Recently, the China Telecom Research Institute, in collaboration with Zhejiang Telecom, Tsinghua University, Shanghai Qingshen Technology, and Beijing Jiefeng Chuangzhi Technology, has successfully completed the in-orbit technical verification of the Non-Terrestrial Network (NTN) protocol under medium-orbit satellite conditions. This achievement was realized by leveraging the integrated space-ground satellite testing capabilities of the Cloud-Network Convergence Major Scientific Innovation Facility. The test lays a critical foundation for communication in special scenarios such as transoceanic and polar regions, as well as for 6G integrated space-ground networking.
The experiment was conducted using the "Smart Sky Net 01" satellite, which operates at an orbital altitude of 20,000 kilometers. It focused on addressing communication needs in scenarios where terrestrial network coverage is unavailable, including polar scientific expeditions, broadband connectivity in remote border areas, and high-seas broadband communication. Configured with a 100 MHz bandwidth in the Ka-band and utilizing a self-developed NTN terminal prototype, the test successfully accomplished in-orbit communication technology verification in transparent forwarding mode with FR2 band n510 parameter configuration, along with a pilot application for maritime broadband. The measured peak downlink rate reached 140 Mbps, fully meeting the high-speed data communication requirements for direct satellite connectivity in the aforementioned special scenarios.
This test achieved three major innovative breakthroughs: First, it represents the industry's first in-orbit test of NTN broadband communication capabilities on a medium-orbit satellite at an altitude of 20,000 km, filling a technical verification gap in this field. Combined with Tsinghua's Smart Sky Net quasi-synchronous constellation design concept, it lays the groundwork for 6G integrated space-ground networking. Second, it overcame synchronization challenges caused by the dynamic nature of medium-orbit satellite-ground links by developing NTN automatic dynamic tracking and channel-adaptive timing and frequency synchronization technologies, ensuring stable and reliable terminal access in complex channel environments.
Third, it addressed the transmission efficiency bottleneck under limited receiving signal-to-noise ratio conditions with large bandwidths. By employing link decoding performance enhancement technology, the spectral efficiency was increased to 1.4 bit/s/Hz, providing a performance reference for the standardization of 6G integrated space-ground systems.