Security requires reliability and redundancy. You need both trusted, tested solutions and defense-in-depth in case any one system fails. The United States lacks an alternative to GPS, which constitutes a major national security vulnerability.
Efforts are underway across government agencies including the FCC, Air Force and Department of Transportation (DOT) to address this lack: more than a dozen companies have received grants to test and develop alternative Positioning, Navigation and Timing (PNT) technologies.
One company, NextNav, is pushing aggressively for an FCC rule change to support their solution—and that’s where this national security issue comes home.
The Lower 900MHz Band: The Backbone of Low-Power Security Systems
Security integrators know all about the principles of reliability and redundancy. The industry employs a complex tapestry of solutions to secure commercial and residential buildings.
Many of these devices rely on wireless communications using the lower 900MHz band: precisely the swath of spectrum real estate NextNav wants to reclassify, permitting high-power 5G signals to broadcast in that frequency range and removing protections for the billions of low-power unlicensed devices that currently operate there.
NextNav has consistently claimed that their 5G PNT signals can co-exist with the low-power signals security and other IoT devices transmit and receive in the lower 900MHz band, but robust technical analysis from both Plum Consulting and Pericle Communications challenges this assertion.
In fact, Pericle estimates that high-power PNT transmissions would block or degrade low-power communications up to 60 percent of the time.
Tellingly, while NextNev disputes this analysis, they also petitioned the FCC to remove interference protections for unlicensed spectrum incumbents.
Real-World Consequences to 900MHz Band
How would harmful interference impact security integrators? Get ready for a lot of service calls, unhappy clients, and potentially life-threatening failures. The lower 900MHz band is used by devices ranging from alarm panels and intrusion detection sensors to smoke and carbon monoxide detectors. 5G interference in the band could cause them to fail at crucial moments and degrade their performance over time.
The impact of this interference may be obvious: an alarm that fails to sound, or a panic button that doesn’t work in an emergency. There may also be insidious effects that don’t look like interference at all.
For instance, a leak sensor battery projected to last 10 years could fail after two or three. Why? Because the sensor was desperately trying to get a signal out through a wall of 5G interference, causing increased transmit cycles and higher-power operations to run the battery down before its time. To the customer, this would look like a broken promise from the integrator and the manufacturer. For integrators, it would be a costly, impossible-to-troubleshoot service problem that would only mount over time.
As organizations including the International Association of Chiefs of Police, the Association of Public-Safety Communications Officials-International, and the National Sheriffs’ Association have noted, destabilizing the unlicensed low-power security devices currently operating in the lower 900MHz band would endanger American lives. The continued uncertainty around the fate of this spectrum also threatens American businesses, including integrators and device manufacturers. But perhaps worst of all, it’s simply not necessary.
Alternative Paths to 900MHz Band
There are many promising PNT alternatives currently under evaluation by the FCC, DOT, and other government agencies. The DOT has issued multiple grants to companies to develop solutions using terrestrial RF, including NextNav – but also solutions based on Low Earth Orbit (LEO) satellite systems, time-over-fiber distribution, and map matching/map tracking.
Though NextNav has repeatedly urged them to pick a winner, the FCC has pursued a course of evidence-based engineering. Six months after NextNav’s initial rule change petition, the agency opened a broad Notice of Inquiry investigating a wide range of PNT alternatives.
Some of the options on the table, such as the Broadcast Positioning System developed by NAB and UrsaNav’s eLoran solution, use the same terrestrial PNT approach as NextNav, but without displacing unlicensed devices.
In fact, NextNav doesn’t technically need to displace these devices either. Though the company has asked to be granted 26MHz of spectrum, the NextNav solution only truly requires 500 KHz. It also doesn’t need to operate in the lower 900MHz range: their proposed solution could piggyback on existing 5G spectrum.
The rule change they are seeking isn’t a requirement for the development of a secure PNT alternative, but it would give them a windfall of suddenly extremely valuable 5G spectrum.
The Cost of Reclassification
Hundreds of American companies and millions of consumers could bear the cost of a NextNav coup. IoT device manufacturers have relied on the lower 900MHz band for 30 years. Billions of devices are designed from the ground up for low-power operation in this spectrum: unlike NextNax’s PNT solution, they cannot simply operate in another band. If their performance degrades too much, installed devices would need to be ripped out and replaced with wholly new designs, which don’t yet exist.
It’s difficult to fathom the reputational damage both security integrators and their vendor partners could face as a result of this rule change. Indeed, even the threat of a rule change is already impacting manufacturers. Faced with uncertainty, they must weigh whether to invest in new and existing product lines operating in the lower 900MHz band.
Call for Engagement and Advocacy
This risk is no longer merely theoretical. NextNav has been granted an experimental license to test their PNT solution in the San Jose area, using a limited number of 5G base stations and adhering to power constraints of 60dBm ERP. This isn’t precisely real-world testing-– the experimental license is power-limited, geographically constrained, and do not replicate the scale, density, or long-term operating conditions of a nationwide commercial deployment—but it is a crucial turning point in the rulemaking process.
We need San Jose-area integrators to be the industry’s eyes and ears. Document wireless device anomalies: connection issues, dropped packets, delayed signals, unexpected battery failures. If harmful interference is occurring, we must investigate and report the issues it causes.
NextNav is required to inform the unlicensed community in the impacted area of potential interference risks and provide clear mechanisms for reporting issues. Presumably, that is forthcoming. In the meantime, many industry consortia, including Z-Wave Alliance, the Security Industry Association, RAIN Alliance, LoRa Alliance, Wi-Fi Alliance, Wi-SUN Alliance, and others are actively working with the FCC, DOT, and other government agencies to advance the responsible development of PNT alternatives.
Engage with these organizations: follow them across social media and subscribe to updates to learn about developments and advocacy opportunities. Together, we can ensure resiliency for America’s PNT systems and existing security systems alike.
Avi Rosenthal is chairman of Z-Wave Alliance.
