ETRI is creating the world’s first 5G DAS (Distributed Antenna System) expertise for indoor use

PICTURE: ETRI researchers review the performance of the indoor 5G optical repeater. view More

Credit: Research Institute for Electronics and Telecommunications (ETRI)

Researchers in Korea have developed an important networking technology that allows users to seamlessly enjoy 5G services indoors. This is expected to be of great help in expanding the 5G coverage area and further improving the domestic telecommunications infrastructure.

The Research Institute for Electronics and Telecommunications (ETRI) announced that it has successfully developed the world’s first 5G-DAS1 for indoor use, which can receive broadband 5G signals based on millimeter waves (28 GHz) from base stations and transmit them inside buildings .

About 80% of the mobile data used in daily life is used indoors. This new technology enables access to 5G technology at a maximum speed of 20 Gbit / s in indoor areas such as airports, train stations and large shopping centers. In particular, this new technology significantly improves the transmission capacity, the device size, the deployment cost, etc. compared to the conventional technology, so that a wide range of applications is expected.

The core of the technology developed by the researchers includes RoF2) technology and 5G base station interface technology3). The RoF technology, which converts wireless 5G signals into optical signals and transmits them without distortion over a maximum distance of up to 5 km. On the other hand, there is the 5G base station interface technology, which connects a 5G base station outdoors and a distributed antenna system indoors using OTA4) technology.

The 5G base station interface installed on the roof of the apartment receives 5G signals from nearby base stations, converts them into optical signals in the basement of the apartment using RoF technology, and then transmits them to several antennas that are distributed in all areas of each floor of the building.

Since this technology can deliver 5G signals by multiplexing them into 32 bands, its transmission capacity is very high. The construction costs can be reduced five times compared to previous DASas, only relatively simple functions have to be implemented.

The researchers showed that they developed a diary-sized RoF optical transceiver5) and installed it in the host unit6) and the antenna unit that make up the indoor distributed antenna system. 5G base station interface technology has also been developed in the form of an independent module the size of a laptop so that it can be easily connected to the host unit.

According to the research team, the recent use of radio frequency bands and the rapid increase in large-capacity data have led to the adoption of RoF technology, which has been studied since the 1990s, and they have been able to accomplish this feat based on this data collected from the original technology and know-how. how.

At the Winter Olympics in PyeongChang in February 2018, ETRI demonstrated the world’s first 5G pilot service with millimeter-wave-based 5G technology for distributed indoor antennas. At that time, 5G signals were multiplexed into two bands, but updated to reach the current level.

The technology has been widely recognized for its excellence, being selected by the world’s most prestigious academic conference in the field of optical communications7 as the best paper7) published in prestigious SCI8) magazines, set as an international standard by the International Telecommunication Union and as one of them was designated the 100 most important national R&D projects in 2020.

“We hope this technology will help create an ecosystem of new convergent industries such as interactive entertainment and smart factories and rejuvenate the stagnant domestic industrial ecosystem related to repeaters for mobile communications, while ensuring quality of service and eliminating radio transmission. ” shaded indoor areas, “said Sunmi Kim, director of ETRI’s network research division.

The research team is also conducting studies on building technologies for next generation communication infrastructures to provide 6G cellular networks beyond 5G in future indoor spaces. It is planned to secure future intellectual property rights and advance the development of related domestic industries while developing next-generation 6G communication network technology based on ultra-wide frequency bands.

Meanwhile, the indoor DAS technology was developed by the Ministry of Science and ICT and jointly by KT Corporation, FRTek and HFR as part of “Development of DAS indoor technology based on analog IFoF9) for 5G mobile communication project.”

The research team has filed 9 SCI papers and 30 domestic and foreign patents and completed a total of 5 technology transfers to optical module and system companies such as HFR, Lightron, Rontech and JT Corporation.

Companies that received technology from ETRI have now exported related products to Japan and the United States through active marketing. As a result, ETRI’s technology is helping to build 5G infrastructure around the world.


About the Research Institute for Electronics and Telecommunications (ETRI)

ETRI is a non-profit, government-funded research institute. Since its inception in 1976, ETRI, a global ICT research institute, has made great efforts to enable Korea to experience remarkable growth in the ICT industry. ETRI supplies Korea as one of the best ICT nations in the world by continuously developing the world’s first and best technologies.

This demonstration technology was developed with the support of the Ministry of Science and ICT (MSIT). An article explaining the results of this research was named one of the 100 largest national R&D projects in 2020.

Glossary description:

1) A technology that converts optical signals to electrical signals, or vice versa, and compensates for transmission loss to remove shaded areas with radio waves and expand the coverage of mobile communication services

2) Abbreviation for Radio over Fiber, a technology that optically transmits radio signals for mobile communication over fiber optic cables.

3) A technology that physically connects the base station and DAS indoors.

4) Over the air: A method of wireless information exchange.

5) A compound word from (optical) transmitter and receiver.

6) network host. Computers or other devices connected to the network.

7) OFC 2019. Conference and exhibition for optical networking and communication

8) IEEE / OSA Journal of Lightwave Technology

9) Intermediate Frequency Over Optical Fiber: A technology that converts wireless signals that have been converted to frequency into light and transmits them over optical fiber.

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