Experimental Trajectory Deviation Detection and Correction for UAV Passing through mmWave Ultra-Spot Using Space-Time Synchronization

In mmWave UAV-to-UAV communication, the most critical aspect is that the flight trajectory through the ultra-high-speed communication spot (ultra-spot) must be precomputed as soon as the position and orientation of the ultra-spot are detected. The challenge is that the UAV must maintain its flight trajectory (including position and altitude) as well as a stable antenna angle while passing through the ultra-spot. Any deviation from the planned trajectory can lead to communication failure or prevent achieving the maximum throughput at the ultra-spot. This study introduces a method for detecting flight trajectory deviations and an adaptive altitude correction mechanism that adjusts the flight path accordingly, based on space-time synchronization using Wireless Two-way Interferometry (Wi-Wi) devices. The results obtained from UAV experiments show that the proposed algorithm successfully detects and corrects altitude deviations with a low latency of 50 ms, maintaining altitude stability during communication at the ultra-spot with a mean error of 19.6 cm. Additionally, we verify experimentally the capability of high-speed data transmission when the UAV flies through the ultra-spot, achieving an ultra-spot utilization rate (USUR) of up to 24.18%.