The Federal Communications Commission (FCC) faces a very serious choice that will impact the critical functionality of key satellites tied to the Global Positioning System (GPS), including those used for communications and weather. Ligado Networks, a commercial communications company, seeks to harness spectrum in a way that may interfere with these crucial systems — systems upon which America’s military and its economy both rely. As a former vice chairman of the Joint Chiefs of Staff, I can confidently say that the FCC needs to pause this process, which began in 2011, and seek a path that unequivocally ensures the wide-ranging interests of the nation are not compromised for a limited business opportunity.
In a world where connectivity is vital to everyday life, spectrum bands — the atmospheric electro-magnetic frequencies through which signals are passed — are growing in demand. The spectrum is not a uniform entity. Certain frequency bands have attributes that lend themselves to specific applications. Deconfliction of band usage is necessary to ensure that certain frequencies and signal power do not disrupt adjacent functions, like a person struggling to speak over the roar of a crowd.
Ligado seeks to launch a new 5G communications service using a mid-band frequency that has the dual benefit of working well in both urban and rural settings; 5G signals are challenging to manage, given that frequency ranges, which work well in cities, are far different than what is practical in less-developed areas. The middle part of the band — precisely where GPS, satellite communications and weather satellites communicate — is the “compromise sector” position that accommodates both regions. The problem is that ground-based 5G signals would be so strong that they would overwhelm other pre-existing systems’ ability to receive their respective data streams.
To provide some perspective, the received GPS signal strength on Earth is only 1/10th of 1 millionth of 1 billionth of a watt. The workaround to this challenge is precisely what other communications firms are employing — avoiding the GPS bands and using a dual-frequency approach to serve urban and rural markets.
We must not underestimate what is at stake with the FCC’s pending decision. Our military, economy and way of life depend on these technologies. Navigation signals vector air-defense fighters that protect our homeland, guide commercial aircraft, help rescue vehicles to navigate, and enable everyday citizens to find directions. Precision timing from GPS empowers a broad range of functions, from ATMs to gas pumps to banking transactions. Satellite communications empower first responders, military personnel and remote outposts. Weather data from satellites inform numerous decisions, from military and intelligence operations that impact our national security to the weather and storm forecasts that help protect our property and personal safety.
Much is at stake in the FCC’s determination. Many government agencies, including top military commanders, have opposed approval of the mid-band use in this manner; they understand the potential risk better than anyone.
According to reports on the issue, the risk of interference is broadly recognized by industry as well. Ligado reached legal settlements with Garmin and John Deere in 2015, and with Trimble Navigation, NovAtel and Topcon in 2016, regarding coexistence of Ligado’s 5G application and the interests of these companies. However, lingering issues remain for many of the actors; Garmin and Trimble filed ex parte notices in 2019 expressing concern and disagreement with Ligado’s most recent claims of non-interference.
To Ligado’s credit, it has proposed mitigating the negative impact of its spectrum usage by decreasing the transmission power of its antennas. However, this is a matter of physics: Signal power is essential to achieving the desired data capacity and speeds. To put this in perspective, a GPS set antenna would have to contend with a Ligado signal that is at least 1.7 billion times stronger than the received GPS signal. A substantial number of key GPS users — including NTIA, GPSIA, RNTF, Boeing, Trimble, Iridium, AAM, ASRI, AOPA, AccuWeather, AWCIA, and NENA 9-1-1 Association — are on record that harmful interference concerns remain unaddressed.
As someone who spent my entire career in military service, I can speak with personal conviction regarding the need to ensure that core functions remain viable for our men and women in uniform. Military operations are fundamentally reliant on GPS, satellite communications and timely weather data. It is impossible to overstate the importance of these functions. A servicemember who is putting everything on the line should not face increased risk because of business interests — especially when alternate spectrum and technical means are available to the telecom sector.
Recent news reports suggest that the FCC is poised to finally approve Ligado’s application after nearly a decade of application denials and opposition from the military, past FCC leaders, Congress, the first-responder community and many industries. I add my voice to those of current Defense Department leaders who warn about the unacceptable harm such a decision would precipitate. I also applaud the bipartisan concerns voiced recently by leaders of the Senate and House Armed Services Committees, as well as the House Committee on Transportation and Infrastructure.
The potential for damage is great. Once approved, there are no mechanisms to limit the commercial development of the allocated spectrum. Then, the burden to identify and mitigate interference will be placed upon the users of adjacent frequencies, military and civil alike.
Spectrum allocations must weigh the interests of many over those of a single company.
Paul Selva retired in 2019 as a four-star general who served in the U.S. Air Force for 39 years. His last active-duty position was as vice chairman of the Joint Chiefs of Staff, the nation’s second highest-ranking military officer and highest-ranking Air Force officer, from July 2015 to August 2019.