CAS Achieves New Breakthrough in Satellite-Ground Communication at 2100 Mbps

Recently, the Aerospace Information Research Institute (AIRI) of the Chinese Academy of Sciences (CAS) collaborated with Beijing Rongwei Technology Co., Ltd. to conduct ground-based technical experiments for a high-throughput star-to-ground data transmission system. These experiments were held at the Lijiang station of AIRI and involved simulating satellite data transmission to achieve an X-band single-channel data rate of up to 2100 Mbps at 128QAM modulation, representing a 75% increase in microwave communication code rates. This mark stands as the highest X-band single-channel data rate currently achieved in China. As remote sensing applications and payload observation capabilities continue to advance, the volume of observational data from satellites is growing exponentially. Currently, civil satellites in China primarily use the X-band for ground communications, with typical data rates ranging from 450 Mbps at QPSK, 900 Mbps at 8PSK, to 1200 Mbps at 16QAM. However, these rates are struggling to meet the increasing demands for data downlink, leading to inefficiencies in satellite utilization. To address this issue, AIRI and Beijing Rongwei jointly developed a high-efficiency data transmission scheme based on advanced modulation techniques in microwave technology. This new scheme aims to boost data transmission rates significantly by upgrading key ground system components such as modulators and demodulators, while minimizing additional hardware complexity and maximizing the reuse of existing resources. The experiment was divided into three phases: desktop integration, wired tests, and wireless link establishment. The first phase, desktop integration, focused on verifying the functionality of the newly developed high-order modulation-demodulation devices. This step ensured that the individual components of the system met the required technical standards. The second phase, the wired test, aimed to validate the performance of the ground system in a closed-loop RF environment, ensuring that the signals could be reliably transmitted and received over a controlled, wired connection. Finally, the wireless link establishment phase involved setting up a simulated satellite signal source approximately 10 kilometers away from the Lijiang station, at an elevation angle of about 4 degrees. This setup created a wireless communication link to mimic real-life satellite data transmission scenarios, where the Lijiang station's data reception system captured and processed the simulated high-order signals. The results of all three phases demonstrated that the existing ground channel equipment, combined with the new high-order modulation-demodulation devices, could successfully support a 2100 Mbps data rate at 128QAM modulation. The constellation diagrams showed minimal distortion, and the error rate was effectively zero, confirming the feasibility of the high-order modulation technology. Key breakthroughs during the experiment included phase noise compensation, non-linear correction, and channel equalization. Notably, deep neural network models were integrated into the core algorithms of the satellite data reception modulator, leveraging artificial intelligence to enhance the efficiency and reliability of star-to-ground communications. This approach offers a promising, cost-effective solution to the current bandwidth limitations in satellite data transmission. The successful wireless link test at the Lijiang station further underscores the potential of this new technology to revolutionize satellite communications. By improving the data rate and reducing latency, the high-order modulation system can significantly enhance the operational efficiency of satellites, particularly in high-demand applications like Earth observation and space exploration. In summary, the collaboration between AIRI and Beijing Rongwei has not only achieved a notable milestone in X-band data transmission but also paved the way for future advancements in satellite communication systems. This development could have far-reaching implications for various sectors, including environmental monitoring, disaster response, and scientific research, by ensuring faster and more reliable data transfer from space to ground.