  Wireless relays can effectively extend the transmission range of information.
However, if relay technology is utilized unlawfully, it can amplify potential
harm. Effectively surveilling illegitimate relay links poses a challenging
problem. Unmanned aerial vehicles (UAVs) can proactively surveil wireless relay
systems due to their flexible mobility. This work focuses on maximizing the
eavesdropping rate (ER) of UAVs by jointly optimizing the trajectory and
jamming power. To address this challenge, we propose a new iterative algorithm
based on block coordinate descent and successive convex approximation
technologies. Simulation results demonstrate that the proposed algorithm
significantly enhances the ER through trajectory and jamming power
optimization.
