China tests new technology for high-speed Internet via satellite

Satellite orbiting around the Earth on starry night background. Illustration of the concept of mobile satellite Internet and space telecommunication technology
Sheila Zabeu -

October 20, 2023

Scientists from the Chinese Academy of Sciences’ Xian Institute of Optics and Precision Mechanics claim to have made important strides with their satellite communication technology using lasers instead of microwaves as the information carrier. According to the group of researchers, this is a development trend and an effective means of solving the communication bandwidth bottleneck and building a satellite Internet with global coverage.

According to the Chinese Academy of Sciences, last August a satellite-mounted communication device based on new space optical switching technology was launched into space by the Chinese Y7 cargo rocket. This was China’s first space-based verification of high-speed optical switching technology. The equipment was able to transmit light signals from one location to another without converting them into electrical signals.

Spatial optical switching technology exchanges optical signals directly, without the need to convert between optical and electrical systems. It has advantages in terms of resource allocation, communication systems and protocols, flexible network expansion and low energy consumption.

The results of the Chinese test showed that all the functions of the space optical switch were normal. After downlinking the information to the ground for analysis, there was zero bit error and zero packet loss, achieving all the objectives set by the researchers.

According to the chinese article published last year, the switch can work at speeds of 40 gigabits per second.

China vs United States

Another Chinese breakthrough in the field of optical communication with satellites, spearheaded by the Aerospace Information Innovation Institute of the Chinese Academy of Sciences, was unveiled last June. A laser-based communication technology on commercial satellites increased the speed of data transfer between space and the ground by 10 times, reaching 10 Gbps.

Li Yalin, head of laser systems technology at the Chinese Academy of Aerospace Science and Technology, explains that current satellite-ground communication structures mainly use microwaves, but the bandwidth resources of this environment are limited and hardly meet the enormous data transmission demands of satellites and terrestrial media. Compared to microwaves, laser spectrum resources are extremely rich, with bandwidths of up to hundreds of gigahertz (GHz).

In addition, because the laser’s divergence angle is small, and the energy is highly concentrated, the power density received by the laser’s ground system is high, so it is possible to achieve ultra-high speeds with much lower volume, weight and energy consumption compared to microwave communication.

Despite recent advances by Chinese scientists, experts say there is still a long way to go before this technology can truly come into practice. In an interview for the South China Morning Post, Huang Tao, general manager of a communications company based in Guangzhou, said that China’s satellite Internet, including space optical switching technology, is still lagging behind that of the United States, as some essential components and materials are dominated by US organizations.

When people talk about satellites for Internet access, the first company that comes to mind is Elon Musk‘s SpaceX. Its services use low earth orbit (LEO) satellites, the latest models of which use laser communication to share signals between satellites, reducing the need for ground stations.

The first satellites with laser interconnection were launched in 2021 and helped provide broadband coverage in the polar regions. In a post on Twitter at the time, Must stated that all satellites launched the following year would have laser links. After more than two years and further launches, Starlink recently announced that it was upgrading its inter-satellite optical link network by launching more V2 Mini satellites into low Earth orbit.

“With more than 8,000 space lasers across the constellation, Starlink satellites are able to connect thousands of kilometres away, beyond the view of ground stations, and thus maintain pointing accuracy to enable the transfer of up to 100 Gbps on each link,” Starlink posted on X (formerly Twitter).