Solving Rain Attenuation in Ka Band with Adaptive Modem Technology Enhances Stability
Demonstrates Independent Development Capability of Communication Satellites, Bright Market Outlook

The Electronics and Telecommunications Research Institute (ETRI) announced that it has developed a communication payload—the core component of the Chollian satellite—and verified world-class technical excellence in performance through satellite control and other operations.

The research team has conducted satellite communication public services, satellite signal measurement, ground terminal testing, and satellite control over the past seven years.

The communication payload developed by ETRI operates in the Ka band, a high-frequency band of 20–30 GHz (gigahertz). The team developed three relay channels for communication and installed them on the satellite to provide satellite communication services.

The research team confirmed that the communication payload demonstrated superior performance and stability in satellite transmission output, reception sensitivity, and other performance metrics compared to leading commercial communication satellites worldwide. This served as a milestone in verifying Korea's independent technology development capability for communication satellites.

In particular, Chollian 1, as a public communication satellite, has been utilized free of charge by nine government agencies for Korea's security and public convenience, including ▲national emergency disaster communication (Ministry of the Interior and Safety) ▲weather data transmission (Korea Meteorological Administration) ▲marine observation data transmission (Ministry of Oceans and Fisheries) ▲military communication services (Ministry of Defense). In the case of KBS, a public broadcasting company, the Chollian satellite is being used for disaster test broadcasts from Hongdo Island in Shinan County, South Jeolla Province.

As such, communication satellites are critical national assets that cannot be dispensed with during emergency situations or disasters. If communication is disrupted due to war, there is no way to make phone calls or establish contact. Communication satellites play a unique role in responding when terrestrial communication networks are severed. Furthermore, beyond emergency communication, they are the only technology capable of providing nationwide Internet of Things (IoT) services and 8K-UHD services.

The Ka band satellite technology applied to Chollian 1 is next-generation core technology enabling broadband services such as 4K ultra-high-definition (UHD) television and high-speed internet. This latest frequency band technology is under competitive commercialization in the United States, Europe, and other regions.

To address the vulnerability of Ka band signals to rain attenuation, the research team developed adaptive modem technology that distinguishes between rainy and non-rainy conditions and automatically changes the signal to cope with rain attenuation.

Additionally, the research team redesigned the printed circuit board (PCB) within the payload using smaller semiconductor chips, improving stability and lifespan while reducing signal loss.

ETRI also developed second-generation ultra-compact satellite terminal (VSAT) technology for transmission and reception on the ground and from satellites. By utilizing ultra-compact satellite terminals to provide satellite communication services to public institutions such as the military, the Korea Coast Guard, and the Fire Department, the team verified that competitive broadband satellite services are possible with Ka band satellites.

The research team completed technology transfer of the developed second-generation ultra-compact satellite terminal (VSAT) technology to satellite communication equipment manufacturers NetCustomize and Asset. In the domestic satellite market, which has high dependence on foreign equipment, the team secured and successfully localized the entire satellite communication system technology, including Ka band communication repeaters.

The achievement is also significant in securing core technology for market entry into high-capacity satellite (HTS) payload markets led by developed countries such as the United States and Europe. Furthermore, communication satellites represent over 50% of the total global satellite market, presenting bright market prospects.

Lee Ho-jin, head of ETRI's Radio and Satellite Research Division, stated, "The United States, China, and Japan are utilizing space communication technology to pursue real-time information across the entire Earth from a space perspective, seeking market unification and market preemption from a global standpoint. Market preemption for clean internet in space utilizing the unique characteristics of space communication is accelerating, requiring preparedness."

The research team explained that while the recently launched Mugunghwa satellite is a communication satellite used for commercial satellite broadcasting communication, the Chollian 2A scheduled for launch next year is a satellite specialized for weather observation. Additional measures are needed to secure communication satellites for public purposes.

Ahn Myung-soo, CEO of NetCustomize, also stated, "The Chollian satellite industrial test bed established at ETRI provided infrastructure that domestic satellite companies can continuously utilize, and through this, we were able to successfully commercialize second-generation VSAT technology."