Latest on the scene is the Fraunhofer Institute for Integrated Circuits (Fraunhofer IIS) 5G Bavaria automotive testbed in Rosenheim, Germany. Comprising a closed 5G network but covering public roads, the new testbed is designed to bridge the gap between existing commercial public mobile networks and the development testbeds used for standardization or preliminary research work.

“The primary focus is on testing transmission technology and evaluating transmitter and receiver components under real conditions,” says Martin Speitel, head of Fraunhofer’s automotive group. “Determining essential performance parameters such as latency, reliability and throughput provides valuable insights into a given application’s quality of service and user experience.”

The new facility covers more than 15km² and was funded by a Bavarian state government keen to provide a test area for its automotive OEMs. As such, the testbed complements a sister facility for Industry 4.0 applications that Fraunhofer IIS runs in Nuremberg, three hours to the north.

Speitel expects the new testbed to find customers in a broad range of development streams and related fields. He notes that although a state permit is still required for driverless vehicle testing, Germany’s federal government recently took its first steps toward permitting Level 4 vehicles on public roads, albeit with restrictions in place.

“We are in a public area, so one target is clearly autonomous vehicle research, but we are also targeting other users, not only the OEMs,” says Speitel, a 20-year veteran of Fraunhofer. “It may also be of interest to application developers for in-car entertainment systems, if you want to see how it behaves in a certain network configuration. Hybrid radio may be another topic of interest and the testbed may also address [the test needs of]insurance companies.”

Got it covered Discussions about the 5G Bavaria testbed began four years ago. Speitel says that considerable work went into finding suitable sites on which to place the 5G infrastructure, but acknowledges that the ongoing pandemic and chip crisis combined to delay the project, which opened for testing in spring 2022. Although four 5G antennae were initially considered, the current network architecture comprises three Ericsson 5G antennae, connected by fiber cable, to create a test area of seven sectors.

“We opted to go into the southern part of Rosenheim, from the city center down to the A8 highway,” Speitel explains, noting the city’s long history as an industrial hub for the communications industry. “With that, we can cover a rural area, an urban area with bridges and underpasses and the highway itself. A small part of the highway can be used for our tests, an area that is prone to traffic jams.”

Speitel believes that the site’s unusual combination of public roads and the latest commercially available 5G infrastructure will help it stand out from the crowd.

“I think we are the only site with a testbed under full control in a public environment,” he says. “Other testbeds are either private and linked to an OEM, or they have other restrictions. We are using the same equipment that Telekom, O2 or Telefónica are buying, and we are contracted to get the new applications and new features that become available, as soon as possible.”

Ericsson will upgrade 5G Bavaria’s infrastructure according to the 5GAA release roadmap. Release 15 is the current standard, with 16 to come and 17 currently in the standardization phase. “We cannot be ahead of what is commercially available,” Speitel stresses. “That’s the nature of this testbed because we are buying commercial equipment. You may be the first to get it, but it must be available.”

Road test Speitel says that the target for the facility is less about prioritizing commercial operation and more to do with exploring “collaborative research projects and new ideas, or proving existing ideas”. As a state-funded enterprise, the pressure to recoup its investment costs in rental fees is reduced, leading to user fees that Speitel describes as “reasonable”.

In return for their outlay, customers will be guaranteed that they are the only ones working in the test area at that time. “Because we have full control, we can configure it to a certain extent – by adjusting power levels, for example,” Speitel explains. “We can adapt it to special test cases and can monitor what’s going on in the network. Customers can test in a controlled environment, but a public one.”

Working remotely and without the need for a central control center, Fraunhofer IIS experts can configure the network and assist with test activities. The level of customer support offered by Speitel’s colleagues will vary on a case-by-case basis, from conducting test drives on behalf of a client to simply handing over a SIM card for them to do their own tests. For particular applications, such as artificial intelligence or image processing, the institute could even pull in experts from other disciplines to support the automotive team. No client has yet requested workshop space, but Speitel says Fraunhofer IIS can adapt its offering to customers’ support needs.

Further possibilities are offered by the presence of a Telekom public 5G network in Rosenheim, paving the way for handover tests between this and 5G Bavaria’s closed network. There’s even C-V2XSim, a simulator that can be used in conjunction with the testbed, enabling users to assess the performance of cellular vehicle-to-everything on virtual streets before heading into the real world, or see whether real-world issues can be reproduced in simulation.

At the time of writing, Fraunhofer was taking measurements in the network and fine-tuning the site, building its knowledge base with information such as the precise boundaries of the coverage area and where handovers from one base station to the next typically take place. As Speitel readily admits, the facility is still very new and, although Fraunhofer IIS has already received inquiries from potential users, it’s too early to say how the testbed will evolve once users start arriving in Rosenheim.

“We don’t yet know what ideas the customers will bring to us,” he sums up. “If someone wanted to connect a roadside unit to the testbed, for example, it’s doable. The future is open, and it’s exciting.”