6G Flagship’s Evolving Experimental Platform Pushes the Technology Envelope to New Heights

6G  Flagship’s evolving experimental platform forms a core part of the Finnish research infrastructure for future wireless technologies  –  6G-FUWIRI – which was recently selected to the National Roadmap for Research, Development and Innovation. The granted status and funding from the Academy of Finland for basic radio technology research resonates with 6G Flagship’s  endeavours in beyond 5G and 6G innovation and eases the financial burden of reaching towards higher frequencies above 100 GHz.

“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.