Virtual personal doppler-free channel for 5G SAT non-terrestrial networks

In space communications, the proportion of personal messages increases at the expense of broad casting. However, existing research and methods for Doppler shift compensation in the space-ground channel are still focused on compensation only in the center of the beam spot on Earth, which results in a significant residual Doppler shift (hundreds of kilohertz in 5G LEO NTN) in the rest of the beam spot. In this paper, we propose a personal Doppler pre-compensation at the transmitting side based on the user’s coordinates on the ground. In this case, a virtual personal channel with zero Doppler shift is created inside the beam, and the endpoint of this channel on the ground is moved by changing the transmitter LO frequency.