The Korea Electronics and Telecommunications Research Institute (ETRI) has developed technology that allows millimeter-wave mobile communication to be used indoors without a relay.
The 6G Wireless Access System Research Lab of the ETRI Mobile Communication Research Division and the Radio Environment Monitoring Research Lab of the Radio Research Division announced on the 20th that they have developed intelligent reflecting surface (RIS) technology with high transmission, wideband, and wide-angle characteristics in the millimeter-wave (mmWave) band.
Because 5G and 6G services use high frequencies with strong directivity, communication signals transmitted from outdoor base stations to indoor environments are mostly blocked by building exteriors. Signals transmitted through windows are also weakened due to the glass. To address this issue, communication carriers have installed expensive relays indoors, leading to increased expenses.
To solve this problem, ETRI researchers are studying RIS technology that receives signals by attaching ultra-small array antennas in the form of transparent films or panels to building windows or walls. This method involves creating micro-patterns of a few micrometers (1 μm is one-millionth of a meter) in size on transparent polyester (PET) films to function as relays.
The micro-patterns on the PET film enhance the transparency as general waves are irradiated onto the antennas. ETRI researchers explained, "If this antenna technology is commercialized, it will be possible to eliminate indoor dead zones simply by sticking it to building windows," adding that "it is a technology that can also increase data speeds."
Existing RIS technology had the drawback of a narrow bandwidth, despite having a high transmittance rate. ETRI researchers integrated wide-angle technology to nearly increase the bandwidth by ten times compared to existing RIS technology. One RIS can be used simultaneously for both 5G and 6G services.
ETRI researchers are also studying 'scattering RIS technology' for indoor communication environment expansion. Scattering RIS is a new concept radio technology that retransmits high-frequency signals propagating indoors over a wide range of dozens of degrees, thereby expanding the communication area. They are also developing transparent RIS that enhances the transmittance of windows. It is expected that the communication quality can be improved simply by attaching the transparent RIS once it is developed.
The research team plans to commercialize this technology within three years. They noted that they will transfer technology to antenna materials and components companies. This research involves Clever Logic Co., Ltd., and Duksan Neko Co., Ltd., among others.
Lee Jeong-nam, the lead researcher at ETRI, stated, "In the future, ETRI will contribute to the expansion of the country's radio technology field by overcoming the limitations of media for waves and providing various services, including communication."