Terahertz waves used to transmit 8K video

Researchers from Osaka University, working together with Rohm Co, have employed terahertz waves from the 300 GHz band as an information carrier that allows for the wireless transmission of uncompressed, 8K ultrahigh-definition (UHD) video with a data rate of 48 Gbps.

The next-generation 6G mobile communication standard beyond the present 5G system is expected to transmit 8K and other UHD videos with low latency and low power consumption. But since the data rate of UHD video is very high, it is necessary to compress the data when being transmitted wirelessly using microwaves or millimetre waves, which results in delays and increased power consumption. Thus, the development of a technology for uncompressed wireless transmission of UHD video is required.

“In general, the higher the frequency, the greater the capacity to transmit information, with terahertz waves having a higher frequency than microwaves and millimetre waves,” said Osaka Assistant Professor Julian Webber. “We focused on terahertz waves in the 300 GHz band.”

The researchers configured a two-channel terahertz transmitter (Tx) by modulating the output of a laser pair with wavelengths in the 1.55 um band, which was set so that the frequency difference was in the 300 GHz band, with an 8K video signal source using an intensity modulator and converting it into terahertz waves using an ultrafast photodiode (PD).

As the 8K video signal source, the team prepared commercially available uncompressed full-resolution 8K video content by Astrodesign, which is output as a four-channel 12 Gbps signal, and used an on-off keying (OOK) modulation signal that was combined to form a two-channel 24 Gbps signal. After the wirelessly transmitted terahertz waves were detected by sensitive terahertz coherent receivers (Rxs) using resonant tunnelling diodes (RTDs), they were split from the two channels into four channels and connected to an 8K monitor via HDMI cable. Using this system, uncompressed 8K video (equivalent to 48 Gbps) was successfully transmitted wirelessly using terahertz waves.

“In general, such ultrahigh-speed data transmission experiments are performed using multilevel modulations via a complex system with high power consumption that uses offline or online digital signal processing,” said team leader Associate Professor Masayuki Fujita. “The present real-time demonstration, which uses the simplest OOK format, shows the capability of ultra-broadband terahertz waves.

“Our achievement demonstrates the usefulness of terahertz waves and is expected to accelerate research and development activities for the realisation of Beyond 5G and eventually 6G. Such uncompressed wireless transmission technology for UHD video will enhance the quality of telemedicine and telework, which are directly related to social issues, and will lead to the advancement of physical-cyber fusion by utilising the big data of UHD video.”

Image caption: Photograph of the real-time 8K experiment. Foreground shows the two photodiode transmitters (Txs) and two resonant tunnelling diode receivers (Rxs) with 8K television (TV) screen in the background.

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