In 6G telecom research today, a crucial portion of wireless spectrum has been neglected: the Frequency Range 3, or FR3, band. The shortcoming is partly due to a lack of viable software and hardware platforms for studying this region of spectrum, ranging from approximately 6 to 24 gigahertz. But a new, open-source wireless research kit is changing that equation. And research conducted using that kit, presented last week at a leading industry conference, offers proof of viability of this spectrum band for future 6G networks.

In fact, it’s also arguably signaling a moment of telecom industry re-evaluation. The high-bandwidth 6G future, according to these folks, may not be entirely centered around difficult millimeter wave-based technologies. Instead, 6G may leave plenty of room for higher-bandwidth microwave spectrum tech that is ultimately more familiar and accessible.

The FR3 band is a region of microwave spectrum just shy of millimeter-wave frequencies (30 to 300 GHz). FR3 is also already very popular today for satellite Internet and military communications. For future 5G and 6G networks to share the FR3 band with incumbent players would require telecom networks nimble enough to perform regular, rapid-response spectrum-hopping.

Yet spectrum-hopping might still be an easier problem to solve than those posed by the inherent physical shortcomings of some portions of millimeter-wave spectrum—shortcomings that include limited range, poor penetration, line-of-sight operations, higher power requirements, and susceptibility to weather.

Pi-Radio’s New Face

Earlier this year, the Brooklyn, N.Y.-based startup Pi-Radio—a spinoff from New York University’s Tandon School of Engineering—released a wireless spectrum hardware and software kit for telecom research and development. Pi-Radio’s FR-3 is a software-defined radio system developed for the FR3 band specifically, says company co-founder Sundeep Rangan.

“Software-defined radio is basically a programmable platform to experiment and build any type of wireless technology,” says Rangan, who is also the associate director of NYU Wireless. “In the early stages when developing systems, all researchers need these.”

For instance, the Pi-Radio team presented one new research finding that infers direction to an FR3 antenna from measurements taken by a mobile Pi-Radio receiver—presented at the IEEE Signal Processing Society‘s Asilomar Conference on Signals, Systems and Computers in Pacific Grove, Calif. on 30 October.

According to Pi-Radio co-founder Marco Mezzavilla, who’s also an associate professor at the Polytechnic University of Milan, the early-stage FR3 research that the team presented at Asilomar will enable researchers “to capture [signal] propagation in these frequencies and will allow us to characterize it, understand it, and model it... And this is the first stepping stone towards designing future wireless systems at these frequencies.”

There’s a good reason researchers have recently rediscovered FR3, says Paolo Testolina, postdoctoral research fellow at Northeastern University’s Institute for the Wireless Internet of Things unaffiliated with the current research effort. “The current scarcity of spectrum for communications is driving operators and researchers to look in this band, where they believe it is possible to coexist with the current incumbents,” he says. “Spectrum sharing will be key in this band.”

Rangan notes that the work on which Pi-Radio was built has been published earlier this year both on the more foundational aspects of building networks in the FR3 band as well as the specific implementation of Pi-Radio’s unique, frequency-hopping research platform for future wireless networks. (Both papers were published in IEEE journals.)

“If you have frequency hopping, that means you can get systems that are resilient to blockage,” Rangan says. “But even, potentially, if it was attacked or compromised in any other way, this could actually open up a new type of dimension that we typically haven’t had in the cellular infrastructure.” The frequency-hopping that FR3 requires for wireless communications, in other words, could introduce a layer of hack-proofing that might potentially strengthen the overall network.

Complement, Not Replacement

The Pi-Radio team stresses, however, that FR3 would not supplant or supersede other new segments of wireless spectrum. There are, for instance, millimeter wave 5G deployments already underway today that will no doubt expand in scope and performance into the 6G future. That said, the ways that FR3 expand future 5G and 6G spectrum usage is an entirely unwritten chapter: Whether FR3 as a wireless spectrum band fizzles, or takes off, or finds a comfortable place somewhere in between depends in part on how it’s researched and developed now, the Pi-Radio team says.

“We’re at this tipping point where researchers and academics actually are empowered by the combination of this cutting-edge hardware with open-source software,” Mezzavilla says. “And that will enable the testing of new features for communications in these new frequency bands.” (Mezzavilla credits the National Telecommunications and Information Administration for recognizing the potential of FR3, and for funding the group’s research.)

