Experimental Evaluation of Antenna Polarization and Elevation Effects on Drone Communications

Abstract

In the next wave of swarm-based applications, unmanned aerial vehicles (UAVs) need to communicate with peer drones in any direction of a three-dimensional (3D) space. On a given drone and across drones, various antenna positions and orientations are possible. We know that, in free space, high levels of signal loss are expected if the transmitting and receiving antennas are cross polarized. However, increasing the reflective and scattering objects in the channel between a transmitter and receiver can cause the received polarization to become completely independent from the transmitted polarization, making the cross-polarization of antennas insignificant. Usually, these effects are studied in the context of cellular and terrestrial networks and have not been analyzed when those objects are the actual bodies of the communicating drones that can take different relative directions or move at various elevations. In this work, we show that the body of the drone can affect the received power across various antenna orientations and positions and act as a local scatterer that increases channel depolarization, reducing the cross-polarization discrimination (XPD). To investigate these effects, we perform experimentation that is staged in terms of complexity from a controlled environment of an anechoic chamber with and without drone bodies to in-field environments where drone-mounted antennas are in-flight with various orientations and relative positions with the following outcomes: (i.) drone relative direction can significantly impact the XPD values, (ii.) elevation angle is a critical factor in 3D link performance, (iii.) antenna spacing requirements are altered for co-located cross-polarized antennas, and (iv.) cross-polarized antenna setups more than double spectral efficiency. Our results can serve as a guide for accurately simulating and modeling UAV networks and drone swarms.

Leveraging Antenna Orientation to Optimize Network Performance of Fleets of UAVs

“…Experiments regarding UAV 802.11 networks and their air-toground and air-to-air links underline that antenna radiation patterns play a big role in the performance of the deployed network [9,16,17]. This conclusion is also highlighted in a very recent work [1] that, via experiments, shows the impact of different physical parameters on the UAV communication performance. Yet, theoretical works and simulations often assume that omnidirectional antennas (also called isotropic antennas) are used in UAV networks.…”

“…In these experiments, IEEE 802.11g is used and there is no indication on the used rate adaptation algorithm or if any such algorithm is disabled. In [1], the authors experimentally show the impact of the antenna orientations on the UAV communications. Different effects are studied like the UAV body, the UAV relative direction and the In [4], an antenna heading control system is proposed for UAVs equipped with directional antenna.…”

“…We provide results in several deployment scenarios involving different rate adaptation algorithms and network sizes. 1…”

A distributed antenna orientation solution for optimizing communications in a fleet of UAVs

“…In these experiments, IEEE 802.11g is used and there is no indication on the used rate adaptation algorithm or if any such algorithm is disabled. In [4], the authors experimentally show the impact of the antenna orientations on the UAV communications. Different effects are studied like the UAV body, the UAV relative direction and the elevation angle on different parameters like the Received Signal Strength and the cross-polarization discrimination.…”

“…In the case of UAVs, often equipped with directional antennas, the antennas' orientation has an impact on the communication quality as shown in [4]. Thanks to some features like motion or orientation, UAVs have the possibility to reach some positions and some orientations that could improve the radio environment quality, and consequently the reached throughput between the UAVs and/or with a ground controller.…”