An Experimental Evaluation of Air-to-Air MIMO Transmission in Wireless LAN Relay Systems Using Drones

A wireless communication system employing drones is investigated. The drones, which are equipped with wireless LAN relay nodes, are used to overcome the terrain height and maintain the line-of-sight wireless communication. To improve the throughput performance of this system, we employ the multiple-input multiple-output (MIMO) in the air-to-air communication between drones. Then, we verify the performance improvement achieved using the MIMO by conducting experiments. The results show that by placing two antennas, which are orthogonal to each other on each drone, the throughput performance of the proposed MIMO transmission system can be improved. This improvement is achieved when the drones operate at an altitude of 30 m or lower. Also, the degradation ratio of the overall throughput performance in the multihop transmission system is about 1/5 compared to the expected value of 1/3 between the drones.