While most semiconductor developers are looking to improve the 5G experience through industry power devices, some manufacturers are looking beyond the horizon of 5G and into 6G networks. To work toward 6G standards, several semiconductor developers have focused their attention on creating design standards for transmitting larger data files through wireless communication.
Real-time photo of the experiment that was able to display an 8K video through the terahertz-based wireless transmission system. Image used courtesy of Osaka University
In collaboration with ROHM Semiconductor, researchers at Osaka University recently announced that they have developed an industry-first device that operates in the terahertz spectrum to transmit large, uncompressed 8K videos uninterrupted within a 300 GHz bandwidth.
Terahertz Research at Osaka University
The research team, led by associate professor, Dr. Masayuki Fujita from the graduate school of engineering at Osaka University, began their efforts by studying terahertz frequencies.
Terahertz frequencies combine the penetrating capabilities of radio waves and the large bandwidth structure of light, which presents itself as a strong candidate for next-generation wireless communication technology.
There are a few challenges that surface from operating at terahertz frequencies. For one, current electronics are not equipped to handle terahertz wavelengths and their associated transmission delays and power consumption. Since terahertz frequencies are right at the threshold of what conventional devices can receive and transmit, large data strings such as 8K videos require video compression.
Terahertz waves bridge the gap between industry-standard frequencies and light wavelengths. Image used courtesy of Osaka University
Compressing videos involves encoding information using fewer bits than the video’s original representation. However, this process often results in lower quality and clarity. To avoid this, the research team implemented a device that utilized terahertz waves to send large amounts of data with minimal signal interruption over a wireless connection.
Tapping Into an On-Off Modulation Technique
Researchers reached their goal of high-frequency operation using an on-off modulation technique. This is the simplest form of amplitude-shift keying modulation, which is denoted as an “ON” state—with a binary signal of 1 when a presence is detected—and an “OFF” state—with a binary signal of 0 and no presence detected.
This technique was then combined with two main components to create a transmission IC, resonant tunneling diodes (RTD), and photonic crystals.
Resonant Tunneling Diodes
Resonant tunneling diodes are a simple low-power component that resonates in terahertz frequencies. This diode is able to act as both a transmitting and receiving device and is useful for small-scale integration. RTDs are very compact and are also capable of ultra-high-speed operation because of their ability to establish quantum tunneling effect.
A wave is emitted when a voltage is placed across an RTD. However, if the voltage rises above a set threshold, the terahertz wave dies out. This is a minor design constraint since most targeted communication devices will operate in low voltages but at higher frequencies.
Photonic Crystals
Characterized by their periodic dielectric structures, photonic crystals can be manipulated to control various light wavelengths. This allowed the research team to design multiplexing communication systems, sensors, and a controllable terahertz oscillator.
The wireless transmission depicted in the block diagram below is received by the two-way RTD, which makes its way through the encoding process. A standard HDMI converter can then read it.
Block diagram of the achieved wireless transmission. Two channels at 24Gbit/s are split into four channels that travel to an 8K monitor via an HDMI cable. Image used courtesy of Osaka University
A video released by Osaka University shows how the researchers sent signals from one transmitter to a receiver and vice versa in order to display an 8K ultra-high-definition video. By using RTDs at terahertz frequencies, the device was able to send the video wirelessly without interruptions.
Only when a sheet of metal was placed in front of the transmitter/receiver was the signal lost and the data untransmittable.
A Powerful Research Partnership With ROHM
ROHM has been putting together the blueprint for terahertz-based technology since 2011, creating RTDs, terahertz modules for LiDAR, and minimized utility sensors. These devices allowed ROHM to develop a device that supports 1.5Gbits/s with claims to be able to reach 30Gbits/s in the future.
Building on ROHM’s foundation and internal research from years past, Osaka University researchers were able to reach the next step in wireless transmission. The resulting IC wirelessly transmitted uncompressed full-resolution 8K video for the first time at 48Gbits/s.
Discussing the importance of his team’s research, Dr. Masayuki Fujita explains, “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 utilizing the big data of UHD video.”
Osaka University is continuing research with a terahertz detector that will allow for extremely rapid wireless data communication and highly-sensitive radar. A continued partnership with ROHM Semiconductor may propel their research to mass production of next-generation wireless communication devices.
