Aug 12 2022

DOD Looks to Spectrum Sharing to Support 5G Efforts

The Defense Department is continuing to mature its 5G wireless deployments while experimenting with dynamic spectrum sharing.

The Defense Department has been investing in 5G wireless technology for years, partnering with commercial partners to test use cases at military bases for everything from edge computing to connected vehicles, base security and more.

As the DOD evolves its use of 5G technology, it is also looking to dynamic spectrum sharing technology to ensure it can continue to use both its core military systems without interference and expand its wireless offerings.

In December, the Pentagon launched experiments at Hill Air Force Base in Utah aimed at “demonstrating the potential for dynamic spectrum sharing between airborne radar systems and 5G technologies operating in the 3.3–3.45GHz band,” as a press release notes

That work in the mid-band spectrum as the base extended its testing partnership to mitigate potential military radar interference with 5G.

The DOD has embraced the sharing of wireless spectrum as it seeks to expand its use of 5G in the military arena. “The traditional model of static frequency allocation is not sufficient, and a new model is needed to address the growing demand for access to an increasingly congested and constrained” electromagnetic spectrum, or EMS, according to an October 2020 EMS superiority strategy document from the DOD.

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What Is the DOD’s 5G Strategy?

In December 2020, the DOD released its 5G Strategy Implementation Plan, which followed the release of a high-level 5G strategy in May 2020

The DOD’s 5G strategy calls the newest generation of wireless a “critical strategic technology” that will transform the way militaries operate, noting that 5G promises “orders of magnitude improvements in multiple areas, including speed, connectivity and reduced latency.”

The DOD sees 5G as critical “because it offers higher performance and additional capabilities, particularly for data-driven applications and for machine-to-machine communication,” the implementation plan notes.

“These capabilities will become the foundation for a new networked way of war that brings together sensors and machines that will revolutionize the battlespace and the logistics and support functions behind the front lines.”

RELATED: Learn how agencies can address obstacles to federal 5G deployment.

The Pentagon also notes that it needs “access to a 5G defense industrial base that provides trustworthy 5G technologies.”

There are four lines of effort the DOD is pursuing to achieve its 5G goals. These include promoting technology development; assessing, mitigating and operating through 5G vulnerabilities; influencing 5G standards and policies; and engaging with partners.

“All of us are very excited about the opportunity to demonstrate 5G capabilities and then work with the services to identify how we take it forward,” Amanda Toman, acting principal director of DOD’s 5G to Future Generation Initiative, tells FedTech.

“That’s really the end goal here: How do we ensure that the investments we’ve made — maybe not all of them, but a lot of them — transition to operational end users?” she adds.

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What Is 5G Dynamic Spectrum Sharing and How Does It Work?

Peter Rysavy, president of Rysavy Research and a wireless spectrum expert, notes that, at its core, the idea of spectrum sharing is that multiple entities can use the same spectrum at the same time.

Most spectrum is shared geographically at long distances, which is why wireless carriers in the U.S. and Canada can use the same frequencies for 4G and 5G service, for example. Sometimes, commercial operators are forbidden from using spectrum in certain areas where government agencies operate, in what are known as exclusion zones.

What is more complex, Rysavy notes, is when there are multiple users using the same radio frequencies in the same geographic area. This is the core of many wireless operations, in which schedulers at base stations coordinate how different mobile devices access spectrum in particular coverage areas; they do not interfere with one another.

This is especially pertinent to the DOD, which wants to avoid interfering with commercial 5G services and — much more important, from the Pentagon’s perspective — wants to avoid commercial 5G interfering with military operations and radar systems.

EXPLORE: How the DOD is spreading 5G across the country.

Generally speaking, lower-spectrum bands provide more coverage but support lower bandwidths. Higher-spectrum bands can provide exceptionally fast downlink speeds but do not penetrate buildings or travel as far as lower-spectrum bands. Dynamic spectrum sharing (DSS) technology is designed to alleviate those differences by allowing concurrent uses of 4G and 5G service on the same spectrum band.

When it comes to the DOD, dynamic spectrum sharing is designed to “permit greater spectrum access while preventing harmful interference to legacy systems,” as the DOD puts it in its 5G implementation document.

DSS relies on using a database and sensing approach, Rysavy says. Before a 5G radio or access point can operate, it must connect to and communicate with a centralized database about what frequencies are available at that exact time and in that exact area to prevent interference.

“Instead of, ‘Oh, I operate in a certain chunk of the spectrum and I’m always living there and I’m always in that chunk of the spectrum and it’s 100% mine,’ we’re going to have to share and we’re going to have to share with industry and we’re going to have to figure out how to incentivize this and we’re going to have to figure out how to get the right technologies,” Kelly Fletcher, principal deputy CIO of the DOD, tells FedScoop. “And that’s going to be critical for getting the right data to the right place.”

(5G) offers higher performance and additional capabilities, particularly for data-driven applications and for machine-to-machine communication.”

Department of Defense, 5G Strategy Implementation Plan, Dec. 15, 2020

What Will Spectrum Sharing Help the DOD Accomplish?

In October 2021, the DOD-backed National Spectrum Consortium (NSC), a research and development organization, launched the Partnering to Advance Trusted and Holistic Spectrum Solutions (PATHSS) Task Group.

PATHSS is working with the DOD to “explore sharing solutions to make more mid-band spectrum available for commercial 5G,” specifically in the 3.1–3.45 gigahertz band, and “will identify and develop use cases based on a shared understanding of federal and commercial needs.”

The Pentagon uses about 100 megahertz of spectrum for defense radar systems for air defense, missile and gunfire control, counter-mortar activities, bomb scoring, battlefield weapon location, air traffic control, and range safety. The Pentagon thinks it can auction off the spectrum and share it with commercial wireless providers without sacrificing those capabilities. DSS will help make that possible.

LEARN ABOUT: How federal agencies are leveraging 5G to expanded network capabilities.

Under the DOD’s experiments, 12 vendors are working in three lines of effort — a 5G test bed, 5G applications and 5G network enhancements — and will be working until early 2025 to test “spectrum co-existence system (SCS) solutions between Hill AFB’s private 5G network and airborne radars operating in the band,” as well as other DOD Spectrum Dependent Systems, according to the DOD.

“We must figure out how to share this band if we are to unleash a new wave of network innovation and break the global dependency on compromised 5G networks sold by state-subsidized, antagonistic peer competitors,” Deb Stanislawski, director of the Office of the Under Secretary for Defense for Research and Engineering’s 5G Tranche Prototyping and Experimentation, said in a statement. “These experiments are designed to rally both the Department and our industrial base to win at 5G and beyond.”

Getty Images/Royyimzy

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