EAB Q&A: Urgent actions needed to protect resilient PNT amid spectrum sharing and GNSS policy shifts

What urgent policy or industry actions are needed to protect and advance resilient PNT services amid spectrum sharing debates and GNSS regulation changes?

In my article, “Is There a Silver Bullet for Resilient PNT?”, I addressed the confusion caused by the numerous and diverse industry initiatives now being offered. Industry is understandably motivated to provide resilient PNT capabilities, but each also wants the government to pick its solution and make policy decisions accordingly. Spectrum sharing decisions that favor a single service provider may harm others in a crowded space, and so are difficult or impractical, as we have seen with the decades of litigation associated with LightSquared/Ligado and the spectrum surrounding the GPS L1 frequency. 

Not everyone can win that competition, and as I noted at the end of the article, “Unless our government accepts responsibility, there will be no PNT silver bullet for domestic CI. Experience shows that industry will not solve this problem alone.”

For years, I have advocated that U.S. PNT technology policy be managed and services acquired holistically as vital dual-use civil/military capabilities. For the civilian community, that means making sure the national leadership understands the reliance our domestic critical infrastructure (CI) has on constant access to precise PNT to maintain continuity of operations across all CI sectors in the face of well-known threats.  The leadership must then decide whether that reliance deserves proactive attention by the government to ensure PNT continuity is not disrupted.

Several years ago, I suggested that significant regulatory changes were needed in how civil PNT services were handled throughout U.S. CI. Both the Departments of Homeland Security and Transportation were assigned responsibility in Presidential Directives for finding a GPS backup to PNT services in domestic CI. I won’t revisit that years-long debate (which is still unsolved), but I will revive the framework of the suggestion.

The DOT has overall responsibility for civil agency PNT matters, and DHS frequently cites lack of regulatory authority as a limitation on its ability to encourage compliance in the CI sectors for which it is responsible. Therefore, I suggested that the National Space-Based PNT Executive Committee consider regulatory changes to expand the definition of the Transportation CI Sector to include safe and uninterrupted transportation of all elements contributing to domestic critical infrastructure.  In addition to current air, road, rail, and oil/gas pipeline transportation, add the interstate transport of information (Communications and IT), electrical energy (Power Grids), economic transactions (Finance), crops (Agriculture), and water, as well as domestic maritime services (U.S. Coast Guard) and possibly emergency response services in the case of large disasters. 

In the spirit of the former Interstate Commerce Commission, which years ago was replaced by a DOT Surface Transportation Board (primarily concerned with freight rail), the DOT may then seek expansions to STB authorities and membership to address the PNT dependencies and vulnerabilities affecting those fundamentally transportation-oriented activities vital to the viability of all U.S. critical infrastructure sectors.

— Jules McNeff
Overlook Systems Technologies

Regulatory authorities must quickly approve and protect RF spectrum allocated for new PNT capabilities, particularly for emerging low-Earth orbit (LEO) constellations. These systems offer clear advantages in signal strength, geometric diversity and resilience against jamming and spoofing. Without timely and well-defined spectrum authorization, along with strong adjacent-band protections, the deployment of GNSS receivers capable of supporting these constellations will be delayed.

On the industry side, LEO PNT developers must urgently finalize signal structures and release Interface Control Documents, enabling GNSS receiver manufacturers to begin implementation, validation and system integration.

— Miguel Amor
Hexagon Positioning Intelligence

Interesting and timely question.  I’ve written quite a few pieces and papers on the need for resilient and robust PNT services.  If I were to point to a single thing that has held the US (and many other countries in the world back (except for China) it is lack of strong mission-oriented, dedicated leadership.  It has been said that the definition of a committee is an entity with four or more legs and no brain. It is time to designate a single entity and a single office and a single person as responsible for ensuring resilient PNT services to US critical infrastructure so as to maintain the safety and security and economic benefits these these sectors support.  Some wise men once came up with the idea that a government must “provide for the common defense” and “support the general welfare.” Resilient PNT is essential to achieving both.

In addition to the lack of empowered, centralized PNT leadership, a key problem that has impeded progress towards resilient PNT is the lingering belief by many that given enough time and money and spectrum, GNSS-sole means is achievable and that all non-GNSS systems (affectionately called “Legacy PNT Systems”) can be discontinued. In fact, over the years budget justifications for GNSS systems have used discontinuance of ground-based systems as “a benefit” to balance out the costs of establishing, updating, and operating GNSS.

Engineering System Designer should never fall in love with their solutions.  The mission, i.e., the needs of the customers must always remain their first concern.  After many years, integrity was added to the list of PNT metrics; coverage has yet to be officially added. Yet, even today, there remains confusion regarding the availability metric and the associated risks.  For GNSS systems, the risk of losing required PNT metrics should always be considered “1.0”, and therefore, for critical infrastructure users and providers, require effective and implementable contingency/continuity of operation plans.  Loss of PNT performance (accuracy, availability, integrity, continuity, and coverage) the using GNSS can no longer be considered a “Black Swan” event.

— Mitch Narins
Strategic Synergies

In the February 2025, Professor Washington Ochieng proposed the following question to the GPS World EAB.

When we discuss the security of GNSS/PNT systems, we nearly always focus on interference — i.e., meaconing, intrusion, jamming or spoofing. However, GNSS/PNT systems are embedded in systems of systems that also offer many other opportunities for cyberattacks. What should we do about it?

I have thought for some time about why this is an issue.  This is an interesting question, and the answer should be straightforward – but it’s not.  For whatever reason, it seems many in the “cyber community” believe they are different, somehow, and apart.  This has been apparent to me in dealing with those in the cyber community regarding their PNT dependencies and vulnerabilities going back to the creation of USCYBERCOM as a separate combatant command within the DoD.  Those in the cyber world seemingly do not see a need to recognize and account for the intersection of PNT and cyber as mutually integral parts of a broader Information Technology ecosystem.  Yet, across that entire IT ecosystem, PNT is simultaneously an enabler and a product of IT functionality, as communications and data systems could not operate without it, and it is likewise vital to IT users in executing their diverse missions.  Ultimately, interference effects, whether from jamming or spoofing in their various forms or from digital intrusions of one kind or another, disrupt vital elements of that IT ecosystem.  Our national and economic security depend on the continuous, reliable, uncorrupted functioning of IT services enabled by and delivering PNT information. So, a straightforward but difficult to implement answer is that we need formal education programs to routinely inform the leaders of industry and government (and the public) of the ubiquitous, vital role of positioning and timing (what we call PNT) throughout all the systems-of-systems whose operation depends on the IT ecosystem – and how to tell if something is amiss.

— Jules McNeff
Overlook Systems Technologies

Read more responses to Professor Ochieng’s question.