By contrast, millimeter-wave 5G and 6G research has to date been bolstered, the team says, by the presence of a wide range of millimeter-wave software-defined radio (SDR) systems and other research platforms.

“Companies like Qualcomm, Samsung, Nokia, they actually had excellent millimeter wave development platforms,” Rangan says. “But they were in-house. And the effort it took to build one—an SDR at a university lab—was sort of insurmountable.”

So releasing an inexpensive open-source SDR in the FR3 band, Mezzavilla says, could jump start a whole new wave of 6G research.

“This is just the starting point,” Mezzavilla says. “From now on we’re going to build new features—new reference signals, new radio resource control signals, near-field operations... We’re ready to ship these yellow boxes to other academics around the world to test new features and test them quickly, before 6G is even remotely near us.”

This story was updated on 7 November 2024 to include detail about funding from the National Telecommunications and Information Administration.

Since 5G began its rollout in 2018 or 2019, fifth-generation wireless networks have spread across the globe to cover hundreds of millions of users. But while it offers lower latency than precursor networks, 5G also requires more base stations. To avoid installing unsightly equipment on more and more shared spaces, Japanese companies are developing transparent glass antennas that allow windows to serve as base stations that can be shared by several carriers.

Because 5G networks include spectrum comprising higher frequencies than 4G, base stations for 5G networks serve a smaller coverage footprint. Which means more base stations are needed compared to 4G. Due to a lack of installation spots and the high cost of rolling out 5G networks, carriers in Japan have been sharing mobile infrastructure.

Last month the Tokyo-based communications company JTower announced the deployment of the new glass antenna, created in part by glassmaker AGC (one of the world’s largest) and the mobile carrier NTT Docomo. The first was installed on a window in Tokyo’s Shinjuku district.

The product is “the world’s first antenna that turns a window into a base station that can be attached to a building window inside and turn the outdoors into a service area without spoiling the cityscape or the exterior appearance of the building,” says Shota Ochiai, a marketing manager at AGC.

NTT Docomo reports that it uses transparent conductive materials as the basis for its antenna, sandwiching the conductive material along with a transparent resin, the kind used in laminated windshields, in between two sheets of glass.

“I don’t think the idea for using transparent conductive materials as an antenna existed before,” said AGC’s Kentaro Oka in a company statement. “The durability of the antenna was significantly increased by placing the conductive materials between glass.”

The transparent antenna can be engineered according to the thickness of the glass to reduce the attenuation and reflection of the radio signals being absorbed and emitted by the window-sized device. “The glass antenna uses our proprietary technology to smooth out the disruption in the direction of radio waves when they pass through a window,” says Ochia.

A brief history of the window antenna

Branded WAVEANTENNA, the antenna is installed on the interior surface of windows. Apart perhaps from its cabling, the WAVEANTENNA is an otherwise inconspicuous piece of equipment that is often tucked out of sight, placed near the top or otherwise at the edges of a window.

It is compatible with frequencies in the 5G Sub6 band—meaning signals that are less than 6 gigahertz (GHz). Sub6 antennas represent critical portions of a 5G deployment, as their lower frequency ranges penetrate barriers like walls and buildings better than the substantially higher-bandwidth millimeter-wave portions of the 5G spectrum.

An earlier version of the product was launched in 2020, while a version that could handle sharing by multiple cell networks was introduced last year, according to AGC. The company says its antenna is optimized for frequencies between 3.7 and 4.5 GHz bands, which still allows for substantial bandwidth—albeit not comparable with what an ideal millimeter-wave 5G deployment could reach. (Millimeter waves can deliver typically between 10 and 50 GHz of bandwidth.)

The glass antenna can help expand 5G coverage as infrastructure sharing will become more important to carriers, AGC says. Besides increasing the number of locations for base stations, the device makes it easier to select the appropriate installation height, according to Ochiai.

AGC has also applied 5G glass antennas to automobiles, where they can help reduce dropped signals. The company reports that users include Halo.Car, an on-demand EV rental service in Las Vegas that relies on high-speed networks for remote drivers to deliver cars to customers.

Telecom engineers and researchers face several challenges when it comes to testing their 5G and 6G prototypes. One is finding a testbed where they can run experiments with their new hardware and software.

The experimentation platforms, which resemble real-world conditions, can be pricey. Some have a time limit. Others may be used only by specific companies or for testing certain technologies.

