The Tianlian network currently consists of six spacecraft－five of the Tianlian I series and Tianlian II-01. Sources close to the system's development said Tianlian II-02 and Tianlian II-03 will be deployed soon.

Compared with the first-generation model, Tianlian II satellites feature stronger capabilities, heavier carrying capacity and longer life spans, according to Zhao Hong, chief designer of Tianlian II-01.

"Because of its newly developed antennas, the data transmission speed of the new-generation type is twice that of the first generation," Zhao said, adding that Tianlian II satellites can serve more spacecraft and have a larger operational range.

Wang Jiasheng, chief engineer of the Tianlian II series, said the Tianlian system has served a variety of space functions such as rendezvous and docking between spaceships and space stations, video links between astronauts and people on the ground, and data transmission for Earth observation, weather and other low-orbit satellites.

On June 23, a video call between President Xi Jinping, who is also general secretary of the Communist Party of China Central Committee, and the three Chinese astronauts on board the country's first space station was connected through Tianlian II-01, Wang said.

In addition, the system has provided long-distance tracking and data relay service to long-range air traffic, experimental hypersonic aircraft tests and scientific ocean expeditions, he said.