“When doing experimental research towards 6G, the equipment needed are extremely costly as they push the technology envelope to new heights,” says Professor Ari Pouttu, 6G-FUWIRI project consortium leader at the University of Oulu. “The status as a national roadmap infrastructure is on one hand evidence of the high-quality research infrastructure that we have been building since 2015 and, on the other hand, it will improve the probability of getting funded for new features of the infrastructure.” The project is a joint effort with Tampere University, Aalto University and VTT Technical Research Centre of Finland Ltd.
Revolutionizing 6G capabilities and integrated solutions
The uniqueness of the experimental platform at the University of Oulu derives from a combination of set-ups which allow for example the exploration of high-frequency communications and virtual reality features among other key components of next-generation wireless systems. “Our sub-THz devices can be used to demonstrate super interesting features of emerging 6G, namely sensing and imaging the environment with the communications signals,” Pouttu says. “Another example is our 144 camera environment that can be used to provide 3-D models of humans or even locations thus giving rise to novel holographic communications.”
Positioning accuracy, and imaging and sensing capabilities, integrated into the same system, are expected to revolutionize the use of wireless connectivity in a wide range of applications. “The most obvious case, I suppose, are autonomous platforms, may they be drones, cars, forklifts, trains, excavators or harvesters,” Pouttu envisions. “In these platforms, the new capabilities intertwined with powerful AI at the edge provided by 6G, will create autonomy or at least seamless remote operation capabilities boosting the productivity of such investments. When looking from human perspective, the 6G signal not only conveys data but can also be used for imaging and sensing the environment and this combined with power-ful AI tools may indicate the birth of a so-called 6th sense, that of predicting the near future.”
The evolving infrastructure takes into account a variety of expected requirements in future integrated solutions which are deemed crucial for evaluating complete systems. As an example, it reflects the major change that took place with the introduction of millimeter wave (mmW) frequencies in the 5G system, which revolutionized the measurement and evaluation principles of telecommunication systems. “The 5G mmW system is specified so that RF performance is solely measured over the air (OTA) -methods, while conductive measurements have been used with previous telecommunication generations,” says Dr. Marko Leinonen, Research Director. “The OTA measurements were introduced as a standard measurement method due to increased parallelism in RF signal paths and antennas in the 5G system. The OTA measurements will play a significant role in the future 6G system, as well, with highly integrated RF solutions without any possibility for conductive testing at operation frequen-cy of the 6G system. The sub-THz operational frequencies with sub-millimeter wave lengths will set still unknown new requirements for 6G OTA testing. Therefore, we are already working with OTA measurements up to 330 GHz. New upcoming measurement equipment will enhance our modulated signal capability significantly towards datarates required by future 6G systems.”
At the same time, radio channel characterization and meas-urements are pivotal to understanding how sub-THz frequencies, which are beyond the currently used 5G frequencies, can be utilized for 6G communication purposes. “The new frequencies, which are expected to be used for 6G communications, are spanning from 5G millimeter wave frequency bands of 40 GHz up to 300 GHz,” says Professor Aarno Pärssinen who leads the Devices and Circuit Technology strategic research area at 6G Flagship. “These sub-THz frequencies have not been previously used for telecommuni-cation purposes, and thus, we are eager to explore them in different use-cases and physical environments.”
The usage of sub-THz frequencies is also a key to supporting the envisioned extreme data rates up to 1 Tbps in 6G communications. The high-data rate 6G signal bandwidth will be tens of GHz and it needs to be allocated sub-THz frequencies, where enough frequencies are available. “In practice, 6G communication will be based on highly directive wireless links, where the beam signal power is highly focused in order to extend the available link range,” Leinonen says. “We have already OTA tested some lens antennas supporting the 300 GHz frequency band, and those have been developed within the 6G Flagship program.”
However, the sub-THz radio circuit developments are constrained by the maximum operation frequency of the manufacturing processes of RFIC, which will set limitations for RF transmission power from the RFIC. Additionally, the noise performance of RF amplifier will be degraded with higher operational frequency of the system. “6G sub-THz radios will require integrated antennas inside of RFICs in order to maximize transmission power from the RFIC,” Pärssinen notes. “The latest and upcoming additions to our trial environment support fresh research ideas and design innovations to merge the sub-THz RF and antenna designs.”
State of the art experimentation and 5G integration
A large part of 6G Flagship’s experimental research is still related to the upcoming releases of the 5G technology. 6G Flagship’s open 5G Test Network is a carrier-grade mobile network where the team functions as network operator providing e.g. SIM-cards. “Due to local operation, it represents the emergence of a new operator business model dubbed micro operator,” Pouttu says. “Being also fully controlled by us, any testing - may it be applications, devices or testing tools - is straightforward to organize. We are also constantly upgrading standard-compliant base stations and UEs to allow state of the art experimentation in ICT technologies and also in eHealth, transportation, energy, Industry 4.0 and so forth. To allow experimentation in these domains, we are integrating 5G technologies to e.g. drones, cameras, cars, excavators, robots, and AR/VR devices.”
6G Flagship’s research teams are currently working in numerous EU Horizon 2020 projects where different sites in Europe are connected together to take global testing of 5G solutions to different vertical businesses. The recently launched H2020 Hexa-X European flagship project towards 6G intensifies these efforts. “Companies and projects of all sizes can benefit of our insights on inter-related technologies - 5G-enabled mobility, augmented and virtual reality, and machine-to-machine communication,” Pouttu concludes. “We invite you to join us for experiments to see how the joint innovation can strengthen your business, products and services in ICT and beyond."
Read more 6G oriented stories in our 6G Waves magazine.
Last updated: 17.9.2021