Spatial Diversity Effect of Wireless Two-way Interferometry for Spot Detection in mmWave Drone-to-drone Communication

This paper proposes a novel spot detection method employing Wireless Two-way Interferometry (Wi-Wi) technology, which helps estimate when drones will enter and exit mmWave or Terahertz communication spots. To overcome issues like RSSI degradation, unstable phase data, and packet loss caused by obstructions from the drone’s body, we propose using multiple Wi-Wi modules with antennas placed at different locations. We conducted two field experiments to validate our methods: the first in an anechoic chamber to assess the impact of UAV body and wings on Wi-Wi signals, and the second experiment took place outdoors to validate the spot detection algorithm’s performance when two UAVs rapidly passed each other. Experimental results on mmWave spot detection reveal millisecond-level accuracy, surpassing the time accuracy when using GNSS-based positioning technology and approaching that of the Real-Time Kinematic (RTK) technique. Additionally, spatial diversity when using multiple Wi-Wi modules assists in mitigating packet loss issues encountered due to obstacles and multipath fading, thereby enhancing the stability of spot detection.