How Lasers Can Light the Path to Spectrum Sharing

By: NTIA

Lidar, a sensing method that uses light waves, has been around since the 1960s when the United States developed it as a military technology for defense and aerospace uses. But the advent of publicly-available lidar data has made it a crucial tool for helping radio scientists inside and outside of government better predict where objects like trees and buildings will likely interrupt a wireless signal. These more accurate predictions can enable more opportunities for government and non-government users to share the airwaves.

By measuring the time it takes for a laser pulse to return to its sending point, a lidar system measures and records the shapes and heights of buildings, trees, and other surface features to create a very precise three-dimensional model of an environment. Spectrum sharing relies on these propagation models to predict signal strength between two points, such as a cell phone and a government system like an air traffic control radar.  

With high-precision information about the environment, radio scientists can better understand the layout and orientation of obstructive objects — known as “clutter” — that can decrease an interfering signal’s strength, increasing the ability of multiple systems to share the same spectrum.

This spring, NTIA’s Institute for Telecommunication Sciences (ITS) led an interactive technical seminar to share best practices for using lidar data to inform spectrum modeling and analysis activities. Participants included spectrum engineers from the U.S. Navy, Defense Information Systems Agency, the Federal Communications Commission, and MITRE.

“If we want to protect federal systems from newly deployed 5G systems in the spectrum sharing scenario, we need to better understand how clutter impacts the strength or direction of a wireless signal traveling through it,” says Billy Kozma, ITS propagation engineer and head of the U.S. Delegation to the International Telecommunications Union Radiocommunication Sector (ITU-R) Study Group 3 (Radiowave Propagation). “The more information we have on the physical geometric layout of an environment, the more precisely we can develop our propagation modeling capabilities.”

Increasing demand for spectrum points to the need for increasingly efficient ways to share it, and Dynamic Spectrum Sharing is a key pillar of the National Spectrum Strategy. “Sharing our methods with the larger DoD spectrum stakeholder community puts power into everybody’s hands, so that everybody can work toward greater accuracy and precision in a cost-effective manner,” Kozma explains.

The workshop is one example of how ITS shares best practices with other federal agency spectrum engineers and analysts. Curious to learn more? ISART 2024, the International Symposium on Advanced Radio Technologies that ITS is hosting June 10-13 in Denver, is all about the impact of clutter on modeling and planning spectrum dependent systems and spectrum sharing. Registration for ISART closes June 7, 2024.