CIRI project to boost resilience of first responders' communication systems

Land mobile radio (LMR) systems are the most commonly used technology for carrying emergency responders’ voice communications. LMR has been in use since the 1930s, but over time it’s grown increasingly sophisticated, offering more advanced functionality—but also new vulnerabilities. One of LMR’s biggest high-tech vulnerabilities is its reliance on the Global Positioning System (GPS) for the timing information used to synchronize the devices participating in an LMR system. Weeks ago, ITI’s DHS-funded Critical Infrastructure Resilience Institute (CIRI) kicked off a new project that will mitigate that vulnerability by finding alternative sources of timing information that LMR systems can use.

“Within communication systems, synchronization and timing of the devices is really important,” explains the project’s principal investigator, Walt Magnussen of Texas A&M University.

In the case of LMR, timing information from GPS satellites is the basis for synchronization of synchronous communications. For example, if a moving device is going to be handed off from the coverage of one LMR repeater site to the coverage of another LMR repeater site, it’s critical for both of those LMR sites to have the same timing information. Today, GPS provides the data reference to make that happen.

However, Magnussen says that “there’s been a lot of concern lately over timing of GPS satellite-based services, for a couple of reasons.”

The first is the physical vulnerability of the constellation of satellites that’s the backbone of GPS. “If there were ever a major war, probably one of the first things that the enemy would do… is send up rockets and disable the entire GPS constellation,” he says.

The second concern is that malicious signal jamming or spoofing could block access to GPS information, or trick systems by providing bad information that appears to come from GPS. “Jamming is becoming more and more and more of a problem,” notes Magnussen.

So what will the new CIRI project do in response?

The team will look at alternative sources of timing and clocking that could conceivably be utilized in the U.S. For example, the precision timing protocol (PTP) runs over fiber, so those signals can’t be jammed or blocked. There are also other satellite systems that provide clocking. The overarching goal, Magnussen says, is “to evaluate what are the best possibilities today and then make recommendations of how we might set up two, three, or four of them in a testbed. And to then go forward with some ongoing testing.”

The researchers on the LMR team are from UIUC and Texas A&M, but a working group of stakeholders are contributing as well. Harris County in Texas and Motorola are among the partners. The project is also working with providers of potential alternative services to help in testing those new services.