Ultra-Wideband Air-to-Ground Propagation Channel Characterization in an Open Area

W. Khawaja, O. Ozdemir, F. Erden, I. Guvenc and D. W. Matolak, "Ultra-Wideband Air-to-Ground Propagation Channel Characterization in an Open Area," in IEEE Transactions on Aerospace and Electronic Systems, vol. 56, no. 6, pp. 4533-4555, Dec. 2020, doi: 10.1109/TAES.2020.3003104.

Abstract: This article studies the air-to-ground ultra-wideband channel through propagation measurements between 3.1 to 4.8 GHz using unmanned-aerial-vehicles (UAVs). Different line-of-sight (LOS) and obstructed-LOS scenarios and two antenna orientations were used in the experiments.

Multipath channel statistics for different propagation scenarios were obtained, and the Saleh–Valenzuela model was found to provide a good fit for the statistical channel model. An analytical path loss model based on antenna gains in the elevation plane is provided for unobstructed UAV hovering and moving (in a circular path) propagation scenarios.

keywords: {Antenna measurements;Receiving antennas;Ultra wideband antennas;Antenna radiation patterns;Loss measurement;Area measurement;Air-to-ground (AG);channel model;drone;multipath channel;path loss;propagation measurements;ultra-wideband (UWB);unmanned-aerial-vehicle (UAV)},

URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9119755&isnumber=9280441

The main contributions of this AG measurement study can be summarized as follows.

1. The received power for the copolarized antennas is mainly dependent on the antenna gain of the LOS component in the elevation plane for unobstructed UAV hovering scenario. For this scenario, we provide an analytical path loss model based on the antenna gain in the elevation plane, and we compare path loss measurements for this scenario with ray tracing simulation results.
2. Antenna orientation mismatch results in higher path loss and RMS-DS, a larger number of weak MPCs, and smaller Ricean K
3. -factor than the copolarized case. Moreover, the OLOS scenario introduces additional attenuation and MPCs due to foliage, resulting in further reduction in the K -factor.
4. The motion of the UAV in an unobstructed circular path provides mitigation against antenna polarization mismatch effects in comparison to the unobstructed UAV hovering scenario. These include smaller path loss and RMS-DS for the unobstructed UAV moving scenario compared to the unobstructed UAV hovering scenario for the cross-polarized case.
5. The SV model is found to provide a better fit for the PDP than the single exponential model.