The millimeter-wavelength bands from 20 GHz to 300 GHz are expected to be called in to use as they supply enormous theoretical bandwidth advantage for high data-rate communications.

Researchers from CEA-Leti (Grenoble, France) and engineering consultancy Siradel SA (Saint Gregoire, France) have discussed the application of 140 GHz radio to several beyond-5G applications in paper prepared for the 6G Wireless Summit. These applications include: high-capacity backhaul, enhanced hot-spot kiosks and short-range device-to-device communication. The applications are characterised by a need for data transfer rates typically greater than 100 Gbps per cell or per link, Leti said.

“Challenges to using D-band wireless communication include free-space wave-propagation losses that increase with the square of the frequency and have to be compensated for using high-gain antennas. That entails severe constraints on antenna directivity and alignment,” said Jean-Baptiste Doré, a CEA-Leti scientist and one of the authors of the paper, in a statement.

D-wave propagation can be blocked or strongly attenuated by walls, trees or even windows and even free-space transfers require high-gain antennas. To address this challenge, CEA-Leti is designing RF technologies with high directivity and an electronically steerable antenna.

“For device-to-device communication, we have demonstrated that is possible to reach multi-Gbps throughput using spatial multiplexing and a simple RF architecture,” Doré said. “The main outcome is that with the proposed mixed-signal, analog and digital, the required power delivered by transistors is limited to microwatts which makes CMOS technologies possible.”

However CMOS silicon is not expected to be able to reach the maximum frequencies required so CEA-Leti is also investigating new materials and devices, and RF circuit designs for the D-band and higher frequencies.

The paper was titled: “Technology roadmap for beyond-5G wireless connectivity in D-band.” And was due to be presented at the 6G Wireless Summit. The event was due to take place in March but was turned into a virtual due to the Covid-19 pandemic.


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