China Sets New National Record with Breakthrough in Satellite-Ground Communication

China has achieved a major milestone in satellite-ground communication. A joint research team from the Aerospace Information Research Institute (AIR) under the Chinese Academy of Sciences and Beijing Rongwei Technology Co., Ltd. has successfully conducted a ground-based experiment, reaching a single-channel X-band transmission rate of 2,100 Mbps using 128QAM modulation. This marks a 75% increase over previous domestic benchmarks and sets a new national record in satellite-ground data transmission.

The experiment was carried out at the Lijiang Ground Station, part of China Remote Sensing Satellite Ground Station. It verified the feasibility of high-order modulation systems for high-rate data transmission—laying the groundwork for more efficient and scalable communication technologies in space applications.

With the rapid advancement of satellite payloads and observation technologies, the volume of data generated by space-based systems has grown exponentially. However, the limited bandwidth of current satellite-ground links has become a critical bottleneck, severely affecting satellite data utilization and mission efficiency. Widely used X-band modulation schemes—QPSK (450 Mbps), 8PSK (900 Mbps), and 16QAM (1,200 Mbps)—are no longer sufficient to meet the growing demand.

To address this challenge, the research team proposed a high-order modulation solution based on microwave technology. Their approach enables significantly higher data transmission rates without extensive upgrades to existing ground infrastructure or increased hardware complexity. The team enhanced core components like modems and incorporated advanced signal processing to maximize the use of current ground resources.

The experiment progressed through three validation phases. Desktop tests confirmed the performance of the newly developed high-order modulation/demodulation hardware. Wired trials tested the radio frequency subsystems in a closed-loop setup. In the final phase, wireless field tests simulated real-world conditions by transmitting signals from a satellite simulator 10 kilometers away, at a 4-degree elevation angle. The Lijiang Ground Station successfully received and decoded the high-order modulated signals, achieving stable 128QAM transmission with near-zero bit error rates and clear constellation diagrams.

The success was underpinned by a series of technical breakthroughs, including phase noise compensation, nonlinear distortion correction, and channel equalization. In a pioneering move, the team also integrated artificial intelligence algorithms, including deep neural networks, into the modem’s core processing. This is the first application of AI in China's satellite-ground communication systems, significantly enhancing signal integrity and transmission efficiency.

“This experiment demonstrates a high-performance, cost-effective solution to the growing data demands of modern satellite missions,” said Professor HUANG Peng, a researcher at AIR and Director of the China Remote Sensing Satellite Ground Station. “By leveraging AI and solving key technical challenges, we’ve taken a major step toward next-generation satellite-ground communication.”

ZHANG Yumeng, Senior Engineer at AIR and project lead, noted the broader implications: “Achieving 2,100 Mbps in the X-band opens up new possibilities for high-resolution Earth observation, space science, and other data-intensive missions. It strengthens China’s capability in space information infrastructure and directly supports our national aerospace strategy.”

Looking ahead, the team plans to further advance the technology for large-scale deployment, boosting the efficiency of China’s satellite operations and enhancing its global competitiveness in the aerospace sector.