Micro-Doppler Shift and Its Estimation in Rotary-Wing UAV Sub-6 GHz Communications

Rotary-wing unmanned aerial vehicles (UAVs) can be potentially used in wireless communications and therefore attract research from both academia and industry recently. However, most UAV air-to-ground channel models under 6 GHz have ignored the micro-Doppler effects due to the UAV’s propellers. In this letter, we reveal its principle and develop a method to estimate the micro-Doppler, including sounding waveform design, channel modeling, and Doppler frequency estimation. Our simulation results demonstrate that the estimated root-mean-squared error of micro-Doppler is smaller than 18.83 Hz for 963.09 Hz micro-Doppler frequency shift resulting from the rotation of the propellers in the rotary-wing UAV sub-6 GHz communications systems.