Telecommunications and broadcasting are part of daily life. Behind them, unseen technology competition and industrial change continue. Shintongbangtong is a series that explains trends in telecoms and broadcasting technology and markets in an easy and interesting way. It also looks at the latest technology and policy, and market changes, with on-the-ground context.

[Digital Today reporter Jin-ho Lee (이진호)] Smartphone screens show full signal bars, and people take ultrafast internet at home and at the office for granted. Anyone can use networks anytime and anywhere and enjoy the benefits of IT technology.

But the situation changes once you move a little away from land. Deep mountains and remote islands, as well as the middle of the sea and the sky, can struggle to benefit from dense terrestrial networks. If natural disasters damage terrestrial networks, even areas with normally good service can quickly become dead zones.

A technology that fills this gap from space is low-earth-orbit satellite communications. Instead of installing base stations and fibre-optic cables across the ground, it creates networks by placing small satellites in orbits close to Earth. It is like a space base station that expands connectivity to places beyond the reach of terrestrial networks.

From 36,000 km to a few hundred km... the space internet market begins to bloom in earnest

Satellite communications are not a new technology. Geostationary satellites are already widely used for broadcasting transmission, international calls and weather observation. Geostationary satellites move at the same speed as Earth's rotation at about 36,000 km above the equator. From the ground, they cover wide areas from such high altitude that they appear to remain fixed over a single point.

Geostationary satellite signals have the drawback of communication delays because the distance between the ground and space is long. By contrast, low-earth-orbit satellites circle Earth at about 200 to 2,000 km above the ground, far lower than geostationary satellites. Because they are closer to Earth, radio waves travel a shorter distance. According to orbit-by-orbit characteristics compiled by the Electronics and Telecommunications Research Institute (ETRI), low-earth-orbit satellites have round-trip latency of about 2 to 27 milliseconds, while geostationary satellites are about 477 milliseconds.

At lower altitudes, the area a satellite can cover is narrower. Because satellites move quickly around Earth, they do not stay above one region for long. To provide uninterrupted service, a constellation system with hundreds to thousands of satellites is needed. As one satellite moves away, the next takes over the connection. It is similar to how a moving smartphone switches to a nearby base station after leaving one base station’s coverage area.

Communications work by sending signals from user devices to satellites, which then deliver them to ground communications facilities. Recently, technology that allows satellites to exchange data directly with each other is also being used. Even in areas without nearby ground communications facilities, users can connect to the internet through multiple satellites. In effect, satellites act not only as signal relays but also as relay stations that link communication routes.

Low-earth-orbit satellite communications are drawing attention as launch costs fall and small satellites are mass-produced. Efforts to build low-earth-orbit satellite networks existed in the past, but huge manufacturing and launch costs made it difficult to secure commercial viability. With the advent of reusable launch vehicles and satellite mass-production technology, business models have become possible that launch dozens of satellites at once and continuously replace satellites when their service life ends.

A leading operator is SpaceX’s Starlink. It places thousands of satellites a few hundred kilometres above Earth to provide internet to homes and businesses, as well as ships and aircraft. Britain’s Eutelsat OneWeb is drawing attention as a rival to Starlink. It operates more than 600 satellites and focuses on corporate and government customers, and the aviation and maritime communications markets.

The domestic market has already been opened. The Ministry of Science and ICT approved cross-border supply agreements signed in May last year by Starlink Korea and SpaceX, and separate agreements signed by Hanwha Systems and KT SAT with Eutelsat OneWeb. Starlink officially launched service in South Korea in December that year.

Everyday life changes first at sea and in the sky

The fastest change is expected at sea. Terrestrial base-station signals weaken the farther they are from the coast. With low-earth-orbit satellite communications, ships in distant waters can smoothly use video calls and online content. Shipping companies can also transmit navigation information, engine conditions and cargo data to onshore control centres in real time.

Internet use on aircraft will also change. Even as aircraft move quickly across oceans and continents, low-earth-orbit satellite networks can improve in-flight Wi-Fi quality. If urban air mobility and drone delivery markets expand, low-earth-orbit satellites can cover airspace that terrestrial networks are likely to miss.

In islands and mountainous areas, it can replace fibre-optic cables. Users can install satellite antennas directly, or connect a village’s base station to a satellite. If existing mobile networks are used from the base station to users’ smartphones, and only the segment from the base station to external internet networks is connected by satellite, communications can be used effectively in areas where laying fibre-optic cables is costly.

The same applies at disaster sites. When base-station power and wired networks are cut by wildfires or floods, temporary networks can be created with portable satellite antennas and power equipment. It becomes easier to build disaster communications systems that send rescue locations, on-site video and damage information to command centres and provide Wi-Fi to residents.

In the long term, direct-to-device connections, in which smartphones connect directly to satellites without separate antennas, are expected to spread. In the early stages, services with low data use such as emergency messages or location transmission in dead zones will be central. As technology advances, it could expand to voice calls and data services.

Not a replacement for terrestrial networks but a complement; costs, capacity and space congestion are challenges

Low-earth-orbit satellite communications will not replace all base stations and fibre-optic cables. In densely populated cities, many users must share limited satellite capacity. Signals can weaken when buildings and trees block the sky. Device and antenna costs and power consumption could also be less favourable than terrestrial networks. In cities that require ultrafast speeds and ultra-low latency, optical communications and 5G mobile networks remain efficient.

Technical difficulty is also high because satellites move quickly. User devices must continuously track the positions of moving satellites. Handoffs from one satellite to another must be repeated. Systems must also correct for frequency changes caused by satellite movement and efficiently allocate limited frequencies and communications capacity.

Competition to secure orbits and frequencies is also intensifying. If the number of satellites surges, risks could grow from collisions, space debris, radio interference and disruptions to astronomical observations. It is also necessary to examine whether networks run by overseas operators can continue to be used in disaster or security situations. That is why low-earth-orbit satellite communications can lead to issues of communications sovereignty and national security.

Targeting an independent network by 2035; pushing to address coverage blind spots

The government is pushing for localisation of core technologies while using overseas services. Its goal is to build a low-earth-orbit satellite communications network made with independent South Korean technology by 2035. Ahead of that, the government decided to carry out a technology development programme through 2030, spending about 300 billion won. It plans to launch 2 test satellites at an altitude of 888 km to verify core technologies.

But there are many hurdles before an independent network can be built. Hundreds of satellites must be continuously launched, and communications technologies between ground stations, user devices and satellites must be secured together. Key tasks also include massive investment costs, securing frequencies and orbits, and creating business models that can draw participation from private operators. The ministry set a first-phase goal of launching more than 200 low-earth-orbit satellites.

Even if a South Korean low-earth-orbit satellite communications network is built, it is expected to play a role in complementing coverage blind spots rather than fully replacing terrestrial networks. In cities, fibre-optic cables and mobile networks would be used, while satellites would take over connections at sea and in the sky, in mountainous regions and at disaster sites.

Commercialisation is also likely to come first in areas where building existing networks is difficult. After use cases increase in ship and aircraft internet services, mountainous and island regions and disaster sites, the scope is expected to expand to services for general users such as direct smartphone connections.