"If You Want to Follow, Come and Try"… Korea's 5G Technologies to Maintain 'World No.1' Status [Reading Science]

[Asia Economy Reporter Kim Bong-su] At midnight on December 1, 2018, South Korea became the first country in the world to launch the first frequency of 5th generation mobile communication (5G). The United States, having missed the lead, launched 5G waves 55 minutes later and deeply regretted it. This was because they lost the title of the world's first commercialization of 5G communication. As such, fierce competition is underway worldwide to develop next-generation mobile communication technologies, 5G and 6G, which will serve as the 'lifeblood' of the 4th Industrial Revolution. Although South Korea was the first to commercialize 5G, it has been struggling with service quality controversies and the pursuit from China and the United States. However, South Korea still firmly maintains its leading position through steady development of related technologies. The following are the latest 5G and 6G technologies in Korea introduced by the National Research Council of Science & Technology.

◇ Combining Satellites and 5G

Although South Korea was the first to commercialize 5G, it has been suffering from service quality controversies contrary to expectations. The three major mobile carriers have built 5G service networks including base stations and terminals mostly in urban areas. However, mountainous, island regions, and small provincial cities still suffer from infrastructure shortages. To solve this, the Electronics and Telecommunications Research Institute (ETRI) developed a technology in January to dramatically expand the 5G service area using satellite communication. ETRI succeeded in demonstrating the world's first 5G-satellite multi-connectivity network, which connects 5G and satellite communication simultaneously, allowing users to maintain satellite communication service in areas lacking or without base stations while using 5G service. This means 5G service can be used anytime and anywhere. Once this technology is actually serviced, continuous ultra-high-speed internet and communication services will be possible not only in island and mountainous areas lacking 5G networks but also at sea or in disaster situations. Notably, by using two 5G-satellite multi-connectivity networks, intercontinental 5G service connecting Korea and France was also realized.

◇ 5G Communication-Based Autonomous Train Driving Technology

The Korea Railroad Research Institute developed the world's first core control technology for a 5G communication-based autonomous train driving system in September 2020. Previously, control methods only considered the train's position, but this technology reflects the preceding train's driving information in real time to control the distance between trains and allows trains to communicate directly to control switches. If trains succeed in direct communication, they can determine and control their own position and direction autonomously, minimizing the need for ground signal facilities. Additionally, with precise interval control technology, the operation interval between trains can be shortened by more than 30% compared to now, enabling efficient operation during peak commuting hours.

◇ Resolving Base Station Data Interference Phenomenon

Compared to 4G, which used the highest frequency band of 2.6GHz, 5G uses not only 3.5GHz but also the ultra-high frequency band of 28GHz, resulting in shorter transmission distances and the need for densely built base stations. However, overly dense base station placement causes data interference, degrading communication quality. The Korea Research Institute of Standards and Science developed a 5G frequency filter in February 2021 that can solve this problem.

A frequency filter allows only specific frequencies to pass and blocks signals in other bands. To improve 5G communication quality, numerous high-performance filters are required. The research team developed a filter that is superior and more affordable than imported products. It is a 50μm film, about half the thickness of a human hair. Unlike imported filters that require additional processes to connect the filter and antenna, it is made in a single-layer metal sheet form, making it flexible and attachable/detachable like a sticker. Especially, it uses a 'metasurface filter' that periodically arranges fine unit structures on a two-dimensional surface to control reflection, refraction, and transmission of electromagnetic waves or light. It offers optimized performance for 5G communication systems, showing superior bandwidth, loss characteristics, and frequency selectivity compared to existing filters.

◇ Enhancing 5G Performance through Electromagnetic Wave Absorbing Materials Development

One of the core technologies of 5G communication networks is minimizing interference from other frequencies. Especially, electromagnetic wave noise generated by many electronic devices around us causes interference with other devices, leading to performance degradation. To prevent this, electromagnetic wave shielding materials are essential. Existing reflective shielding materials use highly conductive materials that reflect over 90% of incoming electromagnetic waves and absorb only about 10%. To effectively utilize the elevated communication frequencies of 5G, shielding materials that can absorb and eliminate waves, not just reflect, were needed.

The Korea Institute of Materials Science developed the world's first 5G communication film in March this year, which perfectly meets this demand. It succeeded in reflecting less than 1% of electromagnetic waves and absorbing over 90%. The research team first mixed magnetic materials and polymers that show excellent absorption performance at frequencies used in 5G communication to create a composite material film, then sewed conductive fibers in a grid pattern on top. The film is thin and flexible, maintaining performance even after being folded and unfolded more than 10 times. It can eliminate radio wave interference and significantly improve 5G communication performance, expected to greatly enhance the reliability of autonomous driving technologies and others.