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4 hours ago
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5G cellular networks could form the basis of a low-cost Earth-based global navigation satellite system (GNSS) back-up. GNSS options, like GPS, provide reliable positioning, timing, and navigation services but are vulnerable to jamming and spoofing attacks. Proponents of the 5G-based alternative, which would be more secure against such attacks, say the technology could be widely available to users equipped with existing receivers within the next three years.
NextNav, based in Reston, Virginia, has trialed the 5G system in a lab earlier this year and is currently awaiting a decision by the Federal Communications Commission (FCC) to proceed with proof-of-concept testing in cooperation with a major mobile carrier. In addition to being indispensable for navigation and positioning, GPS and other GNSS networks underpin many indispensable technologies including financial transaction time-stamping and power grid synchronization.
Despite its critical importance in today’s world, GPS, developed by the U.S. military in the 1980s, is extremely vulnerable to intentional and accidental disruption. Jamming and spoofing has become a common occurrence in and around countries such as Ukraine and Israel, and widespread GPS disturbances have been reported following intense space weather events. Various GPS alternatives are being developed, including low Earth orbit satellite constellations or devices measuring the strength of the planet’s gravity. Most of these alternatives require significant investment in technology development and maturation.
NextNav, on the other hand, claims that its technology could be seamlessly integrated into existing 5G networks with only minor tweaks to the FCC rules governing the use of radio spectrum.
“There is no special equipment that would have to be integrated in order to provide the coordinates,” says Renee Gregory, NextNav’s Vice President of Regulatory Affairs. “Our solution is really an application layer on top of the 5G network.”
How 5G Signals Can Provide Positioning Data
NextNav’s system uses the 900 megahertz radio-frequency band to transmit a positioning reference signal, which is a new type of signal designed for sharing positioning data through 5G networks. (The 900 MHz band is currently used for tolling, freight-tracking, and Internet of Things applications.) The technique relies on the same triangulation principle as GNSS-based positioning—it just uses two 5G base stations to geolocate a user instead of two satellites.
The band used to transmit the signal has a longer wavelength than GPS satellite signals (GNSS use three frequency bands at roughly 1,176 MHz, 1,227 MHz, and 1,575 MHz. The longer wavelength enables the signal to better penetrate buildings and remain reliable even in densely built-up urban environments where satellite signals frequently become too weak and inaccurate. The close proximity of the cell towers to the user devices means the received signal is much stronger than the signal from GPS satellites, and therefore less easily disrupted by jamming and spoofing attacks.
Retired Rear Admiral David Simpson, who served in the past as the FCC’s chief of public safety and home security, says that a widely available terrestrial back-up system could greatly enhance the resilience of position, navigation, and timing (PNT) services for consumers, businesses and defense forces worldwide.
There have been many examples of low-end terrestrial systems interrupting the accuracy or availability of space-based PNT, Simpson says, and it’s obvious depending on a single system is no longer possible. “It’s happening now, it’s happening in and around Ukraine. It’s happening in and around Israel and the Gaza strip.”
Commercial systems integrated into existing 5G networks would, Simpson adds, offer major advantages, as they could run on existing network infrastructure, taking advantage of end-user devices already in wide use.
“We need solutions that don’t require new user equipment,” Simpson says. “That’s the costliest part of the overall system. If we have a solution that requires completely new equipment, it will only reach about 5 percent of the potential user population and will ultimately not solve the problem.”
NextNav is one of several companies exploring the possibilities of integrating PNT distribution into existing communication networks. Israeli-based Asocs conducted a small-scale trial of a similar technology in cooperation with The German airline group Lufthansa in 2023.
NextNav, founded in 2007, is currently providing an altitude positioning service for first responders based on measurements from barometric sensors integrated in many consumer smartphones. The company’ also operates a system relying on a network of beacons to provide a back-up positioning service in two dimensions. The new 5G-based system would integrate both components into a single seamless service, says John Kim, NextNav’s VP of Technology Development.
“Mobile network operators upgrade their networks for multiple reasons to expand their coverage and improve their mobile services,” Kim says. “Once approved by the FCC, the 900 MHz band could be easily included into network upgrade cycles and mobile device chipsets that would make it into the hands of consumers through standard upgrade cycles.”
After a successful lab demonstration earlier this year in Palo Alto in California, NextNav is now planning to test a proof-of-concept network in San Jose, which will validate the lab results and field test using actual 5G signals in a large-scale environment.