The new IEEE 5G/6G Innovation Testbed has eliminated many of those barriers. Built by IEEE, the platform is for those who want to try out their 5G enhancements, run trials of future 6G functions, or test updates for converged networks. Users may test and retest as many times as they want at no additional cost.

Telecom operators can use the new virtual testbed, as can application developers, researchers, educators, and vendors from any industry.

“The IEEE 5G/6G Innovation Testbed creates an environment where industry can break new ground and work together to develop the next generation of technology innovations,” says Anwer Al-Dulaimi, cochair of the IEEE 5G/6G Innovation Testbed working group. Al-Dulaimi, an IEEE senior member, is a senior strategy manager of connectivity and Industry 4.0 for Veltris, in Toronto.

The testbed was launched this year with support from AT&T, Exfo, Eurecom, Veltris, VMWare, and Tech Mahindra.

The subscription-based testbed is available only to organizations. Customers receive their own private, secure session of the testing platform in the cloud along with the ability to add new users.

A variety of architectures and experiments

The platform eliminates the need for customers to travel to a location and connect to physical hardware, Al-Dulaimi says. That’s because its digital hub is based in the cloud, allowing companies, research facilities, and organizations to access it. The testbed allows customers to upload their own software components for testing.

“IEEE 5G/6G Innovation Testbed provides a unique platform for the service providers, and various vertical industries—including defense, homeland security, agriculture, and automotive—to experiment various use cases that can take advantage of advanced 5G technologies like ultra low latency, machine-to-machine type communications and massive broadband to help solve their pain points,” says IEEE Fellow Ashutosh Dutta, who is a cochair of the working group. Dutta works as chief 5G strategist at the Johns Hopkins University Applied Physics Laboratory, in Laurel, Md. He also heads the university’s Doctor of Engineering program.

“The IEEE 5G/6G Innovation Testbed creates an environment where industry can break new ground and work together to develop the next generation of technology innovations.”

The collaborative, secure, cloud-based platform also can emulate a 5G end-to-end network within the 3rd Generation Partnership Program (3GPP), which defines cellular communications standards.

“Companies can use the platform for testing, but they can also use the environment as a virtual hands-on showcase of new products, services, and network functions,” Dutta says.

In addition to the cloud-based end-to-end environment, the testbed supports other architectures including multiaccess edge computing for reduced latency, physical layer testing via 5G access points and phones installed at IEEE, and Open RAN (radio access network) environments where wireless radio functionality is disaggregated to allow for better flexibility in mixing hardware and software components.

A variety of experiments can be conducted, Al-Dulaimi says, including:

• Voice and video call emulation.
• Authentication and encryption impact evaluation across different 5G platforms.
• Network slicing.
• Denial-of-service attacks and interoperability and overload incidents.
• Verifying the functionality, compatibility, and interoperability of products.
• Assessing conformity of networks, components, and products.

The testbed group plans to release a new graphical user interface soon, as well as a test orchestration tool that contains hundreds of plug-and-play test cases to help customers quickly determine if their prototypes are working as intended across a variety of standards and scenarios. In addition to basic “sanity testing,” it includes tools to measure a proposed product’s real-time performance.

The proofs of concept—lessons learned from experiments—will help advance existing standards and create new ones, Dutta says, and they will expedite the deployment of 5G and 6G technologies.

The IEEE 5G/6G testbed is an asset that can be used by the academics, researchers, and R&D labs, he says, to help “close the gap between theory and practice. Students across the world can take advantage of this testbed to get hands-on experience as part of their course curriculum.”

Partnership with major telecom companies

The IEEE 5G/6G Innovation Testbed recently joined the Acceleration of Compatibility and Commercialization for Open RAN Deployments project. A public-private consortium, ACCORD includes AT&T, Verizon, Virginia Tech and the University of Texas at Dallas. The group is funded by the U.S. Department of Commerce’s National Telecommunications and Information Administration, whose programs and policymaking efforts focus on expanding broadband Internet access and adoption throughout the country.

“The 3GPP-compliant end-to-end 5G network is built with a suite of open-source modules, allowing companies to customize the network architecture and tailor their testbed environment according to their needs,” Al-Dulaimi says.

The testbed was made possible with a grant from the IEEE New Initiatives Committee, which funds potential IEEE services, products, and other creations that could significantly benefit members, the public, customers, or the technical community.

Watch this short demonstration of how the IEEE 5G/6G Innovation Testbed works. youtube