NIST researches generic deployables for wireless access

Researchers at the National Institute of Standards and Technology’s Public Safety Communications Research Division are testing deployable communication systems that could serve as mobile networks in regions that lack wireless infrastructure or are suffering from congested network traffic.

When responders don’t have access the carrier-based terrestrial LTE network for connecting to all the different services they use, one of the solutions is to “bring your own service,” said Maxwell Maurice, electronics support technician at the division and lead engineer on the project.

The team, which is working in collaboration with the Homeland Security Department’s Science and Technology Directorate, got approval from AT&T FirstNet to conduct experiments on federal land near Gypsum, Colo. They started by using ground-based and truck-mounted deployable systems to create ad-hoc interoperable networks.

Deployable systems involve a computer capable of voice, texting and video streaming services and wireless technology such as Wi-Fi, LTE or an internet-of-things standard or protocol, Maurice said. Antenna masts extending 7 to 14 feet above the ground are also required. These systems let users host their own Wi-Fi access technology so that they can connect to their broadband services without having to rely on the internet.

Several vendors make deployable systems, but NIST’s goal is to make generic technologies that are independent and completely self-contained readily usable by all first responders.

The team used several methods to test the deployable systems.

The easiest way to check connectivity is simply looking at signal strength indicated by the phone’s network bars -- or just using the phone to see if the signal is strong enough, Maurice said.

A more data-driven method involved the use of a spectrum analyzer to measure the power of the channel that the deployable system provides and demodulating the LTE system to get more data. Team members wore backpacks outfitted with spectrum analyzers and used a computer to query them every 10 seconds to determine the signal. They walked around the area -- a plateau in a secluded part of western Colorado -- sometimes in line of sight of the deployable system and sometimes not.

The results were suboptimal, so the team began testing a drone carrying a commercial LTE network system. It weighed less than five pounds and hovered 400 feet above ground for 15 minutes at a time, enabling line-of-sight connection from almost everywhere, which allowed for better connectivity and a bigger coverage area -- about half a mile from the aerial platform.

“The frequencies that a lot of these systems are on -- as well as the bandwidths that you’re dealing with -- are really ideal when you have line of sight,” Maurice said. “That’s why you see cellular communications equipment on towers…. When you have an obstruction, like hills, trees or foliage or anything, it really degrades the signal.”

The team has been testing deployable systems’ performance since last March and visited the site six or seven times in 2019. This year, they will focus on interoperability, rather than the wireless coverage area.

“This work is forward-looking research, several years away from commercial availability,” said Sam Ray, electronics engineer at NIST. “We are focused on untethered UAS with self-contained communications systems, using multiple technologies,” he said. Current solutions, including those implemented by FirstNet, “use mostly tethered solutions with backhaul to core components using LTE,” he added.

“It’s all about first responders and what they need, so everything is focused on enabling [them] to do their mission and allowing them to be connected,”  Ray said.

About the Author

Stephanie Kanowitz is a freelance writer based in northern Virginia.


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