Performance Measurement of 802.11a Wireless Links from UAV to Ground Nodes with Various Antenna Orientations

We report measured performance of 802.11a wireless links from an unmanned aerial vehicle (UAV) to ground stations. In a set of field experiments, we record the received signal strength indicator (RSSI) and measure the raw link-layer throughput for various antenna orientations, communication distances and ground-station elevations. By comparing the performance of 32 simultaneous pairs of UAV and ground station configurations, we are able to conclude that, in order to achieve the highest throughput under a typical flyover UAV flight path, both the UAV and the ground station should use omni-directional dipole (as opposed to high-gain, narrow- beam) antennas positioned horizontally, with their respective antenna null pointing to a direction perpendicular to the UAV's flight path. In addition, a moderate amount of elevation of the ground stations can also improve performance significantly.