in frequencies adjacent to those used by weak GPS signals, he said “You don’t want to put a rock band next to a retirement home.”
“You don’t want to put a rock band next to a retirement home.”
Parkinson was speaking to the National Space Council’s User Advisory Group (UAG). The UAG was chartered under the Federal Advisory Committee Act in December 2017. Membership includes the CEOs of Lockheed, Boeing and other companies with interests in space, the Governor of Alabama, five former astronauts, and other leaders in space technology and policy.
This was the first time the UAG’s agenda focused on GPS and positioning, navigation, and timing issues. Parkinson was invited to discuss the activities of the U.S. National Space-based Positioning, Navigation, and Timing Advisory Board. The UAG was interested in learning from the PNT Advisory Board’s experience, and about some of the issues it has encountered over the 15 years since its establishment in 2004.
Parkinson used the PNT board’s experience with adjacent band compatibility and the Ligado proposal as an example of a particularly thorny issue. He said the Ligado issue was an ongoing concern that the UAG should share.
Brad Parkinson shared his concerns over lack of Ligado decision with the National Space Council’s User Advisory Group (UAG). (Photo: Rebecca Zia)
Also that spectrum issues writ large should be of great concern to all users of space as the competition for spectrum from terrestrial users will continue increase. He called the Ligado proposal “a grave threat to GPS,” especially for aviation and high-precision users.
During the course of the presentation Parkinson asked for the UAG’s support of the PNT Board’s recommendations on the Ligado proposal. He also asked the group to endorse the National PNT Executive Committee’s adjacent band compatibility methodology to any future such proposals.
Parkinson’s presentation concluded with a discussion of how GPS is increasingly being used to support activities in space. It has long been used for booster guidance during the initial phase of space flight.
Relatively recent work using side lobe signals from GPS satellites has caused engineers to recognize a Space Service Volume for GPS. This allows use of the signals for mid-course launch corrections, satellite station-keeping, rendezvous, and potentially trans-lunar navigation.
Iridium Satellite Communications Inc. filed comments to the U.S. Federal Communications Commission (FCC) on Oct. 29 regarding outdated Ancillary Terrestrial Component (ATC) rules.
The company, operator of the Iridium satellite constellation — 66 low-Earth orbit satellites used for global voice and data communication from handheld satellite phones and other transceiver units — called for the rules to be removed by the FCC and replaced by new rules that better serve the spectrum ecosystem.
“Fifteen years ago, the FCC had a vision of satellite companies integrating terrestrial service into their core satellite business as a supplemental service. This vision has been never been successfully achieved — not once,” said Iridium spokesperson Jordan Hassin. “Instead, the result has been a constant whittling away at the rules to the point they have become irrelevant with a whole lot of collateral damage along the way. Given this history, it is appropriate for the FCC to consider the elimination of these outdated ATC rules while taking into account the realities of existing services and users.”
“ATC is an outdated concept that never developed as intended,” Rob McDowell, former commissioner of the FCC added.
The rules have resulted in proposals to get around them, such as Ligado, and significant fights over harmful spectrum interference to incumbent satellite systems. Ligado has sought to waive three gating criteria established by the FCC.
On Aug. 10, the National Space-Based Positioning, Navigation, and Timing (PNT) Advisory Board, the government’s GPS expert board, sent a letter to the National Executive Committee for Space-Based PNT (a multi-agency body that steers GPS policy) that concluded, “We strongly recommend your opposition to the Ligado proposal.”
The letter sprang from a unanimous vote five days earlier to oppose allowing Ligado Networks to use spectrum neighboring the GPS band for terrestrial communications.
Ligado possesses licenses to broadcast on two satellite bands located adjacent to the GPS frequencies. The company has been seeking permission from the Federal Communications Commission (FCC) to repurpose these licenses from satellite-based use to ground-based use from powerful tower transmitters.
Ligado said in May it would lower the power in its proposal for the 1526–1536 MHz band to 9.98 dBW to avoid interference with certified aviation receivers. However, the PNT Advisory Board reiterated its opposition, saying that even if the transmissions’ power was lowered to just under 10 watts, it “will create totally unacceptable interference for a great number of GPS users in the United States.”
