Avi Rosenthal: A Risky Tradeoff in the Race for GPS Backup

The United States urgently needs a resilient backup to GPS. Threats to this critical system are rising: Jamming and spoofing incidents are increasing precipitously, and the absence of a robust backup system represents a real and growing vulnerability.

The Federal Communications Commission is currently considering a proposal from NextNav that would authorize high-power terrestrial transmissions in the Lower 900 MegaHertz (MHz) band. At first glance, this may sound like an efficient way to advance a ground-based positioning, navigation, and timing (PNT) solution. In reality, it would fundamentally alter one of the most widely used layers of U.S. wireless infrastructure.

The current tenants of the disputed spectrum

For more than 40 years, the Lower 900 MHz band has supported low-power, unlicensed communications used across a vast range of applications. Sub-gigahertz signals offer reliable, low-power connectivity over long distances and through walls: qualities essential for security, safety, and automation systems.

Today, this spectrum supports billions of deployed devices, including home security systems, fire and carbon monoxide detectors, water leak sensors, smart locks, medical alert systems, utility meters, tolling infrastructure, and industrial monitoring equipment. In many cases, they serve life-safety functions where reliability is not optional.

They are also unlicensed. Known as “Part 15” devices, these solutions are designed to operate at low power in a shared environment. They all rely on the Lower 900 MHz band’s predictable spectrum conditions and Part 15 interference protections to deliver consistent performance over years—often a decade on a single battery.

NextNav’s proposal would introduce a fundamentally different operating model into this environment: high-power, wide-area transmissions designed for 5G and PNT services. They are also pushing to remove current interference protections for Part 15 devices.

Risk assessment: Likelihood and impact

The debate over NextNav’s proposal has largely centered on the likelihood of interference. NextNav argues that interference problems would be rare and easily overcome. Experts from Z-Wave Alliance, the Connected Devices for America Coalition (CDAC), Wi-Fi Alliance, Wi-SUN Alliance, LoRa Alliance, RAIN Alliance, the Security Industry Association (SIA), and the International Bridge, Tunnel & Turnpike Association (IBTTA) have all submitted ex parte letters and technical analyses warning of serious interference risks. 

But likelihood is only one side of a risk matrix. We must also consider impact—and the impact would be severe. 

Even intermittent interference can degrade performance in subtle but meaningful ways—reduced range, delayed transmissions, increased retries, and accelerated battery drain. For example, a technical analysis from Pericle Communications found that outdoor security devices such as motion detectors would need to increase signal strength by 500 time to compete with 5G traffic under NextNav’s proposal. 

As Pericle points out, the Lower 900 MHz unlicensed ecosystem includes “panic buttons, carbon monoxide detectors, fire alarms, wireless microphones used by firefighters, and security cameras,” and other life-saving devices, many of which would be rendered inoperable by interference. The nationwide degradation of these systems adds up to a systemic risk.

The cost of miscalculation

If NextNav is wrong—and every low-power industry association is right—the only remedy is hardware replacement. These devices cannot be patched or upgraded over the air to operate under fundamentally different RF conditions, as analysis from Pericle and Kapsch Trafficom affirms. Entire systems would need to be redesigned and replaced.

A group of stakeholders representing smart utility devices, Generac, Itron, and Landis+Gyr, estimated that the direct replacement costs for their currently deployed sub-GHz wireless devices would exceed $100 billion. That’s just one small corner of the Part 15 landscape: The total cost to taxpayers would dwarf the amount the federal government has invested in PNT research thus far.

Granting NextNav’s proposal risks losing critical applications in lower 900 MHz spectrum—but doesn’t guarantee a resilient PNT alternative.

In a report filed with the FCC in February 2026, PNT expert Mark Sturza concluded that NextNav’s solution would only function reliably in dense deployment areas and “does not scale to provide an alternative (backup) to GPS suitable for critical aviation, maritime, or long-haul trucking applications, or rural areas.” He also noted that the system is not inherently tied to the Lower 900 MHz band and could be deployed in other spectrum. NextNav is asking for free reign in the sub-GHz spectrum, but offering little in return.

Seeking a better path forward

Over the past year, I’ve spoken with regulators, lawmakers, analysts, and industry leaders about these issues. They often ask the same question: given the risks, why is this proposal still under consideration?

The answer lies in the urgency of the problem. GPS vulnerabilities are real, and the pressure to act is growing. But urgency should not lead us to accept a solution that introduces new vulnerabilities while failing to solve the original problem.

The United States has already identified a broad range of alternatives. In a 2025 report to the FCC, the National Telecommunications and Information Administration outlined 14 categories of PNT solutions and 51 potential providers. These include terrestrial systems such as Broadcast Positioning System (BPS) and enhanced long-range navigation (eLoran), as well as approaches based on satellite augmentation and time-over-fiber distribution.

Notably, NextNav’s proposal is the only one that requires reallocating spectrum already in use by critical services. That is a significant tradeoff, particularly when other solutions offer broader geographic coverage, built-in redundancy, and the ability to leverage existing infrastructure without disruption.

The need for GPS backup is urgent, but not every proposal moves us closer to that goal. It is time to move on from NextNav’s proposal and focus on solutions that can truly deliver the resilience the nation requires.

Avi Rosenthal serves as the Chair of Board for the Z-Wave Alliance, a standards development organization dedicated to developing and advancing Z-Wave technology as an open and internationally recognized ITU standard (G.9959) for smart home and IoT solutions, and managing partner at BlueConnect Partners, a consulting firm serving the consumer products and connected device sectors. He has more than 25 years of experience in the connected devices industry, bringing insights and resources for developing, manufacturing, and marketing smart home and IoT products and services. Learn more at www.z-wavealliance.org. This Expert Opinion is exclusive to Broadband Breakfast.

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