Development of RIS Technology Compatible with Commercial Satellite Frequencies

Installable on Skyscrapers without the Assistance of Additional Equipment

Based on Transparent Materials, Performance has been Verified by Attaching to a Moving Vehicle

[Edaily Reporter Hyunah Kim] We still have to wait at least 5 years for the commercialization of 6G where satellites become base transceiver stations, but technology that enables 5G operation at satellite frequencies has been recently developed and gaining attention. This technology is expected to maintain connectivity in various environments, including skyscrapers above 60-stories high, KTX trains cruising over the speed of 300km/h, and Urban Air Mobility (UAM, Small aircrafts used in urban areas, anticipated to become a new revolution in transportation).

KT(CEO: Youngshub Kim), along with the Seoul National University (SNU) Department of Electrical and Computer Engineering (ECE) research team announced last 27th that they have developed Reconfigurable Intelligent Surface (RIS) technology that operates at 5G wireless communication frequency bands (3.5GHz) and KT Skylife satellite frequency bands (12GHz). This technology was unveiled by KT at the MWC 2024.

Usage on Outer Walls of Skyscrapers

RIS technology induces the reflection and transmission of electromagnetic waves in desired directions. For example, if we attach RIS to the outer walls of skyscrapers, it enables the transmission of high frequency waves into the building, making it possible for receiving & transmitting such signals without exposing wireless communication equipment outside of the building. Such technology can help the construction of network infrastructures more efficiently.

The RIS technology developed by KT and the research team of SNU ECE Department’s professor Jungsuek Oh, transmits not only 6G candidate frequencies, but also 5G wireless communication frequencies and KT Skylife satellite frequencies, through a small surface area. Until now, KT has been developing RIS materials and technologies that operate in the mmWave frequency bands (28GHz) and 6G candidate frequency bands (8GHz, 15GHz). On the other hand, the commercialization of RIS technology for 5G communication seemed to be more challenging, since it required samples with larger surface area, due to the relatively lower frequencies of the 5G frequency bands.

However, the newly developed RIS simultaneously obtained a wide transmission angle of over 90 degrees (negative refraction angle) and a high transmission rate by utilizing novel structures and surface engineering technologies. The wide transmission angle helps in improving the quality of indoor wireless transmission. Also, due to the transparency of the RIS material, it can be easily installed by attaching it to a vehicle’s window or manufacturing it as an all-in-one structure.

Performance Testing on Car Windows

In order to verify the versatility of their RIS technology, the KT and SNU research team attached the RIS to a vehicle window moving on a freeway. They observed that signals directed perpendicular to the vehicle’s moving direction, such as 5G waves from communication towers of the outskirts of the freeway or KT Skylife satellite signals, were refracted into the vehicle.

KT will continue to collaborate with equipment manufacturers, material & component companies to apply this RIS technology to building & vehicle windows. In addition, it plans to continuously explore key technologies applicable to various wireless network environments such as RIS to secure technological leadership in the field of 6G wireless communication.

Professor Jungsuek Oh from the ECE department of SNU stated, "While most research and demonstrations on conventional transparent RIS have focused mainly on improving penetration loss, our RIS technology and validation have demonstrated for the first time that even under constraints of transparent materials and processing conditions, radio waves can be refracted in arbitrary directions, significantly improving communication coverage."

Executive Director Jongsik Lee of KT Network Research Institute stated, "We anticipate that this RIS technology will enhance wireless service quality within moving vehicles. We aim to strengthen our leadership in new wireless communication technologies and contribute to the establishment of 6G networks."  

Researchers from KT R&D center(Seoul, Seocho-gu) and SNU are testing the performance of their RIS technology (Picture from KT)

Source: https://www.edaily.co.kr/news/read?newsId=02020486638794784&mediaCodeNo=257&OutLnkChk=Y

Translated by: Jiyong Yoo, English Editor of the Department of Electrical and Computer Engineering, cyoo7@snu.ac.kr