Doppler-robust high-spectrum-efficiency VCM-OFDM scheme for low Earth orbit satellites broadband data transmission

High-efficiency satellite-ground downlink data transmission system is being demanded to support increasing volume of data with limited spectrum resource. Considering the dynamic link conditions due to the orbital motion of low Earth orbit (LEO) satellite, variable coding modulated orthogonal frequency division multiplexing (VCM-OFDM) is proposed as an effective way to better exploit link resource. In this study, regarding the relative motion between the satellite on-board transmitter and the ground station receiver, filtered-OFDM signal is designed with adjustable coding modulation sets to achieve higher spectral efficiency and get along with the high-Doppler environment at the same time. Physical layer frame structure is proposed taking the Doppler frequency shift compensation into account with minimum overhead. System performance evaluations prove that transmission throughput in the dynamic communication link can be enhanced significantly by the proposed scheme, which indicates the potential for supporting future gigabit X-band reliable satellite-ground downlink transmissions.