低轨卫星物联网星地距离时间同步及多普勒频偏补偿技术

Time Synchronization of Space-ground Distance and Doppler Frequency Offset Compensation Technology for LEOIoT

针对低轨卫星(LEO)围绕地球做高速运动造成的传播距离远、多普勒频移大的特点,分析多普勒频移对星地同步和通信质量造成的影响,采用基于星历信息和网络规划等态势预测手段实现多普勒频移计算和预补偿技术,对星地多普勒频移进行粗补偿,并结合物理层波形采用的直接扩频序列特点,通过延迟锁定完成频移跟踪修正,保证卫星链路的高质量可靠连接,确保卫星物联网的高效可靠安全运行。

Aiming at the characteristics of long propagation distance and large Doppler frequency shift caused by the high-speed movement of low earth orbit(LEO)satellites around the earth,the impact of doppler frequency shift on satellite to ground synchronization and communication quality is analyzed.doppler frequency shift calculation and pre compensation techniques are implemented based on ephemeris information and network planning and other situation prediction methods to coarse compensate for satellite to ground doppler frequency shift,and the characteristics of direct spread spectrum sequences used in physical layer waveforms are combined,complete frequency shift tracking and correction through delay locking,ensuring high-quality and reliable connection of satellite links,and ensuring efficient,reliable,and safe operation of the satellite internet of things.