European Telco Body Looks Into Terahertz For Future 6G Comms

The European Telecommunications Standards Institute (ETSI) has unveiled a new Industry Specification Group (ISG) to undertake preliminary work on the potential use of terahertz frequencies in 6G communications.

According to ETSI, the newly launched ISG THz already comprises 31 participating companies and recently held its initial meeting to decide upon priorities for work on terahertz frequency bands as a candidate technology for 6G, which is still at an embryonic stage of development.

The group is set to focus on two categories of use cases: mobile applications involving high data rate requirements such as virtual or augmented reality; and applications requiring both communication and sensing capabilities, such as holographic telepresence and interactive robotics.

According to ETSI, the attraction of terahertz frequencies (which could mean anything between 100GHz and 10THz) is that there is a huge amount of bandwidth available, with the International Telecommunication's Union (ITU) identifying 137GHz of available spectrum between 275GHz and 450GHz as suitable.

At such frequencies it is also possible to achieve extremely high data rates – up to several terabits per second, according to a separate report [PDF] from the US Department of Energy – while the small wavelength of the signals allows for compact and miniaturized devices and antennas, ETSI claims.

However, there are challenges in using terahertz frequencies for communication, as the ITU also admits. These include that molecular absorption and spreading losses are much greater for transmissions in the terahertz range compared to the millimeter wave (mmWave) frequencies (between 24GHz and 40GHz, depending on who you listen to) that have been adopted for high-speed 5G services in many territories.

Not surprisingly, areas of focus for the ISG THz will include analysis of specific propagation effects for terahertz communications, including molecular absorption and specific considerations regarding scattering and reflections. It will aim to define the target scenarios and specific frequency bands of interest.

Despite the obstacles, ETSI claims that several European and international initiatives focused on 6G research and development currently anticipate that terahertz wavelengths will play a part in the next generation of cellular networks, and that the ISG THz group will therefore be working in support of future 3GPP standardization work.

However Bill Ray, VP Analyst for Emerging Technology & Trends at Gartner, said he believes 6G will be much more about spectral agility, or the ability to take advantage of spectrum bands based on what frequencies happen to be available, similar to what is happening with the 6GHz spectrum in Wi-Fi 6E and 7.

“The push to higher frequencies is driven by engineers, not end users who have already demonstrated a decided lack of interest in mmWave,” Ray said.

“The only reason ETSI is looking at terahertz frequencies is because they are technically possible, not because anyone wants them,” he added. “Terahertz signals are indeed awful for communication over any distance beyond a few centimetres.”

ETSI states that terahertz communication has certain challenges in common with millimetre wave technology. This will provide opportunity for the ISG THz group to collaborate with others within ETSI, one working on millimetre wave (ISG mWT) and the other on Reconfigurable Intelligent Surfaces (ISG RIS), it said.

Reconfigurable Intelligent Surfaces? No, us neither. It apparently refers to surfaces of some engineered material which is reconfigurable so as to control the propagation of electromagnetic waves by altering the properties of the surface.

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Paolo Pescatore, analyst and founder of PP Foresight, told us that it is too early to be thinking much about 6G when 5G is yet not widely available, but it is still important to conduct research into what is feasible.

“An open collaborative approach towards frameworks and standards is in the best interests for all stakeholders,” he said.

Nokia is just one company that is involved in early research into 6G, as part of the German-funded 6G-ANNA project. Earlier this year, it said it expects 6G standardization work may start in 2025, leading to the first 6G specification in 3GPP Release 21 by 2028, and possible commercial deployments around 2030. ®