Researchers Demo THz Band Comms Aimed at 6G

Researchers have demonstrated a system allowing signal generation and signal analysis at 300 GHz with 2 GHz bandwidth.

While it’s not yet known what 6G wireless mobile communication will look like, work is under way around the world to try and define what’s beyond 5G, especially research into the terahertz (THz) frequency band that could form the basis of the networks, as well as the materials.

Aiming to progress the research in the communications channels, Rohde & Schwarz, the Fraunhofer Institute for Telecommunications, Heinrich Hertz Institute, HHI and the Fraunhofer Institute for Applied Solid State Physics IAF have demonstrated a wireless transmit and receive system operating between 270 and 320 GHz, with further frequency extensions for potential 6G bands already in preparation.

6G research is already underway in industry and academia. While 5G introduces mmWave frequencies with wider bandwidths for higher data rates and enables new applications such as in wireless factory automation (industrial IoT) and for autonomous vehicles, the aim of 6G is to push the boundaries of transmission bandwidths even higher.

Although it is not clear yet which technologies 6G will entail, it is already apparent that frequency bandwidths need to be further increased to enable terabit class data rates. Wide contiguous frequency blocks can only be found at sub-THz and THz bands, i.e. in the frequency range above 100 GHz. The utilization of THz frequencies for 6G is estimated to become commercial in the next 8 to 10 years.

Rohde & Schwarz said it has already presented a demonstrator setup for 300 GHz to customers, which it displayed at the European Microwave Week conference in Paris last month as part of a workshop on mmWave and THz wireless communication; the system consisted of 300 GHz transceiver frontends, the R&S SMW200A vector signal generator and R&S FSW43 signal and spectrum analyzer as well as units for synchronization of transmitter and receiver.

Set up for 300 GHz measurements
The set up for channel propagation measurement experiments up to 300 GHz (Source: Rohde & Schwarz)

Involved in the current collaboration are the Fraunhofer HHI and the Fraunhofer IAF. The HHI works on signal processing, synchronization between transmitter and receiver, and system integration. The IAF contributes with high-performance millimeter-wave transmitter and receiver modules. The joint research targets frequencies above 100 GHz, where the primary focus is on the D-band (150 GHz) and the H-band (300 GHz). Carrier frequencies above 300 GHz are still the subject of fundamental research. A first demonstrator resulting from the research collaboration is a system allowing signal generation and signal analysis at 300 GHz with 2 GHz bandwidth. The signal can be arbitrary modulated for conducting transmission experiments with ‘beyond 5G’ candidate waveforms, which are appropriate for THz communication or for performing channel propagation measurements.

Dr. Taro Eichler, wireless market segment manager at Rohde & Schwarz, said with its tools for research during the early stages of 6G development., “This allows us to engage in in-depth discussions with customers and to monitor the technical and market trends long before the commercialization of 6G. We are excited to partner with Fraunhofer HHI and IAF, benefiting from their leading expertise in development of mobile communication networks and systems, infrastructure and standards.” Dr. Michael Schlechtweg, head of business unit for high frequency electronics at Fraunhofer IAF, said, “As one of the first global providers of chipsets and electronic components capable of reaching already now the high frequencies required by 6G, we are collaborating with valued partner Rohde & Schwarz at the very cutting edge of technology.” Rohde & Schwarz said its 6G research is built on its background in mobile communications test and measurement, beginning from the early stages of 2G all the way up to and including 5G and beyond. Last year, Rohde & Schwarz and NTT DOCOMO set up the world’s first ultra-wideband channel sounder for mobile communications exceeding 100 GHz. They conducted radio wave propagation experiments at frequencies up to 150 GHz. The measurement parameters include the propagation loss (degree of attenuation of radio waves), power delay profile (arrival time of radio waves), angular profile (indicator of spread of radio wave arrival). In this experiment, the test system was placed in an anechoic chamber. The two companies were able to confirm they can measure and analyze the shielding effect of the human body, applying signals up to 150 GHz and in all common 5G frequency bands currently in use or under consideration.