Channel, Doppler Frequency Shift, and Velocity Estimation in UAV Systems with mmWave Communication Links

We address the problem of accurately estimating the channel and the Doppler frequency shift between an Unmanned Aerial Vehicle (UAV) and a Ground Station (GS), and hence the velocity of the UAV, when they communicate using antenna arrays and millimeter wave (mmWave) bands. This estimation process is useful since it leads to higher data rates of the communication link between the UAV and the GS through the adaptation of the modulation and coding scheme and optimization of the antenna array parameters. It also enables the adjustment of the carrier frequency to optimize the communication, tracking of the motion of the UAV and planning of its future trajectory, etc. Estimation schemes proposed in prior work suffer from various limitations such as inapplicability to non-linear channel models, large estimation errors, etc. We propose an improved scheme for estimating the UAV channel, Doppler frequency shift, and velocity. Our technique is based on maximum likelihood estimation (MLE) of the parameters of the UAV and the GS in the beam-space. Using extensive numerical computations, we show that our proposed scheme computes estimates of the channel, Doppler frequency shift, as well as UAV velocity that are highly accurate; also, the mean errors of the estimates of the Doppler frequency shift computed by our proposed scheme are much closer to zero than those of the estimates computed using the state-of-the-art chirplet transform based algorithm.