From the Letter: “This risk is far too great, and far too many questions remain, for Ligado’s proposal to be approved. While there are many broadband alternatives (Ligado would be a very small percentage of this national asset), there is only one GPS. Any impairment to current and future uses is clearly contrary to the national interest. Therefore, implementation of their recently proposed ~10-watt operating scheme will create totally unacceptable interference for a great number of GPS users in the United States. In fact, despite power limits in their current amended application, it is probable they could still be allowed to increase this power over time. This would be even more destructive to GPS users.
“We believe avoiding degradation over at least 90 percent of the region near Ligado transmitters is the absolute minimum protection for GPS receivers in each class. This would be a hypothetical 90 percent Protection Evaluation. This is not an endorsement of this level since, of course, all users would prefer 100 percent protection. The Department of Transportation (DOT) Adjacent Band Compatibility (ABC) study is the only validated test to verify degradation at various received power levels.
“Those results inform that to insure degradation not exceed 10 percent of the Region (90 percent Protection) for High Performance receivers, either:
Ligado maximum power can be no more than .0036 watts at the 400-meter spacing they had earlier planned. Tolerable power would be 3/10ths of 1 percent of their proposed ~10 watts. Or
the closest spacing of Ligado transmitters is 20,000 meters (over 12 miles) for their proposed ~10 watt power level (see Figure 1).”
Figure 1. The PNTAB strongly believes that 90 percent is the minimum Area Protection Criterion (maximum 10 percent degradation). (Chart: PNT Advisory Board)
The U.S. Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office is soliciting research proposals for the development of a new class of atom-based systems using integrated photonics and trapped atoms to enable high-performance, robust, portable clocks and gyroscopes.
The military researchers are asking industry to develop relatively simple portable photonic integrated circuits (PICs) for high-performance position, navigation and timing (PNT) devices as an alternative to GPS for when satnav signals are not available.
A PIC or integrated optical circuit, similar to an electronic integrated circuit, integrates multiple photonic (having to do with light) functions, providing capabilities for information signals imposed on optical wavelengths, typically in the visible spectrum or near-infrared, 850–1650 nanometers.
A-PhI Program
The Atomic-Photonic Integration (A-PhI) program seeks to develop trapped-atom based, high-performance PNT devices, reducing the complexity of these atomic systems by using PICs. According to the DARPA document, the PICs will replace the optical assembly behind devices such as sensitive and accurate angle sensors and clocks, while still enabling the necessary trapping, cooling, manipulation and interrogation of atoms.
A-PhI aims to demonstrate that compact PICs can replace the optical bench of conventional free-space optics for high-performance trapped-atom gyroscopes and trapped-atom clocks without degrading the performance of the underlying physics package.
Physics
Atomic systems using trapped atoms have the potential to be made portable while maintaining their accuracy due to the atomic trap’s small size and the inherent isolation a trap offers an atomic system from the environment, especially from acceleration.
Currently, these systems are bulky, heavy, and not notably portable, because of the complexity of the optical systems used to create the trap.
In the past, efforts to miniaturize the hundreds to thousands of optical components in such benchtop systems have relied on removing optical elements, miniaturizing the remaining elements, and tightly integrating them in a small package.
The products deliver degraded performance with the need to maintain very tight optical alignment, causing both poor environmental robustness and poor tolerance to design errors. Effective miniaturized atomic systems cannot be achieved at a reasonable cost with this approach.
Recent developments in PIC research suggest that on-chip optical frequency combs based on microresonators, optical frequency synthesis, novel on-/off-chip coupling, wavelength demultiplexers, and on-chip phased arrays for dynamic manipulation of light fields can replace optical systems with readily manufacturable, low-cost chips without the alignment sensitivity of conventional free-space optics.
Gyroscopes
A-PhI also seeks to develop proof-of-concept trapped atom gyroscopes, a matter-wave analog of the interferometric fiberoptic gyroscope. Such a miniaturization effort could generate an order of magnitude improvement in angular sensitivity and dynamic range over current free-space products.
A-PhI hopes to develop portable, high-performance, navigation and timing systems: the miniaturization of the optics of atomic systems without a decrease in performance. Subsequent work, the RFP asserts, will be required to incorporate the necessary compact and robust lasers and electronics to achieve a fully functioning, high-performance, portable PNT system.
