Experimentally Analyzing Diverse Antenna Placements and Orientations for UAV Communications
Experimentally Analyzing Diverse Antenna Placements and Orientations for UAV Communications
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DOI：
10.1109/tvt.2020.3031872
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发表时间：
2020-12-01
影响因子：
6.8
通讯作者：
Camp, Joseph
中科院分区：
文献类型：
--
作者：
Badi, Mahmoud;Wensowitch, John;Camp, Joseph
无人机和其他设备正在出现大量潜在应用，从救灾和搜索救援任务到智能农业和物联网系统。当无人机在多个高度上移动时，它们必须能够在三维（3D）空间中的任何方向上进行通信。然而，由于无人机主体的异质性质及其与安装的天线的相互作用，无人机上的不同天线位置可能导致辐射图案的变化。虽然已经有相当数量的机载通信工程，很少考虑的作用，天线定位上产生的传输沿着方位角和仰角平面。在这项工作中，我们研究了无人机的身体和各种天线放置的辐射模式和衰落的无人机为基础的渠道的影响。通过系统的消声室和现场测量，我们表明，无人机的身体改变安装天线的辐射模式，呈现一个恒定的方位角辐射模式无效的共同假设。此外，主体增加了基于drone的通道的偏振混合，导致交叉偏振鉴别（XPD）的显著退化。因此，我们建议使用有效辐射方向图和XPD值，而不是依赖于忽略无人机天线相互作用的测量和/或假设。然后，我们分析了阴影和损失与许多天线设置在不同的仰角无人机的身体，并表明，当安装在对面从地面发射机，阴影增加与相对较高的无人机海拔。为了解释这些身体引起的效应，我们引入了旋转损耗，与忽略这些身体效应的传统模型相比，它可以更好地预测大规模衰落行为。然后，我们分析了各种天线设置的小尺度衰落，并表明，莱斯K因子是强烈依赖于海拔的极化匹配的垂直链路，而它是近似平坦的交叉极化链路。为此，我们在没有周围反射器的高海拔地区进行了一组无人机对无人机（DtD）实验，并将结果与我们的地面对无人机（GtD）测量结果进行了比较。我们发现，虽然在低海拔的地面可以减少10分贝的K因子，在较高的海拔，小规模的衰落是由天线，而不是地面为主。
A vast array of potential applications is emerging for drones and other devices to collaborate from disaster relief and search and rescue missions to smart agriculture and IoT systems. As drones move across multiple altitudes, they must have the ability to communicate across any direction in a three-dimensional (3D) space. However, due to the heterogeneous nature of the drone body and its interaction with the mounted antennas, different antenna positions on the drone can result in variations in the radiation pattern. While there have been a fair number of airborne communication works, few consider the role that antenna positioning has on the resulting transmission along the azimuth and elevation planes. In this work, we study the effects of the drone body and various antenna placements on the radiation pattern and fading of drone-based channels. Through systematic anechoic chamber and in-field measurements, we show that the drone body alters the radiation pattern of the mounted antennas, rendering the common assumption of a constant azimuth radiation pattern invalid. In addition, the body increases polarization mixing of drone-based channels, resulting in significant degradation of the cross-polarization discrimination (XPD). Hence, we propose using effective radiation pattern and XPD values instead of relying on measurements and/or assumptions that disregard drone-antenna interaction. We then analyze the shadowing and losses associated with the drone body for many antenna setups at various elevation angles and show that when mounted on the opposite side from the ground transmitter, shadowing increases with relatively-higher drone elevations. To account for these body-induced effects, we introduce rotational loss that results in better prediction results of the large-scale fading behavior compared to conventional models that neglect these body effects. Then, we analyze the small-scale fading for various antenna setups and show that the Rician K-factor is strongly dependent on elevation for polarization-matched vertical links, while it is approximately flat for cross-polarized links. To do so, we conduct a set of drone-to-drone (DtD) experiments at high altitudes with no surrounding reflectors and compare results to those obtained by our ground-to-drone (GtD) measurements. We find that, while at low elevations the ground can reduce the K-factor by 10 dB, at higher elevations, small-scale fading is dominated by the antennas, not the ground.